Y primero en la lista de preocupaciones se encuentra un producto químico llamado 6PPD, que se agrega a los neumáticos para que duren más tiempo. Cuando los neumáticos se van desgastando por el roce con el pavimento, liberan 6PPD.

Al entrar en contacto con el ozono, esta sustancia reacciona y se convierte en un producto químico diferente, el 6PPD-q, que puede ser extremadamente tóxico, tanto que se ha relacionado con muertes de peces en el estado de Washington.

Pero los problemas no terminan ahí.

Los neumáticos están hechos principalmente de goma natural y goma sintética, pero contienen cientos de otros ingredientes, que a menudo incluyen acero y metales pesados como cobre, plomo, cadmio y zinc.

A medida que los neumáticos se desgastan, la goma desaparece en partículas, tanto trozos que se pueden ver a simple vista como micropartículas. Las pruebas realizadas por una empresa británica, Emissions Analytics, encontraron que los neumáticos de un automóvil emiten 1,000 millones de partículas ultrafinas por kilómetro conducido: entre 5 y 9 libras de goma por automóvil de combustión interna por año.

Y lo que hay en esas partículas es un misterio, porque los ingredientes de los neumáticos son de propiedad exclusiva.

“Tienes un cóctel químico en estos neumáticos que nadie realmente entiende y que los fabricantes de neumáticos mantienen en secreto”, dijo Nick Molden, CEO de Emissions Analytics. “Nos resulta difícil pensar en otro producto de consumo tan prevalente en el mundo y utilizado prácticamente por todos, donde se sepa tan poco sobre lo que contiene”.

Los reguladores apenas han comenzado a abordar el problema de la toxicidad en los neumáticos, aunque ha habido algunas acciones sobre el 6PPD.

El producto químico fue identificado por un equipo de investigadores, dirigido por científicos de la Universidad Estatal de Washington y de la Universidad de Washington, que estaban tratando de determinar por qué estaban muriendo masivamente los salmones coho que regresaban a arroyos del área de Seattle para desovar.

Trabajando para el Washington Stormwater Center, los científicos probaron alrededor de 2,000 sustancias para determinar cuál estaba causando las muertes, y en 2020 anunciaron que habían encontrado al culpable: 6PPD.

La Tribu Yurok en el norte de California, junto con otras dos tribus nativas de la costa oeste, han pedido a la Agencia de Protección Ambiental (EPA) que prohíba el producto químico. La EPA dijo que está considerando nuevas normas que lo regulen.

“No podríamos quedarnos de brazos cruzados mientras el 6PPD mata a los peces que nos sostienen”, dijo Joseph L. James, presidente de la Tribu Yurok, en un comunicado. “Esta toxina letal no tiene lugar en ninguna cuenca salmonera”.

California ha comenzado a tomar medidas para regular el producto químico. El año pasado comenzó a calificar a los neumáticos que lo contienen como un “producto prioritario”, lo que requiere que los fabricantes busquen y prueben sustitutos.

“El 6PPD juega un papel crucial en la seguridad de los neumáticos en las carreteras de California y, actualmente, no hay alternativas más seguras ampliamente disponibles”, dijo Karl Palmer, subdirector del Departamento de Control de Sustancias Tóxicas del estado. “Por esta razón, nuestro marco es ideal para identificar alternativas al 6PPD que sigan garantizado la seguridad de los neumáticos en las carreteras de California, protegiendo al mismo tiempo las poblaciones de peces y las comunidades que dependen de ellas”.

La Asociación de Fabricantes de Neumáticos de EE.UU. (USTMA) dice que ha movilizado un consorcio de 16 fabricantes para llevar a cabo un análisis de alternativas. Anne Forristall Luke, presidenta y CEO de la USTMA, dijo que “proporcionará la revisión más efectiva y exhaustiva posible de si existe una alternativa más segura al 6PPD en los neumáticos”.

Sin embargo, Molden dijo que hay un inconveniente. “Si no investigan, no se les permite vender en el estado de California”, dijo. “Si investigan y no encuentran una alternativa, pueden seguir vendiendo. No tienen que encontrar un sustituto. Y hoy no hay alternativa al 6PPD”.

California también está estudiando una solicitud de la California Stormwater Quality Association para clasificar los neumáticos que contienen zinc, un metal pesado, como un producto prioritario, lo que requeriría que los fabricantes busquen una alternativa. El zinc se utiliza en el proceso de vulcanización para aumentar la resistencia del caucho.

Sin embargo, cuando se trata de partículas de neumáticos, no ha habido ninguna acción, incluso cuando el problema empeora con la proliferación de automóviles eléctricos. Debido a su aceleración más rápida, los vehículos eléctricos desgastan los neumáticos más rápido y emiten aproximadamente un 20% más de partículas que los de un automóvil de gasolina promedio.

Un en el sur de California encontró que las emisiones de neumáticos y frenos en Anaheim representaban el 30% de PM2.5, un contaminante atmosférico de partículas pequeñas, mientras que las emisiones de escape representaban el 19%.

Las pruebas realizadas por Emissions Analytics han encontrado que los neumáticos producen hasta 2,000 veces más contaminación por partículas en masa que los tubos de escape. Estas partículas acaban en el agua y el aire y a menudo se ingieren. Los neumáticos también emiten partículas ultrafinas, incluso más pequeñas que PM2.5, que pueden ser inhaladas y viajar directamente al cerebro.

sugieren que las micropartículas de neumáticos deberían ser clasificadas como un contaminante de “alta preocupación”. En un informe el año pasado, investigadores del Imperial College de Londres dijeron que las partículas podrían afectar al corazón, los pulmones y los órganos reproductivos, y causar cáncer.

Las personas que viven o trabajan junto a carreteras, muchas veces de bajos ingresos, están expuestas a más de estas sustancias tóxicas.

Los neumáticos también son una fuente importante de microplásticos. que llegan al océano provienen de la goma sintética de los neumáticos, según un informe del Pew Charitable Trusts y la empresa británica Systemiq.

Y todavía hay muchas incógnitas sobre las emisiones de neumáticos, que pueden ser especialmente complejas de analizar porque el calor y la presión pueden transformar los ingredientes del neumático en otros compuestos.

Una pregunta pendiente de investigación es si el 6PPD-q afecta a las personas y qué problemas de salud, si los hay, podría causar. Un publicado en Environmental Science & Technology Letters encontró altos niveles del producto químico en muestras de orina de una región del sur de China, con niveles más altos en mujeres embarazadas.

Molden dijo que el descubrimiento del 6PPD-q ha generado un nuevo interés en el impacto sanitario y ambiental de los neumáticos, y espera una gran cantidad de nuevas investigaciones en los próximos años. “Las piezas del rompecabezas se están armando”, dijo. “Pero es un rompecabezas de mil piezas, no de doscientas”.

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At the top of the list of worries is a chemical called 6PPD, which is added to rubber tires to help them last longer. When tires wear on pavement, 6PPD is released. It reacts with ozone to become a different chemical, 6PPD-q, which can be extremely toxic 鈥� so much so that it has been linked to repeated fish kills in Washington state.

The trouble with tires doesn’t stop there. Tires are made primarily of natural rubber and synthetic rubber, but they contain hundreds of other ingredients, often including steel and heavy metals such as copper, lead, cadmium, and zinc.

As car tires wear, the rubber disappears in particles, both bits that can be seen with the naked eye and microparticles. Testing by a British company, Emissions Analytics, found that a car’s tires emit 1 trillion ultrafine particles per kilometer driven 鈥� from 5 to 9 pounds of rubber per internal combustion car per year.

And what’s in those particles is a mystery, because tire ingredients are proprietary.

