Plumbing Seals May Leak Toxic Compounds Into Drinking Water

Rubber plumbing seals may contaminate drinking water with compounds that can damage DNA, according to a small study.

The study published in the ACS’ Environmental Science & Technology Letters shows that the released compounds, which are typically linked to tire pollution, also transformed into other unwanted byproducts.

Manufacturers typically use additives to enhance rubber’s strength and durability. Scientists have shown that tire dust can transport these substances, such as 1,3 diphenylguanidine (DPG) and N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine (6PPD), into waterways. These compounds have been previously detected in drinking water samples, though it’s unclear how they got there.

In their previous study, researchers Dr. Shane Snyder and Mauricius Marques dos Santos found that these rubber additives can react with disinfectants in simulated drinking water. Their lab tests generated a variety of chlorinated compounds, some of which had potentially DNA-damaging effects.

This suggests that DPG reactions with free chlorine doses commonly applied during drinking water treatment or in water distribution networks can lead to the formation of toxic products that could damage DNA.

In their new study, the researchers collected tap water from 20 buildings and detected polymer additives at parts per trillion levels in every sample. Although these compounds are not currently regulated, previous research suggests that the measured levels may be harmful.

The research team discovered that the samples from faucets with aerators contained the highest total amounts of these compounds. DPG and one of its chlorinated byproducts were found in all of the samples, whereas fewer than five samples contained 6PPD and two other chlorine-containing compounds.

Researchers say this is the first report of chlorinated DPG byproducts in drinking water.

When the research team tested rubber O-rings and gaskets from seven commercial devices, such as faucet aerators and connection seals, they found that most seals released DPG and 6PPD additives.

However, the leaching of these toxic materials seems to occur only with certain kinds of plumbing materials, according to Shane Allen Snyder, a professor at the School of Civil and Environmental Engineering at Nanyang Technological University and author of the study.

"Silicone seals do not leach these materials," he told Healthnews.

Snyder says he is "very concerned" about the potential toxicity from exposure to these byproducts.

The study shows that along with tire pollution, the rubber plumbing seals that release DPG and 6PPD into drinking water could be a route of human exposure to these compounds.

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