Documents Vandenberg, Laura N. 2 results

"Evidence increasingly confirms that synthetic chemicals disrupt the endocrine system and contribute to disease and disability across the lifespan. Despite a United Nations Environment Programme/WHO report affirmed by over 100 countries at the Fourth International Conference on Chemicals Management, ‘manufactured doubt' continues to be cast as a cloud over rigorous, peer-reviewed and independently funded scientific data. This study describes the sources of doubt and their social costs, and suggested courses of action by policymakers to prevent disease and disability. The problem is largely based on the available data, which are all too limited. Rigorous testing programmes should not simply focus on oestrogen, androgen and thyroid. Tests should have proper statistical power. ‘Good laboratory practice' (GLP) hardly represents a proper or even gold standard for laboratory studies of endocrine disruption. Studies should be evaluated with regard to the contamination of negative controls, responsiveness to positive controls and dissection techniques. Flaws in many GLP studies have been identified, yet regulatory agencies rely on these flawed studies. Peer-reviewed and unbiased research, rather than ‘sound science', should be used to evaluate endocrine-disrupting chemicals."

"For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health."