We used inductively coupled plasma mass spectrometry (ICP-MS) to assess baseline toenail concentrations for a panel of 16 trace elements (antimony, arsenic, cadmium, chromium, cobalt, copper, iron, lead, mercury, manganese, molybdenum, nickel, selenium, tin, vanadium, and zinc).
#Aj and katie webber skin#
15 Women were eligible for the current study of metals and age at menopause if they were premenopausal at baseline, had no history of hysterectomy or oophorectomy, and had no prior diagnosis of cancer other than nonmelanoma skin cancer (n = 907).Įxposure assessment: toenail metal concentrations Metal concentrations were assessed for 2,617 women with toenail samples collected at baseline who were part of a subset of participants in a sister-matched case-control study of young-onset breast cancer. Response rates have remained at approximately 90% for each update. Participants complete annual health updates and more extensive follow-up questionnaires to assess changes in their health including menopausal status. Women were asked to remove their nail polish and provide clippings from each toenail. The women completed a home visit with a trained examiner who collected biospecimens and conducted anthropometric measurements including height and weight to calculate body mass index (BMI). 17 Study participants were enrolled from 2003 to 2009 to be eligible, they had to be between the ages of 35 to 74, reside in the United States or Puerto Rico, have a sister who had been previously diagnosed with breast cancer and have no history of breast cancer themselves.Īt the time of study enrollment, participants completed extensive questionnaires on their demographics, lifestyle factors, and medical history including information on reproductive history and menopausal status. The Sister Study is a prospective cohort of 50,884 women designed to identify environmental and lifestyle risk factors for breast cancer. We hypothesized that women with higher exposure to metals, specifically nonessential metals such as cadmium and lead, would tend to have an earlier age at menopause. The aim of this prospective study was to evaluate whether toenail metal and/or trace element concentrations (antimony, arsenic, cadmium, chromium, cobalt, copper, iron, lead, mercury, manganese, molybdenum, nickel, selenium, tin, vanadium, and zinc, to be henceforth referred to as metals), individually or in combination, were associated with age at menopause. Metals also have diverse biologic functions and may be expected to have differing associations with the timing of menopause some are essential (e.g., cobalt, copper, nickel, and chromium) and are necessary for normal physiologic function whereas others are considered nonessential and are often referred to as being “toxic” (e.g., lead, arsenic, cadmium, and mercury). 15 However, previous studies have not considered the association with menopause given these coexposure patterns which could result in residual confounding. Multiple metals can arise from similar sources (e.g., smoking, occupational exposures, dietary sources), which may partly explain correlation of multiple metals within individuals. 12 Higher levels of lead measured in the bone were associated with earlier menopause in a subpopulation of the Nurses’ Health Study cohort 13 and similar associations were observed for blood lead in the National Health and Nutrition Examination Survey. An earlier age at menopause was observed in a small population occupationally exposed to lead from smelting compared with similar aged women without occupational exposure. 11 Previous epidemiologic research on metals and menopause has been focused on exposure to lead. There is evidence that some metals, such as cadmium and lead, have endocrine-disrupting properties 8– 10 and that lead in particular may act as a reproductive toxicant.
Metals are one plausible group of environmental chemicals that may influence the timing of menopause. 6, 7 Achieving a better understanding of how environmental factors may be related to timing of menopause could provide clues for potential biologic mechanisms underlying associations between environmental chemicals and chronic disease. Loss of ovarian function and decreases in endogenous estrogen production that occur with menopause are plausible biologic mechanisms by which timing of menopause may influence these health outcomes. 3– 5 Thus, the length of the reproductive lifespan is an important factor in a woman’s later-life health. Earlier age at menopause is associated with reduced fertility and a higher risk of cardiovascular disease and death 1, 2 and a lower risk of breast, endometrial, and ovarian cancer.
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