Exposure to low-levels of some contaminants can cause disruption of endocrine functions, such as reproduction, in animals.
This disruption occurs when the contaminants modulate, mimic or interfere with normal hormonal activity. Examples of endocrine-active contaminants are chemicals such as synthetic hormones, certain pesticides, some pharmaceuticals, detergent degradation products such as nonylphenol, and many others.
Among aquatic life, one example of endocrine disruption is intersex, or the presence of male and female characteristics within the same fish. Experts are observing this abnormality in fish in streams across the nation, according to the U.S. Geological Survey. Endocrine disruption can result in adverse effects on the development of the brain and nervous system, the growth and function of the reproductive system and the response to stressors in the environment. These disruptions can have ruinous impacts on fish populations.
For example, a 2008 Colorado study showed the population of fish downstream of wastewater discharge from a sewage treatment plant was dominated by females, and 18 to 22 percent of fish exhibited intersex.
Another 2008 study documented complex effects of fish exposure to nonylphenol, a degradation product used in large quantities in commercial and household detergents. Scientists reported in the journal Aquatic Toxicology that low doses of nonyphenol “primed” the males for breeding competition, whereas higher exposures inhibited their breeding behavior.
Another product found in ground and surface water, bisphenol A, has been linked to the early onset of puberty in laboratory animals, according to a 2009 study published in Environmental Health Perspectives. BPA is commonly found in plastic bottles, containers and even the linings of metal and infant formula food cans, though it was banned from baby bottles in 2012.
The ubiquitous presence of these synthetic compounds and their effects on life are one reason ECU researchers are taking a closer look at septic systems in eastern North Carolina.
“If (organisms) are exposed to these compounds from the time they are conceived to the time they are ready to reproduce, that’s their entire developmental process,” said Jamie DeWitt, an assistant professor of pharmacology and toxicology at the Brody School of Medicine at ECU.