Assessment of cadmium impregnation in women suffering from endometriosis: a preliminary study
Introduction
Cadmium is a naturally occurring component of the earth's crust. Due to its physicochemical properties (e.g. low melting point,…), cadmium has been extensively used in industry essentially in alkaline batteries, in anti-corrosive coatings, as stabiliser or pigment in plastics (e.g. cadmium yellow) (IPCS, 1992).
In the general population, exposure to cadmium is mainly through the consumption of contaminated food and/or by tobacco smoking. Cadmium is a cumulative toxicant stored in the liver and kidneys (biological half-life >10 years). The cadmium body burden can be usually assessed by monitoring cadmium urinary excretion (CdU) whereas cadmium concentration in blood (CdB) rather reflects recent exposure. Excessive occupational or environmental exposure has been associated with kidney (tubular dysfunction) and bone (osteoporosis) damage (Lauwerys and Hoet, 2001).
The average gastro-intestinal absorption of cadmium (generally less than 5% in adults) varies considerably between individuals and is increased in iron-depleted subjects (Flanagan et al., 1978). As women of childbearing age tend to have reduced iron stores, it may be expected that gastro-intestinal absorption will be higher in this subpopulation. Accordingly, it has consistently been shown that women have higher levels of cadmium in renal cortex than men (Elinder et al., 1976, Friis et al., 1998).
Cadmium has also been suspected for some time to be an endocrine disruptor and to possess oestrogen-like activity. Martin et al. observed that cadmium mimics oestrogen activity in breast cancer cells and that cadmium binds to and activates oestrogen receptor alpha (Martin et al., 2003, Stoica et al., 2000). Recently, the same team has reported vaginal epithelial cornification and increased uterine weight after cadmium exposure in ovariectomised rats and these effects did not occur in the presence of anti-oestrogenic drugs (Johnson et al., 2003).
Endometriosis is an oestrogen-dependent disease characterised by the extra-uterine growth of endometrial glands and stroma (Kitawaki et al., 2002). Main sites of such aberrant tissues are the ovaries (ovarian endometriosis) and the peritoneum (peritoneal endometriosis) (Donnez et al., 2002). The consequences of this ectopic tissue are internal bleeding, inflammation and scarring often leading to infertility. The prevalence of endometriosis in Belgium is high and reaches 20% in reproductive age women. A particular localisation of endometriosis has been reported as a different clinical and pathological entity: adenomyosis or deep endometriotic nodules of the recto-vaginal septum (Nisolle and Donnez, 1997). The implication of endocrine disruptors in the onset or the growth of endometriosis and/or adenomyosis has been suggested (Gerhard and Runnebaum, 1992, Donnez et al., 2002).
In this study, we investigated a putative relationship between cadmium body burden and the presence of endometriosis or deep endometriotic (adenomyotic) nodules. Cadmium urinary excretion and blood concentration were used as biomarkers of cadmium body burden.
Section snippets
Patients
In the frame of a case-control study examining environmental risk factors for endometriosis, 59 Belgian women provided urine and blood for cadmium analysis. All patients suffered from peritoneal or ovarian endometriosis (n = 25) or deep endometriotic (adenomyotic) nodules (n = 13) as confirmed during surgery. Control women (n = 21) did not show any suggestive symptoms or signs of endometriosis or deep endometriotic (adenomyotic) nodules and were recruited from the consultation of the
Results and discussion
This preliminary study was designed to assess the cadmium body burden in women suffering from endometriosis in Belgium because the environment has been historically polluted by cadmium due to the non-ferrous metal activity during the last century (Staessen et al., 1992).
The main characteristics of the studied population are described in Table 1. Age and BMI did not differ significantly among the groups. Similar proportions (one-third) of smoking women were found in each group but control women
Acknowledgments
The authors gratefully acknowledge the assistance of Dr. K. Rosenkranz, Dr. O. Donnez, Dr. F. Grandjean, Dr. L. De Buyl, A.T. Ha and R. Rousseau with data collection. This study was financed by a grant (No. 3.4587.01) from the Fonds de la Recherche Scientifique Médicale (Belgium).
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