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The study focused on a chemical called permethrin, one of the pyrethroid pesticides, commonly used in agriculture and to kill termites, fleas and household bugs, says lead author Megan Horton of the Columbia Center for Children's Environmental Health. Most of the pregnant women in this New York-based study were exposed by spraying for cockroaches.
Permethrin - among the most commonly detected pesticides in homes - is being used more often today as older organophosphorous pesticides are phased out because of concerns that they harm brain development, says Horton, whose study is being published today in Pediatrics.
Researchers measured 348 pregnant women's exposures by asking them to wear backpack air monitors, Horton says. Researchers followed the women and their children for three years.
Children exposed to the highest pesticide levels before birth were three times as likely to have a mental delay compared to children with lower levels, the study says. Children with the highest prenatal exposures also scored about 4 points lower on an intelligence test, the Bayley Mental Developmental Index. That test has a mean score of 100, with most people's scores falling within 15 points of that range.
That's about the same intelligence loss caused by lead, says Philip Landrigan, a pediatrics professor and environmental health expert at New York's Mount Sinai School of Medicine.
Pyrethroid pesticides kill bugs by "being toxic to the developing brain," Landrigan says. The results are "very believable and should be taken seriously," Landrigan says.
Because the study is the first to link permethrin with brain damage, researchers need to conduct additional studies before concluding that the pesticide really harms the brain, says Mary Fox, an assistant professor at John Hopkins' Bloomberg School of Public Health.
Even without definitive data, however, Fox says it makes sense for pregnant women to reduce their exposure to bug sprays and other pesticides.
To control bugs, for example, she suggests fixing water leaks, keeping food tightly covered and, if necessary, spraying outside instead of inside the home.
This is not surprising and should have been anticipated. Following the accumulation of some 17000 complaints about organophosphate pesticides like Dursban, Carole Browner's EPA finally withdrew permission for the use of a few members of this most commonly used class to be applied in residences and schools. It was known to damage the central nervous system by suppressing production of an enzyme called acetylcholinesterase, essential to inhibiting nerve cells from continuing to fire after the need ended. Hyperactive nerve cell firing can lead to damage and death for cells.
Pyrethroids replaced this class in many homes, schools and offices. It merely uses another mechanism to damage nerve cells causing hyperactivation, damage and death. The problem remains that applications do not require advance notification to building occupants in most situations. While the organophosphate exposures could be assessed medically through blood and/or urine testing for enzyme suppression and chemical metabolites, our government has failed to make such tests available for the pyrethroids.
Widespread exposure was proven in 2002 by the CDC when 70% of Americans (N=3,000) had those metabolites in their urine. However, only research labs look for such findings. Veterinary labs can test your pets for these chemicals but doctors can't prescribe similar tests for humans. I sought assistance from the EPA and the CDC who informed me they were not required to find or require labs to do such testing. It also appears that cholinesterase enzymes may be elevated from baseline in a protective manner but this has not been yet used as a clinical tool for positive identification in medicine.
The major problem is that these are farm chemicals displaced to indoor settings where they behave differently. There is no 'indoor pest control industry' per se. An effort made to remove neuro-toxic pesticides from school settings has been blocked by the House Agriculture Committee for a decade now although the "School Environment Protection Act" was passed twice by the Senate.
My experiences in examining this problem are written up here: [Link] This is a 'no-brainer' when it comes to legislation. There is no reason to place chemicals that damage brains in buildings meant to develop brain functions.
Our schools.
Barbara Rubin
Former Educator, disabled by Pesticides
www.armchairactivist.us