Silicone tags used to identify dogs’ pollution exposures

Researchers see potential as a new tool for environmental monitoring

Silicone tags attached to a collar could someday help veterinarians gather details on a pet’s chemical exposures.

Catherine Wise, PhD, who is a postdoctoral associate at   Duke University Nicholas School of the Environment, led a recent study to validate the use of the tags to measure exposure to household chemicals among dogs and their owners.

“One of the major advantages of using these is that it doesn’t require a clinical visit,” Dr. Wise said. “So you can measure exposures in a dog, and it’s noninvasive. You don’t have to take them to get blood drawn, don’t have to chase them around and try to collect their urine.”

Simbaa posing on a couch
This dog, Simbaa, is modeling one of the silicone tags used in a recent study to monitor chemical exposures. She belongs to Catherine Wise, PhD, a postdoctoral associate who led the study. (Courtesy of Dr. Wise)

Researchers from Duke University, North Carolina State University, and the Centers for Disease Control and Prevention collaborated on the study, which involved measuring residues that accumulated in tags worn on the collars of 30 dogs and wristbands worn by 30 of their owners over five days. The results, published Dec. 29, 2021, in Environmental Science and Technology, indicate that higher concentrations of certain pest control chemicals absorbed by the tags and bands—the insect repellent DEET and the insecticide permethrin—significantly correlated with higher concentrations of related metabolites in urine samples from the dogs and dog owners as well as with questionnaire answers provided by those owners about their use of such products.

“These data further demonstrate that silicone passive samplers have the potential to be valuable tools for the cross-species assessment of exposures, showing high correlations between the exposures that people and their pet dogs share in their everyday environment,” the article states. “However, careful considerations need to be accounted for, particularly the potential differences in metabolism and excretion of certain chemicals that may mediate the causal pathway for disease among different species.”

The researchers also found that people who reported using flea and tick preventives containing fipronil had higher fipronil concentrations on their wristbands and their dogs’ tags.

Though silicone tags and wristbands are not yet sold for exposure monitoring, multiple research teams see potential uses in animal and human medicine.

Other potential uses

Dr. Wise works in the laboratory of Heather M. Stapleton, PhD, who has been leading studies for several years to validate the use of silicone wristbands for collecting data on chemical exposures to support human health research. Those studies have used similar comparisons between the pollutants picked up on the bands and the metabolite concentrations in urine and blood samples.

She said the researchers next plan to use the silicone tags to investigate links between environmental exposures and bladder cancer in dogs.

A research group at Oregon State University, led by professor and environmental chemist Kim Anderson, PhD, first identified the bands’ usefulness in absorbing pollutants and, since then, has also compared those external exposures with metabolite concentrations inside a person’s body. A university announcement from 2014 indicates Dr. Anderson’s research team had created silicone bracelets with a porous surface and found they were useful for absorbing pollutants.

People already wear similar wristbands, which were popularized by the yellow LiveStrong bracelets of the mid-2000s and are often distributed today for other charitable causes or given to children as party favors.

Though the bands are inexpensive, performing a test for about 150 chemicals costs about $250—almost all of that from the analysis involving mass spectrometers, analytical standards, and labor, Dr. Stapleton said. But she expects those costs would drop over time if the process became routine.

More than a snapshot

Dr. Lauren Trepanier, who is not part of the team that studied use of silicone tags, is assistant dean for clinical and translational research and a professor of internal medicine at the University of Wisconsin-Madison School of Veterinary Medicine, where she leads studies on the intersections of household pollutant exposures, genetics, and cancer risk in dogs. Her team recently found that dogs with lymphoma were more likely to live in counties with high airborne concentrations of volatile organic compounds.

“It would be very interesting to use these tags to look at VOC exposures,” particularly in dog breeds with high risk for lymphoma, she said.

Dr. Trepanier said the tags and wristbands are exciting new tools for environmental monitoring, and they are good for measuring exposures to volatile organic compounds such as pesticides and flame retardants. She said it’s still important to measure blood or urine concentrations of certain chemicals, especially those that do not adsorb to silicone or that are primarily inhaled.

Substances such as silica, ash, and heavy metals aren’t picked up by silicone bands or tags, she said, and her research team is, for example, investigating links between arsenic and bladder cancer. While silicone tags can pick up what is in the air near a dog’s face, that might differ from what makes it into the dog’s bloodstream.

Dr. Stapleton expects the bands could be useful in gathering information on an array of exposures to chemical products over time. In comparison with the snapshot provided by urine or blood tests, she thinks the wristbands can provide a better measure of average exposure.

“If you want to know how exposure is linked to a health outcome, you need the best exposure measurement possible because there’s a delay often between exposure and when a disease manifests,” Dr. Stapleton said. “So unless you have accurate measures of exposure, you might miss the connection.”

A version of this article appears in the March 15, 2022, print issue of JAVMA.