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

MERCURY 116
2. HEALTH EFFECTS
Organic Mercury. Data on renal toxicity associated with ingestion of methylmercury in humans come from
several case studies. An outbreak of ethylmercury fungicide-induced poisoning was reported by Jalili and
Abbasi (1961). Affected individuals exhibited polyuria, polydypsia, and albuminuria. Two boys who
ingested meat from a hog that had consumed seed treated with ethylmercuric chloride also had increased
blood urea, urinary protein, and urinary sediment (Cinca et al. 1979); an autopsy revealed nephritis. A
13-month-old boy who ate porridge made from flour treated with an alkyl mercury compound (specific
mercury compound not reported) experienced albuminuria, red and white cells, and casts in the urine
(Engleson and Herner 1952). In autopsies carried out to evaluate the cause of death in 4 adults and 4 infants
from the Iraqi epidemic of 1972, one case exhibited tubular degeneration in the kidneys (whether an adult or
child was not specified) (Al-Saleem and the Clinical Committee on Mercury Poisoning 1976).
Organic mercury-induced nephrotoxicity has been demonstrated in rodents following acute-, intermediate-,
and chronic-duration exposure. The usefulness of results from subchronic studies may be limited because
the pathological changes observed were often not distinguished as primary or secondary effects (i.e.,
pathological changes secondary to induced shock). Nonetheless, they provide some useful indication of
potential effects.
Administration of methylmercuric chloride to mice in a single gavage dose of 16 mg Hg/kg resulted in
decreased renal function (decreased phenolsulfonphthalein excretion), increased plasma creatinine, and
swelling of tubular epithelial cells, with exfoliation of the cells into the tubular lumen (Yasutake et al.
1991b). Although no effects were observed after a single gavage dose of 8 mg Hg/kg (Yasutake et al.
1991b), 5 daily gavage doses of 8 mg Hg/kg/day as methylmercuric chloride in rats resulted in vacuolization
and tubular dilation in the proximal tubules with ongoing regeneration (Magos et al. 1985). Similar effects
were observed after 5 doses of 8 mg Hg/kg/day as ethylmercuric chloride (Magos et al. 1985).
In an intermediate-duration study, histopathological changes were observed in the kidneys of female rats
exposed to 0.86, 1.68, or 3.36 mg Hg/kg/day as methylmercury dicyanidiamide by gavage 5 days a week for
3–12 weeks (Magos and Butler 1972). The low-dose group exhibited large foci of basophilic tubular
epithelial cells, desquamation, fibrosis, and inflammation in the renal cortex; however, no control group was
used in the study (Magos and Butler 1972). A 12-week diet containing 0.08 mg Hg/kg/day as methylmercury
caused ultrastructural changes (cytoplasmic masses containing ribosomes and bundles of smooth
endoplasmic reticulum) in kidney proximal tubule cells of female rats, despite the normal appearance of the