Reproductive toxicity of occupational mercury. A review of the literature
Introduction
Most dentists and their assistants are exposed daily to mercury, in particular elemental mercury vapour (Hg0), by handling dental silver amalgam. Of the inhaled vapour, about 80% is absorbed into the blood. Furthermore, like everyone else, they also absorb inorganic mercury (mercuric salts, mercurous compounds) via the gastrointestinal tract from their diet, organomercurials from fish, and mercury stemming from their own amalgam fillings. The health risks of the uptake of mercury have been summarized with emphasis on dental patients 1, 2, 3, 4, 5, 6, 7, 8. Reproductive sequelae of occupational mercury exposure have been published mainly in non-dental journals and the few reviews on this subject are incomplete 4, 5, 8. Therefore, the knowledge acquired in experimental studies on animals and from case reports and epidemiologic research is presented here.
Section snippets
Reproductive problems: animal experiments
According to reviews, all chemical forms of mercury administered to animals, often in very high doses (mg/kg body weight) during and even prior to the gestation, resulted in reproductive problems, such as spontaneous abortion, stillbirths, congenital malformations, infertility, disturbances in the menstrual cycle, inhibition of the ovulation and behaviourial effects of the offspring 5, 9, 10. A dose–response has not always been demonstrated, but may exist. For instance, exposure to air with 1000
Discussion
Experiments in animals have shown that high concentrations of all the chemical forms of mercury may cause serious reproductive effects. Thus it is of interest to look for such effects in humans, even in the case of lower mercury exposure. The findings in epidemiological studies of women occupationally exposed to (elemental) mercury vapour are not in agreement. Very serious sequelae are reported 5, 20, 23, but they must be considered to result most probably from mercury concentrations larger
Conclusions
The (retrospective) studies establishing a relationship between occupational mercury and reproductive problems most likely concern women exposed to mercury concentrations approaching or exceeding the TLV. Although high mercury concentrations may cause reproductive problems, it seems warranted to conclude that the handling of amalgam does not, provided that a good mercury hygiene is maintained. At present, hygienic measures will get more attention than in the past, thereby reducing the risk. The
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