Academic journal article Environmental Health Perspectives

Cadmium-Related Mortality and Long-Term Secular Trends in the Cadmium Body Burden of an Environmentally Exposed Population

Academic journal article Environmental Health Perspectives

Cadmium-Related Mortality and Long-Term Secular Trends in the Cadmium Body Burden of an Environmentally Exposed Population

Article excerpt

BACKGROUND: Few population studies have reported on the long-term changes in the internal cadmium dose and simultaneously occurring mortality.

OBJECTIVE: We monitored blood cadmium (BCd), 24-hr urinary cadmium (UCd), and mortality in an environmentally exposed population.

METHODS: Starting from 1985, we followed BCd (until 2003), UCd (until 1996), and mortality (until 2007) among 476 and 480 subjects, randomly recruited from low-exposure areas (LEA) and high-exposure areas (HEA). The last cadmium-producing plant in the HEA closed in 2002.

RESULTS: From 1985-1989 to 1991-1996, BCd decreased by 40.3% and 18.9% in the LEA and HEA, respectively (p < 0.0001 for between-area difference). From 1991-1996 until 2001-2003, BCd remained unchanged in the HEA (+ 1.8%) and increased by 19.7% in the LEA (p < 0.0001). Over the entire follow-up period, the annual decrease in BCd averaged 2.7% in the LEA (n = 258) and 1.8% in the HEA (n = 203). From 1985-1989 to 1991-1996, UCd fell by 12.9% in the LEA and by 16.6% in the HEA (p = 0.22), with mean annual decreases of 2.7% (n = 366) and 3.4% (n = 364). Over 20.3 years (median), 206 deaths (21.5%) occurred. At baseline, BCd (14.6 vs. 10.2 nmol/L) and UCd (14.1 vs. 8.6 nmol/24-hr) were higher in death than in survivors. The risks (p [less than or equal to] 0.04) associated with a doubling of baseline UCd were 20% and 44% for total and noncardiovascular mortality, and 25% and 33% for a doubling of BCd.

CONCLUSIONS: Even if zinc-cadmium smelters close, historical environmental contamination remains a persistent source of exposure. Environmental exposure to cadmium increases total and noncardiovascular mortality in a continuous fashion without threshold.

KEY WORDS: cadmium, environmental exposure, mortality. Environ Health Perspect 116:1620-1628 (2008). doi:10.1289/ehp.11667 available via http://dx.doi.org/ [Online 24 July 2008]

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Cadmium is a metal with high toxicity, has as estimated elimination half-life of 10-30 years, and accumulates in the human body, particularly in the liver and the kidney (Jarup et al. 1983; Nordberg et al. 2007). Urinary excretion of cadmium over 24 hr (UCd) is a biomaker of lifetime exposure, whereas the blood cadmium concentration (BCd) reflects recent exposure over months (Nordberg et al. 2007). Exposure to cadmium occurs through intake of contaminated food or water or by inhalation of tobacco smoke or polluted air (Hogervorst et al. 2007; Nordberg et al. 2007). Environmental exposure to cadmium in northeastern Belgium, in the neighborhood of zinc-cadmium smelters, has been associated with a nearly 30% increased urinary cadmium excretion (Sartor et al. 1992b), renal dysfunction (Buchet et al. 1990; Staessen et al. 1994), increased calciuria (Staessen et al. 1991b), osteoporosis (Staessen et al. 1999), a 35% population-attributable risk of fractures (Staessen et al. 1999), and a 67% population-attributable risk of lung cancer (Nawrot et al 2006).

Studies of Japanese populations living in areas heavily polluted by cadmium have shown that the cadmium-induced renal tubular injury (Arisawa et al. 2001, 2007a, 2007b; Nakagawa et al. 2006; Nishijo et al. 2004, 2006; Uetani et al. 2006), even in the presence of moderate elevations of the urinary [[beta].sub.2]-microglobulin excretion (300-1,000 [mu]g/g creatinine), adversely affected life prognosis. To our knowledge, no cohort studies in a general population have reported on long-term changes in the body burden of cadmium and the simultaneous incidence of mortality. In our environmentally exposed cohort, living in Belgium, we monitored BCd from 1985 until 2003, urinary cadmium from 1985 until 1996, and mortality from 1985 to 2007. During this period, cadmium emissions ceased, but the soil remained contaminated with cadmium. Our primary objective was to assess the association between mortality and the internal dose of cadmium. We also evaluated how attrition by cadmium-related mortality (Arisawa et al. …

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