by Janisse Ray
Silent Spring opened the floodgates of inquiry into environmental contaminants and their effects on wildlife and humans, an investigation that accelerated in the 1990s. Weâ€™ve looked at chemicals in high doses as lethal. Weâ€™ve looked at chemicals as carcinogenic. But they may be affecting us in other life-threatening ways.
In the past two decades, study after study has shown what Rachel Carson predicated. Chemicals are disturbing normal hormone-controlled development, affecting gender, sex, and reproduction. And, we are now seeing, low doses are disruption enough.
Fish appear particularly at risk of hormone disruption. Near a bleached kraft paper mill on Lake Superior, white suckers exhibited lower levels of hormones, took longer to mature, developed smaller sexual organs, and, once mature, produced fewer eggs. Some eggs refused to grow, although some did hatch, and some of these larvae survived. Lake whitefish showed similar results.
Four miles downstream from pulp and paper mills in north Floridaâ€™s Fenholloway River, mosquitofish females developed a male sex organ called a gonopodium and attempted to mate with female fish. The scientific term for dual sex anatomy is intersex, which means an abnormal presence of traits of both sexes in one specimen. Intersex roach, as well as other species of fish, were found in rivers in the United Kingdom, with incidences significantly higher downstream of sewage treatment works.
Recently, the fish pathologist Vicki Blazer, searching for a reason for a die-off of smallmouth bass in the South Branch of the Potomac River, found that almost all of the male bass surveyed were intersex in that they contained immature eggs in their testes. They also had lower sperm counts and the sperm were less motile than in healthy bass.
The abnormalities, of course, are not restricted to fish.
Scientists have found female marine snails that developed male genitalia. Theyâ€™ve found gulls becoming feminized, meaning a sex ratio skewed toward the female, with many males not mating or parenting. One beluga whale in the St. Lawrence estuary of Quebec had two ovaries, two testes, male genitalia, and partial female organs. Female black bears in Alberta have exhibited some degree of male sex organs.
In fact, a report published in 2003 by the Scientific Committee on Problems of the Environment and the International Union of Pure and Applied Chemistry states that more than two hundred animal species are known or suspected to have reproductive disorders that might be attributed to endocrine disrupting chemicals (EDCs), synthetic compounds that, when absorbed in the body, disrupt its natural functions. Over 100,000 chemicals, most inadequately tested, are now on the market.
Our endocrine system is composed of glands — including the hypothalamus, pineal, pituitary, thyroid, thymus, adrenal, kidney, pancreas, ovaries, and testes — that secrete hormones. These hormones, including adrenaline, insulin, thyroxin, estrogen, testosterone, androgen, and melatonin, are secreted directly into the bloodstream. Since hormones function away from their source (the pituitary serves as control center) they are known as â€œmessengers.â€ The human endocrine system controls growth, metabolism, and fertility, and assists our bodies in tasks both minor and major, such as reaction to fear, transformation during puberty, control of brain development, and storage of energy.
A developing fetus receives messages not only through its own hormone system but also its motherâ€™s. These signals guide its development, shaping characteristics as blatant as number of toes to those as intricate as details of the brain.
Some chemicals are more proven than others to cause endocrine disruption.
DDT, of course, bioaccumulated in wildlife and caused eggshell thinning, leading to reduced populations of many bird species.
Diethylstilbestrol, or DES, is a synthetic estrogen that was prescribed to millions of pregnant women in the United States from the 1940s to the 1970s to prevent miscarriage. It causes a rare form of vaginal cancer in daughters of women who took the hormones and other adverse affects in both daughters and sons.
For fifty years polychlorinated biphenyls (PCBs) were used in products ranging from fluorescent light fixtures to adhesives to coolant fluids inside electronics. Though they were banned in the United States in 1977 and are restricted through much of the world, PCBs remain in the environment and can be found in our food chain, including in mothers milk.
Many, many other pesticides and chemicals are suspected to be EDCs.
But not only reproductive and gender-related systems are affected. The endocrine system regulates all hormone activity. The negative effects may be legion. Declining intelligence. Immune suppression. Behavioral abnormalities. Sleep abnormalities. Testicular cancer. Prostate cancer. Breast cancer. Hyperthyroidism. Obesity. Diabetes.
All over the world, citizen-advocacy groups are calling for decreased exposure to chemicals. Evidence mounts, study after chilling study, until I am convinced that worldwide exposure to endocrine-disrupting chemicals is a dangerous, unplanned, vast experiment in human health, the upshot of which we may not realize for generations to come.
My family has rallied to weaken the role of plastic in our household, and to avoid pesticides, herbicides, and chemicals in general. Weâ€™ve mostly replaced bleach with peroxide and we buy unbleached products. We clean with baking soda and vinegar. Weâ€™ve bought stainless steel water bottles. I wonder how I can ever, even with my cloth grocery bags and pottery lids, get away from human made molecules. Theyâ€™re everywhere.