Reproductive toxicity of occupational mercury. A review of the literature

https://doi.org/10.1016/S0300-5712(97)00039-0Get rights and content

Abstract

Objectives: This paper aims to give the dental practitioner insight into the potential reproductive effects of handling dental silver amalgam, c.q. mercury.

Data sources: Experimental studies on animals, case reports and epidemiologic studies.

Study selection: Experimental animal studies show high doses/concentrations of mercury to increase the risk of reproductive disorders, e.g. infertility, spontaneous abortion, stillbirth and congenital malformations. Some case reports suggest an association between the disorders in humans and high levels of mercury. Therefore, the present article reviews epidemiological studies on the relationship between occupational exposure to mercury, mainly as vapour in the dental practice, and females' procreative ability. Studies concerning the reproductive effects of males' occupational mercury body burden are scarce. The reproductive risk of patients' mercury uptake from silver amalgam fillings is assessed.

Conclusions: It seems warranted to conclude that negative reproductive effects from exposure to mercury in the dental office are unproven, but safe levels have not been established. Seemingly problems are unlikely to occur, unless a poor hygiene causes the mercury concentration in the air to exceed females' time-weighted long-term Threshold Limit Value (TLV). Consequently, in view of the in general low amounts of mercury stemming from dental amalgam fillings, the population at large is at even less risk than dental staff. The effects of occupational elemental mercury concentrations lower than the TLV on the menstrual cycle, conception, male fertility and children's behaviour need, however, more research.

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

References (101)

  • B.G Svensson et al.

    Fish as a source of exposure to mercury and selenium

    Sci Total Environ

    (1992)
  • M Wilhelm et al.

    Biological monitoring of mercury vapour exposure by scalp hair analysis in comparison to blood and urine

    Toxicol Letters

    (1996)
  • M.D Martin et al.

    Factors contributing to mercury exposure in dentists

    J Am Dent Assoc

    (1995)
  • J.A Weiner et al.

    An estimation of the uptake of mercury from amalgam fillings based on urinary excretion of mercury in Swedish subjects

    Sci Total Environ

    (1995)
  • W.D Kuntz et al.

    Maternal and cord blood background mercury levels: a longitudinal study

    Am J Obstet Gynecol

    (1982)
  • D.W Jones

    The enigma of amalgam in dentistry

    J Can Dent Assoc

    (1983)
  • B.M Eley et al.

    Mercury from dental amalgam fillings in patients

    Br Dent J

    (1987)
  • Hörsted-Bindslev P, Magos L, Holmstrup P, Arenholt-Bindslev D, editors. Dental amalgam—A health hazard? Copenhagen:...
  • World Health Organization. Environmental Health Criteria 118. Inorganic mercury. Geneva: World Health Organization,...
  • C Molin

    Amalgam—fact and fiction

    Scand J Dent Res

    (1992)
  • B.M Eley et al.

    The release, absorption and possible health effects of mercury from dental amalgam: a review of recent findings (erratum to the original review published on September 11, 1993)

    Br Dent J

    (1993)
  • Subcommittee on Risk Management. Dental amalgam: a scientific review and recommended public health service strategee...
  • B.J Koos et al.

    Mercury toxicity in the pregnant woman, fetus, and newborn infant

    Am J Obstet Gynecol

    (1975)
  • World Health Organization. Environmental health criteria 101. Methylmercury. Geneva: World Health Organization,...
  • A.J Steffek et al.

    Effects of elementary mercury vapour exposure on pregnant Sprague-Dawley rats

    J Dent Res

    (1987)
  • M Berlin et al.

    Prenatal exposure to mercury vapour: effects on brain development

    Fund Appl Toxicol

    (1992)
  • I.P Lee et al.

    Effects of mercury on spermatogenesis studied by velocity sedimentation cell separation and serial mating

    J Pharmacol Experiment Therapeut

    (1975)
  • K Warfvinge

    Mercury exposure of a female dentist before pregnancy

    Br Dent J

    (1995)
  • J.M Thorp et al.

    Elemental mercury exposure in early pregnancy

    Obstet Gynecol

    (1992)
  • G.S Nixon et al.

    Pregnancy outcome in female dentists

    Br Dent J

    (1979)
  • Gordon H. Pregnancy in female dentists. A mercury hazard? In: Proceedings: International Conference on Mercury Hazards...
  • R Sikorski et al.

