Fishes (Representational Image)
Fishes (Representational Image)Reuters

American authorities recently found intersex fish in three river basins in Pennsylvania, a severe indication that water may be contaminated with harmful chemicals.

Male fishes were discovered carrying eggs in the drainage areas of the Susquehanna, Delaware and Ohio rivers, according to a new study led by the US Geological Survey (USGS).

USGS researchers explained that two fish species, smallmouth bass and white sucker, exhibited intersex characteristics, which is linked to chemicals behaving like the hormone estrogen. The chemicals are believed to have most likely got into streams and rivers from agricultural and human waste, eventually making its way into the fishes, according to the researchers.

"The sources of estrogenic chemicals are most likely complex mixtures from both agricultural sources, such as animal wastes, pesticides and herbicides, and human sources from wastewater treatment plant effluent and other sewage discharges," study author Vicki Blazer, a fish biologist with the USGS, said in a statement.

The researchers explain that estrogenic chemicals disturb the endocrine system of living beings, which regulates the release of hormones like estrogen and testosterone, thereby interfering with the ability of the fish to reproduce.

In order to study the factor in details, Blazer and his colleagues collected fish from 16 different sites in the Susquehanna, Delaware and Ohio river basins. They found intersex males at every site where smallmouth bass were collected.

The researchers also took into account white and redhorse suckers but neither species exhibited any intersex characteristics, even though the team did find an egg cell precursor in the blood of some white suckers. Further research will be carried out for better characterizing the timing and sources of exposure to these complex chemical mixtures in relation to fish health.

Researchers have long examined Endocrine-disrupting chemicals (EDC), which can be found in pharmaceutical drugs, herbicides, personal care products and even pesticides.

However, it is not yet clear how the study may affect humans  but Blazer said: "I think any findings on the effects of endocrine disruptors may have implications for humans who can be exposed via the water they drink but also through other ways."

They have even estimated the effects of it on humans, though humans cannot be experimentally exposed to verify the effects. However, conditions like testicular cancer in men, low sperm counts as well as breast cancer, autism and obesity have been linked to EDC exposure, explained Blazer.

The details of the findings were published online in the journal Environmental Monitoring and Assessment.