Enclosure (1) TO COMDTINST 16478.12
chemically analyzed new, spent, and recovered primary batteries from trial
cleanup operations, and they reviewed the Volpe Center's design of the
environmental impact studies.
Battery Composition
The batteries examined were manufactured by Edison, McGraw-Edison, and Saft,
and consist principally of a zinc anode and alkaline electrolyte. The
electrolyte was found to be the largest component by weight in the samples
taken, and it consisted of either nearly pure sodium hydroxide
(NaOH) or potassium hydroxide (KOH).These materials are very corrosive.
Electrolyte is classified as hazardous waste, but NaHO and KOH are non-toxic
in low concentrations. The researchers concluded that electrolyte would be
harmless when diluted by the water at an aquatic disposal site. However,
elemental mercury (Hg(0)) was found in all the samples taken from the zinc
anodes. About 20 g of Hg(0) is applied to the zinc plates (anodes) during
manufacture. This mercury
coating helps catalyze the electricity producing reaction, and it keeps the
zinc plate from corroding. No other hazardous battery materials were
identified.
The potential threat of mercury is complex to assess because it may be found
in many forms in the environment. Mercury exists in the environment in three
principal forms: elemental (Hg(0)), ironic (Hg(+)), and organometallic (
(CH(3))Hg(+), (CH(3))(2)Hg).Elemental mercury, because of it's low solubility,
is considered the least potentially hazardous of the three forms, but the
adverse effects of inhaling elemental mercury vapor are well documented
(Heast, 1993), and vapor exposure standards have been established. Highly
soluble ionic (oxidized) mercury is the dominant form of natural and anthropic
mercury pollution.It is a precursor to formation of highly toxic
organometallic mercury by bacteria in stagnant water. Organometallic mercury
is water soluble, it is readily absorbed and retained by tissue, which results
in it's bioaccumulation in biota, fish, and eventually humans. Therefore, the
researchers were interested not only in the total amount of mercury at the
disposal sites, but also in the potential for the mercury to be converted into
this more bioavailable and toxic form.
Methyl mercury has long been considered a potent neurotoxin that can
accumulate in the food chain, and recent studies have prompted the EPA to re-
examine its standards for safe human exposure (Stern, 1993).The current EPA
reference dose (0.3g/kg/day) to limit the developmental effects, in utero, due
to mercury exposure (USEPA, 1990).
Analytical Techniques
Morel and Mason examined spent primary batteries taken directly from an AtoN.
Even though these batteries were never submerged, less than 20 percent (3 g)
of
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