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Folic Acid May Mitigate Autism Risk From Pesticides

Summary: Researchers from UC Davis report pregnant women who take 800 micrograms of folic acid could help lower risks of autism in their children, even when they were exposed to pesticides associated with increasing autism risk.

Source: UC Davis.

Researchers at UC Davis and other institutions have shown that mothers who take recommended amounts of folic acid around conception might reduce their children’s pesticide-related autism risk.

In the study, children whose mothers took 800 or more micrograms of folic acid (the amount in most prenatal vitamins) had a significantly lower risk of developing autism spectrum disorder (ASD) – even when their mothers were exposed to household or agricultural pesticides associated with increased risk. The study appears today in the journal Environmental Health Perspectives.

“We found that if the mom was taking folic acid during the window around conception, the risk associated with pesticides seemed to be attenuated,” said Rebecca J. Schmidt, assistant professor in the Department of Public Health Sciences and first author on the paper. “Mothers should try to avoid pesticides. But if they live near agriculture, where pesticides can blow in, this might be a way to counter those effects.”

In the paper, which used data from the Childhood Autism Risks from Genetics and the Environment (CHARGE) study, researchers looked at 296 children between 2 and 5 who had been diagnosed with ASD and 220 who had developed typically. Mothers were interviewed about their household pesticide exposure during pregnancy, as well as their folic acid and B vitamin intake. The team also linked data from California Pesticide Use reports, which provide important details about agricultural spraying, with the mothers’ addresses.

Mothers who took less than 800 micrograms and encountered household pesticides had a much higher estimated risk of having a child who developed an ASD than moms who took 800 micrograms of folic acid or more and were not exposed to pesticides. The associated risk increased for women exposed repeatedly. Women with low folic acid intake who were exposed to agricultural pesticides during a window from three months before conception to three months afterward also were at higher estimated risk.

“Folic acid intake below the median and exposure to pesticides was associated with higher risk of autism than either low intake or exposure alone,” said Schmidt, a UC Davis MIND Institute faculty member. “The mothers who had the highest risk were the ones who were exposed to pesticides regularly.”

Image shows a pregnant woman.

Mothers who took less than 800 micrograms and encountered household pesticides had a much higher estimated risk of having a child who developed an ASD than moms who took 800 micrograms of folic acid or more and were not exposed to pesticides. The associated risk increased for women exposed repeatedly. Women with low folic acid intake who were exposed to agricultural pesticides during a window from three months before conception to three months afterward also were at higher estimated risk. NeuroscienceNews.com image is in the public domain.

While folic acid did reduce the associated risk of a child developing autism, it did not entirely eliminate it.

“It would be better for women to avoid chronic pesticide exposure if they can while pregnant,” Schmidt said.

The authors caution that this is a case-control study that relied heavily on participants’ memories. In addition, they have yet to establish a causal link. However, these results certainly warrant larger studies to validate them. The team is also eager to investigate the mechanisms that contribute to folic acid’s possible protective effects.

“Folate plays a critical role in DNA methylation (a process by which genes are turned off or on), as well as in DNA repair and synthesis,” said Schmidt. “These are all really important during periods of rapid growth when there are lots of cells dividing, as in a developing fetus. Adding folic acid might be helping out in a number of these genomic functions.”

About this neuroscience research article

Other researchers included Janie F. Shelton, Lora Delwiche, Robin L. Hansen, Sally Ozonoff, Deborah H. Bennett, Irva Hertz-Picciotto and Daniel Tancredi at UC Davis; Vladimir Kogan and Heather E. Volk at UCLA; and Claudia C. Ma Erin and C. McCanlies at the National Institute for Occupational Safety and Health.

Funding: This study was funded by the National Institute of Environmental Health Sciences, National Institute of Child Health and Human Development, part of the National Institutes of Health (R21-ES021330, R01-ES015359, P01-ES11269, 2K12HD051958, R21-ES19002, P30-ES023513 and U54-HD079125); The Environmental Protection Agency STAR program (R-42 829388 & R833292) and the UC Davis MIND Institute.