“You’ve got a chemical cocktail in these tires that no one really understands and is kept highly confidential by the tire manufacturers,” said Nick Molden, CEO of Emissions Analytics. “We struggle to think of another consumer product that is so prevalent in the world and used by virtually everyone, where there is so little known of what is in them.”

Regulators have only begun to address the toxic tire problem, though there has been some action on 6PPD.

The chemical was identified by a team of researchers, led by scientists at Washington State University and the University of Washington, who were trying to determine why coho salmon returning to Seattle-area creeks to spawn were dying in large numbers.

Working for the Washington Stormwater Center, the scientists tested some 2,000 substances to determine which one was causing the die-offs, and in 2020 they announced they’d found the culprit: 6PPD.

The Yurok Tribe in Northern California, along with two other West Coast Native American tribes, have petitioned the Environmental Protection Agency to prohibit the chemical. The EPA said it is considering new rules governing the chemical. “We could not sit idle while 6PPD kills the fish that sustain us,” said Joseph L. James, chairman of the Yurok Tribe, in a statement. “This lethal toxin has no place in any salmon-bearing watershed.”

California has begun taking steps to regulate the chemical, last year classifying tires containing it as a “priority product,” which requires manufacturers to search for and test substitutes.

“6PPD plays a crucial role in the safety of tires on California’s roads and, currently, there are no widely available safer alternatives,” said Karl Palmer, a deputy director at the state’s Department of Toxic Substances Control. “For this reason, our framework is ideally suited for identifying alternatives to 6PPD that ensure the continued safety of tires on California’s roads while protecting California’s fish populations and the communities that rely on them.”

The U.S. Tire Manufacturers Association says it has mobilized a consortium of 16 tire manufacturers to carry out an analysis of alternatives. Anne Forristall Luke, USTMA president and CEO, said it “will yield the most effective and exhaustive review possible of whether a safer alternative to 6PPD in tires currently exists.”

Molden, however, said there is a catch. “If they don’t investigate, they aren’t allowed to sell in the state of California,” he said. “If they investigate and don’t find an alternative, they can go on selling. They don’t have to find a substitute. And today there is no alternative to 6PPD.”

California is also studying a request by the California Stormwater Quality Association to classify tires containing zinc, a heavy metal, as a priority product, requiring manufacturers to search for an alternative. Zinc is used in the vulcanization process to increase the strength of the rubber.

When it comes to tire particles, though, there hasn’t been any action, even as the problem worsens with the proliferation of electric cars. Because of their quicker acceleration and greater torque, electric vehicles wear out tires faster and emit an estimated 20% more tire particles than the average gas-powered car.

A in Southern California found tire and brake emissions in Anaheim accounted for 30% of PM2.5, a small-particulate air pollutant, while exhaust emissions accounted for 19%. Tests by Emissions Analytics have found that tires produce up to 2,000 times as much particle pollution by mass as tailpipes.

These particles end up in water and air and are often ingested. Ultrafine particles, even smaller than PM2.5, are also emitted by tires and can be inhaled and travel directly to the brain. suggests tire microparticles should be classified as a pollutant of “high concern.”

In a , researchers at Imperial College London said the particles could affect the heart, lungs, and reproductive organs and cause cancer.

People who live or work along roadways, often low-income, are exposed to more of the toxic substances.

Tires are also a major source of microplastics. of microplastics entering the ocean come from the synthetic rubber in tires, according to a report from the Pew Charitable Trusts and the British company Systemiq.

And there are still a great many unknowns in tire emissions, which can be especially complex to analyze because heat and pressure can transform tire ingredients into other compounds.

One outstanding research question is whether 6PPD-q affects people, and what health problems, if any, it could cause. A published in Environmental Science & Technology Letters found high levels of the chemical in urine samples from a region of South China, with levels highest in pregnant women.

The discovery of 6PPD-q, Molden said, has sparked fresh interest in the health and environmental impacts of tires, and he expects an abundance of new research in the coming years. “The jigsaw pieces are coming together,” he said. “But it’s a thousand-piece jigsaw, not a 200-piece jigsaw.”

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La BCG (Bacille Calmette-Guérin), desarrollada en 1921, sigue siendo la única vacuna contra la tuberculosis (TB). Si bien tiene una eficacia del 40% al 80% en niños pequeños, su efectividad es muy baja en adolescentes y adultos, lo que impulsó un esfuerzo mundial para encontrar una vacuna que sea más potente.

El Centro de Medicina Translacional de la Universidad de Montana está llevando a cabo una iniciativa en este sentido. El Centro se especializa en mejorar y crear vacunas, agregando los que se denominan “adyuvantes novedosos”.

Un adyuvante es una sustancia que se incluye en la vacuna, por ejemplo moléculas grasas o sales de aluminio, y que potencia la respuesta inmunitaria. Los adyuvantes novedosos son los que aún no se han utilizado en humanos. Los científicos están comprobando que estos adyuvantes generan una inmunidad más fuerte, precisa y duradera que los antígenos, que solo crean anticuerpos.

Provocar respuestas específicas del sistema inmunológico, y profundizar y ampliar su efectividad con adyuvantes, es algo que se conoce como “vacunación de precisión”.

“No es una solución única para todos, no se trata de una vacuna única”, explicó Ofer Levy, profesor de Pediatría de la Universidad de Harvard y director del Programa de Vacunas de Precisión del Hospital Infantil de Boston. “Una vacuna puede funcionar de forma diferente en un recién nacido, un adulto mayor o en una persona de mediana edad”, agregó.

Una vacuna de precisión definitiva, según Levy, brindaría protección de por vida contra una enfermedad con un solo pinchazo. “Una protección de una sola dosis que fuera efectiva contra la gripe o contra el covid sería el Santo Grial”, enfatizó Levy.

Jay Evans dirige el Centro de la Universidad de Montana y, a la vez, es cofundador y director científico y de estrategias, de Inimmune, una empresa privada de biotecnología de Missoula. Evans contó que su equipo lleva 15 años trabajando en una vacuna contra la tuberculosis y que aún faltan cinco años para que ésta pueda distribuirse ampliamente. La asociación público-privada está desarrollando vacunas e intentando mejorar las existentes, afirmó.

En el Centro no ha pasado inadvertido que este trabajo de investigación y producción de vacunas de vanguardia se realiza en Montana, el estado que aprobó una de las leyes antivacunas más extremas del país en 2021, durante la pandemia.

La ley prohíbe a empresas y gobiernos dar un trato diferente a las personas que no estén vacunadas contra covid u otras enfermedades. De hecho, prohíbe a los empleadores públicos y privados que les exijan a los trabajadores que se vacunen contra covid o cualquier otra enfermedad. dictaminó después que la ley no puede aplicarse en entornos sanitarios, como hospitales y consultas médicas.

A mediados de marzo, el Instituto de Investigación Médica Bill y Melinda Gates anunció que había iniciado en siete países la tercera y última fase de los ensayos clínicos de la nueva vacuna contra la tuberculosis. Los ensayos tardarán unos cinco años en completarse. La investigación y la producción se están llevando a cabo en varios lugares, incluida una planta de fabricación en Hamilton, propiedad de GSK, un gigante farmacéutico.

Conocida como “la pandemia olvidada”, la tuberculosis, a pesar de que se puede prevenir y tratar, mata hasta a 1,6 millones de personas al año, la mayoría en zonas empobrecidas de Asia y África.

En Estados Unidos se ha producido un aumento de esta enfermendad en la última década. Muchos inmigrantes tienen TB sin saberlo; en 2022 el número de casos aumentó un 16%. La tuberculosis es la principal causa de muerte entre las personas que viven con VIH, cuyo riesgo de contraer esta enfermedad es 20 veces mayor que el de las personas sin el virus.

