revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY 279
2. HEALTH EFFECTS
more than 30 amalgams a week had 4 or more poor mercury-hygiene factors. Among women preparing a
comparable number of amalgams, there were differences in "fecundability," based on the number of selfreported
poor hygiene factors. The study is limited in that a group of unexposed women had lower fertility
than the low exposed group suggesting other unaccounted for exposures or confounding factors.
Animal data suggest that mercury may alter reproductive function and/or success when administered to
either males or females. In males, mercury exposure results primarily in impaired spermatogenesis, sperm
motility, and degeneration of seminiferous tubules. Oral administration of methylmercury to males has
resulted in decreases in litter size due to preimplantation loss (presumably due to defective sperm) in rats
(Khera 1973), decreases in sperm motility in monkeys (at 0.025 mg Hg/kg/day for 20 weeks) (Mohamed et
al. 1987), and tubular atrophy and decreased spermatogenesis in mice after prolonged exposure (Hirano et al.
1986; Mitsumori et al. 1990). Parenteral administration of methylmercury has shown similar results. A
single intraperitoneal injection of 10 mg/kg of methylmercury in male mice resulted in decreased
implantations in females (Suter 1975), and a single intraperitoneal injection of 1 mg/kg of methylmercury
resulted in a reversible failure of spermatogenesis and infertility in male mice (Lee and Dixon 1975).
Repeated intraperitoneal injections of methylmercury (3.5 mg Hg/kg/day for 6 weeks) in male rats resulted
in decreased sexual activity, depression of testosterone levels (Burton and Meikle 1980), and decreased
spermatogenesis (0.004 mg Hg/kg/day for 15–90 days) (Vachhrajani et al. 1992). Less is known about the
effects of inorganic mercury on the male reproductive system, but a single intraperitoneal injection of
mercuric chloride (1 mg Hg/kg) in male rats resulted in decreased conceptions in females (Lee and Dixon
1975), and 0.74 mg Hg/kg resulted in tubular degeneration (Prem et al. 1992). An in vitro study (Mohamed
et al. 1987) suggested that the decrease in sperm motility observed in monkeys may be due to interference
with microtubule assembly or dynein/microtubule sliding function.
In females, mercury exposure results primarily in increases in resorptions and decreases in implantations.
Inhalation exposure of female rats to metallic mercury vapor (2.5 mg/m 3 , 6 hours a day, 5 days a week
for 21 days) resulted in a prolongation of the estrous cycle (Baranski and Szymczyk 1973). Oral
administration of mercuric acetate (22 mg Hg/kg) to pregnant hamsters resulted in an increase in
resorptions (Gale 1974). Oral administration of methylmercury to pregnant guinea pigs (11.5 mg Hg/kg)
resulted in an increase in abortions (Inouye and Kajiwara 1988), and 3 mg Hg/kg resulted in a
decrease in the number of pups in the litter from pregnant mice (Hughes and Annau 1976). Pregnant mice
given a single dose of 20 mg Hg/kg as methylmercuric chloride had increased resorptions, decreased live
fetuses, and decreased fetuses per litter (Fuyuta et al. 1978). Repeated oral administration of methylmercury