Which Drugs Are Likely To Leach Into Aquifers?

New research on drug traces in sewage is pinpointing which pollutants are most likely to leach into groundwater.

“Of 11 pharmaceuticals commonly found in sewage, seven of them have the potential to leach into [groundwater], one poses an uncertain risk, and the remaining three — which are perhaps the most likely to impact humans and animals at low doses — are unlikely to leach into [aquifers],” Honolulu Civil Beat reported.

The findings come from University of Hawaii graduate student Jeffrey Murl, who focused on Oahu, an island in Hawaii. His research aims to support Hawaii health regulators as they consider how recycled water should be used “given that it is likely laden with contaminants of emerging concern,” the report said.

Murl tested three estrogens in his research; six prescribed antibiotics; Carbamazepine, an epilepsy medication; and Propranolol, a beta blocker. He tested the leaching potential of each of these contaminants.

“He found that Carbamazepine, Clarithromycin, Ciprofloxacin, and Propranolol were all likely to leach throughout Oahu (except for conservation areas where no wastewater was expected). Ofloxacin, Roxythromycin, and Azithromycin were likely to leach through all but the southwest corner of the island. As for sulfamethoxazole, the model found that it would likely leach in a few scattered areas, but it was uncertain whether it would leach elsewhere,” Civil Beat reported, noting that none of the estrogens were likely to leach.

Hawaii health regulators are working to rewrite water-reuse rules in a way that protects water sources from pharmaceuticals and personal care products (PPCPs), the report said.

“These contaminants are ubiquitous and include everyday products such as detergents, cosmetics, antimicrobials, insect repellant and drugs. As they’ve only been detectable since the early 2000s, no federal regulatory standards exist regarding their release into the environment,” the report said.

Some contaminants are more concerning than others.

“The most damaging is estrogen, which can work in concentrations as low as 1 nanogram per liter,” Murl said, per the report.

Murl is a proponent of recycled water despite studying the dangers.

“I actually think recycling wastewater is great,” Murl replied. “The model is just kind of a first-order swipe. It’s not a definitive, ‘this will happen; this won’t happen.’”

Pharmaceutical contamination, even at trace levels, appears to have an impact on aquatic life. Even in some of the cleanest waters in the U.S., pollution appears to be altering the sex functions of fish and making them intersex, a condition that hinders reproduction. The problem is endocrine disruption. In fish populations, this refers to “the presence of female eggs in male testes indicates some kind of hormonal confusion,” National Geographic reported.

Various estrogens and other pharmaceuticals are on the EPA’s fourth contaminant candidate list, a precursor to regulatory action.

To read more about PPCPs visit Water Online’s Source Water Contamination Solutions Center.