(Beyond Pesticides, March 29, 2010) Prenatal exposure to pesticides at levels that do not cause adverse health effects in the mother can lead to delayed brain developmental in the child, according to the new study, “Neurobehavioral Deficits and Increased Blood Pressure in School-Age Children Prenatally Exposed to Pesticides,” published last month in the early online edition of the journal Environmental Health Perspectives. Many pesticides are suspected of being capable of damaging the nervous system, in particular the development of a child’s brain during pregnancy and the early postnatal years of life. Now an international research team led by Philippe Grandjean, M.D., from the University of Southern Denmark and Harvard School of Public Health, has shown a delayed brain development up to two years in school children, whose mothers worked in a greenhouse during pregnancy. The exposed children also had increased blood pressure, while the mothers do not suffered adverse symptoms themselves.
“The results support the notion that, in this cohort of children, prenatal exposures to pesticides are more harmful than current exposures, thereby confirming previous results of other environmental studies of neurodevelopmental toxicity and the theory of window of vulnerability of central nervous system during uterine life,” write the authors.
Eighty-four children, age 6-8 years, from an intensive floriculture area of northern Ecuador underwent a series of neurobehavioral tests. The children were also tested for current levels of certain pesticides in their urine and blood. The mothers of these children were interviewed for information about their work, living conditions and social background. The floriculture greenhouses, producing long-stemmed roses for export, use around thirty different pesticides routinely, most commonly of which are organophosphates. The mothers tend to work up until delivery when possible. None of the women had worked with pesticides themselves, but they were exposed from touching the plants after spraying. Thirty-five of the children had been exposed during fetal development from the mother’s work, and 23 could have had indirect exposure due to the father’s work during the same period.
When nutrition and social conditions were taken into account, a definite negative effect was found in the children, whose mother had been exposed to pesticides during pregnancy. The effect was the strongest for motor coordination, spatial performance and visual memory. Thus, the children were 1.5 to 2 years behind in the development of these functions, which is a very marked shift at age 6-to-8 years, where brain development is particularly rapid. The researchers also found increased blood pressure, likely a result of adverse effect on brain nuclei responsible for regulation of cardiovascular functions.
The study authors write, “Pesticide exposure therefore may contribute to a ”˜silent pandemic’ of developmental neurotoxicity.”
“When such changes can be observed at school age, they are most likely irreversible,” said Dr. Grandjean. “The time has come to determine whether we will protect developing brains against pesticides.”
In 2006, Dr. Grandjean published, with Philip Landrigan, M.D., M.Sc., a pediatrician and Director of the Center for Children’s Health and the Environment at the Mount Sinai School of Medicine, a highly influential article in the medical journal The Lancet, where the researchers predicted that pollution with toxic metals, solvents, pesticides, and other brain poisons, will lead to a silent pandemic of developmental neurotoxicity. The pandemic is silent, because each substance may not cause an effect sufficiently large to be detected, but the overall outcome may be serious. Dr. Grandjean said at the time, that the silent pandemic can be prevented only if a decision is made to apply the precautionary principle.
Several recent studies have similar findings. On Friday, March 26, 2010, Beyond Pesticides’ Daily News posted a similar piece on a new study linking exposure to the insecticide chlorpyrifos, an organophosphate pesticide, to early childhood developmental delays. In addition, another new study concludes that exposures during pregnancy and childhood to insecticides that target the nervous system, such as organophosphates (OPs) and carbamates, are associated with childhood brain tumors.
For more information on children’s exposure to pesticides, including information on how you can protect your family from pesticides and the latest studies and news on this topic, see Beyond Pesticides Children and Schools program page.