associations were found for a number of sites, including, in men, cancer of the lip, salivary gland, nasopharynx, nose, nasal cavity, middle ear, breast, eye, thyroid, thymus and endocrine glands, and multiple myeloma and, in women, cancer of the salivary gland, nasopharynx, large intestine, liver, gallbladder, bile ducts, larynx, bone, connective tissue, kidney and uterus, eye, thymus, and endocrine glands, and lymphosarcoma, reticular sarcoma, Hodgkin's disease, multiple myeloma, and leukemia. The consequences of adjusting for smoking at the state level were also examined.

Mifune and colleagues (1992) described cancer mortality for 1952–1988 in inhabitants of the Misasa spa area in Japan, comparing standardized mortality ratios based on national data with those in a control area. In the spa area, there are 90 hot-spring sources, and average radon concentration was reported to be 26 mBqL-1 in outdoor air and 35 mBqL-1 in indoor air. Routes of exposure included use of the hot springs for bathing and the medical treatment of patients. Overall, there was no excess of all cancers, and the risk of lung-cancer death in the Misasa area was only 55% of that in the control area.

REPRODUCTIVE OUTCOMES

The committee identified only a single new investigation relevant to concern about reproductive outcomes. Shields and others (1992) conducted a case-control study of congenital abnormalities, stillbirths, developmental disorders, and deaths from causes other than injuries. The case series included 266 cases and an equal number of controls with a normal birth. Exposure variables included the occupations of the parents and grandparents; the nearness of the subject's residences to uranium mines, mine dumps, and mill tailings; and living in a home constructed with uranium-mine rock. There was no evident effect of the fathers' being employed in a uranium mine or mill. There was increased risk for adverse pregnancy outcome if the mother lived near tailings or mine dumps. Interpretation of the findings is limited by lack of statistical power, particularly within the categories of specific adverse outcomes.

CONCLUSIONS

Although it has been nearly 10 years since the BEIR IV committee reviewed the evidence on health effects of radon-progeny exposure other than lung-cancer, the database is still limited. Nevertheless, the committee found several conclusions to be warranted. In regard to cancers other than lung-cancer, the committee interpreted the pooled analysis reported by Darby and colleagues (1995) as not indicating excess risk for cancers other than cancer of the lung in radon-exposed miners. Although 95% confidence limits are wide for some sites, the data provide evidence that radon and its progeny are not a major cause of non-lung-cancers and leukemias in the general population, as suggested by some ecologic studies.



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