“La tuberculosis es un patógeno complejo que ha acompañado a los seres humanos durante siglos”, dijo Alemnew Dagnew, que dirige el programa para la nueva vacuna en el Instituto de Investigación Médica Gates. “Debido a esta situación, ha evolucionado y ha podido desarrollar mecanismos para evadir al sistema inmunológico. Y la inmunología de la TB aún no se comprende completamente”.

En conjunto, el Centro de Medicina Translacional de la Universidad de Montana e Inimmune tienen 80 empleados especializados en la investigación de una variedad de adyuvantes con el propósito de comprender los detalles de las respuestas inmunitarias a diferentes sustancias. “Hay que adaptarlos al patógeno contra el que se vacuna, como si fueran un instrumento en una caja de herramientas”, dijo Evans. “Tenemos toda una biblioteca de moléculas y formulaciones de adyuvantes”.

Las vacunas se vuelven en gran medida más precisas mediante el uso de adyuvantes. Hay tres tipos básicos de adyuvantes naturales: sales de aluminio; escualeno, que se obtiene del hígado de tiburón; y algunos tipos de saponinas, que son moléculas grasas. No se sabe muy bien cómo estimulan el sistema inmunitario. El Centro de Missoula también ha creado y patentado un adyuvante sintético, el UM-1098, que induce un tipo específico de respuesta inmunitaria y que se añadirá a las nuevas vacunas.

Una de las moléculas más prometedoras que se están utilizando para potenciar la respuesta del sistema inmunológico a las vacunas es una molécula de saponina de la corteza del árbol de quillay, recolectada en Chile de árboles que tienen por lo menos una década.

Estas moléculas fueron utilizadas por Novavax en su vacuna contra covid y por GSK en Shingrix, su vacuna contra la culebrilla (shingles), de uso generalizado. Estas moléculas también son un componente clave en la nueva vacuna contra la tuberculosis, conocida como la vacuna M72.

Pero hay margen para mejorar.

“La vacuna muestra una eficacia del 50%, lo que no parece mucho, pero como actualmente se carece de otra vacuna más efectiva, el 50% es bastante mejor que lo que hay”, sostuvo Evans. “Buscamos aprovechar lo que aprendimos de ese desarrollo de la vacuna con adyuvantes adicionales para tratar de mejorarla y llevar ese índice desde el 50% hasta el 80% o más”.

Las vacunas contra el sarampión, en cambio, han alcanzado una efectividad del 95%.

Según el sitio web Medscape, en este momento se están desarrollando alrededor de 15 vacunas que son candidatas a reemplazar la BCG, y tres de ellas se encuentran en la fase 3 de ensayos clínicos.

Una alternativa que el Centro de Evans está investigando para mejorar la eficacia de la nueva vacuna es tomar una parte de la bacteria que causa la tuberculosis, sintetizarla y combinarla con el adyuvante QS-21, elaborado a partir del árbol de quillay. “Estimula el sistema inmunológico de una manera específica para la tuberculosis y genera una respuesta inmune que se acerca aún más a lo que obtenemos de las infecciones naturales”, dijo Evans.

Por su parte, el Centro de la Universidad de Montana está investigando el tratamiento de varias afecciones que generalmente no se consideran susceptibles de ser abordadas mediante vacunación. Por ejemplo, están ingresando en la primera fase de ensayos clínicos para una vacuna contra las alergias y para otra, contra el cáncer.

Avanzado este año, comenzarán los ensayos clínicos para obtener vacunas capaces de bloquear los efectos de opioides como la heroína y el fentanilo. La Universidad de Montana recibió la mayor subvención de su historia, $33 millones, para investigar una vacuna contra los opioides. Funciona creando un anticuerpo que se une a la droga en el torrente sanguíneo, evitando que entre al cerebro y produzca el efecto de euforia.

Por ahora, sin embargo, los expertos en salud de todo el mundo tienen sus ojos puestos en los ensayos de las nuevas vacunas contra la tuberculosis, que, si tienen éxito, podrían ayudar a salvar innumerables vidas en las regiones más pobres del mundo.

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The BCG (Bacille Calmette-Guérin) vaccine, created in 1921, remains the sole TB vaccine. While it is 40% to 80% effective in young children, its efficacy is very low in adolescents and adults, leading to a worldwide push to create a more powerful vaccine.

One effort is underway at the University of Montana Center for Translational Medicine. The center specializes in improving and creating vaccines by adding what are called novel adjuvants. An adjuvant is a substance included in the vaccine, such as fat molecules or aluminum salts, that enhances the immune response, and novel adjuvants are those that have not yet been used in humans. Scientists are finding that adjuvants make for stronger, more precise, and more durable immunity than antigens, which create antibodies, would alone.

Eliciting specific responses from the immune system and deepening and broadening the response with adjuvants is known as precision vaccination. “It’s not one-size-fits-all,” said Ofer Levy, a professor of pediatrics at Harvard University and the head of the Precision Vaccines Program at Boston Children’s Hospital. “A vaccine might work differently in a newborn versus an older adult and a middle-aged person.”

The ultimate precision vaccine, said Levy, would be lifelong protection from a disease with one jab. “A single-shot protection against influenza or a single-shot protection against covid, that would be the holy grail,” Levy said.

Jay Evans, the director of the University of Montana center and the chief scientific and strategy officer and a co-founder of Inimmune, a privately held biotechnology company in Missoula, said his team has been working on a TB vaccine for 15 years. The private-public partnership is developing vaccines and trying to improve existing vaccines, and he said it’s still five years off before the TB vaccine might be distributed widely.

It has not gone unnoticed at the center that this state-of-the-art vaccine research and production is located in a state that passed one of the nation’s most extreme anti-vaccination laws during the pandemic in 2021. The law prohibits businesses and governments from discriminating against people who aren’t vaccinated against covid-19 or other diseases, effectively banning both public and private employers from requiring workers to get vaccinated against covid or any other disease. that the law cannot be enforced in health care settings, such as hospitals and doctors’ offices.

In mid-March, the Bill & Melinda Gates Medical Research Institute announced it had begun the third and final phase of clinical trials for the new vaccine in seven countries. The trials should take about five years to complete. Research and production are being done in several places, including at a manufacturing facility in Hamilton owned by GSK, a giant pharmaceutical company.

Known as the forgotten pandemic, TB kills up to 1.6 million people a year, mostly in impoverished areas in Asia and Africa, despite its being both preventable and treatable. The U.S. has seen an increase in tuberculosis over the past decade, especially with the influx of migrants, and the number of cases rose by 16% from 2022 to 2023. Tuberculosis is the leading cause of death among people living with HIV, whose risk of contracting a TB infection is 20 times as great as people without HIV.

“TB is a complex pathogen that has been with human beings for ages,” said Alemnew Dagnew, who heads the program for the new vaccine for the Gates Medical Research Institute. “Because it has been with human beings for many years, it has evolved and has a mechanism to escape the immune system. And the immunology of TB is not fully understood.”

The University of Montana Center for Translational Medicine and Inimmune together have 80 employees who specialize in researching a range of adjuvants to understand the specifics of immune responses to different substances. “You have to tailor it like tools in a toolbox towards the pathogen you are vaccinating against,” Evans said. “We have a whole library of adjuvant molecules and formulations.”

Vaccines are made more precise largely by using adjuvants. There are three basic types of natural adjuvants: aluminum salts; squalene, which is made from shark liver; and some kinds of saponins, which are fat molecules. It’s not fully understood how they stimulate the immune system. The center in Missoula has also created and patented a synthetic adjuvant, UM-1098, that drives a specific type of immune response and will be added to new vaccines.

