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Chemicals in agriculture are big business in California.
Every year, farms using pesticides, herbicides, and fertilizers in California produce crops valued at $38 billion in the field, which are turned into food products that sell for hundreds of billions of dollars around the world.
California farmers use 200,000,000 pounds (a little under 100,000,000 kilos) of agricultural chemicals every year. The use of these chemicals is regulated by the State of California, and in farm communities, there is an unwritten code that one does not criticize the agricultural chemical industry.
That doesn't mean, however, that agricultural chemicals are safe.
The study, conducted at the University of California at Davis Mind Institute, found that the added risk of autism after exposure to these agricultural chemicals is about 2/3, and that exposure in the second and third trimesters is more dangerous than exposure earlier in pregnancy. And, study author and principal investigator Irva Hertz-Picciotto, a professor of public health, notes that this most recent study confirms the findings of two studies before it.
The UC Davis researchers conducted the study by correlating a database of applications to spray pesticides with medical records of 1,000 mothers participating in the study. The data were available for mothers and children in who lived in California's Bay Area, Sacramento Valley, and north Central Valley.
The study examined the possible effects of three kinds of pesticides:
- Pyrethroids, which are a "natural" pesticide,
- Organophosphates, which are in the same class of chemicals as nerve gas, and
- Carbamates, once considered non-toxic to humans and even used in chemotherapy, but now known to be toxic to the nervous system.
The researchers theorized that women who lived within 1 mile (1600 meters) of farms where these chemicals were sprayed would be at higher risk of having children with autism. The study found that children of women who lived in one-mile proximity to pesticide spraying during their second trimester had a 50 to 640% greater frequency of autism than children of women who did not, and that children of women who lived in one-mile proximity to pesticide spraying during their third trimester had a 10 to 260% greater frequency of autism than children of women who did not.
Why would women expose their children to pesticides?
In many cases, there simply is not anywhere else to go. Researchers at the nearby University of California of San Francisco interviewed women who were exposed to pesticides during pregnancy and learned that generally women who lived next to, or on, toxic farms were generally more concerned about getting the food they need for themselves and the baby and paying their rent.
Doctors, the UC San Francisco surveyors found, were not especially well equipped to help these mothers.
Only 1 in 5 obstetricians even asks about exposure to agricultural chemicals, even though chemical based agriculture is a huge industry in Central California.