LONDON, May 15 (Xinhua) -- Insecticides in pet
shampoos trigger autism spectrum disorder (ASD), according to survey results
presented Thursday at the International Meeting for Autism Research in London.
According to one of the first large-scale
population-based studies to look how environmental factors and their
interactions with genes contribute to the condition, mothers of children with an
ASD were twice as likely to have reported using pet shampoos containing a class
of insecticide called pyrethrins as those of healthy children.
The risk was greatest if the shampoo was used during
the second trimester of pregnancy, the study showed.
Previous studies in insects and rodents have
suggested that pyrethrins could damage the blood-brain barrier during early
life, and cause neuronal damage. They may also interfere with the transmission
of signals along nerve fibres.
Autism is associated with an imbalance between
excitatory and inhibitory neurotransmitters within the brain.
While many chemicals have previously been blamed for
triggering autism, there have been very few rigorous studies designed to
investigate the link.
To remedy this, researchers led by Irva
Hertz-Picciotto at the University of California in Davis, United States, studied
333 children with ASD and 198 healthy children, and their families.
The researchers made the findings after collecting
blood and urine samples, conducting in-depth questionnaires on medical history
and any possible exposure to medications, household products or metals that
could have occurred around the time of conception, during pregnancy, or after
birth, as well as collecting information on lifestyle.
However, lead researcher Irva Hertz-Picciotto and
other experts caution that pyrethrins were unlikely to be the only cause of
autism, which is increasingly recognized as being caused by a complex interplay
of both genetic and environmental factors.
Another study suggested that exposure to
organophosphate insecticides double the risk of developmental disorders,
including autism.
