A friend of mine worked in the petroleum industry for much of her professional career, now consults on ecological business practices, and in the year 2000 found herself in a conversation with the Global Head of Shell Chemicals. They discussed the risks to human health posed by petroleum compounds, and when he outlined industry safety precautions, she asked him, "So, what keeps you awake at night?"

Without hesitation, perhaps in a moment of unguarded honesty, the scientist responded, "Endocrine disruption."

Certain synthetic, hydrocarbon-based chemicals – PCBs, bisphenols, dioxins, and so forth – can mimic the body's endocrine hormones and disrupt cell messaging and response. The endocrine system in mammals – including the pancreas, ovaries, testes, pituitary, pineal, thyroid, hypothalamus, and adrenal glands – secretes hormones that regulate the body's metabolism, growth, tissue function, healing, sexual function, fetal development, sleep, emotions, and mood.

The chemicals that disrupt this system are so common now – found in thousands of products, landfills, oil spills, household goods, and chemical effluents – that they have exposed almost everyone on Earth. Their effects are linked to developmental dysfunction ranging from learning disabilities to diabetes and depression. Recent studies reveal effects from combinations of these compounds even at very low doses.

The Shell scientist felt concern about these chemicals because the hydrocarbon and chemical companies remain potentially liable for the massive modern epidemic of endocrine system dysfunction in human health. When my friend asked him, "What could be done about it?" he hung his head and whispered to her, "Nothing - and I only hope I am dead by the time it is figured out."

The disruptors

Rachel Carson introduced the danger of endocrine disrupting chemicals (EDCs) over fifty years ago in Silent Spring, and she identified three critical points: Human health has an ecological context, the effects of these toxins are intergenerational, and they potentially impact every living creature because they work at the cellular level.

Endocrine disruptor diagram, European Parliamentary Research Service (http://epthinktank.eu/2012/07/05/health-threats-from-endocrine-disruptors-a-scientific-and-regulatory-challenge/)Endocrine Disruptors mimic hormones, image by European Parliament Research Service.

EDCs that chemically resemble the body's hormones, trick receptor cells with false messaging, and can result in cancer, birth defects, and other developmental disorders. They bioaccumulate in organisms through the food chain, building up in large carnivores, including humans. These petroleum chemicals are carbon-based organic molecules that are naturally adept at building new versions of themselves. They act in combination to create health effects, and merge to create new compounds with new effects.

Carson understood and warned that EDCs are passed to fetuses in the womb, which may be the most pervasive human and wild animal health risk. "These exposures now begin at or before birth," she said, "and – unless we change our methods – will continue through the lifetime of those now living."

A 2011 US study found EDCs in 99% of pregnant women. This is a recipe for an epidemic of endocrine related disabilities, which we now witness in heavily industrialized societies. "Exposure to endocrine-disrupting chemicals during early development can have long-lasting, even permanent consequences," writes Jean-Pierre Bourguignon, Professor of Pediatrics at the University of Liège in Belgium. "The science is clear."

Many of these compounds are well known, while others can be obscure. Industry creates hundreds of new chemicals every year.

DDT: Revealed in the 1940s to harm humans, birds, insects, fish, and marine invertebrates. DDT is typically found in the eggshells of large birds, as described by Carson, and appears in higher concentrations in carnivores through bioaccumulation. DDT interferes with reproductive development, increases risk of obesity, and causes other developmental dysfunction. DDT is banned for agricultural use, but is still used as an insecticide, primarily in Africa and Asia.

PCBs (Polychlorinated biphenyls) are gasoline byproducts, refined with chlorine, and used as a coolant or lubricant. The health risks have been known since 1933 when US chemical workers developed skin acne from contact. Monsanto acquired the rights and downplayed the risks. General Electric used PCBs in electronic products and by 1977 had dumped over 500,000 pounds of PCBs into New York's Hudson River. The poisoning of thousands of Japanese citizens in the 1960s led to a global ban in 1977, but they persist to this day in Earth's ecosystem. Studies show that PCBs interfere with the endocrinefunctions of the liver and thyroid; increase obesity and diabetes risk in children exposed in utero; and increase the risk of skin, liver, and brain cancers.

PBDEs (Polybrominated diphenyl ethers) are flame retardants found in plastic cases for electronic gear, computers, military weapons, clothing, textiles, carpets, and many household items. Evidence suggests they act as neurotoxins and are associated with learning disabilities. The European Union banned some PBDEs in 2006.

