Tipping the Balance of Autism Risk: Potential Mechanisms Linking Pesticides and Autism

By Shelton, Janie F.; Hertz-Picciotto, Irva et al. | Environmental Health Perspectives, July 2012 | Go to article overview
Save to active project

Tipping the Balance of Autism Risk: Potential Mechanisms Linking Pesticides and Autism

Shelton, Janie F., Hertz-Picciotto, Irva, Pessah, Isaac N., Environmental Health Perspectives

BACKGROUND: Autism spectrum disorders (ASDs) have been increasing in many parts of the world and a portion of cases are attributable to environmental exposures. Conclusive replicated findings have yet to appear on any specific exposure; however, mounting evidence suggests gestational pesticides exposures are strong candidates. Because multiple developmental processes are implicated in ASDs during gestation and early life, biological plausibility is more likely if these agents can be shown to affect core pathophysiological features.

OBJECTIVES: Our objectives were to examine shared mechanisms between autism pathophysiology and the effects of pesticide exposures, focusing on neuroexcitability, oxidative stress, and immune functions and to outline the biological correlates between pesticide exposure and autism risk.

METHODS: We review and discuss previous research related to autism risk, developmental effects of early pesticide exposure, and basic biological mechanisms by which pesticides may induce or exacerbate pathophysiological features of autism.

DISCUSSION: On the basis of experimental and observational research, certain pesticides may be capable of inducing core features of autism, but little is known about the timing or dose, or which of various mechanisms is sufficient to induce this condition.

CONCLUSIONS: In animal studies, we encourage more research on gene x environment interactions, as well as experimental exposure to mixtures of compounds. Similarly, epidemiologic studies in humans with exceptionally high exposures can identify which pesticide classes are of greatest concern, and studies focused on gene x environment are needed to determine if there are susceptible subpopulations at greater risk from pesticide exposures.

KEY WORDS: autism spectrum disorders, carbamate, gene--environment interaction, immune, mitochondria, neuroexcitation, organochlorine, organophosphate, oxidative stress, pesticide, pyrethroid. Environ Health Perspect 120:944-951 (2012). http://dx.cloi.org/10.1289/ehp.1104553 [Online 25 April 2012]

Causes for the recent rise in autism diagnoses throughout the United States remain largely unknown. In California, a 600% increased incidence in autism was observed among children up to 5 years of age for births from 1990 to 2001, yet only one-third of the rise could be explained by identified factors such as changing diagnostic criteria and a younger age at diagnosis (Hertz-Picciotto and Delwiche 2009). Across the United States, autism spectrum disorders (ASD) are now estimated to affect 1 in 88 eight-year-olds, with much higher prevalence in boys (1 in 54) than girls (1 in 252) (Centers for Disease Control and Prevention 2012). Autism is a heterogeneous, behaviorally defined condition often diagnosed in children prior to age 3 years. Although each individual diagnosis must meet specific criteria related to deficits in social interaction and language and to the presence of repetitive behaviors or restricted interests, autism phenotypes vary widely, even among concordant twins (Le Couteur et al. 1996).

Idiopathic autisms are diagnosed 4-5 times more often in boys than girls and frequently involve a wide range of genes that confer susceptibility as opposed to a singular heritable factor (Geschwind 2011). Genetic contributions to autism risks involve rare mutations, complex gene x gene interactions, and copy number variants (CNVs) including deletions and duplications (Stankiewicz and Lupski 2010). In a recent series of papers, rare de nova point mutations were associated with autism in parent--child trios with sporadic ASD (Neale et al. 2012; O'Roak et al. 2012; Sanders et al. 2012), and those mutations were more frequently derived from fathers, increasing with paternal age (O'Roak et al. 2012). Although twin studies have demonstrated evidence of heritability--a stronger concordance among monozygotic than dizygotic twins (Bailey et al.

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
Loading One moment ...
Project items
Cite this article

Cited article

Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited article

Tipping the Balance of Autism Risk: Potential Mechanisms Linking Pesticides and Autism


Text size Smaller Larger
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

While we understand printed pages are helpful to our users, this limitation is necessary to help protect our publishers' copyrighted material and prevent its unlawful distribution. We are sorry for any inconvenience.
Full screen

matching results for page

Cited passage

Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.

Are you sure you want to delete this highlight?