Biology Reference
In-Depth Information
In a heavily polluted site (Duwamish Waterway) in Puget Sound, Washington, USA,
on the Pacific coast, the level of hepatic DNA adducts in English sole could reach 140 ±
27 nmol adducts mol
-1
nucleotides, whereas biliary fluorescent metabolites were present
at 250 ng mg
-1
protein and sediment contamination was 3600 ng ΣPAHs (18 congeners)
g
-1
sediment (fresh weight) and 570 ng ΣPCBs g
-1
. Higher levels of hepatic DNA adducts
(275 ± 50 nmol adducts mol
-1
nucleotides) were found in the black croaker (
Cheilotrema
saturnum
), in San Diego Bay, California (Reichert et al. 1998); this species is very sensitive
to genotoxic pollutants and to neoplasia, and at the same site, other fish species such as
the white croaker (
G. lineatus
) present much fewer DNA adducts and are less prone to
liver lesions.
In addition to ecological factors, metabolic and toxicokinetic specificities of PAH metabo-
lites play a role in species sensitivity differences. For instance, the starry flounder (
P. stel-
latus
), a sympatric species to the English sole (
P. vetulus
), rarely develops neoplasia. Yet,
levels of hepatic DNA adducts are identical in the two species sampled at the same site
(Reichert et al. 1998). This example explains why a combined use of several indicators,
including histopathological examination of liver in this case, is an optimal approach in
environmental biomonitoring.
In Puget Sound, the site of Eagle Harbor was designated as a superfund site in 1987,
because of its high level of sediment contamination and the highest recorded prevalence
of hepatic lesions in the resident epibenthic flatfish, such as the English sole (
Parophrys
vetulus)
. PAH sediment contamination originated from a facility that used creosote as
a wood preservative. The closure of the facility and remediation of sediments from
1993 to 2002 contributed to reduced PAH exposure in English sole (Myers et al. 2008).
The results of the biological survey up to 2004 confirmed that xenobiotic-DNA adduct
level was a highly significant risk factor for toxicopathic hepatic lesions and neoplasia
in English sole, with each additional unit of adduct increasing the risk of initiating
neoplastic lesions by 1.036 times. The level of biliary FACs was also a significant risk
factor for several of the toxicopathic liver lesions, but not of the occurrence of hepatic
neoplasms. On the other hand, hepatic CYP1A levels, as estimated by aryl hydrocarbon
hydroxylase activities, were not significant risk factors of any of the hepatic lesions cat-
egories and correlated poorly with biliary FACs and hepatic DNA adducts. Therefore,
their use as a monitoring tool in Eagle Harbor has been discontinued (Myers et al. 2008;
Chapter 15).
Hepatic neoplasia in flounder
Platichthys flesus
have been recorded in different
areas in the Baltic Sea, especially in the southern Baltic Sea off the German and Polish
coasts, during fish disease surveys in the late 1980s (Lang and Dethlefsen 1994) and in
more recent studies (Lang et al. 2006). DNA adducts as molecular indicators of PAH
exposure were screened in the flounder in a short retrospective study over 1995-1996,
but bulky hydrophobic DNA adducts were not found as a major factor in the etiology
of preneoplastic and neoplastic liver lesions during these sampling years (Malmström
et al. 2009).
DNA adducts were also studied after oil spill accidents that occurred during the past
two decades to evaluate their impacts on marine species. In Europe, this concerns the
wrecks of the
Sea Empress
near the South coast of Wales (UK) in February 1996 and of
the
Erika
near the Atlantic coast of France in December 1999. No specific biomarker for
genotoxicity was used during the
Exxon Valdez
disaster (March 1989) in South Alaska. The
ecosystem effects of this oil spill, and of the recent oil spill produced by the explosion of
the Deepwater Horizon (DWH) drilling platform in the Gulf of Mexico (April 2010) will be
discussed in Section 13.2.1.
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