Bisphenol A (BPA): Commonly found in plastic bottles, food containers, dental materials, the linings of metal food cans, infant formula cans, and in heat-treated cash register receipts used at grocery stores and restaurants. Animal studies have found that even low levels of BPAs can cause elevated rates of diabetes, mammary and prostate cancers, decreased sperm count, early puberty, obesity, and neurological problems. Prenatal exposure to BPAs, even at levels below safety standards, can cause physical and neurological problems. The 2011 University of California study found BPAs in 96% of pregnant women. Still, the US and World Health Organization have not banned them.

Bisphenol S (BPS) appear in plastics and personal care products, and commonly in household dust. Most plastic products, even those promoted as "BPA free," often contain BPS.

Phthalates appear in toys, flooring, medical equipment, cosmetics, and air "fresheners." They have been linked to the increase in male birth defects. Europe and California have banned them from toys. The US Food and Drug Administration has documented "effects on the development of the male reproductive system and production of normal sperm in young animals," and has "cautioned" against exposing male babies to phthalates, but has not banned them.

Hundreds of endocrine disruptors exist in household goods, our food, air, water, and soil. Alkylphenols, found in fuel additives, lubricants, fragrances, tires, adhesives, and other products – imitate estrogen. Perfluorooctanoic acid – found in carpets, cleaning products, microwave popcorn bags, and coated cookware – can alter thyroid hormone levels, increase pregnancy terms, and bring on early puberty in girls. Dioxins, furans, and polycyclic aromatic hydrocarbons, all common in oil spills, can mimic human hormones.

Syngenta's Atrazine weed killer contaminated some 2,000 water districts around the world, for which the company paid $105 million to settle a class action lawsuit. University of California professor Tyrone Hayes resigned from Syngenta after finding that Atrazine "is a potent endocrine disruptor with ill effects in wildlife, laboratory animals, and humans. Atrazine chemically castrates and feminizes wildlife and reduces immune function… induces breast and prostate cancer, retards mammary development, and induces abortion in laboratory rodents … studies suggest that Atrazine poses similar threats to humans.

Endocrine disruptors have been linked to infertility in deer and declines in the populations of otters, sea lions, and other marine mammals. According to the Endocrine Society, EDCs are linked to rising diabetes, obesity, and cancer rates.

Deadly beauty

Many sunscreens contain oxybenzone, which blocks UV radiation, but also appears to have estrogenic effects in humans.

Even painting your nails can expose you to endocrine system effects. Thousands of nail polish products contain triphenyl phosphate (TPHP), a plasticizer linked to hormone irregularities and obesity. A Duke University and Environmental Working Group (EWG) study demonstrated that TPHP can directly enter the body when polish is applied, both by breathing and skin absorbtion. In the study, Nailed, by Dr. Johanna Congleton at EWG and Dr. Heather Stapleton at Duke, found TPHP in eight out of 10 nail polishes that did not disclose TPHP on their labels. EWG reports that about half of the 3,000 tested nail polishes and treatments list TPHP, and data suggests that most others may also.

The petroleum and chemical companies knew all along that these compounds were toxic waste, yet they found ways to build them into consumer products. "The evidence is more definitive than ever before," says Andrea Gore, Professor of pharmacology at the University of Texas. "EDCs disrupt hormones in a manner that harms human health. Hundreds of studies are pointing to the same conclusion."

Rex Weyler is an author, journalist and co-founder of Greenpeace International.


Chemical exposure linked to rising diabetes, obesity risk

The Endocrine Society report on endocrine disrupting chemicals, September, 2015, Endocrine Review

"Low dose mixture effects of endocrine disrupters: implications for risk assessment and epidemiology,"  Andreas Kortenkamp, International Journal of Andrology; Volume 31, Issue 2, p. 233–240, April 2008.

"Endocrine disruption and human health effects — a call to action,"  Richard M. Sharpe, MRC Centre for Reproductive Health, University of Edinburgh, Nature Review Endocrinology v.7 , 633–634 (2011); doi:10.1038/nrendo. 2011.165

"National Report on Human Exposure to Environmental Chemicals". Centers for Disease Control and Prevention, U.S. Department of Health and Human Services.

Science Daily: "99% of pregnant women in US test positive for multiple chemicals including banned ones;" 163 chemicals, including many endocrine disruptors; University of California, 2011.

Nail polish as a source of exposure to triphenyl phosphate, Dr. Emma Mendelssohn, Dr. Heather Stapleton, et. al, Environment International, v. 86, January 2016, Pages 45–51

Endocrine disruptor nail polish, Treehugger.