Our pets share our environment. They sleep in our beds, drink our water and play on our lawns. As a result, they are exposed to many of the same environmental agents that are known to affect human health. And because pets acquire a spectrum of illnesses similar to humans – on a much shorter timescale – they can provide early warning of human health risks.
A national academy of science, engineering and medicine (NASEM) workshop held from December 1 to 3 examined the potential role of companion animals as sentinels of environmental exposures relevant to humans that may influence aging and cancer.
“We want to challenge the emerging field of exhibition science because we all know we are not dealing with one chemical at a time or at a single point in our lives,” said Linda Birnbaum, scientist emeritus of the NIEHS, who chaired the workshop and planning committee.
She told participants that exposure data collected from pets throughout their lives can provide important information that complements traditional toxicology research, such as cell studies and tests on laboratory animals. The event drew dozens of experts to NASEM headquarters in Washington, DC, with more than 500 people joining virtually.
Canary in the coal mine
The classic example of sentinel animals for environmental hazards is the canary in the coal mine, noted Peter Rabinowitz, MD, from the University of Washington.
He said that canaries possess three key qualities that make them good sentinels: greater sensitivity, greater exposure to danger, and shorter latency, which means compared to humans, it takes significantly less time for them. birds to get sick after exposure. If canaries at a mine got sick from carbon monoxide or other poisonous gases, workers had time to put on respiratory masks before they fell ill themselves.
Likewise, dogs can serve as useful sentinels for cancer in humans, according to Rabinowitz. He noted that dogs are sensitive to the effects of carcinogens, pointing out that there is a high incidence of cancer in animals. Dogs spend more time at home than humans, at least in the days leading up to the pandemic, and they come in closer contact with their surroundings. And their lifespan is much shorter than that of humans.
“Studies of dogs as sentinels have untapped potential to detect and better understand environmental carcinogens, which can be difficult to study in humans,” Rabinowitz said.
Such research could help scientists detect both new and known carcinogens and understand exposure patterns, which could improve cancer prevention in humans, he added.
Pets, companion studies
Death rates are falling for many forms of cancer, thanks to advances in early detection and treatment. However, the incidence of some cancers – such as early-onset skin, liver, kidney and colorectal cancers – is increasing, according to Gary Ellison, Ph.D., acting director of the Research Division. and NIEHS extramural training. Ellison said he believes environmental factors are contributing to this increase.
“However, the environment is incredibly complex and research into environmental exposures presents several challenges,” he said. Ellison noted that more work is needed to address this complexity, which involves types and sources of exposure, spatial and temporal aspects of exposures, and effects on biological pathways.
He described the National Cancer Institute (NCI) Cohort consortium, which includes seven million human study participants from 15 countries and four continents, as a resource that will help scientists explore how the environment influences cancer. Ellison also discussed new cohorts – part of a collaboration between NCI and NIEHS – that will allow researchers to study how emerging and significant environmental exposures may affect cancer risk.
Several participants, including Birnbaum, suggested that valuable knowledge could be gained by including pets in this long-term research. Prospective studies on dogs are already underway, such as the Golden Retriever Lifetime Study and the Dog aging project.
(Marla Broadfoot, Ph.D., is a contract writer for the NIEHS Office of Communications and Public Liaison.)