One of the most promising molecules being used to juice up the immune system response to vaccines is a saponin molecule from the bark of the quillay tree, gathered in Chile from trees at least 10 years old. Such molecules were used by Novavax in its covid vaccine and by GSK in its widely used shingles vaccine, Shingrix. These molecules are also a key component in the new tuberculosis vaccine, known as the M72 vaccine.

But there is room for improvement.

“The vaccine shows 50% efficacy, which doesn’t sound like much, but basically there is no effective vaccine currently, so 50% is better than what’s out there,” Evans said. “We’re looking to take what we learned from that vaccine development with additional adjuvants to try and make it even better and move 50% to 80% or more.”

By contrast, measles vaccines are 95% effective.

According to Medscape, around 15 vaccine candidates are being developed to replace the BCG vaccine, and three of them are in phase 3 clinical trials.

One approach Evans’ center is researching to improve the new vaccine’s efficacy is taking a piece of the bacterium that causes TB, synthesizing it, and combining it with the adjuvant QS-21, made from the quillay tree. “It stimulates the immune system in a way that is specific to TB and it drives an immune response that is even closer to what we get from natural infections,” Evans said.

The University of Montana center is researching the treatment of several problems not commonly thought of as treatable with vaccines. They are entering the first phase of clinical trials for a vaccine for allergies, for instance, and first-phase trials for a cancer vaccine. And later this year, clinical trials will begin for vaccines to block the effects of opioids like heroin and fentanyl. The University of Montana received the largest grant in its history, $33 million, for anti-opioid vaccine research. It works by creating an antibody that binds with the drug in the bloodstream, which keeps it from entering the brain and creating the high.

For now, though, the eyes of health care experts around the world are on the trials for the new TB vaccines, which, if they are successful, could help save countless lives in the world’s poorest places.

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These hunters, however, are not just on the front lines of an American tradition. Infectious disease researchers say they are also on the front lines of what could be a serious threat to public health: chronic wasting disease.

The neurological disease, which is contagious, rapidly spreading, and always fatal, is caused by misfolded proteins called prions. It currently is known to infect only members of the cervid family 鈥� elk, deer, reindeer, caribou, and moose.

Animal disease scientists are alarmed about the rapid spread of CWD in deer. shows that the barrier to a spillover into humans is less formidable than previously believed and that the prions causing the disease may be evolving to become more able to infect humans.

A response to the threat is ramping up. In 2023, a coalition of researchers began “working on a major initiative, bringing together 68 different global experts on various aspects of CWD to really look at what are the challenges ahead should we see a spillover into humans and food production,” said , an expert in infectious disease at the University of Minnesota and a leading authority on CWD.

“The bottom-line message is we are quite unprepared,” Osterholm said. “If we saw a spillover right now, we would be in free fall. There are no contingency plans for what to do or how to follow up.”

The team of experts is planning for a potential outbreak, focusing on public health surveillance, lab capacity, prion disease diagnostics, surveillance of livestock and wildlife, risk communication, and education and outreach.

Despite the concern, tens of thousands of infected animals have been eaten by people in recent years, yet there have been no known human cases of the disease.

Many hunters have wrestled with how seriously to take the threat of CWD. “The predominant opinion I encounter is that no human being has gotten this disease,” said Steve Rinella, a writer and the founder of MeatEater, a media and lifestyle company focused on hunting and cooking wild game.

They think, “I am not going to worry about it because it hasn’t jumped the species barrier,” Rinella said. “That would change dramatically if a hunter got CWD.”

Other prion diseases, such as bovine spongiform encephalopathy, also known as mad cow disease, and Creutzfeldt-Jakob disease, have affected humans. Mad cow claimed the lives of , mostly in the United Kingdom and France. Some experts believe Parkinson’s and Alzheimer’s also may be caused by prions.

First discovered in Colorado in captive deer in 1967, CWD has since spread widely. It has been found in animals in at least 32 states, four Canadian provinces, and four other foreign countries. It was for the first time in Yellowstone National Park.

Prions behave very differently than viruses and bacteria and are virtually impossible to eradicate. Matthew Dunfee, director of the Chronic Wasting Disease Alliance, said experts call it a “disease from outer space.”

Symptoms are gruesome. The brain deteriorates to a spongy consistency. Sometimes nicknamed “zombie deer disease,” the condition makes infected animals stumble, drool, and stare blankly before they die. There is no treatment or vaccine. And it is extremely difficult to eradicate, whether with disinfectants or with high heat 鈥� it even survives autoclaving, or medical sterilization.

Cooking doesn’t kill prions, said Osterholm. Unfortunately, he said, “cooking concentrates the prions. It makes it even more likely” people will consume them, he said.

Though CWD is not known to have passed to humans or domestic animals, experts are very concerned about both possibilities, which Osterholm’s group just received more than $1.5 million in funding to study. CWD can infect more parts of an animal’s body than other prion diseases like mad cow, which could make it more likely to spread to people who eat venison 鈥� if it can jump to humans.

Researchers estimate that between 7,000 and 15,000 infected animals are unknowingly consumed by hunter families annually, a number that increases every year as the disease spreads across the continent. While testing of wild game for CWD is available, it’s cumbersome and the tests are not widely used in many places.

A major problem with determining whether CWD has affected humans is that it has a long latency. People who consume prions may not contract the resulting disease until many years later 鈥� so, if someone fell sick, there might not be an apparent connection to having eaten deer.

Prions are extremely persistent in the environment. They can remain in the ground for many years and even be taken up by plants.

Because the most likely route for spillover is through people who eat venison, quick testing of deer and other cervid carcasses is where prevention is focused. Right now, a hunter may drive a deer to a check station and have a lymph node sample sent to a lab. It can be a week or more before results come in, so most hunters skip it.

Montana, for example, is famous for its deer hunting. CWD was first detected in the wild there in 2017 and now has spread across much of the state. Despite warnings and free testing, Montana wildlife officials have not seen much concern among hunters. “We have not seen a decrease in deer hunting because of this,” said Brian Wakeling, game management bureau chief for the Montana Department of Fish, Wildlife & Parks. In 2022 Montana hunters killed nearly 88,000 deer. Just 5,941 samples were taken, and 253 of those tested positive.

Experts believe a rapid test would greatly increase the number of animals tested and help prevent spillover.

Because of the importance of deer to Indigenous people, several tribal nations in Minnesota are working with experts at the University of Minnesota to come up with ways to monitor and manage the disease. “The threat and potential for the spread of CWD on any of our three reservations has the ability to negatively impact Ojibwe culture and traditions of deer hunting providing venison for our membership,” said , a tribal biologist for the White Earth Nation, in a statement announcing the program. (The other groups referenced are the Leech Lake Band of Ojibwe and Red Lake Band of Chippewa.) “Tribes must be ready with a plan to manage and mitigate the effects of CWD 鈥� to ensure that the time-honored and culturally significant practice of harvesting deer is maintained for future generations.”

is an assistant professor in the College of Veterinary Medicine at the University of Minnesota and co-director of the . The center was formed to study numerous aspects of prions as part of the push to get ahead of possible spillover. “Our mission is to learn everything we can about not just CWD but other prionlike diseases, including Parkinson’s and Alzheimer’s disease,” he said. “We are studying the biology and ecology” of the misfolded protein, he said. “How do prions move within the environment? How can we help mitigate risk and improve animal health and welfare?”

Part of that mission is new technology to make testing faster and easier. Researchers have developed a way for hunters to do their own testing, though it can take weeks for results. There’s hope for, within the next two years, a test that will reduce the wait time to three to four hours.

“With all the doom and gloom around CWD, we have real solutions that can help us fight this disease in new ways,” said Larsen. “There’s some optimism.”

