Progress in Chronic Disease Prevention Reduction of Children's
Arsenic Exposure Following Relocation -- Mill Creek,
Montana
Soil in the communities surrounding Anaconda, Montana, remains
contaminated with arsenic, even though the copper smelter located
there has been closed since 1980. Because of concern that children
might be exposed to arsenic by hand-to- mouth activity, those who
lived near the smelter and were between 2 and 6 years of age were
tested for urinary arsenic in March and again in July 1985.
Children living in the small community of Mill Creek, which had
the highest levels of arsenic in soil, had elevated levels of
urinary
arsenic at both testings. Their mean level of urinary arsenic was
66.0
ugmg/l in March and 54.1 ugmg/l in July. (In the control community
of
Livingston, Montana, mean levels of urinary arsenic were 10.6
ugmg/l
in March and 16.6 ugmg/l in July.) Since a level of 50 ugmg/l has
been
considered indicative of excess exposure in the past (1),
additional
urine samples were obtained between July and November 1985. The
children's levels of urinary arsenic remained elevated. In the
summer
of 1986, the U.S. Environmental Protection Agency temporarily
relocated 10 Mill Creek families until a permanent solution to the
problem could be developed.
To evaluate the effect of relocation on levels of urinary
arsenic,
urine samples were obtained from as many members of the families
being
relocated as possible. Each individual was asked to supply a total
of
six urine samples taken upon waking up in the morning. Three were
to
be taken in July, before relocation, and three, afterward, in
October.
Levels of urinary arsenic were measured using atomic absorption
spectrophotometry. The average pre- and post-move concentrations of
urinary arsenic were calculated for each person. These averages
were
used to calculate group averages.
Forty-one persons provided at least one urine sample. Four of
these people did not move from Mill Creek. Thirty-two of the 37
people
who were relocated provided samples both before and after
relocation.
The average pre-move level of urinary arsenic for the 6 relocated
children who were less than8 years of age was 76.0 ugmg/l; their
average post-move level was 15.3ugmg/l. The average pre-move level
for
persons greater than or equal to8 years of age was 17.2 ugmg/l;
their
average post-move level was 14.6 ugmg/l. Although five individuals
had
levels of urinary arsenic greater than50 ugmg/l prior to the move,
none had levels greater than50 ugmg/l after relocation from Mill
Creek. Reported by: JK Gedrose, MN, State Epidemiologist, Montana
State Dept of Health and Environmental Sciences. Div of
Environmental
Hazards and Health Effects, Center for Environmental Health, CDC.
Editorial Note
Editorial Note: Arsenic is believed to be potently carcinogenic,
both
through ingestion and through inhalation. About 70 of a daily dose
of
arsenic, which has a half-life of 10-30 hours, is eliminated in the
urine in a biphasic manner (2). Levels of urinary arsenic are
generally considered the best indicators of exposure to arsenic
occurring within the few days preceding testing (3).
Mean levels of urinary arsenic among Mill Creek residents
decreased after relocation. However, relocation is a controversial
strategy for reducing exposure to environmental contaminants. A
decision about the long-term management of the contamination in
Mill
Creek has not yet been reached.
The finding that children's pre-move levels of urinary arsenic
were so much greater than the levels of adults is consistent with
the
hypothesis that the children were being exposed to arsenic through
ingestion of soil. As with lead poisoning, hand-to-mouth activity
is
believed to be the primary route of exposure. The results of
testing
in Mill Creek indicate that children can serve as a sentinel
population for nonoccupational exposure to environmental hazards
when
the primary pathway is through soil ingestion.
References
Landrigan PJ. Arsenic. In: Rom WN, ed. Environmental and
occupational medicine. Boston, Massachusetts: Little, Brown and
Company, 1983:473-9.
Crecelius EA. Changes in chemical speciation of arsenic after
ingestion by man. Environ Health Perspect 1977;19:147-50.
Lauwerys RR. Industrial chemical exposure: guidelines for
biological monitoring. Davis, California: Biomedical
Publications,
1983.
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