November 10, 2004

APERC to Follow Up on Colorado Intersex Fish Research

Recent newspaper and television media reports have covered research conducted at the University of Colorado at Boulder that finds intersex fish in Colorado rivers downstream from wastewater treatment plants. The researchers are quoted as being concerned that the intersex fish, which display characteristics of both males and females, are being affected by exposure to natural human estrogens and "estrogen mimickers," which are present in wastewater effluent. Unfortunately, the recent media reports appear to overemphasize the relevance of alkylphenols in their discussion.

The finding that highly potent estrogenic compounds from human waste are present at low levels in treated wastewater effluent is not surprising. In fact, the detection of alkylphenols, such as nonylphenol, in effluent is also not remarkable given the compound's use patterns. However, these compounds are typically found at only trace levels in the aquatic environment and their estrogenic potency is ten thousand to one million times less than that of natural estrogen. Indeed, numerous studies have already demonstrated that the major estrogenic activity present in effluents of sewage treatment plants is from the hormones in human waste (e.g., human estrogen, birth control pills) not from weakly estrogenic compounds like nonylphenol. Most recently, a study sponsored by EPA's National Risk Management Research Program on Endocrine Disrupting Chemicals (Esperanza et al., 2004) found that the removal rate for nonylphenol ethoxylates from the discharge of two lab scale wastewater treatment plants exceeded 96%, while removal rates for some natural estrogens were as low as 50%.

While specific monitoring data from the University of Colorado study are not yet available and APERC is still investigating the specific circumstances related to those locations, a well-founded understanding of the environmental levels of alkylphenols in US surface waters exists. A statistical analysis of environmental monitoring data taken from the peer-reviewed literature shows that levels of nonylphenol, its ethoxylates and biodegradation intermediates in the United States are generally well below EPA's proposed Water Quality Criteria for nonylphenol, which also adequately addresses any endocrine related risks. Given the widespread use of nonylphenol and its derivatives, the low levels found in the environment likely reflect the compound's treatability in well functioning wastewater treatment plants, the use of good disposal practices and the generally high standard of wastewater treatment in the United States.

Studies Find Human Waste is Principle Source of Estrogens in Treated Sewage

EPA Proposes Water Quality Criteria for Nonylphenol

Environmental Levels of Alkylphenols and Their Ethoxylates in the United States                                                                                                                              

 

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