Another study has linked childhood behavioral problems to pesticide exposure, this time to pyrethroid insecticide exposure. Pyrethroids are synthetic pesticides (insecticides) that are increasingly used for personal use (mosquito repellents and treatments for head lice, scabies), on pets (for fleas), home use (e.g., Raid pesticides), and in agriculture.
Until recently, they have been viewed as "safer" and posing fewer risks to human health than older pesticides, but a growing body of research is finding that pyrethroid pesticides share similar neurocognitive health effects as older pesticides. Neurocognitive refers to the neural processes of the brain and central nervous system involved in cognitive functioning. Pyrethroids get into people various ways: through inhalation, absorbed through the skin, and ingested in food. And yes, they cross the placenta (they have been detected in the placental cord immediately after birth).
In this study, researchers looked at levels of pyrethroid metabolites (the breakdown products from pyrethroids) in the mother's urine during early pregnancy and in the child's urine when the child was 6 years of age. They looked at how social a child is (altruism), whether the child is inhibited and has difficulty sharing problems or asking for help (internalizing behaviors), as well as how defiant or disruptive a child is (externalizing behaviors, which can include hyperactivity and oppositionality).
Pyrethroids (the metabolites) were regularly detected in both mothers and children participating in the study. Internalizing disorders were associated with high levels of one pyrethroid metabolite (cis-DCCA, a breakdown product of permethrin, cypermethrin, and clyfluthrin) in pregnant mothers’ urine. Childhood exposure to pyrethroids (as measured in the child's urine) was linked to externalizing disorders. Researchers hypothesized that the behavioral difficulties were due to changes in the child’s brain. The authors stated: “The current study suggests that exposure to certain pyrethroids at the low environmental doses encountered by the general public may be associated with behavioural disorders in children.” "Internalizing behaviors are inhibited and overcontrolled in nature, while children with
Other studies have also found negative health effects on children from pyrethroids - for example, an association between synthetic pyrethroid exposure and ADHD hyperactivity and impulsivity. Recent research found that living near a farm field where pyrethroids are applied during a mother’s third trimester or just before conception corresponds with a greatly increased risk of having a child with autism spectrum disorder.
What can one do? Main one: try to avoid using and ingesting (in food) synthetic pyrethroids. This means avoid routine "pesticide treatments" of your home and garden, and instead use least-toxic methods to control pests around the home and garden (such as baits for insects, caulk holes, etc.). Try viewing weeds in the lawn as native wildflowers and the flowers as bee habitats (yes, you'll also be saving bees!). Eat as many organic foods (especially fruits and vegetables) as possible - this will lower the amount of pesticides in your body. This is because synthetic pyrethroids are not allowed in organic farming. The good news is that pyrethroid pesticides leave the body within days, so with some lifestyle changes you can really lower your pesticide levels.
From Medscape: 'Safe' Insecticides Tied to Neurobehavioral Problems in Kids
Prenatal and childhood exposure to pyrethroid insecticides may adversely affect neurobehavioral development in children up to age 6 years, new research shows. A group of French researchers led by Jean-François Viel, MD, PhD, and Prof Andreas G. Franke, MD, both of the University of Mainz, Germany, investigated the associations between exposure to pyrethroid insecticides and behavioral skills in 6-year-olds.
Using a longitudinal design, the researchers assessed pyrethroid exposure in children prenatally and at age 6 years. They found that in 6-year-old children, increased prenatal concentrations of the cis-dimethylcyclopropane carbolic acid metabolite were associated with internalizing difficulties. A positive association was also found between the presence of childhood 3-phenoxybenzoic acid (3-PBA) and externalizing difficulties.
The researchers used a longitudinal design to assess the relationship between prenatal and childhood pyrethroid concentrations, using data from the French PELAGIE mother-child study. That study enrolled 3421 pregnant women from Brittany, France, between 2002 and 2006. Of this cohort, 287 randomly selected mothers agreed to participate in neuropsychological follow-up. Psychologists who were blinded to pyrethroid exposure levels in the study participants conducted neurodevelopmental assessments and maternal interviews to assess the home environment. They also collected children's urine samples as well as dust samples.