Toxic Exposure: Presence Of Chemicals In Pet Feces, Urine Suggests Risks To Human Health

A group of researchers has found traces of chemicals in cat and dog feces, which shed light on how human beings too may be exposed to such toxic substances.

Primary aromatic amines are chemicals that are used in the production of items such as pesticides, food colorants, dyes and pharmaceuticals, noted the researchers of a new study published in the journal Environment International. The chemicals can also be found in tobacco smoke.

"Several primary aromatic amines (AAs) are known or suspected carcinogens," the researchers wrote. "Despite this, the exposure of pet animals to this class of chemicals is unknown."

The researchers examined the occurrence of 30 AAs and two tobacco chemical markers in the urine and feces of dozens of cats and dogs from homes, veterinary hospitals and animal shelters in the Albany area in New York City.

Indeed, the researchers found traces of the chemicals in the samples, with the AA called 2,6-dimethylaniline accounting for the highest concentrations in them. Interestingly, they did not find a correlation between AAs and nicotine, suggesting that the pets were exposed to AAs from sources other than tobacco smoke.

Furthermore, the concentrations in the samples also show that the pets have both direct and indirect exposures to AAs. For instance, previous research had shown that the microbes in the animals' digestive system can break down the tick- and flea- control medication called amitraz into 2,6-dimethylaniline, NYU Langone Health noted in a news release.

And with the rates of AAs in the fecal excretion being higher than the intake rates, the scientists assume that the pets are also exposed to dyes or food colorants, which are then "biotransformed" to generate AAs in the gut.

The results suggest pets' "widespread exposure" to AAs.

"Our findings suggest that pets are coming into contact with aromatic amines that leach from products in their household environment," said study lead author Sridhar Chinthakindi, of NYU Langone Health. "As these substances have been tied to bladder, colorectal, and other forms of cancer, our results may help explain why so many dogs and cats develop such diseases."

Dogs, in particular, are "specifically sensitive to AA-induced bladder cancer," the researchers noted.

They also found that cats had higher concentrations of the chemicals compared to dogs, with "at least triple" the AA concentrations in their urine. One possible explanation for this would be the differences between the species' metabolisms, as cats don't break down some compounds "as efficiently as dogs" do. 

However, this may also be explained by the differences in their diets, as well as indoor and outdoor exposures to such chemicals, the researchers added. Further studies are needed to determine the sources of exposure.

The researchers also found little differences in the AA concentrations of the pets in homes, veterinary hospitals and animal shelters. This suggests how common the substances are and how hard they are for pets to avoid, Chinthakindi noted.

Not only does the research highlight how much our pets may be exposed to the chemicals in the environment, including in our homes, it also shows that humans may also be exposed to such chemicals.

The AA concentrations in the pet urine were lower than in smokers' urine, but were "comparable to those in the general human population."

"Since pets are smaller and more sensitive to toxins, they serve as excellent 'canaries in the coal mine' for assessing chemical risks to human health," said study senior author Kurunthachalam Kannan, of NYU Langone. "If they are getting exposed to toxins in our homes, then we had better take a closer look at our own exposure."

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