Environmental scientists and neurobiologists generally regarded the pesticide chlorpyrifos as being detrimental to development of the brain and nervous system of fetuses and young children.  In 2015, the previous Administration initiated a ban on the pesticide after many studies were published confirming interference in neural development.  EPA scientists at the time accepted both U.S. and international published studies that in fact led to banning the chemical in the EU. 

In 2017, the then EPA Administrator, Scott Pruitt reversed the 2015 decision stimulating legal opposition to his decision.  The EPA was under court order to decide whether to ban chlorpyrifos no later than July 2019.  The current EPA Administrator Andrew Wheeler has rejected petitions by organizations representing public health and the environment.

At issue is the requirement imposed by the EPA that they will not consider published studies in peer-reviewed journals in their deliberations and decisions unless they have access to raw data. The peer-review process evaluates experimental design, procedures, statistical analysis conclusions and the integrity of authors and their institutions. Examination of raw data is not a normal practice and is resorted to only in the event of allegations of academic dishonesty. The issue of the so-called "secret science" barrier has enabled the EPA to selectively exclude important published research studies thereby providing cover for both delays in rule-making and adverse decisions. 

Recently the EPA issued a statement to the effect that "despite several years of study the science addressing neurodevelopmental effects of chlorpyrifos remains unresolved".  This is a cynical and deliberate neglect of established science, placing political and economic considerations above public health and wellbeing. The EPA acknowledged to a three-judge panel of the U.S. Court of Appeals for the Ninth Circuit that the Agency accepts that chlorpyrifos can cause neurodevelopmental effects. The Agency claims that there are disputes over the relationship between the level of exposure and harm. Chlorpyrifos is certainly a case for application of the precautionary principle even if scientific evidence did not support an outright ban.

The well being of the next generation is far more important than the narrow political agendas of decision makers who have the obligation to protect health and well being.