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Six-foot-tall corn plants tower over large green squash and black-and-yellow sunflowers. Around the perimeter, stalks of sweetgrass grow.

The seeds for some of these plants grew for millennia in Native Americans’ gardens along the upper Missouri River. It’s one of several Native American ancestral gardens growing in the Bozeman area, totaling about an acre. Though small, the garden is part of a larger, multifaceted effort around the country to promote “food sovereignty” for reservations and tribal members off reservation, and to reclaim aspects of Native American food and culture that flourished in North America for thousands of years before the arrival of European settlers. Restoring bison to reservations, developing community food gardens with ancestral seeds, understanding and collecting wild fruits and vegetables, and learning how to cook tasty meals with traditional ingredients are all part of the movement.

“We are learning to care for plant knowledge, growing Indigenous gardens, cultivating ancestral seeds 鈥� really old seeds from our relatives the Mandan, Hidatsa, and Arikara: corn, beans, squash, and sunflowers,” said Jill Falcon Ramaker, an assistant professor of community nutrition and sustainable food systems at Montana State. She is a member of the Turtle Mountain Band of Anishinaabe.

“A lot of what we are doing here at the university is cultural knowledge regeneration,” she said.

But it also has a very practical application: to provide healthier, cheaper, and more reliable food supplies for reservations, which are often a long way from supermarkets, and where processed foods have helped produce an epidemic of diabetes and heart disease.

Many reservations are food deserts where prices are high and processed food is often easier to come by than fresh food. , a 2020 paper funded by the U.S. Department of Agriculture, processed foods contribute to chronic inflammation, which in turn leads to heart disease, cancer, and diabetes, which occurs at in Native Americans as it does in white people.

Studies show that people’s mental and physical health declines when they consume a processed food diet. “In the last decade there’s a growing amount of research on the impact of good nutrition on suicide ideation, attempts, and completion,” said KayAnn Miller, co-executive director of the Montana Partnership to End Childhood Hunger in Bozeman, who is also involved with the BNFSI.

All Native American reservations in Montana now have community gardens, and there are at least eight gardens on the Flathead Reservation north of Missoula, home to the Confederated Salish and Kootenai Tribes. The tribe is teaching members to raise vegetables, some of them made into soup that is delivered to tribal elders. This year members grew 5 tons of produce to be given away.

Ancestral seeds are part of the effort. Each year the BNFSI sends out 200 packets of seeds for ancestral crops to Indigenous people in Montana.

Creating foods that appeal to contemporary tastes is critical to the project. The BNFSI is working with Sean Sherman, the “Sioux Chef,” to turn corn, meat, and other Native foods into appealing dishes.

Sherman founded the award-winning Owamni restaurant in Minneapolis and in 2020 opened the Indigenous Food Lab, through his nonprofit, North American Traditional Indigenous Food Systems. The lab, in downtown Minneapolis, is also a restaurant and an education and training center that creates dishes using only Indigenous foods from across the country 鈥� no dairy, cane sugar, wheat flour, beef, chicken, or other ingredients from what he calls the colonizers.

“We’re not cooking like it’s 1491,” Sherman said last year on the NPR program “Fresh Air,” referring to the period before European colonization. “We’re not a museum piece or something like that. We’re trying to evolve the food into the future, using as much of the knowledge from our ancestors that we can understand and just applying it to the modern world.” Among his signature dishes are bison pot roast with hominy and roast turkey with a berry-mint sauce and black walnuts.

The Bozeman-based nonprofit HRDC built a $29 million building with a state-of-the-art kitchen that will house the country’s second Indigenous food lab, Ramaker said. It will open next year and expand the ongoing work creating recipes, holding cooking workshops, and preparing cooking videos.

Angelina Toineeta, who is Crow, is studying the BNFSI at Montana State as part of her major in agriculture. “Growing these gardens really stuck out to me,” she said. “Native American agriculture is something we’ve lost over the years, and I want to help bring that back.”

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During her time in the Florida Legislature, Cruz had supported a new law allowing the use of treated wastewater in local water systems. But many Tampa residents were staunchly opposed to a plan by their water utility to do just that, and Cruz was forced to backtrack, with her spokesperson asserting she had never favored the type of complete water reuse known as “toilet to tap.” She lost anyway, and the water plan has been canceled.

Tampa’s showdown may be a harbinger of things to come as climate change and drought cause water shortages in many parts of the country. With few alternatives for expanding supply, cities and states are rapidly adding recycled water to their portfolios and expanding the ways in which it can be used. Researchers say it’s safe 鈥� and that it’s essential to move past the 20th century notion that wastewater must stay flushed.

“There is no reason to only use water once,” said Peter Fiske, director of the National Alliance for Water Innovation at the Lawrence Berkeley National Laboratory. “We’ve got to be more clever with the water we’ve got.”

But proponents are still fighting an uphill battle to overcome the “yuck” factor. A found that reused water is not only safe but that it’s actually cleaner than conventionally sourced water 鈥� yet acceptance is “hindered by perceptions of poor water quality and potential health threats.”

Several projects were canceled in California in the 1990s because of such worries. In San Gabriel, Miller Brewing Company opposed a water reclamation project when people started joking about “beer aged in porcelain.”

“You have to have a lot of education in a community to say why [recycled water] is needed” and what experts are doing to ensure the safety of the water, said Noelle George, the Texas managing director for the trade association WateReuse.

Many forms of water reuse have long been routine. Water from yard sprinklers, for example, soaks into the groundwater. Or, if it is processed in a treatment plant, it goes into a river or lake, where it’s used again. Municipalities and others often treat a form of wastewater known as gray water to use for irrigation.

But in the world of water reuse, the gold standard is known as direct potable reuse 鈥� cleaning wastewater, including sewage, to drinking water standards.

With DPR systems, the water from showers, sinks, and toilets first goes to a conventional treatment plant, where it is disinfected with chemicals and aeration. Then it gets a second scrubbing in a multistage process that first uses a bioreactor to break down nitrogen compounds, then employs microfiltration to clean out particles and reverse osmosis to remove viruses, bacteria, and salts. Finally, hydrogen peroxide is added and the water goes through an ultraviolet light processing, which is supposed to kill any contaminants that are left.

Experts say the water that emerges at the end of this process is so clean it has no taste, and that minerals must be added to give the water flavor. It’s also free of a little-known health hazard; chlorine, often used to disinfect conventional water, can react with organic material in the water to create chloroform, exposure to which can cause negative health effects.

Big Spring, Texas, is the only place in the country with a DPR municipal water system, in which all wastewater is treated and sent back to the tap. Another notable DPR system is the Changi Water Reclamation Plant in Singapore, which cleans 237 million gallons each day.

In Tampa, intense opposition focused on the high cost of the water treatment and the possible presence of pharmaceuticals, hormones, and so-called forever chemicals, .

“We have never thought that it was necessary to drink wastewater,” said Gary Gibbons, the vice chair of the Tampa Bay Sierra Club, in September 2022. He said the project, which the city referred to by the acronym PURE, would result in contaminants in the drinking water and the groundwater aquifer.

Experts reject these concerns as uninformed and say properly treated wastewater is safer than a lot of conventional drinking water sources.

“I would almost rather have an advanced treatment plant of the type used for potable water recycling than water that comes from a river that has several cities and farms and industries upstream that are discharging into it,” said David L. Sedlak, an expert on potable reuse at the University of California-Berkeley.

With higher temperatures and long-term pressure on water sources including aquifers and mountain snowpacks, a lot more water reuse is coming.

In Texas, the state permits DPR plants on a case-by-case basis, and the city of El Paso is building one that’s slated to be online by 2026. Colorado last year DPR. In California, regulations spelling out the approach to DPR by the end of this year, with some cities setting goals of recycling all water by 2035. Florida and Arizona are also moving to expand direct potable reuse.

