325
Chapter fourteen: Toxicology and poisons
codon into a functional protein requires a specific sequence in the 3′ untranslated region
(Berry et al. 1991) as well as specialized tRNA and translation factors (Leinfelder et al. 1988;
Forchhammer et al. 1989). We emphasize the role of Se in both toxic metal detoxification as
well as defense against oxidative stress through (1) direct interactions between Se and other
metals and (2) indirect actions of Se cofactor requiring proteins.
14.6 Other poisons
Following catastrophic anthropogenic release of crude oil, such as the Exxon Valdez oil spill
(1989) or the Deepwater Horizon (2010), there is a large amount of public and scientific concern devoted to the health and status of local cetacean populations. Species that depend on
fur or feathers for insulation are at risk of pelage contamination and subsequent dysfunction, which can result in both poor temperature regulation, transfer to young (nursing), and
oral exposure to crude hydrocarbons following grooming/preening. However, cetaceans
generally have very thick skin (odontocetes epidermal layer is 10–20 times thicker than
terrestrial mammals) and deep blubber tissue (hypodermal) (Geraci et al. 1986; Reeb et al.
2007). Thus the main threat to cetaceans following oil spills may in fact be inhalation of
toxic fumes or irritation of mucous membranes (eyes, blowhole) (Chapter 13, Geraci 1990;
Smultea and Würsig 1995). The vapors of volatile hydrocarbons contain a number of harmful toxicants which can cause localized inflammation of lung tissue, and some compounds
can accumulate in blood and filtering organs causing hepatoxicity and neurotoxicity (Geraci
and St. Aubin 1982). Polycyclic aromatic hydrocarbons (PAHs), chemical constituents of
crude and refined oil, have been found in a number of marine mammal tissues (Carvan
and Busbee 2003; Kannan and Perrotta 2008) and are known to be toxic through the production of reactive intermediates during biotransformation. However, there are limited studies
examining the effects of these compounds in marine mammals (Carvan and Busbee 2003).
These compounds are known to have endocrine disrupting effects, although these effects
are generally seen in acute exposure scenarios, and there is a dearth of information concerning chronic low level exposure, as one might hypothesize in marine mammals.
There is some evidence to suggest that bottlenose dolphins (Tursiops truncatus) are able
to detect oil slicks, however reports of avoidance behavior are mixed and may depend
on environmental conditions and the nature of the oil product involved. We caution that
generalizations should not be made. In an experimental oil spill, three female dolphins
appeared to avoid surfacing in oil slicks following initial contact, however in observational
studies, such as those following the Mega Borg oil spill in the Gulf of Mexico in 1990, nine
groups of bottlenose dolphins did not show consistent avoidance of most types of oil slicks
(Smith et al. 1983; Smultea and Würsig 1995). The mechanism of chemodetection of oil
slicks is unknown, and may be related to visual signaling, echolocation, tactile or olfactory
sensing or combinations of these.
14.7 Emerging tools
The emergence of next-generation sequencing tools (DNA and RNA) has undoubtedly
advanced the field of toxicology, and a number of intrepid researchers have attempted to
apply these tools to non-model organisms such as marine mammals. Edwards et al. (2013)
developed a workflow incorporating undergraduate students and novel coursework and
sequenced metagenomes of the California sea lion, proving that next- generation sequencing tools are accessible and validated for work with marine mammals. At the time of
writing, there are seven genomes available on NCBIs website including the minke whale,
Chapter fourteen: Toxicology and poisons
codon into a functional protein requires a specific sequence in the 3′ untranslated region
(Berry et al. 1991) as well as specialized tRNA and translation factors (Leinfelder et al. 1988;
Forchhammer et al. 1989). We emphasize the role of Se in both toxic metal detoxification as
well as defense against oxidative stress through (1) direct interactions between Se and other
metals and (2) indirect actions of Se cofactor requiring proteins.
14.6 Other poisons
Following catastrophic anthropogenic release of crude oil, such as the Exxon Valdez oil spill
(1989) or the Deepwater Horizon (2010), there is a large amount of public and scientific concern devoted to the health and status of local cetacean populations. Species that depend on
fur or feathers for insulation are at risk of pelage contamination and subsequent dysfunction, which can result in both poor temperature regulation, transfer to young (nursing), and
oral exposure to crude hydrocarbons following grooming/preening. However, cetaceans
generally have very thick skin (odontocetes epidermal layer is 10–20 times thicker than
terrestrial mammals) and deep blubber tissue (hypodermal) (Geraci et al. 1986; Reeb et al.
2007). Thus the main threat to cetaceans following oil spills may in fact be inhalation of
toxic fumes or irritation of mucous membranes (eyes, blowhole) (Chapter 13, Geraci 1990;
Smultea and Würsig 1995). The vapors of volatile hydrocarbons contain a number of harmful toxicants which can cause localized inflammation of lung tissue, and some compounds
can accumulate in blood and filtering organs causing hepatoxicity and neurotoxicity (Geraci
and St. Aubin 1982). Polycyclic aromatic hydrocarbons (PAHs), chemical constituents of
crude and refined oil, have been found in a number of marine mammal tissues (Carvan
and Busbee 2003; Kannan and Perrotta 2008) and are known to be toxic through the production of reactive intermediates during biotransformation. However, there are limited studies
examining the effects of these compounds in marine mammals (Carvan and Busbee 2003).
These compounds are known to have endocrine disrupting effects, although these effects
are generally seen in acute exposure scenarios, and there is a dearth of information concerning chronic low level exposure, as one might hypothesize in marine mammals.
There is some evidence to suggest that bottlenose dolphins (Tursiops truncatus) are able
to detect oil slicks, however reports of avoidance behavior are mixed and may depend
on environmental conditions and the nature of the oil product involved. We caution that
generalizations should not be made. In an experimental oil spill, three female dolphins
appeared to avoid surfacing in oil slicks following initial contact, however in observational
studies, such as those following the Mega Borg oil spill in the Gulf of Mexico in 1990, nine
groups of bottlenose dolphins did not show consistent avoidance of most types of oil slicks
(Smith et al. 1983; Smultea and Würsig 1995). The mechanism of chemodetection of oil
slicks is unknown, and may be related to visual signaling, echolocation, tactile or olfactory
sensing or combinations of these.
14.7 Emerging tools
The emergence of next-generation sequencing tools (DNA and RNA) has undoubtedly
advanced the field of toxicology, and a number of intrepid researchers have attempted to
apply these tools to non-model organisms such as marine mammals. Edwards et al. (2013)
developed a workflow incorporating undergraduate students and novel coursework and
sequenced metagenomes of the California sea lion, proving that next- generation sequencing tools are accessible and validated for work with marine mammals. At the time of
writing, there are seven genomes available on NCBIs website including the minke whale,