Pesticides, Neurodevelopmental Disagreement, and Bradford Hill’s Guidelines

ABSTRACT

Neurodevelopmental disorders such as autism affect one-eighth of all U.S. newborns. Yet scientists, accessing the same data and using Bradford-Hill guidelines, draw different conclusions about the causes of these disorders. They disagree about the pesticide-harm hypothesis, that typical United States prenatal pesticide exposure can cause neurodevelopmental damage. This article aims to discover whether apparent scientific disagreement about this hypothesis might be partly attributable to questionable interpretations of the Bradford-Hill causal guidelines. Key scientists, who claim to employ Bradford-Hill causal guidelines, yet fail to accept the pesticide-harm hypothesis, fall into errors of trimming the guidelines, requiring statistically-significant data, and ignoring semi-experimental evidence. However, the main scientists who accept the hypothesis appear to commit none of these errors. Although settling disagreement over the pesticide-harm hypothesis requires extensive analysis, this article suggests that at least some conflicts may arise because of questionable interpretations of the guidelines.

KEYWORDS:

• Bradford-Hill
• cause
• neurodevelopment
• pesticide
• statistical significance
• trimming the data

Funding

This research was made possible by grants SES-0724781 and SES-82-05112 to K.S-F. (principal investigator) from the U.S. National Science Foundation (NSF). The contents of this article are solely the responsibility of the authors, not NSF.

Additional information

Funding

This research was made possible by grants SES-0724781 and SES-82-05112 to K.S-F. (principal investigator) from the U.S. National Science Foundation (NSF). The contents of this article are solely the responsibility of the authors, not NSF.