Everyday chemicals are damaging the brains of unborn and young children, leading to conditions like autism, ADHD, dyslexia and lost IQ points, according to two prominent doctors.
In an article published Friday in the journal Lancet Neurology, the two argue that chemicals should be better tested before being allowed on the market, and called for a global prevention strategy.
"We need to do something to protect the next generation's brains," said Philippe Grandjean of the Harvard School of Public Health in Boston.
This is the second time Grandjean and Philip Landrigan, a pediatrician at the Icahn School of Medicine at Mount Sinai in New York City, have sounded an alarm about the behavioral and brain effects of chemical exposures during pregnancy and early childhood.
In 2006, they said that five chemicals - lead, methylmercury, arsenic, PCBs and toluene - should be considered toxic to the developing brain. The doctors did not conduct new studies on these substances, but now, based on a reading of new research, which has been exploding in recent years, they've added six more:
• Manganese, a natural chemical found in drinking water in places like Bangladesh.
• Fluoride, in high concentrations, which has caused problems in China, though the low levels added to American drinking water are presumed safe.
• Chlorpyrifos, an insecticide used on golf courses and in agriculture among other places.
• Dichlorodiphenyltrichloroethane (DDT), an insecticide banned in the U.S. in the 1970s, but still used in some countries.
• Tetrachloroethylene (PERC), a solvent used in dry cleaning and metal degreasing.
• Polybrominated diphenyl ethers (PBDE), also known as flame retardants and often found in furniture, electronics and clothing, including children's pajamas.
Upsetting the careful balance of brain development can cause problems that range from a few lost IQ points to severe autism, Landrigan said.
Pregnancy, he said, "is a vulnerable time." A pregnant woman's body is well designed to protect the baby in case of a fall, he said, but doesn't do much to protect against chemicals, many of which can pass through the mother into the fetus.
Low-dose exposures are not enough to make pregnant women sick, so they don't know their fetus has received a harmful amount of the substance, Grandjean said.
The chemical industry wasn't any more impressed with the pair's new study than with their 2006 publication.
In a prepared statement, the American Chemistry Council, an industry trade association, dismissed Landrigan and Grandjean's findings as "flawed" and accused the doctors of ignoring "the fundamental scientific principles of exposure and potency."
They criticize the scientists for focusing on chemicals whose problems are well known and quite out of the ordinary. "They then extrapolate that similar conclusions should be applied to chemicals that are more widely used in consumer products without evidence to support their claims. Such assertions do nothing to advance true scientific understanding and only create confusion and alarm," according to the statement.
Landrigan and Grandjean said they no longer consider chemicals like lead and mercury exceptions. The message of their new study, they said, is that many, many chemicals have similar damaging effects on the fetal and early childhood brain.
"We're now concluding there is a pattern here," Grandjean said.
The problem is that we simply don't know the effect of more than 99% of chemicals on the market, they both said in separate phone interviews this week.
The chemical industry is extremely concerned about safety and takes adequate precautions to ensure their products are safe if used as intended, according to the American Chemistry Council statement.
Council members do agree with the scientists that the 38-year-old Toxic Substances Control Act needs to be updated. "A strong, comprehensive federal chemical assessment and risk management program enhances the safety of all Americans," the statement read.
Suggestions for avoiding dangerous exposures during pregnancy and early childhood:
1) Eat organic food when possible during pregnancy.
2) Stay away from paint thinners, removers, pesticides and strong cleaning agents during pregnancy.
3) Get young children checked for lead exposure.
4) Ensure that sports fields are not sprayed with pesticides shortly before children use them.
Sources: Philippe Grandjean and Philip Landrigan