There’s also a lot of activity around what’s known as indirect potable reuse. Orange County, California, has the world’s largest IPR facility, which cleans 130 million gallons of water a day to irrigation standards, passes it through advanced purification, and finally injects it into groundwater, which serves as an environmental buffer. The water is then piped to all municipal users.

San Francisco is pioneering another approach. Since 2015, the San Francisco Public Utilities Commission, which operates the dams, reservoirs, and aqueducts that deliver water from the Sierra Nevada to the city, has required all buildings over 100,000 square feet be equipped for recycling gray water. The downtown Salesforce Tower has its own recycling plant: Sinks, laundry machines, and showers drain into the basement recycling system, and the water is then reused for flushing toilets and irrigation, saving about 30,000 gallons a day.

“We don’t need to flush toilets with drinking water,” said Fiske, noting that toilets make up about 30% of all water use.

San Francisco water officials are studying the feasibility and safety of cleaning all wastewater to potable standards at the building level. The headquarters of the water utility has a blackwater system called the Living Machine that uses engineered wetlands in the sidewalks around the building to treat wastewater, cutting water use by two-thirds. (Blackwater systems recycle water from toilets; gray water systems reuse water from all other drains.)

Some experts see a day when buildings will not have to be hooked up to external sewer and water systems at all, with advanced recycling systems augmented by rainwater. For the moment, though, educational campaigns are still needed to bring recycled water into the mainstream.

Epic Cleantec, which created a recycling system for a new San Francisco apartment tower, thought beer might help. The company last year teamed up with a local brewery to produce beer from recycled water. The Epic OneWater Brew by Devil’s Canyon Brewing isn’t sold; rather, it’s a demonstration product, given away and served at events.

While people might not want to drink recycled water, they will usually try the beer.

“We made beer out of recycled water, because we’re trying to change the conversation,” said Aaron Tartakovsky, CEO of Epic Cleantec. “We’re fundamentally trying to help people rethink how our communities handle water.”

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En aquella época, a esta ciudad desbordante y rodeada de montañas, de más de 15 millones de habitantes, se la conocía como la más contaminada del mundo, con una densa y constante neblina de contaminación.

En 2002, la toxicóloga y neuropatóloga Lilian Calderón-Garcidueñas, afiliada a la Universidad del Valle de México en Ciudad de México y a la Universidad de Montana, examinó el tejido cerebral de 40 perros que habían vivido en la ciudad y de otros 40 de una zona rural cercana con aire más limpio.

Descubrió que los cerebros de los perros urbanos mostraban signos de neurodegeneración, mientras que los del campo tenían cerebros mucho más sanos.

Calderón-Garcidueñas pasó a de 203 personas residentes en Ciudad de México, de los cuales sólo uno no mostraba signos de neurodegeneración.

Esto llevó a la conclusión de que la exposición crónica a la contaminación atmosférica puede afectar negativamente al sistema olfativo de las personas a una edad temprana, y puede hacerlas más susceptibles a enfermedades neurodegenerativas como el alzheimer y el parkinson.

El principal contaminante es la materia de partículas en el aire, dijo Calderón-Garcidueñas Contiene que son tan pequeñas que pueden inhalarse y causar problemas de salud graves.

“Podemos detectar nanopartículas dentro de las neuronas, dentro de las células gliales, dentro de las células epiteliales. También vemos cosas que no deberían estar ahí: titanio, hierro y cobre”, agregó.

El trabajo que realiza la científica mexicana se suma al creciente conjunto de pruebas que demuestran que respirar aire contaminado no sólo provoca daños cardíacos y pulmonares, sino también neurodegeneración y problemas de salud mental.

que la contaminación atmosférica es perjudicial para el cuerpo humano y afecta a casi todos los órganos. El asma, las enfermedades cardiovasculares, el cáncer, la muerte prematura y los derrames cerebrales figuran en la listade fecciones que puede disparar la contaminación. Según la Organización Mundial de la Salud (OMS), encabeza la lista de amenazas para la salud en todo el mundo, causando 7 millones de muertes al año. Los niños y los bebés son especialmente susceptibles.

Averiguar el impacto de la contaminación atmosférica en el cerebro ha sido más difícil que en otros órganos debido a su inaccesibilidad, por lo que no se ha investigado tan a fondo.

La cuestión de si la contaminación puede causar o contribuir al alzheimer o al parkinson no está científicamente comprobado. Pero el trabajo de Calderón-Garcidueñas está a la vanguardia para demostrar que la contaminación atmosférica afecta directamente al cerebro a través del aire que se respira, y tiene graves repercusiones.

“Si hacemos ejercicio y pasamos tiempo en la naturaleza nos volvemos más resistentes”, afirmó Kristen Greenwald, trabajadora social medioambiental y profesora de la Universidad de Denver.

Megan Herting, que investiga el impacto de la contaminación atmosférica en el cerebro en la Universidad del Sur de California, señaló que, hoy en día, los factores ambientales deberían incorporarse a las evaluaciones de los médicos, especialmente en lugares como el sur de California y la Front Range de Colorado, donde los altos niveles de contaminación atmosférica son un problema crónico.

“Cuando voy a una consulta médica, rara vez me preguntan dónde vivo y cómo es mi entorno familiar”, explicó. “Dónde vivimos, a qué estamos expuestos, es importante a la hora de pensar en la prevención y el tratamiento”.

Las investigaciones demuestran que al aspirarse por la nariz y la boca, y que viajan directamente al cerebro. Las partículas finas y ultrafinas, que proceden de los gases de escape de los motores diésel, el hollín, el polvo y el humo de los incendios forestales, entre otras fuentes, suelen contener metales, lo que empeora su impacto.

Es probable que el cambio climático agrave los efectos de la contaminación atmosférica sobre el cerebro y la salud mental. El ozono , la disminución de la plasticidad cerebral, la muerte de neuronas y el deterioro del aprendizaje y la memoria. Los niveles de ozono son extremadamente altos en Los Angeles y en los valles montañosos del Oeste, como el Front Range de Colorado, Phoenix y Salt Lake City.

La contaminación atmosférica también causa daños por inflamación crónica. “A tu cuerpo no le gusta estar expuesto a la contaminación atmosférica y produce una respuesta inflamatoria”, explicó Patrick Ryan, investigador del Hospital Infantil de Cincinnati, en un correo electrónico. “A tu cerebro tampoco le gusta. Hay más de 10 años de ciencia toxicológica y estudios epidemiológicos que demuestran que la contaminación del aire causa neuroinflamación”.

Gran parte de la investigación actual se centra en cómo la contaminación causa problemas de salud mental.

Los daños en el cerebro son especialmente perniciosos porque es el panel de control principal del organismo, y los daños de la contaminación pueden causar toda una serie de trastornos neuropsiquiátricos.

Uno de los focos de investigación en la actualidad es cómo los daños causados por la contaminación afectan a las áreas del cerebro que regulan las emociones, como la amígdala, el córtex prefrontal y el hipocampo.

La amígdala, por ejemplo, controla como procesamos el temor y las emociones, y su deterioro puede causar ansiedad y depresión. En una revisión reciente, que analizaban los cambios físicos y funcionales de las áreas del cerebro que regulan las emociones mostraban un impacto de la contaminación atmosférica.

publicado en febrero en JAMA Psychiatry, realizado por investigadores de las universidades de Oxford y Pekín, y del Imperial College de Londres, realizó un seguimiento de la incidencia de la ansiedad y la depresión en casi 400,000 adultos del Reino Unido durante 11 años. Y descubrió que la exposición, a largo plazo, incluso a niveles bajos de una combinación de contaminantes atmosféricos 鈥攑artículas en suspensión, dióxido de nitrógeno y óxido nítrico鈥� aumentaba la aparición de depresión y ansiedad.

