Pollution: When Pets Become "Sentinels" for Our Health

They breathe the same air as us, often drink the same water, and sometimes sleep in our beds. Thus, pets, especially dogs and cats, can help us decipher the dangers that threaten our lives. They act as true environmental "sentinels." This is especially true given some often overlooked aspects: birds, for example, are particularly vulnerable to pollution, extracting significantly higher amounts of oxygen from the air than mammals. Furthermore, dogs and cats are fatally exposed to a greater risk of exposure to potentially carcinogenic chemical contaminants, given that they tend to spend a lot of time in contact with the ground, also exposed to dust, where heavy metals tend to accumulate. So why not take advantage of it? The New York Times asks this question in an article that explores the opportunities for understanding the environment around us through the help—passive, of course—of our four-legged friends.

There's no shortage of iconic stories: in 2023, for example, a freight train carrying toxic chemicals derailed near the American town of East Palestine, Ohio. An environmental catastrophe with significant consequences, difficult to quantify. Scientists then focused on dogs, asking their owners to attach special absorbent silicone tags to their collars. Preliminary research findings revealed exposure to unusually high levels of certain chemicals for dogs living near the accident. Research is now investigating whether it could trigger genetic alterations associated with cancer. "Studies like this should always be initiated after disasters," Elinor Karlsson , a geneticist at UMass Chan Medical School and the Broad Institute, explained to the New York Times . "After all," she added, "pets living in our homes are exposed to the same substances we are ." There is therefore no doubt, according to scientists, that understanding more about how pollution affects the health of pets can provide insights that can protect us from illnesses and critical conditions . The most cited example is the fortunately anachronistic one of coal canaries , birds used in coal mines as an alarm system to detect the presence of toxic gases like carbon monoxide. "But in that case the animals were sacrificed, while this doesn't happen with our dogs and cats," notes Audrey Ruple , a veterinary epidemiologist at the renowned Virginia Tech University.

Fires and their effects on four-legged friends

Scientific literature, moreover, shows cases in which pets have already proven effective environmental sentinels. This happened, for example, in 2020 in California, during an extraordinary forest fire season. Stephen Jarvis , then a student, noticed that certain symptoms (headache, irritated eyes, shortness of breath, and chest pain) he shared with his partner's asthmatic cat, Manolo. So Jarvis, now a professor at the London School of Economics, had a kind of enlightenment: he analyzed five years of veterinary data from across Great Britain, cross-referencing it with levels of fine particulate matter in the air, one of the main pollutants found in forest fire smoke and harmful to human health. Together with a team of researchers, he thus documented how the increase in air pollution increased the number of veterinary visits for dogs and cats . The report states that if the country kept air pollution below the WHO-recommended threshold, between 80,000 and 290,000 veterinary visits per year could be avoided. This would, among other things, result in cost savings. This report is certainly thought-provoking, especially given the consequences of the ongoing climate crisis, not least the intensification of forest fires. "When we think about how to protect ourselves from unhealthy air, we should also think about our pets and wildlife," emphasizes Olivia Sanderfoot , an ecologist at Cornell University whose studies focus on the effects of smoke on wild animals.

Constant monitoring to read cancer risks

Among the most complex issues, however, is regular exposure to low levels of harmful substances, which in some cases can increase the risk of cancer over the course of a lifetime. Pets have shorter lifespans than humans and are more likely to spend them in a single geographic area, making it easier for scientists to identify some of these potential effects. "Not only that, but people are often understandably concerned about their pets," emphasizes Elinor Karlsson , who also leads "Darwin's Dogs," a large community science project that aims to identify the genetic and environmental factors that contribute to the health and behavior of dogs. "This attention is an opportunity for us to seize," she adds. Tens of thousands of American dog owners have signed up their pets for Darwin's Dogs and similar initiatives, including the Dog Aging Project and the Golden Retriever Lifetime Study. These scientific projects collect information on animals' daily exposure to chemicals , measure herbicide levels in their urine, mail absorbent silicone pads to dogs, and ask owners to send in water samples. "The turnout is massive, not so much because people trust scientific research but because love for dogs is a very strong lever."