Hehir R M, McNamara B P, McLaughlin J, Willigan D A, Bierbower G, Hardisty J F
Environ Health Perspect. 1981 Oct;41:63-72. doi: 10.1289/ehp.814163.
Vinyl chloride monomer (VCM), already identified as a human animal carcinogen, was selected as a model agent to explore an area of concern for single and intermittent low level exposure. In traditional cancer bioassay, animals are repeatedly exposed over their lifespan to a dose of suspected chemical. In the current studies rats and mice were exposed in an inhalation chamber to single one-hour doses of VCM ranging from 50 to 50,000 ppm. A second group was given 10 one-hour exposures to 500 ppm or 100 one-hour exposures to 50 ppm of the same chemical. All animals were then observed for the remainder of their lives, generally 18-24 months. Moribund animals were euthanized, and survivors were sacrificed on schedule and their tissues examined for pathological changes. Specifically, the oncogenic study demonstrated dose related effects for single one-hour exposure of VCM at high levels, i.e., 5,000 and 50,000 ppm. These concentrations increased the incidence of pulmonary adenomas and carcinomas in mice. Repeated exposure of A/J mice to the same chemical at 500 ppm X 10 one-hour exposures also increased the incidence of pulmonary adenomas and carcinomas which are considered highly one-hour exposure, no significant increase in tumors was observed. Rats exposed to identical concentrations of VCM failed to elicit a tumorigenic response.
氯乙烯单体（VCM）已被确认为人类和动物致癌物，被选作一种模型物质，以探究单次和间歇性低水平暴露所涉及的一个问题领域。在传统的癌症生物测定中，动物在其整个生命周期内反复接触一定剂量的可疑化学物质。在当前的研究中，大鼠和小鼠在吸入舱中暴露于单次一小时剂量的VCM，剂量范围为50至50,000 ppm。第二组动物接受了10次一小时的500 ppm VCM暴露，或100次一小时的50 ppm相同化学物质暴露。然后对所有动物的余生进行观察，通常为18 - 24个月。濒死的动物实施安乐死，存活的动物按计划处死，并对其组织进行病理变化检查。具体而言，致癌性研究表明，单次一小时的高水平VCM暴露（即5,000和50,000 ppm）存在剂量相关效应。这些浓度增加了小鼠肺腺瘤和癌的发生率。将A/J小鼠反复暴露于500 ppm的相同化学物质下10次一小时，也增加了肺腺瘤和癌的发生率，而被认为是高度致癌的单次一小时暴露，则未观察到肿瘤有显著增加。暴露于相同浓度VCM的大鼠未引发致瘤反应。
