Risk of bladder cancer and lymphoma in dogs is associated with pollution indices by county of residence

Abstract

Human urothelial cell carcinoma (UCC) and non-Hodgkin lymphoma are considered environmental cancers in people, but less is known about environment risk for UCC and lymphoma in dogs. The objective of this study was to determine whether dogs with these cancers, compared to unaffected control dogs, live in counties with higher tap water contaminants or higher levels of air pollution as measured by the Environmental Protection Agency (EPA) and by National Air Toxics Assessment chemical exposure risk estimates. Dogs with available home addresses from two previously published case-control populations were included: 66 dogs with UCC and 70 unaffected controls; and 56 boxer dogs with lymphoma and 84 unaffected boxer controls. Tap water total trihalomethanes, which are water disinfection by-products, were more than threefold higher in UCC case counties of residence compared to controls (p < .0001), and a higher proportion of dogs with UCC lived in counties exceeding EPA ozone limits (41.8%) compared to controls (13.6% p = .0008). More boxers with lymphoma lived in counties exceeding EPA ozone limits (52.1%) compared to controls (29.0%; p = .018), with higher exposure risk estimates for airborne 1,3-butadiene and formaldehyde (p = .004-.005). These data support the hypothesis that tap water contaminants and airborne environmental pollutants contribute to the risk of both urothelial carcinoma and lymphoma in dogs. If these findings reflect causal relationships, then it is possible that tap water filtration units and more effective air pollution controls could decrease the overall incidence of these cancers in dogs.

Environmental exposures and lymphoma risk: a nested case–control study using the Golden Retriever Lifetime Study cohort

“…Unlike previous studies in Boxer dogs, living in a county with elevated average ozone levels (over 70 ppm) was not associated with lymphoma risk in this population [ 40 ]. This was unexpected, as increased near-surface ozone levels generally indicate higher industrial pollutant burden.…”

Urinary and household chemical exposures in pet dogs with urothelial cell carcinoma

“…We found that UCC dogs lived in areas with higher reported TTHM concentrations in municipal drinking water compared with unaffected dogs. This is consistent with our previous findings in a separate case–control population of dogs with UCC, 29 and along with our swimming pool data, supports the hypothesis that TTHM exposure may contribute to UCC risk in dogs.…”

“…Total trihalomethanes (TTHMs) are chlorination byproducts found in drinking water, which have been associated with UCC in people 15 and in our recent study of a separate population of dogs with UCC. 29 Publicly available data on TTHM concentrations in municipal drinking water were accessed through the Environmental Working Group (https://www.ewg.org/tapwater/), which is a non-profit that compiles annual water monitoring data provided by public utilities. Water data were available from 2014 to 2019.…”

Canine on the Couch: The New Canary in the Coal Mine for Environmental Health Research

“…A more recent study found that dogs with bladder cancer lived in areas with higher ambient ozone levels compared to controls. 43 Although ozone is not a direct anthropogenic pollutant, it is influenced by solar radiation and the presence of airborne anthropogenic pollutants, such as volatile organic compounds, and is considered a marker for poor air quality. These data are consistent with human studies that have shown urban living environments and air pollution are associated with increased risk of bladder cancer incidence and mortality.…”