Two recent studies, both done in California, looked at different aspects of pesticide exposure. They highlight how people can be exposed to pesticides in the air they breathe, especially if they live in areas where pesticides are heavily applied (such as farms). But keep in mind that even in suburbia, every time a neighbor applies pesticides on the lawn or trees - there is drift, and so you are also exposed (e.g., breathing it, droplets on the skin).
The first study found that pregnant women with high pesticide exposure (living in areas near farms using pesticides) had increases in adverse birth outcomes (low birth weight, shorter pregnancy length, preterm birth, birth defects or abnormalities). No effects were seen with low pesticide exposure. But note that these results are what could be seen at birth - they do not include effects that can only be seen later, such as delayed development, learning disabilities, lower intelligence, asthma, autism - all effects found in some studies.
The other was a California Department of Pesticide Regulation (CDPR) 2016 report on air monitoring results (from 6 sites) of 32 chemicals (pesticides and breakdown products) in California. Some pesticides were not detected, some were only at trace amounts, and some were detected at higher amounts - and the amounts fluctuated over the year and from site to site. [NOTE: They did not monitor for 2 widely used pesticides: glyphosate, which is in Roundup, and 2,4-D. Hmm...]. A Kern County high school monitoring site showed levels of the pesticide chlorpyrifos more than 18 times higher than EPA's "level of concern for pregnant women" - but yet these levels are considered OK for the general public.
Chlorpyrifos is "controversial" in that scientists (including EPA scientists), medical professionals, and farmworker organiztions asked that its use be banned due to its serious health effects on humans, but this year EPA chief Scott Pruitt refused to do so (he gave in to pesticide industry lobbying). The bottom line: What effect do the mixtures of pesticides (at chronic low levels) that we're exposed to have on us? Unknown.
From Medical Xpress: Researchers unravel the negative effects of pesticide exposure on birth outcomes
Although common opinion holds that exposure to pesticides increases adverse birth outcomes, the existing body of scientific evidence is ambiguous..... A new study by researchers at UC Santa Barbara addresses the issue in a novel way—by analyzing birth outcomes in California's San Joaquin Valley. With more than one-third of the country's vegetables and two-thirds of its fruits and nuts produced there, the San Joaquin Valley, not surprisingly, is a heavy pesticide-use region. The UCSB team investigated the effect of exposure during pregnancy in this agriculturally dominated area and observed an increase in adverse outcomes accompanying very high levels of pesticide exposure.
"For the majority of births, there is no statistically identifiable impact of pesticide exposure on birth outcome," said lead author Ashley Larsen, an assistant professor in UCSB's Bren School of Environmental Science & Management. "Yet mothers exposed to extreme levels of pesticides, defined here as the top 5 percent of the pesticide exposure distribution, experienced between 5 and 9 percent increases in the probability of adverse outcomes with an approximately 13-gram decrease in birth weight."
Using individual birth certificate records for more than 500,000 single births between 1997 and 2011, coupled with pesticide use data at a fine spatial and temporal scale, the scientists were able to determine if residential agricultural pesticide exposure during gestation—by trimester and by toxicity—influenced birth weight, gestational length or birth abnormalities.
They found negative effects of pesticide exposure for all birth outcomes—birth weight, low birth weight, gestational length, preterm birth, birth abnormalities—but only for mothers exposed to very high levels of pesticides—the top 5 percent of the exposure distribution in this sample.... Numerous chemicals are used daily in close proximity to residential areas, making it difficult to ascertain a specific responsible agent. As a result, in this study, the researchers looked at the combined results from all pesticides used in the region. [Original study.]
Excerpts from Beyond Pesticides: Neurotoxic Pesticide Detected in Air at High Levels in California County
The California Department of Pesticide Regulation (CDPR) released its 2016 air monitoring data where it was revealed that chlorpyrifos air concentrations for a one-month period at the air monitoring site on the campus of Shafter High School in Kern County was 39.4 nanograms per cubic meter (ng/m3) – more than 18 times higher than EPA’s level of concern for pregnant women (2.1 ng/m3). Shafter High School is some distance from fields in an area where chlorpyrifos use is not as high as in other parts of Kern County or elsewhere in California.
High chlorpyrifos levels at a school means that children and unsuspecting teachers and parents, especially those that may be pregnant, are breathing in unusually high levels of chlorpyrifos. Children exposed to high levels of chlorpyrifos have developmental delays, attention problems, attention-deficit/hyperactivity disorder problems, and pervasive developmental disorders.