Testing toxic pesticides in humans: health risks with no health benefits

The ethics of human volunteer studies involving experimental exposure to pesticides: unanswered dilemmas

The controversy about the use of data from human volunteer studies involving experimental exposure to pesticides as part of regulatory risk assessment has been widely discussed, but the complex and interrelated scientific and ethical issues remain largely unresolved. This discussion paper, generated by authors who comprised a workgroup of the ICOH Scientific Committee on Rural Health, reviews the use of human experimental studies in regulatory risk assessment for pesticides with a view to advancing the debate as to when, if ever, such studies might be ethically justifiable. The discussion is based on three elements: (a) a review of discussion papers on the topic of human testing of pesticides and the positions adopted by regulatory agencies in developed countries; (b) an analysis of published and unpublished studies involving human testing with pesticides, both in the peer-reviewed literature and in the JMPR database; and (c) application of an ethical analysis to the problem. The paper identifies areas of agreement which include general principles that may provide a starting point on which to base criteria for judgements as to the ethical acceptability of such studies. However, the paper also highlights ongoing unresolved differences of opinion inherent in ethical analysis of contentious issues, which we propose should form a starting point for further debate and the development of guidelines to achieve better resolution of this matter.

Benzene-induced cancers: abridged history and occupational health impact

Benzene-induced cancer in humans was first reported in the late 1920s. Carcinogenesis findings in animals were not reported conclusively until 1979. Industry exploited this "discrepancy" to discredit the use of animal bioassays as surrogates for human exposure experience. The cardinal reason for the delay between first recognizing leukemia in humans and sought-after neoplasia in animals centers on poor design and conduct of experimental studies. The first evidence of carcinogenicity in animals manifested as malignant tumors of the zymbal glands (sebaceous glands in the ear canal) of rats, and industry attempted to discount this as being irrelevant to humans, as this organ is vestigial and not present per se in humans. Nonetheless, shortly thereafter benzene was shown to be carcinogenic to multiple organ sites in both sexes of multiple strains and multiple species of laboratory animals exposed via various routes. This paper presents a condensed history of the benzene bioassay story with mention of benzene-associated human cancers.

The occupational toxicologist: professionalism, morality and ethical standards in the context of legal and non-litigation issues

By its very nature, practice and intended applications, the profession of occupational toxicology has individual and collective responsibilities related to the design, conduct, interpretation and extrapolation of laboratory and controlled human clinical studies in order to determine the potential for industrial xenobiotics to produce adverse effects. The implications for health-related adverse effects in the workplace, and in the domestic and general environment carries many and various responsibilities for the toxicologist which are related to multiple and wide-ranging ethical issues. This review presents and discusses some of the major areas where the occupational toxicologist may experience potential ethical problems related to the conduct of routine professional activities. Emphasis is placed on the design, conduct, interpretation and reporting of laboratory studies; animal welfare; regulatory activities; human clinical volunteer studies; roles and responsibilities in defining workplace safety and protective measures; malpractices in various disciplines and work practices; misconduct in publication; and codes of ethical behavior.