The Rivers Brew

By Britt Bailey

The United States Geological Survey (USGS) just completed the first nationwide examination of the occurrence of contaminants in streams across thirty states. The USGS study indicates that of the 139 sampled rivers, eighty percent were found to contain levels of pesticides, residues from over the counter drugs and prescription drugs, antibiotics, caffeine, and hormonal chemicals from estrogen-laced birth control and replacement therapies. Residues of drugs from intensified livestock practices, including steroids and anti-microbials were also detected.

While little is known about what the findings mean from a clinical standpoint, the results of the study should provide reason for pause. Antibiotic residues could affect human health by promoting the resistance of bacteria. Plasticizers and estrogenic substances could encourage the outgrowth or progression of various cancers. While long-term effects remain uncertain, the quality of the water in our rivers and the health of the organisms and ecosystems supported, including the twenty six salmon runs and habitats in the Pacific Northwest, is almost certainly weakened under the weight of this newly disclosed contamination.

Six California rivers were sampled, including the Sacramento River, Cucamonga Creek, and San Timoteo Creek. Pesticides have been suspected of leading to declines in aquatic populations, and even if concentrations are below the lethal thresholds, the combination of multiple pesticides and their metabolites could potentially cause effects ranging from developmental to reproductive changes. Salmon, whose health as a keystone species reflects the conditions of our environment, have been declining over the years. Pacific salmon have disappeared in 40% of their historic runs and where salmon remain their populations are in jeopardy. Forty percent of the streams contained levels of hormones. Low levels of such hormones can also interfere with the production of sperm and juvenile development including proper formation of immune systems and the ability to swim properly. Secondary effects to salmon may include the reduction of food sources, which may be diminished by the toxicity of some of the chemicals, as well as the impairment of habitat for spawning and juvenile salmon. The recovery and restoration efforts for salmon populations could be dramatically impaired by the emerging findings of contaminants presenting cumulative hazards.

The USGS's report does not mirror the health of all rivers, though it does focus on the most vulnerable streams, those running through urban areas or industrialized agricultural rural zones. While some of the contaminants found may or may not become a part of our drinking water, the findings of nicotine byproducts and excreted ibuprofen clearly show that our wastewater treatment plants are not filtering out the host of drugs and chemicals we ingest. The chemicals found also include many from agricultural discharges, which have previously been excluded from the federal Clean Water Act. At a minimum, the findings should prompt the federal government to begin placing limits on discharges from agricultural pesticides, steroids and antibiotics used in livestock operations and other biologically active metabolites that easily find their way into waterways.

The Food and Drug Administration has responded to the USGS report by reviewing the need to reinstate tests for environmental effects during the drug approval process. Under the Clinton administration, the drug evaluation program was simplified, and testing for environmental effects was all but eliminated for many drugs including hormones. However, it is precisely these hormones that many physicians believe require renewed scrutiny because of their suspected effects in children and fetuses. Hormone containing substances are thought to be responsible for changing sexually related features such as onset of puberty in young girls, changing incidence in certain male-related birth defects, and increased prevalence of hormone related cancers, and diminishing rates of sperm in males.

The USGS report is the first step in quantifying and perhaps limiting the degree to which we pollute our waters. While all of the contaminant levels have not been fully established, this survey should act as a wake-up call to federal and state agencies. Where there are gaps in regulations, the holes should be filled. The implications of highly active antibiotics, hormones, and drug-byproducts in our waterways are an index of an unprecedented degree of environmental contamination. While the immediate and even long-range effects remain imprecise, there is little doubt that the trends exposed by the USGS study are matters of urgent concern.