The number of industrial chemicals, heavy metals and pesticides proven capable of derailing normal brain development -- and robbing children and society of dollars, IQ points and future potential -- has doubled over the last several years, according to a new paper published Friday.
Dr. Philippe Grandjean, one of the co-authors, suggested that the world is facing a "silent pandemic" of "chemical brain drain."
"We have an ethical duty to protect the next generation," he said. "In particular, the next generation’s brains."
As a medical student in the 1970s, Grandjean remembers watching a young Japanese teenager, Shinobu Sakamoto, on the TV news. Sakamoto struggled to walk and talk, but was determined to let the world know about her people's plight. Many in her fishing village of Minamata had unknowingly consumed seafood heavily tainted with methylmercury. Her mom had done so while Sakamoto was in her womb.
"I was shocked, as they didn't teach us anything about the effects of pollution on human health" in medical school, recalled Grandjean, chair of environmental medicine at the University of Southern Denmark and an adjunct professor at the Harvard School of Public Health. "That was the moment I decided to do something about it."
Grandjean has spent the decades since investigating chemicals capable of damaging the developing brain. He started with lead, then mercury. "Every time I turned over a stone, I found something new," he said.
The line-up has now grown to a dozen "bona fide brain drainers," said Grandjean. That's twice as many chemicals as he and co-author Philip Landrigan, chairman of the department of preventative medicine at the Mount Sinai School of Medicine in New York City, listed in their first review of the science in 2006.
Joining methylmercury, lead, arsenic, PCBs, toluene and ethanol, according to the authors' updated list, are manganese, fluoride, DDT, chlorpyrifos, tetrachloroethylene and polybrominated biphenyl ethers.
The consequences of exposure in the womb or during the first years of life to any of these heavy metals, pesticides, solvents, flame retardants and other industrial compounds may not always be as obvious as they were for Sakamoto. But the effects on society, experts warn, can be profound.