20 In Vitro Toxicity and Histopathological Effects Induced in the Mantle. . .
235
et al. 1987; Nelson 1990; O’Connor 2002; Monirith et al. 2003). Due to the
commercial importance of mussel culture, the toxic effects of PAHs identified here
could constitute a significant risk for mussel production, as well as a risk to human
health following mussel consumption.
The chemical analysis of tar mixture used for cleaning culture mussel rafts
suggests its potential toxicity. The lethal and histopathological effects induced in
mussels, during this laboratory study, confirm its harmful effects at concentrations
higher than 10 ppm.
Mortality and histopathological effects caused by tar mixtures in the laboratory
depend on dose and time exposure, suggesting a cumulative toxic effect as described
in vertebrates (Richburg et al. 2002; Strmac and Braunbeck 2002). However,
lethality caused by high concentrations of tar (60, 80 ppm) could be enhanced by
asphyxia of different organs as described by Iniesta y Blanco (2005).
Histopathological effects follow a progressive sequence of malignancy until
the development of carcinoma in situ, affecting germinal cells. This sequence
starts with the desquamation of germinal cells by untimely spawning induction,
as described in testicular pathologies from vertebrates, or related to pollution in
invertebrates (Cajaraville 1991; Cajaraville et al. 1992; Tay et al. 2003; Jing-Jing
et al. 2009; Aarab et al. 2011). Next, the atrophy and hypoplasia of follicles
occurs, accompanied by scarce proliferation and differentiation of germinal cells,
as well as by many, large and vacuolated auxiliary cells within them. Similar
histopathologies with abnormal follicles, consisting of abnormal auxiliary cells
with a clear cytoplasm and deposits of eosinophilic material, have been reported
in seminomas from vertebrates, caused by toxic damage (Nistal 1973; Nistal et al.
1998; Chapin et al. 1984; Boekelheide 2005). Membrane hyalinization of gonadal
follicles and fibrosis have also been described in gonadal neoplasias of vertebrates
in individuals exposed to chemicals, where it may become an irreversible process
(Nistal 1973; Nistal et al. 1998). The sea urchin is the only invertebrate exposed
to phenanthrene, where an increase of collagen fibers around the gonadal follicles,
has been described (Sch¨ afer and K¨ ohler 2009). Other effects observed in the latter
work, like aggregation of spermatocytes and spermatids, or existence of large
and multinucleated germinal cells, are similar to the spermatogenic alterations
reported after prolonged exposure to pollutants (Ono et al. 2008). Hyperplasia and
hypertrophy of vesicular cells observed in this study are similar to those described in
interfollicular connective tissue cells of gonadal carcinomas in situ from vertebrates
(Dieckmann and Skakkebaek 1999; Ulbright 2005) and of gonadoblastomas from
marine invertebrates (Elston et al. 1992; Peters et al. 1994; Ford et al. 1997). All
of these chemically mediated effects suggest a possible endocrine disruption in
mussels as described in vertebrates (Irvine 2000; Swan et al. 2003), resulting from
the xenoestrogenic activity of several PAHs species from the tar mixture used.
Our results show that the tar mixture tested is lethal for mussels at high
concentrations, but at sublethal doses can cause serious pathologies, sufficient to
affect their reproduction. Moreover, the mussels’ capacity to accumulate lipophilic
compounds such as hydrocarbons could constitute a risk to human health. So, use of
235
et al. 1987; Nelson 1990; O’Connor 2002; Monirith et al. 2003). Due to the
commercial importance of mussel culture, the toxic effects of PAHs identified here
could constitute a significant risk for mussel production, as well as a risk to human
health following mussel consumption.
The chemical analysis of tar mixture used for cleaning culture mussel rafts
suggests its potential toxicity. The lethal and histopathological effects induced in
mussels, during this laboratory study, confirm its harmful effects at concentrations
higher than 10 ppm.
Mortality and histopathological effects caused by tar mixtures in the laboratory
depend on dose and time exposure, suggesting a cumulative toxic effect as described
in vertebrates (Richburg et al. 2002; Strmac and Braunbeck 2002). However,
lethality caused by high concentrations of tar (60, 80 ppm) could be enhanced by
asphyxia of different organs as described by Iniesta y Blanco (2005).
Histopathological effects follow a progressive sequence of malignancy until
the development of carcinoma in situ, affecting germinal cells. This sequence
starts with the desquamation of germinal cells by untimely spawning induction,
as described in testicular pathologies from vertebrates, or related to pollution in
invertebrates (Cajaraville 1991; Cajaraville et al. 1992; Tay et al. 2003; Jing-Jing
et al. 2009; Aarab et al. 2011). Next, the atrophy and hypoplasia of follicles
occurs, accompanied by scarce proliferation and differentiation of germinal cells,
as well as by many, large and vacuolated auxiliary cells within them. Similar
histopathologies with abnormal follicles, consisting of abnormal auxiliary cells
with a clear cytoplasm and deposits of eosinophilic material, have been reported
in seminomas from vertebrates, caused by toxic damage (Nistal 1973; Nistal et al.
1998; Chapin et al. 1984; Boekelheide 2005). Membrane hyalinization of gonadal
follicles and fibrosis have also been described in gonadal neoplasias of vertebrates
in individuals exposed to chemicals, where it may become an irreversible process
(Nistal 1973; Nistal et al. 1998). The sea urchin is the only invertebrate exposed
to phenanthrene, where an increase of collagen fibers around the gonadal follicles,
has been described (Sch¨ afer and K¨ ohler 2009). Other effects observed in the latter
work, like aggregation of spermatocytes and spermatids, or existence of large
and multinucleated germinal cells, are similar to the spermatogenic alterations
reported after prolonged exposure to pollutants (Ono et al. 2008). Hyperplasia and
hypertrophy of vesicular cells observed in this study are similar to those described in
interfollicular connective tissue cells of gonadal carcinomas in situ from vertebrates
(Dieckmann and Skakkebaek 1999; Ulbright 2005) and of gonadoblastomas from
marine invertebrates (Elston et al. 1992; Peters et al. 1994; Ford et al. 1997). All
of these chemically mediated effects suggest a possible endocrine disruption in
mussels as described in vertebrates (Irvine 2000; Swan et al. 2003), resulting from
the xenoestrogenic activity of several PAHs species from the tar mixture used.
Our results show that the tar mixture tested is lethal for mussels at high
concentrations, but at sublethal doses can cause serious pathologies, sufficient to
affect their reproduction. Moreover, the mussels’ capacity to accumulate lipophilic
compounds such as hydrocarbons could constitute a risk to human health. So, use of