Enclosure (1) TO COMDTINST 16478.12
Human exposure through inhalation of mercury vapor or ingestion of
contaminated water is not a concern. Contamination of drinking water is
unlikely because elemental mercury does not easily dissolve. Neither is
exposure through inhalation a concern because the mercury is spent batteries
is tightly bonded to the carbon and zinc components, and no vapor was
detected.
Given is low solubility, the most likely release of pathway for elemental
mercury is to surrounding sediments through battery casing decay. Evidence
from prototype investigations indicate that battery casings tend to remain
intact in freshwater environments but decay in open marine environments (CH2M
Hill, 1993(b), 1994(a), 1994(b)). When these casing decay, the components of
the battery containing elemental mercury may be exposed. However, due to the
properties of the open marine environment, "methylation is not a pathway of
primary concern at open marine sites" (Matta, 1994). While the elemental
mercury is still potentially toxic, its relatively toxicity is significantly
less than methyl mercury (EPA 1985). Therefore, it's direct threat to human
health is negligible.
Elevated sediment concentrations near batteries may result in very small -
localized environmental hazards. The potential for environmental impact will
probably be limited to organisms that attach to batteries or reside in nearby
sediments. Evidence from the prototype investigations indicate that some of
these organisms have higher measured levels of mercury in their tissue than
other biota at the same AtoN.
IMPLICATIONS FOR BATTERY REMOVAL
The evidence from the study, which indicates that the contents of batteries
themselves is relatively harmless, suggests that the presence of batteries in
most environments is not a hazard. Because of the potential effect on local
organisms, removal of batteries and attached biota is prudent. Measured
levels of mercury in surrounding sediments do not indicate that sediment
removal along with batteries is warranted.
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