Chemicals in the Water Still Bending Genders
In Iceland, the river Kolgrima makes its way to sea. Photo: National Geographic Brazil
As the world takes pause to recognize the importance, and often perilous state, of its water supply--from massive islands of plastic drifting in the ocean, to industrial runoff and poorly managed waste polluting lakes and rivers--it's all too easy to feel overwhelmed. But, as disturbing the image of animal tangled in our discarded waste is, one less visible contaminant continues to wreak havoc on aquatic ecosystems worldwide, and its implications are almost more troubling. For decades, substances found in many common products have found their into our planet's water and are altering the hormones of wildlife until, in some cases, it changes their sex entirely--and the same thing may be happening to us.Endocrin Disruptors Alter Hormone Levels
According to a recently published article in the journal Unesp Science, changes in the sexual organs and reproductive problems are being increasingly observed in various species around the world, and the culprits are endocrine disrupters. Such contaminants are found in some of the most common products, though their effects on wildlife is profound.
Luciana Christante of Universidade Estadual Paulista, writes:
From plastics to pesticides, cosmetics substances for industrial use, through to detergents and human urine, the sources [of endocrine disrupters] are numerous and diffuse. The molecules are chemically very distinct from each other, but they have in common the ability to interact with estrogen receptors that most animals carry in their cell membrane. "Disguised" hormone, they produce a misleading message that can make the cell multiply, die or produce certain proteins at the wrong time, for example.
Males Hermit Crabs Are Becoming Females
Perhaps the most dramatic effect of endocrine disrupters on developing organisms are there ability feminize males, and occasionally make females more masculine. While these substances are suspected to have lead to a drop in fertility among polar bears, penguins, and other exposed species--a study involving hermit crabs is shedding light onto the extent of the problem in one region of the world.
After surveying 25 estuaries along the coast of Brazil, a researcher from Biosciences Institute of Unesp found that 8 percent of the crabs possessed both male and female reproductive organs. It is believed that a substances called TBT is to blame. The chemical is found in type of paint used by sailors to keep barnacles from growing on the hauls of their ships.
In recent years, use of the paint has been banned, though clearly the problem persists. In fact, many substances containing potential endocrine disrupters have been outlawed, such as DDT, but others are still in use. Some plastics, for one, have been found to contain the gender-bending contaminant, reports Unesp Science.
But What is it Doing to Us?
Some researchers suspect that endocrine disrupters have been manipulating the hormone levels in humans as well. There has been a drastic decline in the sperm count of men over the past 60 years, and the substance may be to blame, but with some many possible culprits introduced in that period, proving a connection may be impossible. Animal testing with endocrine disrupters, however, has produced similar responses.
Wilson Garden of the Institute of Chemistry at Unicamp:
It is very difficult and sometimes frustrating, to confirm a causal link between these contaminants and human health. But the environmental impact of them is already well established.
Although there has been a push to limit the presence of endocrine disrupters in the world's ecosystems, research shows that it is still changing the sex of some aquatic organisms, which may continue to find its way into humans later on down the food chain. But sadly, it may take a measurable human toll to renew the fight for cleaner oceans, lakes, and streams--since few things make people more uncomfortable than undergoing an unsolicited sex-change.