How Chemicals Affect Us
By NICHOLAS D. KRISTOF

Damon Winter/The New York Times
Nicholas D. Kristof
These days there is also growing evidence linking this class of chemicals to problems in humans. These include breast cancer, infertility, low sperm counts, genital deformities, early menstruation and even diabetes and obesity.
Philip Landrigan, a professor of pediatrics at Mount Sinai School of Medicine, says that a congenital defect called hypospadias — a misplacement of the urethra — is now twice as common among newborn boys as it used to be. He suspects endocrine disruptors, so called because they can wreak havoc with the endocrine system that governs hormones.
Endocrine disruptors are everywhere. They’re in thermal receipts that come out of gas pumps and A.T.M.’s. They’re in canned foods, cosmetics, plastics and food packaging. Test your blood or urine, and you’ll surely find them there, as well as in human breast milk and in cord blood of newborn babies.
Last month, the Endocrine Society, the leading association of hormone experts, scolded the Food and Drug Administration for its failure to ban bisphenol-A, a common endocrine disruptor known as BPA, from food packaging. Last year, eight medical organizations representing genetics, gynecology, urology and other fields made a joint call in Science magazine for tighter regulation of endocrine disruptors.
Researchers warn that endocrine disruptors can trigger hormonal changes in the body that may not show up for decades. One called DES, a synthetic form of estrogen, was once routinely given to pregnant women to prevent miscarriage or morning sickness, and it did little harm to the women themselves. But it turned out to cause vaginal cancer and breast cancer decades later in their daughters, so it is now banned.
Scientists have long known the tiniest variations in hormone levels influence fetal development. For example, a female twin is very slightly masculinized if the other twin is a male, because she is exposed to some of his hormones. Studies have found that these female twins, on average, end up slightly more aggressive and sensation-seeking as adults but have lower rates of eating disorders.
Now experts worry that endocrine disruptors have similar effects, acting as hormones and swamping the delicate balance for fetuses in particular. The latest initiative by scholars is a landmark 78-page analysis to be published next month in Endocrine Reviews, the leading publication in the field.
“Fundamental changes in chemical testing and safety determination are needed to protect human health,” the analysis declares. Linda S. Birnbaum, the nation’s chief environmental scientist and toxicologist, endorsed the findings.
The article was written by a 12-member panel that spent three years reviewing the evidence. It concluded that the nation’s safety system for endocrine disruptors is broken.
“For several well-studied endocrine disruptors, I think it is fair to say that we have enough data to conclude that these chemicals are not safe for human populations,” said Laura Vandenberg, a Tufts University developmental biologist who was the lead writer for the panel.
Worrying new research on the long-term effects of these chemicals is constantly being published. One study found that pregnant women who have higher levels of a common endocrine disruptor, PFOA, are three times as likely to have daughters who grow up to be overweight. Yet PFOA is unavoidable. It is in everything from microwave popcorn bags to carpet-cleaning solutions.
Big Chem says all this is sensationalist science. So far, it has blocked strict regulation in the United States, even as Europe and Canada have adopted tighter controls on endocrine disruptors.
Yes, there are uncertainties. But the scientists who know endocrine disruptors best overwhelmingly are already taking steps to protect their families. John Peterson Myers, chief scientist at Environmental Health Sciences and a co-author of the new analysis, said that his family had stopped buying canned food.
I’m taking my cue from the experts, and I wish the Obama administration would as well.
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Prenatal Pesticide Exposure May Harm Kids’ Brains
Compared to children with low prenatal exposure, those with high exposure to the pesticide chlorpyrifos had abnormalities in the cortex (the outer area of the brain), says Virginia Rauh, ScD, professor and deputy director of the Columbia Center for Children’s Environmental Health at the Mailman School of Public Health at Columbia University.
The cortex helps govern intelligence, personality, muscle movement, and other tasks.
The study is published in Proceedings of the National Academy of Sciences’ Early Edition.
In 2001, the U.S. EPA banned the residential use of chlorpyrifos. It still allows it on crops. It can also be sprayed in public places such as golf courses.
Some environmental advocates have petitioned the EPA to ban agricultural use.
Prenatal Exposure to Pesticides: Study Details
Rauh’s team selected 40 children from a larger group of 369 children, followed from birth.
All had been born between 1998 and 2001, before the household-use ban. Rauh had sent their umbilical cord blood samples to the CDC to analyze pesticide levels.
For this study, she selected 20 children with high prenatal exposure and 20 with low prenatal exposure. She took MRIs of their brains when they were about 6 to 11 years old.
Overall brain size did not differ much between the two groups. However, the high-exposure group had enlargements in many areas and reduced volumes in other areas.
The findings reflect those from animal studies, Rauh says. In other studies, Rauh has found higher exposure to the pesticide is linked with lower IQs and a decline in working memory in children.
The pesticide works by blocking an enzyme needed by pests — and people — for proper nerve functioning. It belongs to a class known as organophosphates.
Chlorpyrifos and the Food Supply
In 2007, the Natural Resources Defense Council petitioned the EPA to cancel all agricultural registrations for the pesticide.The EPA is reviewing the role of chlorpyrifos in agriculture.
Symptoms of poisoning from the pesticide include nausea, dizziness, confusion, and sometimes loss of respiratory muscle control and death, according to the NRDC.
‘Prenatal Pesticide Exposure: Two Perspectives
The new research finding is concerning, says Sonya Lunder, MPH, senior analyst at the Environmental Working Group. EWG supports a ban on the pesticide.
“Once you have changed the way the brain is born, and the structure, we are talking about things you can’t offset with a good education or a good diet,” she tells WebMD.
Meanwhile, industry groups say the pesticide should not be banned.
On a web page, “Chlorpyrifos Protects,” Dow AgroSciences, its manufacturer, says: “Growers clearly need a trusted, well-established product to protect a wide range of crops from a diverse spectrum of damaging pests.”
Since the pesticide was registered by the EPA in 1965, its use has become common in more than 50 crops, according to Dow. Among them are citrus fruits, apples, soybeans, sweet corn, and peanuts.
Research offers little support for claims that prenatal exposure could lead to reduced IQ scores, according to Dow.
Advice for Pregnant Women
Rauh advises women who are pregnant to avoid farming jobs.
Wash produce well before eating, she says. Buying organic produce is a good idea, she says, though not always practical. “It’s a very expensive way to go and I think is out of reach of the average person,” Rauh says.
SOURCES:
Rauh, V. PNAS Early Edition, April 30, 2012.
Sonya Lunder, MPH, senior analyst, Environmental Working Group.
Carolyn O’Donnell, spokeswoman, California Strawberry Commission.
Dow AgroSciences web site: “Chlorpyrifos Protects.”
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