Scrutinizing three trichloroethylene carcinogenicity classifications in the European Union--implications for the risk assessment process

An academic researcher's guide to increased impact on regulatory assessment of chemicals

The interactions between academic research and regulatory assessment of chemicals may in theory seem straightforward: researchers perform studies, and these studies are used by regulators for decision-making. However, in practice the situation is more complex, and many factors decide a research study's regulatory use. According to several EU chemical legislations, all available and relevant studies can be used in hazard and risk assessment of chemicals. However, in practice, standard tests conducted under GLP and sponsored and provided by industry are predominantly used. Peer-reviewed studies from independent sources are often disregarded or disputed since they often do not comply with regulatory data requirements and quality criteria. To help bridge such a gap, the aim of this paper is to give an overview of the general workings of legislation of chemicals and propose a set of actions to increase the usability of research data. In the end, this may increase the use of academic research for decision-making and ultimately result in more science-based policies. From a policy perspective, useful scientific evidence comprises those studies that are sufficiently reliable and relevant. This is not in contradiction to the aims of research and generally accepted scientific standards.

Principles and practices of health risk assessment under current EU regulations

Risk assessments serve as the foundation of regulatory decision-making on whether to take actions to reduce (or otherwise manage) a toxicological or ecotoxicological risk or not. To understand the complex process that leads from the generation of scientific data, via risk assessment to risk management decision-making, close studies of the scientific basis and risk assessment methods must be undertaken. This paper consists of two main parts. In the first part the principles of the European Union process for risk assessments, as defined by legislations and official guidelines, are briefly outlined. In the second part the actual workings of this system are exemplified by the results from case studies of the risk assessment processes for trichloroethylene and for acrylamide. The analysis and comparison of these two cases illustrates: (1) that generation of a large amount of data does not ensure consensus among risk assessors, (2) that controversy can regard different levels of detail, (3) that controversy can arise at different organizational and theoretical levels, (4) that risk assessments may be subject to (public) criticism even if the experts agree, and (5) that "scientific" controversies have a significant policy component.

Acrylamide and cancer risk—expert risk assessments and the public debate

This study has two parts. In the first part, fourteen carcinogen risk assessments of acrylamide made by different expert groups during the years 1976-2002 are compared in terms of their overall conclusions and their use of primary data. In the second part, the public debate on acrylamide and cancer risks and the questioning of the expert risk assessment, that arose as a reaction to the identification of this substance in staple food is discussed. In the first part it is shown that the expert risk assessors concur to a large degree about the assessment of the acrylamide potential to cause cancer. Three risk assessors have concluded that acrylamide is neither carcinogenic to humans nor to animals, while eleven risk assessors have concluded that acrylamide is carcinogenic in animals and is likely to be carcinogenic in humans. The differences in the overall conclusions seem to a large extent be explained by an evolving database. The risk assessors agree considerably on how to interpret and evaluate the available primary data, but the coverage of the available references is low. These results are also compared to those previously published on risk assessments of trichloroethylene. In the second part the arguments used in the public debate to question the expert risk assessment are summarized and it is argued that they are not based on the principles generally accepted in toxicological risk assessment.

Indicators of uncertainty in chemical risk assessments

For most of the chemical substances that are subject to regulatory and industrial decision making, important toxicological data are missing. The available dataset is often difficult to interpret, and the differences between alternative, scientifically reasonable interpretations may have major impact on decision making. Since such uncertainties are an important factor in decision making it is essential that they be reported in a transparent and understandable way. In order to clarify how toxicologists report uncertainties, 30 risk assessments for one and the same substance (trichloroethylene) from the years 1973-2001 were searched for phrases indicating uncertainty. These phrases can be divided between four categories: contentual, epistemic, conditionalising, and inferential uncertainty indicators. A typology of uncertainty indicators, based on these categories, is proposed. It is concluded that the use of uncertainty indicators in these texts is not transparent and that the development of standardised uncertainty indicators should significantly improve communications both within the scientific community and between scientists and policymakers.

Scrutinizing ACGIH risk assessments: the trichloroethylene case

BACKGROUND

The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) for occupational exposure to chemicals and physical agents have been very influential in the setting of occupational exposure limits in many countries.

METHODS

Three ACGIH risk assessments of the chlorinated solvent trichloroethylene (TCE) [ACGIH (1989): 5th edition; ACGIH (1992): 5th edition. Revised Vol II; ACGIH (1996): Suppl. 6th edition] are compared to 26 other risk assessments made of the same chemical substance. The documents are compared in terms of their overall conclusions and the data selected for assessment.

RESULTS

It is shown that these ACGIH risk assessment documents were based on incomplete and biased data sets.

CONCLUSIONS

The data on which the ACGIH [ACGIH (1996): Suppl. 6th edition] base their TCE risk assessment do not adequately reflect the available scientific knowledge about TCE toxicity and carcinogenicity. This may have influenced their conclusion that TCE is not carcinogenic in either animals or humans which stand out compared to contemporary risk assessments.