A new study published in the journal Nature Communications (and featured in the press today) documents that pregnant women living in the most heavily pesticided areas of the Central Valley have an increased chance of having a baby born prematurely or with abnormalities.
For most residents - more than 50% - pesticide exposures were low level, and these families did not have increased risks for premature births or abnormalities. But in areas which ranked among the top 5% of pesticide use, the risks were increased by 5-9% above average. For the top 1% the risks were even higher.
Pesticide exposure ranged from an average of 975 kilograms per acre to a high of 4,000 kilograms per acre. Those in the 4,000 kg/acre areas had a 8% higher chance of a premature birth and a 9% higher chance of having a birth abnormality.
The study was co-authored by three researchers from UC Santa Barbara at the Bren School of Environmental Science & Management. The researchers used data from 500,000 births over a period from 1997-2011 coupled with Pesticide Use Report data from the State of California.
The area the researchers studied - San Joaquin County - lies south of Sacramento County and extends to south of Manteca. It includes the prime grape growing region of Lodi, where grapes are by far the largest crop by acre and revenue.
About 60 percent of California wine comes from grapes grown in the San Joaquin Valley (which is larger than the county per se). However in the county alone, there are 98,000 acres of grape vines (including both wine grapes and table grapes), with the crop valued at $425 million.
"Commodities such as grapes received nearly 50 kg per hectare per year of insecticides alone in the San Joaquin Valley region, while other high value crops such as pistachios receive barely a third of that amount," the researchers wrote.
However, grapes often receive a higher amount of weight of pesticides, because of the use of sulfur, compared to other crops. I couldn't tell from the published research how much this fact impacted the results.
Here's the Ag Pesticide Mapping Tool results for a query on "reproductive and developmental toxins" applied to "wine grapes" in San Joaquin County so you can see where the highest concentrations of these specific substances are applied to vineyards.
Map Source: California Environmental Health Tracking Program, Agricultural Pesticide Mapping Tool (Data from 2014 Pesticide Use Reports); Pounds Per Acre (Wine Grapes only, Reproductive and Developmental Toxins only)
While the article divided toxicity measure into higher and lower levels in the study, the paper does not list which pesticides were in the highest risk categories.
It also does not include a crop breakdown of which crops created the most risks for populations.
I have emailed the lead author on the study to see if more details can be obtained.
The study also points out that the closer farmworkers live to pesticided fields, the more the workers are at risk. "Our results may under predict adverse birth outcomes in regions where a larger proportion of workers reside in employer-provided housing or adjacent to fields, where a larger fraction of pesticides are applied...," the paper states.
The study also noted that pesticides applied to the ground (versus aerial spraying) were most likely to have a health impact (as this method of application is more common).
The study did not look at male exposures to pesticides and those impacts on child health.
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