Research on rats, in the womb and immediately after birth, suggests that very low doses of the organophosphate chlorpyrifos, well below the level which would have any apparent toxic effect, may affect the nervous system, causing long-term activation of serotonin nerves and associated behaviour problems.

When these rats reached early adulthood brain activity was measured. It was found that although neurotransmitter content was largely
unaltered, activity at the serotonin synapses was increased across multiple brain regions.

The authors believe that the most likely explanation for their findings is a miswiring of the nerves. These defects will lead to behavioural
problems such as depression, which they predict will not be treatable with the standard depression drugs such as serotonin reuptake inhibitors.

Aldridge JE, Meyer A, Seidler FJ, Slotkin TA, Alterations in Central Nervous System serotonergic and Dopaminergic Synaptic Activity in Adulthood after Prenatal or Neonatal Chlorpyrifos Exposure, Environmental Health Perspectives 2005, 113: 1027-1031

Courtesy of PAN UK 020 7065 0905 www.pan-uk.org

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First Published in April 2006

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