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Monday, Jan 30, 2023

Drugs in the Water Supply? Not to Fear, Scientists Say

Minute traces of pharmaceutical waste in drinking water supplies aren’t cause for alarm, say local scientists and researchers, because San Diegans are routinely exposed to small amounts of chemicals.

A five-month investigation published this month by The Associated Press found trace levels of everything from antidepressants to sex hormones in the drinking water supplies of 24 major metropolitan areas, including San Diego.

Water supplies here were found to have traces of an anti-epileptic drug, anti-anxiety drug and ibuprofen, commonly found in pills to reduce fever and inflammation.

Most medications end up in water supplies through human excrement , the body doesn’t completely absorb medicine , and through pills and other medications flushed down the toilet.

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Metropolitan water plants treat wastewater before it is discharged into reservoirs, rivers or lakes. The plants cleanse the water again before it is piped to consumers.

City water departments, including San Diego’s, do not test for pharmaceuticals, which are excluded from an Environmental Protection Agency list of chemicals to test.

“If it’s not on the list, it’s outside the scope of what we’re testing for,” Heather Lade, a spokeswoman with San Diego’s wastewater department, told the Business Journal in September about a proposed statewide drug take-back program.

Multiple phone calls seeking more information from the department were not returned by last week’s deadline.

Scientists say consumers have little to fear because the pharmaceuticals appeared in amounts of parts per billion and parts per trillion, likely too small to have adverse effects on the body.

“If you look at the levels and if you look at the health risk by current mechanisms that we know, there’s no immediate cause for concern,” said Richard Gersberg, a professor of environmental health at San Diego State University.

Trace Amounts

Dr. Richard Clark, director of UC San Diego’s Division of Medical Toxicology and medical director of the San Diego division of the California Poison Control System, points to trace amounts of cocaine on dollar bills and morphine on poppy seed bagels as evidence of everyday drug exposure. He says pharmaceuticals in such small amounts aren’t enough to evoke a physiological reaction.

“The only thing I would be worried about is an allergic reaction or something,” he said.

Clark said he wasn’t aware whether studies have been conducted to determine the concentration thresholds for allergic reactions.

Christian Daughton, chief of environmental chemistry at the EPA, said the agency is concerned about “inappropriate exposure,” or the ingestion of medicines intended for topical use. Topical drugs typically involve higher concentrations since they are intended to be absorbed by the skin.

Additionally, he said a person’s “window of vulnerability,” or stage of exposure, is important to know.

“Those are just big unknowns, but those unknowns apply to all chemicals,” he said.

Cause For Concern

Reproductive abnormalities have been found in some species of fish that swim in contaminated waters, but little is known about the health effects in humans.

Some researchers fear the pharmaceuticals could cause pathogenic resistance to antibiotics and the disruption of endocrine systems, instrumental in regulating metabolism, growth, development, puberty and tissue function.

“I think it’s an evolving field,” Gersberg said. “We know that it causes some effects in fish, but there are a lot of other organisms in the water and we don’t know the full suite of effects.”

Additional studies to test the effects of ingesting low levels of medicines would be necessary but difficult to conduct, given the ethical problems of exposing people to drugs and difficulty in determining how multiple drugs interact, say researchers.

“We are doing a good job on the analytical research side,” said Jeff Mosher, executive director of the National Water Research Institute in Fountain Valley. “What’s not keeping up is the understanding of ‘What does that mean from a health perspective?’ ”

California is introducing a pilot program this year that requires pharmacies to offer drop boxes for unused or expired pharmaceuticals. The program is aimed at reducing the amount of drugs flushed down toilets.


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