Source: Dorsey Griffith – UC Davis
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Full open access research for “Combined Prenatal Pesticide Exposure and Folic Acid Intake in Relation to Autism Spectrum Disorder” by Rebecca J. Schmidt, Vladimir Kogan, Janie F. Shelton, Lora Delwiche, Robin L. Hansen, Sally Ozonoff, Claudia C. Ma, Erin C. McCanlies, Deborah H. Bennett, Irva Hertz-Picciotto, Daniel J. Tancredi, and Heather E. Volk in Environmental Health Perspectives. Published online September 2017 doi:10.1289/EHP604

Cite This NeuroscienceNews.com Article
UC Davis “Folic Acid May Mitigate Autism Risk From Pesticides.” NeuroscienceNews. NeuroscienceNews, 11 September 2017.
<http://neurosciencenews.com/folic-acid-autism-pesticide-7464/>.
UC Davis (2017, September 11). Folic Acid May Mitigate Autism Risk From Pesticides. NeuroscienceNew. Retrieved September 11, 2017 from http://neurosciencenews.com/folic-acid-autism-pesticide-7464/
UC Davis “Folic Acid May Mitigate Autism Risk From Pesticides.” http://neurosciencenews.com/folic-acid-autism-pesticide-7464/ (accessed September 11, 2017).

Abstract

Combined Prenatal Pesticide Exposure and Folic Acid Intake in Relation to Autism Spectrum Disorder

BACKGROUND:
Maternal folic acid (FA) protects against developmental toxicity from certain environmental chemicals.

OBJECTIVE:
We examined combined exposures to maternal FA and pesticides in relation to autism spectrum disorder (ASD).

METHODS:
Participants were California children born from 2000–2007 who were enrolled in the Childhood Autism Risks from Genetics and the Environment (CHARGE) case–control study at age 2–5 y, were clinically confirmed to have ASD (n=296) or typical development (n=220), and had information on maternal supplemental FA and pesticide exposures. Maternal supplemental FA and household pesticide product use were retrospectively collected in telephone interviews from 2003–2011. High vs. low daily FA intake was dichotomized at 800 μg (median). Mothers’ addresses were linked to a statewide database of commercial applications to estimate agricultural pesticide exposure.

RESULTS:
High FA intake (≥800 μg) during the first pregnancy month and no known pesticide exposure was the reference group for all analyses. Compared with this group, ASD was increased in association with <800 μg FA and any indoor pesticide exposure {adjusted odds ratio [OR]=2.5 [95% confidence interval (CI): 1.3, 4.7]} compared with low FA [OR=1.2 (95% CI: 0.7, 2.2)] or indoor pesticides [OR=1.7 (95% CI: 1.1, 2.8)] alone. ORs for the combination of low FA and regular pregnancy exposure (≥6 mo) to pet pesticides or to outdoor sprays and foggers were 3.9 (95% CI: 1.4, 11.5) and 4.1 (95% CI: 1.7, 10.1), respectively. ORs for low maternal FA and agricultural pesticide exposure 3 mo before or after conception were 2.2 (95% CI: 0.7, 6.5) for chlorpyrifos, 2.3 (95% CI: 0.98, 5.3) for organophosphates, 2.1 (95% CI: 0.9, 4.8) for pyrethroids, and 1.5 (95% CI: 0.5, 4.8) for carbamates. Except for carbamates, these ORs were approximately two times greater than those for either exposure alone or for the expected ORs for combined exposures under multiplicative or additive models.

CONCLUSIONS:
In this study population, associations between pesticide exposures and ASD were attenuated among those with high versus low FA intake during the first month of pregnancy. Confirmatory and mechanistic studies are needed.

“Combined Prenatal Pesticide Exposure and Folic Acid Intake in Relation to Autism Spectrum Disorder” by Rebecca J. Schmidt, Vladimir Kogan, Janie F. Shelton, Lora Delwiche, Robin L. Hansen, Sally Ozonoff, Claudia C. Ma, Erin C. McCanlies, Deborah H. Bennett, Irva Hertz-Picciotto, Daniel J. Tancredi, and Heather E. Volk in Environmental Health Perspectives. Published online September 2017 doi:10.1289/EHP604

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