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

MERCURY
2. HEALTH EFFECTS
In case reports of individuals exposed to inorganic mercury vapor for an intermediate duration, similar
effects were reported (Barber 1978; Fagala and Wigg 1992; Foulds et al. 1987; Friberg et al. 1953; Sexton
et al. 1976; Taueg et al. 1992). After 6 months of exposure to a spill of metallic mercury in the place where
she slept, a 12-year-old girl experienced dizziness, joint pains, weakness, insomnia, numbness and tingling
in her palms, decreased pinprick and vibration sensations in the lower extremities, intentional tremors, a
slowing of the background rhythms on electroencephalograms, irritability, outbursts of temper, shyness,
sensitivity, auditory hallucinations, and photophobia (Fagala and Wigg 1992). Similarly, a 4-year-old boy
exposed for approximately 1 month to mercury vapors released from paint containing phenylmercuric
acetate exhibited irritability, personality change, insomnia, headaches, weakness, and nerve dysfunction in
the lower extremities (Aronow et al. 1990). This study is not discussed under organic mercury because the
exposure was to metallic mercury vapors released from the paint.
Two adolescents (ages 13 and 15) who were unintentionally exposed to concentrated mercury vapors for
3 months developed a variety of more immediate- and long-term effects (Yeates and Mortensen 1994). In
the 15-year-old male, the earliest symptoms included declining school performance, irritability, depression,
neurobehavioral complaints, tremor, rash, hypertension, cold intolerance, diaphoresis, headaches, sleep
disturbance, paresthesias, and anorexia. He was referred to a pediatric teaching hospital, where he was
diagnosed with acrodynia and mercury poisoning. Before undergoing two courses of chelation therapy with
2,3-dimercaptosuccoinic acid (DMSA), his average 24-hour urine mercury and blood mercury levels were
1,314 µg/L and 23 µg/L, respectively. His 13-year-old half-sister, who was also exposed, had pretreatment
average 24-hour urine mercury and blood mercury levels of 624 µg/L and 69 µg/L, respectively; her pretreatment
medical symptoms included tremor, rash, anorexia, paresthesias, and neuropsychiatric complaints
(e.g., irritability, social withdrawal, and emotional lability). On hospital admission, she was diagnosed with
acrodynia and underwent three courses of DMSA treatment, which were complicated by severe peripheral
neuropathy, accompanied by a significant weight loss. Although the neuropathy was relatively mild at the
time of initial neurological evaluation, it became progressively worse, and eventually the patient required a
wheelchair and assistance eating. The neuropathy had resolved by the 1-year follow-up neuropsychological
evaluation; however, despite removal from exposure, return of blood and urinary mercury to acceptable
levels, and resolution of clinical signs of mercury poisoning and associated neuropsychiatric symptoms,
both patients continued to show major deficits in visuoperceptual and constructional skills, nonverbal
memory, and abstract reasoning.
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