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Archived Comments for: Mortality among US employees of a large computer manufacturing company: 1969–2001

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  1. Cancer mortality rates at IBM may be related to low solar UVB/vitamin D

    William B. Grant, Sunlight, Nutrition and Health Research Center (SUNARC)

    24 October 2006

    The article by Clapp [1] is a useful analysis of cancer mortality risk of IBM employees but may not have the correct interpretation. What was overlooked is that the employees may have lower serum 25-hydroxyvitamin D (calcidiol) levels due to geographic location and indoor occupation. It was noted in [1] that there are IBM facilities in California, Minnesota, New York, and Vermont. Inspection of the Cancer Atlas of the United States [2] indicates that cancer mortality rates are higher in MN, NY, and VT than the country average. It has been shown that the high cancer rates there are related to low solar ultraviolet-B (UVB) irradiance and vitamin D production [3], even when other risk-modifying factors are included [4]. The role of vitamin D in cancer risk reduction was also shown in the Health Professionals Follow-up Study [5].

    The article [1] points out that the cancers with elevated risk in semiconductor manufacturing are brain, breast, lung, non-Hodgkin’s lymphoma (NHL), and renal cancer. Brain, breast, NHL and renal cancer are inconsistently elevated in the study population, and lung cancer rates are reduced compared to the U.S. rate for males. Also, of the 11 cancers for which significantly elevated proportional cancer mortality ratios (PCMRs) were found for the entire workforce, only six were found for those employees involved in manufacturing, and only one, renal cancer, was found for both sexes. It is also interesting to note that in a study of cancer rates in UK semiconductor workers, only breast, pancreatic and rectal cancer and melanoma rates were elevated [6]. The authors concluded that the cancers with elevated risk may be due to factors unconnected to their occupation.

    On the other hand, all 12 cancers with elevated PCMRs in [1] and [6] have been identified as vitamin D-sensitive in one or more studies [3-5, 7-8]. There is even strong evidence that melanoma is a vitamin D-sensitive cancer [9], with ultraviolet A (320-400 nm) as an important risk factor [10], with indoor workers are at greater risk than outdoor workers [11].

    Thus, it is premature to claim that exposure to solvents and other chemicals explains the findings in [1] until the impact of likely lower solar UVB irradiance and calcidiol levels than the national average is assessed, although some impact from chemical exposure is certainly likely.

    References

    1. Clapp RW. Mortality among US employees of a large computer manufacturing company: 1969-2001. Environmental Health: A Global Access Science Source. 2006, 5:30.

    2. Devesa SS, Grauman DJ, Blot WJ, Pennello GA, Hoover RN, Fraumeni JF Jr. Atlas of Cancer Mortality in the United States, 1950-1994. NIH Publication No. 99-4564, 1999. http://cancer.gov/atlasplus/new.html (accessed October 22, 2006)

    3. Grant WB. An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation. Cancer. 2002;94:1867-75.

    4. Grant WB, Garland CF. The association of solar ultraviolet B (UVB) with reducing risk of cancer: multifactorial ecologic analysis of geographic variation in age-adjusted cancer mortality rates. Anticancer Res. 2006;26:2687-99.

    5. Giovannucci E., Liu Y, Rimm EB, Hollis BW, Fuchs CS. Stampfer MJ, Willett WH. Prospective study of predictors of vitamin D status and cancer incidence and mortality in men. JNCI 2006; 98:451-9.

    6. Nichols L, Sorahan T. Cancer incidence and cancer mortality in a cohort of UK semiconductor workers, 1970-2002. Occup Med (Lond). 2005;55:625-30.

    7. Grant WB. Ecologic studies of solar UV-B radiation and cancer mortality rates. Recent Results Cancer Res. 2003;164:371-7.

    8. Grant WB. An ecologic study of cancer mortality rates in Spain with respect to indices of solar UV irradiance and smoking. Int J Cancer, in press.

    9. Osborne JE, Hutchinson PE. Vitamin D and systemic cancer: is this relevant to malignant melanoma? Br J Dermatol. 2002;147:197-213.

    10. Garland CF, Garland FC, Gorham ED. Epidemiologic evidence for different roles of ultraviolet A and B radiation in melanoma mortality rates. Ann Epidemiol. 2003;13:395-404.

    11. Garland FC, White MR, Garland CF, Shaw E, Gorham ED. Occupational sunlight exposure and melanoma in the U.S. Navy. Arch Environ Health. 1990;45:261-7.

    Competing interests

    The author has received speaker's fees and expenses reimbursed for various appearances in which he discussed the health benefits of ultraviolet B irradiance and vitamin D. However, his research is unfunded.

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