Lead Exposure: A Contributing Cause of the Current Breast Cancer Epidemic in Nigerian Women

Breast cancer incidence in Nigerian women has significantly increased during the past three decades in parallel with the rapid industrialization of that country. This suggested that the associated widespread contamination of the soil and of the water supplies by lead (Pb) and other industrial metals was a major contributing cause. Because of its many domestic, industrial, and automotive uses, Pb is of particular concern as it has been shown to promote the development of mammary tumors in murine mammary tumor virus-infected female C3H mice at levels as low of 0.5 ppm Pb in the drinking water. Lead belongs to the group of selenium-antagonistic elements that interact with selenium (Se), abolishing its anti-carcinogenic effect. Lead on chronic, low-level exposure in addition also accelerates tumor growth rates. Higher levels of Pb were found in blood and head hair samples of newly diagnosed patients with breast cancer, all with infiltrating ductal carcinoma, the most common form of breast cancer in Nigeria, seen at Obafemi Awolowo University, than in cancer-free controls from the same area. Evidence for interactions between Pb and Se was obtained from blood, hair, and tumor biopsy tissue analyses. Furthermore, the Pb levels in hair samples of the patients were directly correlated with the volumes of their tumors, in accord with the tumor growth-promoting effects of Pb. Conversely, Se levels in hair and blood were inversely correlated with the tumor volumes, consistent with the anti-proliferative effects of Se. Several other elements, e.g., Cd, Hg, Cr, Sn, and As, were detected in the scalp hair of the patients and the controls, although at significantly lower levels than those of Pb. However, correlation calculations revealed them also to interact with Se, suggesting that only a fraction of the Se in organs and tissues is actually present in bioactive forms. In metal-exposed subjects, a state of latent Se deficiency may exist, resulting in depressed immune functions and increased cancer susceptibility. Evidence is presented to show that Pb and other metals also interact with iodine, another vitally important essential trace element believed to protect against breast cancer development. Public health programs aiming at lowering the breast cancer risk of Nigerian women thus will have to include effective measures to protect the population from exposures to Pb and other industrial metals that are presently contaminating the environment and the water supplies

Lithium and Other Elements in Scalp Hair of Residents of Tokyo Prefecture as Investigational Predictors of Suicide Risk

Abstract The high suicide rates in Japan and several reports of inverse associations of suicide rates with the levels of lithium (Li) in drinking water prompted determinations of Li along with other elements in samples of scalp hair of 100 male and 100 female residents of Tokyo Prefecture. In more than half of the samples of both genders, Li levels were below the instrumental detection limit or below or the lower limit of the laboratory reference ranges. Among other elements, the concentrations namely of cobalt were also frequently below the laboratory reference range, suggesting that low circulating levels of vitamin B 12 were common in this study population. As vitamin B 12 deficiency is associated with depression and other psychiatric conditions, and there is evidence of interactions between Li and vitamin B 12 , Li deficiency as well as suboptimal vitamin B 12 status must be considered as potential suicide risk factors. In view of its established positive effects on mood and brain function, an adequate supply of selenium (Se) is important as well. Although the analytical results suggested that the Se status of the subjects was generally adequate, as seafood was a major dietary source of Se, much of it was actually sequestered by mercury and only a fraction was bio-available. In addition, the hair samples were found to contain not insignificant levels of As, Cd, Ni, and Pb, arising from the adventitious presence of these elements in foods and the environment. As these elements also interact with Se in vivo and are known to adversely affect mood and behavior, in investigational studies, subjects at risk need to be evaluated also with respect to these elements