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Long-term Behavioral and Reproductive Consequences of Embryonic Exposure to Low-dose Toxicants
Published on: March 6, 2018
Establishing evidence for early action: the prevention of reproductive and developmental harm
1Strategic Knowledge and Innovation, European Environment Agency, Copenhagen, Denmark. david.gee@eea.europa.eu
Abstract:
Developmental and reproductive toxicants that cause serious disease and dysfunction, either lifelong or occurring late in life, can be initiated in the early life stages of human beings and other species. It is often the timing of the dose more than the dose itself that distinguishes harmful from harmless exposures to such toxicants. As much of the harm is irreversible, and sometimes multigenerational, the timing of actions to prevent such harm is also critical. In determining when there is a sufficiency of evidence to justify early prevention of harm, decision-makers need to take account of the implications of multicausality, the methodological biases within environmental sciences, and the need to take precautionary, as well as preventive actions to eliminate or reduce exposures. The widely used Bradford Hill causal 'criteria' are briefly reviewed in light of multicausality. Reaching agreement between stakeholders on a sufficiency of evidence for early action to reduce exposures to toxicants requires the consistent use of transparent definitions of the concepts and terms used to characterize the strength of evidence between causes and effects. Proposals are made to improve those in current use, including a definition of the precautionary principle.
Insights
Early life exposures to developmental toxicants can cause irreversible, lifelong harm. The timing of exposure and preventive action is critical, necessitating a review of evidence and the precautionary principle.
Area of Science:
- Environmental Health Sciences
- Toxicology
- Reproductive Health
Background:
- Developmental and reproductive toxicants can initiate serious, irreversible diseases and dysfunctions during early life stages.
- The timing of toxicant exposure is often more critical than the dose itself in determining harm.
- Harm can be irreversible and multigenerational, underscoring the urgency of preventive actions.
Purpose of the Study:
- To evaluate the sufficiency of evidence for early prevention of harm from developmental and reproductive toxicants.
- To address challenges in decision-making related to environmental exposures, including multicausality and methodological biases.
- To review the Bradford Hill causal criteria in the context of multicausality and propose improvements for evidence assessment.
Main Methods:
- Review of existing literature on developmental and reproductive toxicants.
- Analysis of the implications of multicausality and methodological biases in environmental sciences.
- Examination of the Bradford Hill causal criteria for assessing evidence strength.
- Development of proposals for transparent definitions and improved use of the precautionary principle.
Main Results:
- The timing of exposure is a key factor in the initiation of toxicant-induced harm.
- Multicausality and inherent biases in environmental sciences complicate evidence assessment for early intervention.
- Current frameworks for evaluating evidence may require refinement to consistently support timely preventive actions.
Conclusions:
- Early intervention is critical to prevent irreversible harm from developmental and reproductive toxicants.
- Transparent definitions and consistent application of evidence assessment, including the precautionary principle, are essential for effective risk management.
- Improved methodologies are needed to strengthen the basis for early preventive actions against environmental exposures.
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