IARC MONOGRAPHS ON THE EVALUATION OF CARCINOGENIC ...

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(d ) Biodegradation
Studies on biodegradation of polycyclic aromatic hydrocarbons in soil suggest that
absorption to organic matter significantly reduces the bioavailability and thus the
biodegradability of naphthalene (Heitzer et al., 1992; Weissenfels et al., 1992; Agency
for Toxic Substances and Disease Registry, 1995a). Reported naphthalene half-lives in
soil vary considerably. The estimated half-life of naphthalene reported for a solid waste
site was 3.6 months, while in typical soils more rapid biodegradation is expected to occur
(Heitkamp et al., 1987; Howard, 1989).
Biodegradation of naphthalene is accomplished via the action of aerobic microorganisms
and generally declines precipitously when soil conditions become anaerobic
(Klecka et al., 1990). Naphthalene biodegrades to carbon dioxide in aerobic soils with
salicylate as an intermediate product (Heitzer et al., 1992; Agency for Toxic Substances
and Disease Registry, 1995a).
Although polycyclic aromatic hydrocarbons are persistent in a strictly anaerobic
environment, naphthalene can be degraded anaerobically under sulfate-reducing
conditions: it was oxidized to carbon dioxide in petroleum-contaminated marine harbour
sediments in San Diego, CA (Coates et al., 1997).
(e) Food
IARC MONOGRAPHS VOLUME 82
Naphthalene was detected in only two of 13 980 samples of foods analysed in six
states of the USA in 1988–89 (Minyard & Roberts, 1991). Naphthalene is not generally
reported to be present in fish, but has been detected in shellfish in the USA, with concentrations
ranging from 5 to 176 μg/kg in oysters, from 4 to 10 μg/kg in mussels and from
< 1 to 10 μg/kg in clams (Bender & Huggett, 1989).
Naphthalene was found in 1993 in many samples of edible portions of nine types of
shrimp and fish in Kuwaiti seafood at concentrations ranging from 2 to 156 μg/kg dry wt.
These elevated concentrations of naphthalene were attributed to the pollution of Kuwait’s
territorial waters with crude oils as a result of oil spillage during the Gulf War or the
chronic pollution due to oil production, transportation or natural seepage from the
seabed. Naphthalene constituted the highest burden of the 14 polycyclic aromatic hydrocarbons
screened (Saeed et al., 1995).
Mean concentrations of naphthalene of 19.5 μg/kg dry wt have been found in edible
muscle of fish collected from the Red Sea coast of Yemen (DouAbul et al., 1997).
Naphthalene has been found at maximum concentrations of 27.7 μg/kg and 137 μg/kg in
muscle and liver tissue, respectively, of burbot fish from lakes in the Northwest Territories
in Canada (Lockhart et al., 1992).
Naphthalene has also been detected in various fish species collected from the Gulf of
Naples, Italy, e.g., in muscle samples of anchovy, comber and rock goby at concentrations
of 63, 4 and 20 μg/kg wet wt, respectively, and in razor fish, wart venus and
short-necked clams, at levels of 20, 25 and 32 μg/kg wet wt, respectively (Cocchieri
et al., 1990).