Human risk assessment of carcinogens from an administrative perspective

Our plain-English summary of Human risk assessment of carcinogens from an administrative perspective, by I. Tesseraux, A. Lommel, I. Ollroge, et al (Regulatory Toxicology and Pharmacology, 1990).

The study

• Authors: I. Tesseraux, A. Lommel, I. Ollroge, A.D. Kappos, G. Koss
• Journal: Regulatory Toxicology and Pharmacology
• Published: 1990;11(1):63-7
• Type of article: Review
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

For evaluation of the carcinogenic potency of an environmental chemical or a mixture of chemicals, epidemiological or workplace studies, animal studies, and in vitro tests are the three major strategies used. Asbestos fibers and 1,2-dichloroethane are chosen as examples. They illustrate that the strategies may enable the implementation of measures by health authorities.

In plain English

This short overview, not a new study, came from authors at a labor, health and social affairs authority in Hamburg, Germany. They described how health authorities can use existing human, animal and laboratory evidence on cancer, with asbestos fibers and 1,2-dichloroethane (EDC) as examples. They cited numerous earlier occupational studies linking asbestos to pleural and intraperitoneal mesothelioma and bronchiogenic carcinoma, with cancer death rates tied to cumulative exposure. They noted that no direct human information existed on cancer risk at the low exposures usually found indoors and outdoors. In cited animal studies, rats inhaling asbestos developed malignant lung tumors, but mesothelioma was never observed. For administrative action aimed at preventing health hazards, the authors considered an agent carcinogenic if it met any one of three criteria: positive human data, sufficient positive animal data, or positive in vitro data, especially from human or mammalian cells. Although low-exposure cancer risk to the general population cannot be proven, they concluded the risk must be minimized. Asbestos regulations, they noted, hold that no product that might release airborne fibers should remain inside buildings, with priority to schools.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Overview and commentary from a health-authority perspective; no new data were collected. Asbestos and EDC were used as worked examples of existing evidence.
• Who was studied: No study population. The authors drew on previously published occupational (worker) studies, animal studies (rats, mice, hamsters, baboons) and laboratory (in vitro) tests. The authors were based at a Hamburg health authority in the Federal Republic of Germany.
• Exposure: Asbestos fibers (no specific fiber type named in the text) and 1,2-dichloroethane (EDC). The concern was low-level environmental exposure in indoor and outdoor air.
• Main results:
  • According to the earlier occupational studies the authors described, asbestos fibers have been implicated in pleural and intraperitoneal mesothelioma and bronchiogenic carcinoma, as well as in asbestosis (pulmonary fibrosis).
  • Citing Schneiderman et al. (1981), the authors reported that workplace studies found death rates from asbestos-associated cancer correlated with the size of cumulative exposure, and that smokers were an especially sensitive group.
  • The authors stated that no empirical information was available on cancer effects at the low exposures usually found in the outdoor and indoor environment.
  • In a cited baboon study (Goldstein et al., 1978), animals exposed to about 166 million (166 x 10 to the 6th) airborne asbestos fibers per cubic meter for 9 months did not develop malignancies. The exception was a few animals in which bronchioalveolar carcinoma could not be excluded.
  • In cited animal studies, hamsters developed no carcinomas of the upper airways and no mesotheliomas. Rats inhaling asbestos fibers developed malignant lung tumors, but mesothelioma was never observed.
  • In laboratory tests, asbestos was not mutagenic in bacterial tests, while chromosomal damage occurred with asbestos in some mammalian cell types.
  • For deciding whether an agent is carcinogenic in terms relevant for administrative action, with the aim of preventing health hazards, the authors applied three criteria. The third was positive in vitro data, especially from human or mammalian cells, because human and animal data take a long time to obtain.
  • The authors stated that even though the cancer risk to the general population at low exposure levels cannot be proven, the risk must be minimized in terms of preventing health hazards.
  • The authors described the regulatory principle that no asbestos product that might be a source of airborne fibers should remain inside a building, with priority to schools.
• The authors' conclusion: For administrative action aimed at preventing health hazards, the authors considered an agent carcinogenic if it met any of three criteria: positive human data, sufficient positive animal data, or positive in vitro data (especially human or mammalian cells). Even though the cancer risk to the general population at low exposure cannot be proven, they held that the risk must be minimized. They concluded that the evaluation strategies, despite their limitations, are helpful and enable health authorities to take measures.
• Limitations the authors state:
  • The authors stated that the available data allow a qualitative evaluation but rarely a quantitative one.
  • The authors stated that low-dose risk can only be crudely estimated, for asbestos by extrapolating from occupational study data.
  • The authors stated that unit risk estimates give only a rough indication of cancer potency. They do not account for differences among people such as genetic constitution and life-style, or for effects of other carcinogens.
  • The authors stated that the linear extrapolation model gives an upper, worst-case risk limit, and the true risk is supposed to be lower.

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenic.

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