Otro estudio reciente, de Erika Manczak, de la Universidad de Denver, descubrió que los adolescentes expuestos al ozono predecían “un aumento más pronunciado de los síntomas depresivos a lo largo del desarrollo adolescente”.

Pero la investigación epidemiológica presenta deficiencias debido a factores confusos difíciles de explicar. Algunas personas pueden estar genéticamente predispuestas a la susceptibilidad y otras no. Algunas pueden sufrir estrés crónico o ser muy jóvenes o muy mayores, lo que puede aumentar su susceptibilidad. Las personas que residen cerca de zonas verdes, que reducen la ansiedad, pueden ser menos susceptibles.

“Las personas que viven en zonas más expuestas a los contaminantes, tienen menos reursos y muchos problemas sistémicos. Hay más casos de estrés, depresión y ansiedad”, explicó Manczak. “Dado que esas zonas han sido marginadas por muchas razones, es un poco difícil decir que estos casos se deban a la exposición a la contaminación atmosférica”.

La mejor forma de saberlo con seguridad sería realizar ensayos clínicos, pero eso conlleva problemas éticos. “No podemos exponer aleatoriamente a los niños a la contaminación atmosférica”, afirmó Ryan.

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In the 1990s, residents of Mexico City noticed their dogs acting strangely 鈥� some didn’t recognize their owners, and the animals’ sleep patterns had changed.

At the time, the sprawling, mountain-ringed city of more than 15 million people was known as the most polluted in the world, with a thick, constant haze of fossil fuel pollution trapped by thermal inversions.

In 2002, toxicologist and neuropathologist Lilian Calderón-Garcidueñas, who is affiliated with both Universidad del Valle de México in Mexico City and the University of Montana, examined brain tissue from 40 dogs that had lived in the city and 40 others from a nearby rural area with cleaner air. She discovered the brains of the city dogs showed signs of neurodegeneration while the rural dogs had far healthier brains.

Calderón-Garcidueñas went on to of 203 human residents of Mexico City, only one of which did not show signs of neurodegeneration. That led to the conclusion that chronic exposure to air pollution can negatively affect people’s olfactory systems at a young age and may make them more susceptible to neurodegenerative diseases such as Alzheimer’s and Parkinson’s.

The pollutant that plays the “big role” is particulate matter, said Calderón-Garcidueñas. “Not the big ones, but the tiny ones that can cross barriers. We can detect nanoparticles inside neurons, inside glial cells, inside epithelial cells. We also see things that shouldn’t be there at all 鈥� titanium, iron, and copper.”

The work the Mexican scientist is doing is feeding a burgeoning body of evidence that shows breathing polluted air not only causes heart and lung damage but also neurodegeneration and mental health problems.

It’s that air pollution takes a serious toll on the human body, affecting almost every organ. Asthma, cardiovascular disease, cancer, premature death, and stroke are among a long list of problems that can be caused by exposure to air pollution, which, according to the World Health Organization, sits atop the list of health threats globally, causing 7 million deaths a year. Children and infants are especially susceptible.

Sussing out the impact of air pollution on the brain has been more difficult than for other organs because of its inaccessibility, so it has not been researched as thoroughly, according to researchers. Whether air pollution may cause or contribute to Alzheimer’s or Parkinson’s is not settled science. But Calderón-Garcidueñas’ work is at the leading edge of showing that air pollution goes directly into the brain through the air we breathe, and has serious impacts.

Some psychotherapists report seeing patients with symptoms stemming from air pollution. Not only does the pollution appear to cause symptoms or make them worse; it also takes away forms of relief.

“If we exercise and spend time in nature we become extra resilient,” said Kristen Greenwald, an environmental social worker and adjunct professor at the University of Denver. “A lot of folks do that outside. That’s their coping mechanism; it’s soothing to the nervous system.”

On polluted days a lot of her clients “can’t go outside without feeling they are making themselves more sick or distressed.”

Megan Herting, who researches air pollution’s impact on the brain at the University of Southern California, said environmental factors should be incorporated in doctors’ assessments these days, especially in places like Southern California and Colorado’s Front Range, where high levels of air pollution are a chronic problem.

“When I go into a medical clinic, they rarely ask me where I live and what is my home environment like,” she said. “Where are we living, what we are exposed to, is important in thinking about prevention and treatment.”

In the last two decades, with new technologies, research on air pollution and its impact on the human nervous system has grown by leaps and bounds.

Research shows tiny particles as they are breathed in through the nose and mouth and travel directly into the brain. Fine and ultrafine particles, which come from diesel exhaust, soot, dust, and wildfire smoke, among other sources, often contain metals that hitchhike a ride, worsening their impact.

A changing climate is likely to exacerbate the effects of air pollution on the brain and mental health. Warmer temperatures react with tailpipe emissions from cars to create more ozone than is generated when it’s cooler. And more and larger forest fires are expected to mean more days of smoky skies.

Ozone has been , decline in cerebral plasticity, the death of neurons, and learning and memory impairment. Ozone levels are extremely high in Los Angeles and the mountain valleys of the West, including the Front Range of Colorado, Phoenix, and Salt Lake City.

Air pollution also causes damage from chronic inflammation. As air pollution particles enter the brain, they are mistaken for germs and attacked by microglia, a component of the brain’s immune system, and they stay activated.

“Your body doesn’t like to be exposed to air pollution and it produces an inflammatory response,” said Patrick Ryan, a researcher at Cincinnati Children’s Hospital, in an email. “Your brain doesn’t like it either. There’s more than 10 years of toxicological science and epidemiologic studies that show air pollution causes neuro-inflammation.”

Much of the current research focuses on how pollution causes mental health problems.

Damage to the brain is especially pernicious because it is the master control panel for the body, and pollution damage can cause a range of neuropsychiatric disorders. A primary focus of research these days is how pollution-caused damage affects areas of the brain that regulate emotions 鈥� such as the amygdala, prefrontal cortex, and hippocampus. The amygdala, for example, governs the processing of fearful experiences, and its impairment can cause anxiety and depression. In one recent review, looking at both physical and functional changes to areas of the brain that regulate emotion showed an impact from air pollution.

published in February in JAMA Psychiatry, by researchers from the universities of Oxford and Peking and Imperial College London, tracked the incidence of anxiety and depression in nearly 400,000 adults in the United Kingdom over a median length of 11 years and found that long-term exposure even to low levels of a combination of air pollutants 鈥� particulate matter, nitrogen dioxide, and nitric oxide 鈥� increased the occurrence of depression and anxiety.

Another recent study, by Erika Manczak at the University of Denver, found adolescents exposed to ozone predicted “for steeper increases in depressive symptoms across adolescent development.”

But the epidemiological research has shortcomings because of confounding factors that are difficult to account for. Some people may be genetically predisposed to susceptibility and others not. Some may experience chronic stress or be very young or very old, which can increase their susceptibility. People who reside near a lot of green space, which reduces anxiety, may be less susceptible.

“Folks living in areas where there is greater exposure to pollutants tend to be areas under-resourced in many ways and grappling with a lot of systemic problems. There are bigger reports of stress and depression and anxiety,” said Manczak. “Given that those areas have been marginalized for a lot of reasons, it’s a little hard to say this is due to air pollution exposure.”

The best way to tell for sure would be to conduct clinical trials, but that comes with ethical problems. “We can’t randomly expose kids to air pollution,” Ryan said.

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Los murciélagos en todo el mundo son vectores primarios para la transmisión de virus de animales a humanos. Generalmente esos virus son inofensivos para los murciélagos, pero pueden ser mortales para los humanos.

