| Both the Environment and Genes Are Important for Concentrations of Cadmium and Lead in Blood Lars Björkman,1,2 Marie Vahter,1 and Nancy L. Pedersen1,3 1Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
2Department of Basic Oral Science, Karolinska Institutet, Stockholm, Sweden
3Department of Medical Epidemiology, Karolinska Institutet, Stockholm and Department of Psychology, University of Southern California, Los Angeles, California, USA Abstract
Concentrations of cadmium and lead in blood (BCd and BPb, respectively) are traditionally used as biomarkers of environmental exposure. We estimated the influence of genetic factors on these markers in a cohort of 61 monozygotic and 103 dizygotic twin pairs (mean age = 68 years, range = 49-86) . BCd and BPb were determined by graphite furnace atomic absorption spectrophotometry. Variations in both BCd and BPb were influenced by not only environmental but also genetic factors. Interestingly, the genetic influence was considerably greater for nonsmoking women (h2 = 65% for BCd and 58% for BPb) than for nonsmoking men (13 and 0%, respectively) . The shared familial environmental (c2) influence for BPb was 37% for men but only 3% for women. The association between BCd and BPb could be attributed entirely to environmental factors of mutual importance for levels of the two metals. Thus, blood metal concentrations in women reflect not only exposure, as previously believed, but to a considerable extent hereditary factors possibly related to uptake and storage. Further steps should focus on identification of these genetic factors and evaluation of whether women are more susceptible to exposure to toxic metals than men. Key words: aging, blood, cadmium, environment, genes, human, lead, twins. Environ Health Perspect 108:719-722 (2000) . [Online 23 June 2000] http://ehpnet1.niehs.nih.gov/docs/2000/108p719-722bjorkman/ abstract.html Address correspondence to M. Vahter, Institute of Environmental Medicine, Karolinska Institutet, Box 210, S-171 77 Stockholm, Sweden. Telephone: 46 8 728 7540. Fax 46 8 337039. E-mail: marie.vahter@imm.ki.se We thank M. Bæcklund for help with preliminary analyses. The Swedish Adoption Twin Study of Aging was supported by the National Institute on Aging (grants AG-04563 and AG-10175) , the MacArthur Foundation Research Network on Successful Aging, and the Swedish Council for Social Research. In addition, the Swedish Environmental Protection Agency provided support for this study. Received 28 December 1999 ; accepted 30 March 2000.
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