Agencies can't quantify risk from pharmaceuticals in groundwater

by Rob Ruth

Representatives of three different regulatory agencies publicly presented the latest test data from Sunnyside neighborhood water wells on Monday, but they couldn’t cite regulatory guidelines for some detected contaminants.

According to a handout the agency reps provided Monday afternoon at the Washington County Commission’s weekly regular meeting, the Idaho State Department of Agriculture (ISDA) and the Idaho Department of Environmental Quality (DEQ) took samples in November from 17 domestic wells and 12 monitoring wells in the neighborhood of the Sunnyside Feedlot. Seven of the wells were located on feedlot property.

As everyone had expected, testing of the samples showed that nitrates continue to abound in the groundwater at Sunnyside, an area already established as one of Idaho’s highest-priority locations for battling nitrate contamination. The mean average across the fall samples was 15 milligrams per liter (mg/L, equivalent to parts per million), which is well above the 10 mg/L level the government has set as a warning mark. At 10 mg/L, the government advises that it’s not a good idea for young children and pregnant women to consume the water.

Gary Bahr, ISDA’s Water Quality Bureau chief, noted that nitrate levels in many of the wells had changed significantly since a previous round of testing in fall of 2002. Concentrations were up in some and down in others. For example, two wells immediately southwest of the feedlot saw measurements shoot up by 12 and 14 mg/L in the three-year period, but two wells west of the feedlot — one roughly an eighth of a mile away, the other a little over a quarter of a mile out — realized decreases of 3 mg/L and 12 mg/L, respectively.

“In a general sense, some of the wells increased in concentration, and some decreased in concentration,” Bahr said, adding that approximately half had gone up while the other half had gone down. He called the phenomenon “sort of a mix in results.”

He suggested that reduced concentrations in the wells to the west could indicate effectiveness of some of the measures the feedlot has taken to limit contamination. The wells are down-gradient from the feedlot.

Between the 2002 and 2005 sampling events, the feedlot operation reconstructed its on-site wastewater lagoons to exceed NRCS standards for clay-lined lagoons, Bahr said.

Gary McRae, a Boise-based agricultural specialist for the Environmental Protection Agency, told commissioners there’s hardly any applicable regulation governing the feedlot’s waste once it’s passed to another party’s possession, however, even if it stays in the neighborhood. “It is a huge loophole in federal law in manure management,” McRae said.

Much of Monday afternoon’s discussion concerned relative newcomers to the contaminants mix, pharmaceuticals. Two antibiotics, sulfamethizine and sulfamethoxazole, and one growth-promoting steroid, estradiol, were detected in low concentrations in about a dozen wells.

The agency reps couldn’t offer much information about the possible human health implications of the finds, apparently because not much has yet been developed by the scientific community.

Tom Neace, a DEQ hydrologist, told commissioners there’s “sort of an evolving science for these [chemical] constituents” and no federal or state standards for their concentrations in water currently exist.

Jeff Fromm, a toxicologist for DEQ, said the chemicals “are commonly used at CAFOs both for treatment of infections and prophylactically for growth promotion,” but the two sulfa drugs have also “been prescribed for humans.”

Fromm said the concentrations recently detected around Sunnyside “are low,” but he couldn’t confidently state “how much of a risk these might be.” He later added: “There’s great uncertainty with any sort of analysis such as this, but I indicated a concern.”

Where antibiotics are involved, he said, the main focus of concern wouldn’t be about “overtoxicity unless a person has a very special sensitivity.” Instead, a larger worry is that ingestion of low amounts of antibiotics over a long period of time could contribute to “developed resistance” of bacteria to the antibiotics, an ongoing problem which threatens to limit the number of weapons available in the health-care community’s arsenal for fighting illness.
 

--WEISER SIGNAL AMERICAN
1/25/06