Delays seen in children exposed to pesticides before birth.

Apr 06, 2010

Harari, R, J Julvez, K Murata, D Barr, DC Bellinger, F Debes and P Grandjean. 2010. Neurobehavioral deficits and increased blood pressure in school-age children prenatally exposed to pesticides. Environmental Health Perspective

Synopsis by Emily Barrett

A new study reports that prenatal – but not current – pesticide exposure affects children’s neurodevelopment and blood pressure at ages 6 to 8.

Children exposed to insecticides before birth through their mothers – who worked in the flower growing industry – were up to two years behind in thinking, learning and memory abilities when they reached ages 6 to 8 years old, finds a study of children from northern Ecuador. They also had higher blood pressures.

The results mimic those of a pilot study done by the same research group and agree with a growing body of evidence that suggests fetal exposure to pesticides during development – especially during certain windows – is of concern.

Animal and human studies find that certain insecticides may be detrimental to the developing brain, interfering with nerve action and potentially causing permanent deficits in behavior and cognition. In total, the research suggests that pesticide use – even at low levels – should be limited at work, especially for pregnant women. 

Scientists studied second- and third-grade children from a small community in northern Ecuador whose adult residents have high levels of exposure to insecticides – most commonly organophosphates used in the local flower growing industry. Two groups of children – one exposed to pesticides during development and the other not – were compared. Standardized tests determined if the children between the ages of 6 to 8 showed any cognitive or developmental delays. The tests measured everything from dexterity to memory to intelligence. The researchers also evaluated the children’s current level of pesticide exposure and gave them basic health exams.

Children whose mothers were exposed to insecticides during their pregnancies showed significant cognitive deficits, particularly motor speed, motor coordination, and performance on visual tasks involving copying pictures (in real time or from memory). The impairments approximate a 1½ to 2 year developmental delay. The children's blood pressure was elevated and they were smaller than children whose mothers had not been exposed. Notably, none of the mothers reported pesticide-related health concerns during pregnancy, suggesting that these developmental effects may occur at very low levels of exposure.

These effects were not found in children with current exposure and those whose fathers worked in the flower industry. The effects were seen only in those children who were likely exposed to pesticides through their mothers during development.

The study had some limitations. The study addresses only work exposures – which are usually higher than those at home – and relies on the mothers’ recollection of occupational exposures from years earlier. Ideally, future studies would follow women through their pregnancies, measuring exposures and tracking the children's health.