Por ejemplo, en China, los murciélagos de herradura se citan como una causa probable del brote de covid-19. Y los investigadores creen que la presión ejercida sobre los murciélagos por el cambio climático y la invasión del desarrollo humano han aumentado la frecuencia con la que los virus saltan de estos animales a las personas, causando lo que se conoce como enfermedades zoonóticas.

“Estos eventos indirectos son el resultado de una cascada de factores estresantes: el hábitat de los murciélagos cambia, el clima se vuelve más extremo, los murciélagos se trasladan a áreas humanas para encontrar comida”, dijo Raina Plowright, ecologista de enfermedades y coautora de un artículo reciente en la y otro en sobre el papel de los cambios ecológicos en las enfermedades.

Es por eso que Agnieszka Rynda-Apple, inmunóloga de la Universidad Estatal de Montana (MSU), planea traer murciélagos frugívoros (o de la fruta) de Jamaica a Bozeman este invierno para iniciar una colonia de reproducción y acelerar el trabajo de su laboratorio como parte de un equipo de 70 investigadores en siete países.

El grupo, llamado BatOneHealth, fundado por Plowright, espera encontrar formas de predecir dónde el póximo virus mortal podría dar el salto de los murciélagos a las personas. “Estamos colaborando para responder a la pregunta de por qué los murciélagos son un vector tan fantástico”, dijo Rynda-Apple.

“Estamos tratando de entender qué es lo que hace que sus sistemas inmunológicos retengan el virus y cuál es la situación en la que lo eliminan”, agregó.

Para estudiar el papel del estrés nutricional, explicó que los investigadores crean diferentes dietas para estos mamíferos, “los infectan con el virus de la influenza y luego estudian cuánto virus están eliminando, la duración de la eliminación viral y su respuesta antiviral”.

Si bien Rynda Apple y sus colegas ya han estado haciendo este tipo de experimentos, la cría de murciélagos les permitirá ampliar la investigación. Es un esfuerzo arduo comprender a fondo cómo el cambio ambiental contribuye al estrés nutricional, y predecir mejor el efecto indirecto.

“Si realmente podemos entender todas las piezas del rompecabezas, eso nos dará herramientas para volver atrás y pensar en medidas contra-ecológicas que podemos poner en práctica para romper el ciclo de los efectos indirectos”, dijo Andrew Hoegh, profesor asistente de estadísticas en MSU que está creando modelos para posibles escenarios indirectos.

El pequeño equipo de investigadores de la MSU trabaja con un investigador del Rocky Mountain Laboratories de los Institutos Nacionales de Salud en Hamilton, Montana.

Los artículos recientes publicados en Nature y Ecology Letters se centran en el virus Hendra en Australia, que es donde nació Plowright.

Hendra es un virus respiratorio que causa síntomas similares a los de la gripe y se propaga de los murciélagos a los caballos, y luego puede transmitirse a las personas que tratan a los caballos. Es mortal, con . De las siete personas que hasta el momento se sabe que contrajeron esta infección, cuatro murieron.

La pregunta que impulsó el trabajo de Plowright es por qué Hendra comenzó a aparecer en caballos y personas en la década de 1990, a pesar de que los murciélagos probablemente han albergado al virus por millones de años.

La investigación demuestra que la razón es el cambio ambiental. Plowright comenzó su investigación sobre murciélagos en 2006. En muestras tomadas de murciélagos australianos llamados zorros voladores, ella y sus colegas rara vez detectaron el virus.

Después de que el ciclón tropical Larry frente a la costa del Territorio del Norte australiano acabara con la fuente de alimento de los murciélagos en 2005-06, cientos de miles de animales simplemente desaparecieron. Sin embargo, encontraron una pequeña población de murciélagos débiles y hambrientos cargados con el virus Hendra.

Eso llevó a Plowright a centrarse en el estrés nutricional como un factor clave en el efecto indirecto. El equipo analizó 25 años de datos sobre la pérdida de hábitat, el derrame y el clima, y descubrieron un vínculo entre la pérdida de fuentes de alimento causada por el cambio ambiental y las altas cargas virales en murciélagos estresados por la comida.

En el año posterior a un patrón climático de , con sus altas temperaturas, que ocurren cada pocos años, muchos árboles de eucalipto no producen las flores con el néctar que necesitan los murciélagos. Y la invasión humana de otros hábitats, desde las granjas hasta el desarrollo urbano, ha eliminado las fuentes alternativas de alimentos. Entonces, los murciélagos tienden a mudarse a áreas urbanas con higueras, mangos y otros árboles deficientes y, estresados, propagan los virus.

Cuando los murciélagos excretan orina y heces, los caballos las inhalan mientras huelen el suelo. Los investigadores esperan que su trabajo con murciélagos infectados con Hendra ilustre un principio universal: cómo la destrucción y la alteración de la naturaleza pueden aumentar la probabilidad de que los patógenos mortales pasen de los animales salvajes a los humanos.

Las tres fuentes más probables de contagio son los murciélagos, los mamíferos y los artrópodos, especialmente las garrapatas. Alrededor del que infectan a los humanos provienen de animales, y alrededor de dos tercios de ellas provienen de animales salvajes.

La idea de que la deforestación y la invasión humana de las tierras salvajes alimentan las pandemias no es nueva. Por ejemplo, expertos creen que el VIH, que causa el SIDA, infectó a los humanos por primera vez cuando la gente comía chimpancés en África central. Un brote en Malasia a fines de 1998 y principios de 1999 del virus Nipah transmitido por murciélagos se propagó de murciélagos a cerdos. Los cerdos lo amplificaron y se propagó a los humanos, con un brote que infectó a 276 personas, y mató a 106.

Ahora está emergiendo la conexión con el estrés provocado por los cambios ambientales.

Una pieza crítica de este complejo rompecabezas es el sistema inmunológico de los murciélagos. Los murciélagos frugívoros de Jamaica que vivirán en la MSU ayudarán a los investigadores a obtener más información sobre los efectos del estrés nutricional en su carga viral.

Vincent Munster, jefe de la unidad de ecología de virus de Rocky Mountain Laboratories y miembro de BatOneHealth, también está analizando diferentes especies de murciélagos para comprender mejor la ecología del contagio. “Hay 1,400 especies diferentes de murciélagos y hay diferencias muy significativas entre los que albergan coronavirus y los murciélagos que albergan el virus del Ébola”, dijo Munster. “Y murciélagos que viven cientos de miles juntos versus murciélagos que son relativamente solitarios”.

Mientras tanto, Gary Tabor, esposo de Plowright, es presidente del Center for Large Landscape Conservation, una organización sin fines de lucro que aplica la ecología de la investigación de enfermedades para proteger el hábitat de la vida silvestre, en parte, para garantizar que la vida silvestre esté adecuadamente alimentada y protegerse contra la propagación de virus.

“La fragmentación del hábitat es un problema de salud planetaria que no se está abordando lo suficiente, dado que el mundo continúa experimentando niveles sin precedentes de deforestación”, dijo Tabor.

A medida que mejore la capacidad de predecir brotes, otras estrategias se vuelven posibles. Los modelos que pueden predecir dónde podría extenderse el virus Hendra podrían conducir a la vacunación de los caballos en esas áreas. Otra posible solución es el conjunto de “contramedidas ecológicas” a las que se refirió Hoegh, como la plantación a gran escala de eucaliptos en flor para que los murciélagos zorros voladores no se vean obligados a buscar néctar en áreas desarrolladas.

“En este momento, el mundo está enfocado en cómo podemos detener la próxima pandemia”, dijo Plowright. “Desafortunadamente, preservar o restaurar la naturaleza rara vez es parte de la discusión”.

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