    Women in dental surgeries: reproductive hazards in occupational exposure to metallic mercury

    Int Arch Occup Environ Health

    (1987)
  • Slooff W, Bont PFH, Van Ewijk M, Janus, JA. Exploratory report mercury. Report no. 710401006. Zeist: Rijksinstituut...
  • K.S Larsson

    Teratological aspects of dental amalgam

    Adv Dent Res

    (1992)
  • M Nordentoft et al.

    Intrauterine growth retardation and premature delivery: the influence of maternal smoking and psychosocial factors

    Am J Public Health

    (1996)
  • A.S Rowland et al.

    Nitrous oxide and spontaneous abortion in female dental assistants

    Am J Epidemiol

    (1995)
  • F De Rosis et al.

    Female reproductive health in two lamp factories: effects of exposure to inorganic mercury vapour and stress factors

    Br Ind Med

    (1985)
  • A.S Rowland

    The effect of occupational exposure to mercury vapour on the fertility of female dental assistants

    Occup Environ Med

    (1994)
  • L.Z Heidam

    Spontaneous abortions among dental assistants, factory workers, painters, and gardening workers: a follow-up study

    J Epidemiol Community Health

    (1984)
  • J.B Brodsky et al.

    Occupational exposure to mercury in dentistry and pregnancy outcome

    J Am Dent Assoc

    (1985)
  • S.R Lauwerys et al.

    Fertility of male workers exposed to mercury vapor or to manganese dust: a questionnaire study

    Am J Indust Med

    (1985)
  • K.H Alcser et al.

    Occupational mercury exposure and male reproductive health

    Am J Indust Med

    (1989)
  • S Cordier et al.

    Paternal exposure to mercury and spontaneous abortions

    Br J Indust Health

    (1991)
  • A Ericson et al.

    Pregnancy outcome in women working as dentists, dental assistants or dental technicians

    Int Arch Occup Environ Health

    (1989)
  • T.D Matte et al.

    Case-control study of congenital defects and parental employment in health care

    Am J Indust Med

    (1993)
  • J Sundby et al.

    Are women in the workplace less fertile than women who are not employed?

    J Women's Health

    (1994)
  • I Gerhard et al.

    Diagnostik von Schwermetallbelastungen mit dem peroralen DMPS-Test und dem Kaugummitest

    Zeitschr Klin Labor

    (1992)
  • T Watanabe et al.

    Effects of mercury compounds on ovulation and meiotic and mitotic chromosomes in female gold hamsters

    Teratology

    (1982)
  • L Kosta et al.

    Correlation between selenium and mercury in man following exposure to inorganic mercury

    Nature

    (1975)
  • M Nylander et al.

    Mercury accumulation in tissues from dental staff and controls in relation to exposure

    Swed Dent J

    (1989)
  • Cited by (77)

    • Exposure to multiple toxic metals and the risk of early embryonic arrest among women undergoing assisted reproductive techniques

      2022, Environmental Research
      Citation Excerpt :

      One study suggested that Pb may be an important factor in infertility (Pillai et al., 2002). Previous studies have shown that Hg can affect the reproductive system, causing miscarriages, stillbirths, infertility and congenital malformations (Schuurs, 1999; Gardella and Hill, 2000). A study by Choy et al. showed that Hg was associated with poor IVF outcomes (Choy et al., 2002).

    • Environmental Contaminants and Medicinal Plants Action on Female Reproduction

      2022, Environmental Contaminants and Medicinal Plants Action on Female Reproduction
    • Mercury leads to features of polycystic ovary syndrome in rats

      2019, Toxicology Letters
      Citation Excerpt :

      Human Hg exposure leads to heterogeneous and complex toxicologic effects on the nervous, immune, and cardiovascular systems (Cariccio et al., 2018; Genchi et al., 2017; Houston, 2011; Hui et al., 2016; Schofield, 2017; Zahir et al., 2005). In addition, Hg occupational and experimental exposures have shown that Hg induces several reproductive and metabolic abnormalities, such as reproductive cyclicity disturbances, irregular ovarian follicular development, ovulation inhibition, infertility, spontaneous miscarriage, increase visceral adiposity, risk of diabetes mellitus, and metabolic syndrome in rodent and human models (Al-Saleh et al., 2008; Altunkaynak et al., 2016; Davis et al., 2001; Gardella and Hill, 2000; Lamperti and Printz, 1974; Park et al., 2017; Roy et al., 2017; Schuurs, 1999; Sikorski et al., 1987; Yoshida, 2002). Thus, some toxicologic consequences are similarly found in the PCOS features, as reported in previous studies (Diamanti-Kandarakis and Dunaif, 2012; Dumesic et al., 2015).

    View all citing articles on Scopus
    View full text