Carcinogens Case-control studies

Tubal ligation is another procedure that has shown potential for risk reduction. However, it is not recommended as a sole procedure in prophylaxis. Protective effect may be due to limiting exposure of the ovary to environmental carcinogens. A case-control study conducted by Narod and colleagues found that a history of tubal ligation in /f RCA-positive women was associated with a statistically significant 63% reduction in risk.22... 

Mineral Oil Hydraulic Fluids. There is limited information on the toxicity of mineral oil hydraulic fluids in humans. A single case report of a child accidentally ingesting a single dose of automotive transmission fluid provides limited information on death and systemic effects. A case-control study provides some information on the carcinogenicity of mineral oil hydraulic fluids. The study population was exposed via inhalation and dermal routes. An occupational exposure study provides information on neurotoxicity following chronic dermal exposure. Information on the toxicity of mineral oil hydraulic fluids is limited to a series of inhalation, oral, and dermal acute-duration exposures. These studies provide information on death, systemic effects, and neurotoxicity by inhalation, oral, and dermal routes, and immunotoxicity following dermal exposure. 

There are limited epidemiological data regarding carcinogenicity in humans following chronic inhalation exposure to kerosene. In one case-control study, there was no association between the use of kerosene stoves for cooking and bronchial cancer in nonsmoking women (Chan et al. 1979). In another case-control study, there was no association between renal cell cancer and occupational exposure to fuel oils. 

Among a small factory population, two cases of lung cancer were found in men primarily involved in the production of benzoyl peroxide, but they were also exposed to benzoyl chloride and benzotrichloride. Benzoyl peroxide exposure was associated with a greater frequency of malignant melanoma in one of two case control studies it was not associated with basal cell carcinomas of the skin in another study. The lARC has determined that there is limited evidence for the carcinogenicity of benzoyl peroxide in experimental animals and that it is not classifiable as to its carcinogenicity to humans. 

In humans methylene chloride exposure has been associated with a wide variety of cancers in a number of cohort and case control studies pancreatic, prostate, lung, liver, cervical, breast, and astrocytic brain tumors have been reported. Limitations in these studies include small sample size, incomplete exposure information, and concomitant exposure to other carcinogenic substances. The lARC has stated that there is not a sufficiently consistent elevation of risk across studies to make a causal interpretation credible. In a recent study of 1473 workers, followed for nearly 50 years, methylene chloride exposure level was not related to mortality due to all causes, malignant neoplasms, or lung and pancreatic cancers. ... 

One case-control study in humans found no significant associations between exposure and various cancers no information was given on exposure levels or possible confounding effects of other exposures. The lARC has determined that there is inadequate evidence in humans for the carcinogenicity of propylene oxide but that it is possibly carcinogenic to humans. ... 

There are no specific reports on turpentine carcinogenicity or mutagenicity. However, in one case control study, paternal exposure to turpentine was one of several substances associated with an increased risk of neuroblastoma in offspring. ... 

Three types of epidemiological studies of cancer contribute to the assessment of carcinogenicity in humans—cohort studies, case-control studies and correlation (or ecological) studies. Rarely, results from randomized trials may be available. Case series and case reports of cancer in humans may also be reviewed. 

Cancer. The only information regarding carcinogenicity of PBDEs in humans is available from a case-control study that found no clear association between risk of non-Hodgkin s lymphoma and exposure to 2,2 4,4 -tetraBDE in a small group of Swedish men and women. 

Dement JM. 1991. Carcinogenicity of chrysotile asbestos A case control study of textile workers. Cell Biol Toxicol 7 59-65. 

IARC (1989d) concluded that there was inadequate evidence for the carcinogenicity of jet fuel in humans and animals, but noted that there is limited evidence for the carcinogenicity in experimental animals of straight-run kerosene and hydrotreated kerosene. IARC s review included a cohort mortality study that found no increased cancer risk in men exposed to jet fuel, aviation kerosene, and other fuels in the Swedish Air force elevated risk for kidney cancer in men exposed to jet fuel in a Canadian case-control study and both positive and negative findings for skin cancer in studies of mice dermally exposed to jet fuels. 

A number of studies of the carcinogenicity of dermal application of crude oil to animals have been reviewed by IARC (1989c), which concluded that there is limited evidence for the carcinogenicity of crude oil to experimental animals. A cohort study of U.S. petroleum-producing and pipeline workers, and case control studies that included exposure during crude oil exploration and production, were evaluated by IARC (1989c), which concluded that there is inadequate evidence for the carcinogenicity of crude oil in humans. 

Selected Case-Control Studies. Luce et al. (1993b) attempted to detennine whether occupational exposure to fonnaldehyde was associated with an increased risk of sinonasal cancer in humans. Case subjects were patients with primary malignancies of the nasal and paranasal sinuses. Odds ratios for squamous cell carcinomas in formaldehyde-exposed workers, when adjusted for wood dust and glue exposure, were not significantly elevated. The odds ratio for adenocarcinomas was confounded by the frequent co-exposure to wood dust, a known carcinogen. However, in those exposed to wood dust, an increased odds ratio was noted in those also exposed to formaldehyde. The authors concluded that the data did not support an increased risk of nasal cancers due to formaldehyde alone. 

Cancer. Carcinogenicity of PCBs in humans has been investigated in retrospective occupational studies that evaluated cancer mortality in workers exposed during capacitor manufacturing and repairing, and in case-control studies of the general population that examined associations between cancer and serum or adipose tissue levels of PCBs resulting from environmental exposures. Based on indications of... 

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