Chief Science Correspondent
You wouldn't notice it just by looking at them, but something strange is happening to fish in rivers across the Northeastern United States.
Researchers have discovered that an increasing number of male fish are displaying feminine characteristics, including egg production. In her June 2014 paper "Reproductive health indicators of fishes from Pennsylvania watersheds: association with chemicals of emerging concern," Vicki Blazer reports findings of intersex males in the smallmouth bass (Micropterus dolomieu), white sucker (Catostomus commersonii), and redhorse sucker (Moxostoma carinatum), sampling Pennsylvania watersheds from the Delaware, Susquehanna, and Ohio Rivers.
Scientists believe this phenomenon is due to the introduction of synthetic estrogen and estrogen-like chemicals into the rivers, which disrupt hormone production in previously normal males. These chemicals enter the water through human waste, as well as agricultural and industrial production.
The phenomenon has been associated with women's birth control pills. However, researchers believe other synthetic chemicals, such as polychlorinated biphenyl (PCB) used in cooling fluids, and Bisphenol A (BPA) used in many plastics.
On an individual level, this finding serves as a reminder for consumers not to flush unused birth control pills - or any other medication - down the toilet. The synthetic chemicals go straight to the waters, exposing fish populations to their effects. But Sierra Club New Jersey Chapter Executive Director Jeff Tittel says consumer actions will not counteract the entire effect.
“When you see these kinds of problems with fish, it’s like a canary in a coal mine - an indicator of bigger problems,” Tittel said.
The Sierra Club has pushed for legislation requiring New Jersey to regulate the dumping of synthetic chemicals into the state's waters. Although a representative from the U.S. Geological Survey says the fish do not pose a threat to humans, Tittel says he believes the chemicals are likely to build up over time through biomagnification.
It is likely impossible to truly determine the effects of these altered fish on human health; and we shouldn't have to wait around to find out.
It is largely unknown how this effect could alter reproduction in these populations. As of now, the male fish eggs do not reach maturity. So we won't see fathers becoming mothers, at least for now.
However, Blazer reported at least one intersex defect in nearly every male individual white sucker and smallmouth bass sampled. If the effect lowers male fertility, the populations may be unable to sustain adequate population numbers in the future. Even if we can reverse the effect within the next decade, a generational bottleneck would severely decrease population diversity, leading to lower overall fitness and a decreased likelihood of population survival.
If we want to save our fish populations, it is evident that our industrial behavior must change. In addition to the obvious solution of banning BPA and PCBs, it may be time to consider the use of more natural chemicals in our medications.
For instance, birth control pills do not need to be made from synthetic estrogen-like chemicals. One brand, Qlaira, bills itself as the "natural birth control pill" because it is derived from the plant hormone estradiol, rather than a hormone produced in a laboratory.
I am nor endorsing Qlaira, as I know little about its effectiveness as a medical alternative or its effects on fish populations. However, Qlaira demonstrates that there may be another way for us to continue our everyday lives without harming the natural species that we rely on for both food, both as a source and an element of the aquatic ecosystem.