Environmental awareness on a large scale dates from the publication 50 years ago of Rachel Carson's book "Silent Spring." Because of her book's focus upon the persistent, toxic effects of the insecticide DDT, that agent was eventually banned.
A recent study in the medical journal Endocrine Reviews raises similar concerns about a number of less publicized toxins with far-reaching, unintended effects on our glandular systems. These substances, called endocrine-disrupting chemicals (EDCs), have been widely studied for years. EDCs block receptors on our cells that normally respond to the hormones produced and released by our various endocrine glands.
EDCs are unique in causing effects at extremely low concentrations. Testing for toxic effects of chemicals often does not extend to concentrations of parts per billion. Some EDCs show different effects as the concentration of the chemical increases. Thus, some toxic effects will be missed by standard tests for side effects.
The review summarizes data for 27 chemicals with documented effects as EDCs. These include components of plastics, pesticides, sunblocks, preservatives and industrial byproducts. A further listing of chemicals with suspected EDC properties includes cosmetics and personal care products, flame retardants and anti-bacterial agents.
Bis-phenol A (BPA) is one of four chemicals highlighted. BPA, which acts as a weak estrogen, is a component of many plastics including those used in the liners of canned goods, storage containers and bottles for water and soft drinks. BPA slowly leaches into contents of these vessels, the process being accelerated by heating. BPA is steadily released into soil and groundwater as billions of plastic containers find their way into landfills every year. Most of us have measurable levels of BPA in our blood and urine.
Multiple animal studies document BPA effects on prostate glands and breast tissue. BPA has been linked to later development of breast cancer whether exposure occurs before or after birth. Other studies link BPA to slowed intellectual development and impaired immunity.
In January 2010 the Food and Drug Administration raised concerns about BPA and announced efforts to reduce its use in food packaging. On March 31 the Environmental Protection Agency announced plans to study BPA to determine if it should be added to its "list of chemicals of concern." Lobbying to maintain the status quo is intense. Both FDA and EPA are chronically underfunded and subject to continuing attack by politicians opposing governmental regulations in general.
The scientific evidence is quite strong that BPA poses major risks to health. While hobbled agencies act with glacial speed, concerned consumers need to avoid BPA-containing products and pressure our various representatives to study and to act on a dangerous chemical.
BPA is but one of numerous chemicals to which we are exposed every day. The meticulous study in Endocrine Reviews highlights other chemicals that act as EDCs. Atrazine, a widely used herbicide, interferes with sexual differentiation and production of sex hormones in a variety of species. EPA has set a limit of Atrazine in drinking water at 3 micrograms per liter. Environmental levels, including concentrations in streams and ponds, may exceed this. Laboratory studies suggest that Atrazine may exert its effects at concentrations far below "safe" levels.
Perchlorate, another EDC, is a byproduct of explosives and solid fuels used in rocketry. The chemical interferes with the function of the thyroid gland and is found widely in groundwater and most foods. Perchlorate can be detected in the urine of most Americans.
Dioxin, one of the most toxic by-products of modern times, acts as an EDC by interfering with sexual development, this is in addition to its actions as a carcinogen and liver toxin.
Studies focus on a single chemical at a time. We, however, are exposed to multiple chemicals every day. We are clueless regarding the effects of simultaneous exposures to an array of toxins. We can remain unconcerned at our peril. We can insist our elected officials tune out lobbyists and take seriously environmental threats to our health.
Contact Clif Cleaveland at firstname.lastname@example.org.