There is concern over the presence of pollutants in our water supply. Among the pollutants that have elicited the greatest alarm are those that can alter the development and reproduction of aquatic organisms and potentially harm human health. These chemicals, generally referred to as endocrine disrupting compounds (EDCs), enter waterways as runoff from farms, effluent from wastewater treatment and manufacturing plants, and leachate from septic systems.
The Assabet River in eastern Massachusetts is a highly impacted waterway with nine towns along the 31 miles of the mainstem. Four municipal wastewater treatment plants; Westborough, Marlborough, Hudson, and Maynard discharge into the Assabet. Seven of the nine Assabet main towns take all or part of their public water supply from groundwater and surface sources in the Assabet Watershed, greatly reducing flow. It is estimated that at certain times of the year as much as 90% of the Assabet River is effluent. Two groups of EDCs frequently detected in effluent are estrogenic and dioxin-like (also called CYP1A1-inducing) compounds. All estrogens, both natural hormones and synthetic compounds can to some extent 'turn on' genes to produce proteins that make cells grow and divide. 17beta-estradiol is a natural estrogen, which is critical for normal growth and development. Levels of 17beta-estradiol vary during development, between the sexes, and, for adult women, throughout the month. Exposure to estrogens, either natural or synthetic, outside of the range needed for normal functioning can disrupt cellular activity and increase the risk of developing disease.
A wide range of natural and synthetic compounds share a molecular structure that allows induce the production of the enzyme, cytochrome P4501A1 or CYP1A1. CyP1A1 plays a pivotal role in metabolizing drugs and environmental pollutants, as well as natural hormones and other compounds produced by the body. Overproduction of the enzyme CYP1A1 is associated with increased risk of several diseases. Thus exposure to CYP1A1-inducing compounds can be a serious health risk. Many human-made compounds including polycyclic aromatic hydrocarbons and dioxin-like compounds, bind the aryl hydrocarbon receptor with high affinity.
Given the highly-impacted nature of the Assabet River and the ability of many compounds to mimic the actions of estrogenic and CYP1A1-inducing compounds, we have selected to use a biological assay to monitor the Assabet River for the presence of these EDCs. We will use the Japanese medaka, a small fresh water fish, easily maintained in the laboratory to monitor water from the Assabet River. When male Japanese medaka are exposed to estrogenic compounds a gene is turned on that is normally off in males. Measuring mRNA of this gene, vitellogenin, allows us to determine the levels of estrogens in the water. Likewise measuring the extent to which exposure to water from the Assabet River turns on the CYP1A1 gene, allows us to know how much CYP1A1-inducing compounds are in the Assabet. Monitoring the levels and locations of EDCs in the Assabet River can be useful in protecting the aquatic environment.