During your work as a health professional, you have probably discovered how practical it is to be able to consult a list with all the substances that have been known for their reproductive hazard. Today, we will look behind the scenes and find out how difficult it is to decide whether substances should be on this list or not. How to weigh the evidence from animal experiments when no human data are available? Is a reduction in growth rate of a pup an adverse effect? What is the critical effect of a substance and when do we consider an effect adverse? In this meeting, we want to compare the methods of classification of chemicals for reproductive toxicity used in the USA and The Netherlands.
In the USA, the state of California publishes a list of chemicals known to cause developmental toxicity as part of Proposition 65 (http://www.oehha.org/prop65/prop65_list/Newlist.html is the website; it includes a link to the complete current list). Chemicals can be proposed for listing on Proposition 65 by a variety of ways, including those based on an evaluation conducted by an authoritative body. One authoritative body is the Center for the Evaluation of Risks to Human Reproduction (CERHR), as part of the National Toxicology Program (more information at http://cerhr.niehs.nih.gov/). For this meeting, we invited the acting director of this program, Dr. Kristina Thayer, to explain their selection mechanism and the procedure followed for the classifications, and to highlight some of the dilemmas encountered in the process of classification.
The classification in the Netherlands is carried out by the Subcommittee on Classification of Reproduction toxic substances of the Dutch Expert Committee on Occupational Safety (DECOS) of the Health Council (more information at http://www.gezondheidsraad.nl/en). This committee currently uses the Directive 93/21/EEC of the European Union to classify chemicals at the request of the Minister of Social Affairs and Employment. Two members of this subcommittee will participate in the meeting. Dr. Nel Roeleveld will present the methodology used for classification and explain the difficulties regarding classification based on human studies and hazard information, while trying to perform an assessment in terms of risk. Dr. Aldert Piersma will focus on classification based on animal studies. He will also discuss agreement on a unified methodology for classification of chemicals for reproductive hazards in a globally harmonized system (GHS) on both sides of the Atlantic.