POLYCYCLIC AROMATIC HYDROCARBONS
Michael J. Kennish
Department of Marine and Coastal Sciences,
School of Environmental and Biological Sciences,
Rutgers University, New Brunswick, NJ, USA
Synonyms
PAHs; Polynuclear aromatic hydrocarbons; Poly-aromatic
hydrocarbons
Definition
Polycyclic aromatic hydrocarbons (PAHs) are a group of
widespread atmospheric and aquatic pollutants of major
concern because of their potential carcinogenicity, mutagenicity, and teratogenicity to a broad spectrum of organisms (Kennish, 1997). These organic xenobiotics consist
of hydrogen and carbon arranged in the form of two or
more fused aromatic (benzene) rings in linear, angular,
or cluster arrangements with unsubstituted groups possibly attached to one or more rings (Eisler, 1987).
Description
PAH compounds range from naphthalene (two rings) to
coronene (seven rings); the low-molecular-weight PAH
compounds containing two or three rings are
noncarcinogenic but acutely toxic to many estuarine and
marine organisms, whereas the high-molecular-weight
PAH compounds containing four or more rings have greater
carcinogenic potential but are less toxic. Anthracene,
fluorene, naphthalene, and phenanthrene are examples of
low-molecular-weight PAH compounds that tend to be
toxic; benzo(a)pyrene, benzo(c)phenanthrene, dibenzo(a,i)
pyrene, and 3-methylcholanthrene are examples of highmolecular-weight, carcinogenic compounds. While some
PAH compounds are synthesized by bacteria, fungi, and
plants or are derived from natural fires, marine seeps, and
volcanic emissions, most PAHs released to the environment
originate from human activities (Kennish, 1992).
Highest levels of PAHs typically occur in urbanized estuaries and nearby coastal marine waters in close proximity to
highly populated metropolitan centers. PAH-contaminated
sites are often problematic sources of PAHs to local waterways (Lundstedt et al., 2007). The pyrolysis of organic matter, notably fossil fuels, is a primary delivery system of PAH
compounds to estuarine environments. Other important
delivery pathways include sewage releases, storm sewer
runoff, oil refinery wastewaters, and oil spills. Urban and
agricultural runoff and municipal and industrial discharges,
therefore, play a major role in transporting PAH compounds
to estuarine and coastal marine systems (Kennish, 2001).
PAHs are hydrophobic. Because they readily sorb to
particulate matter in the water column and bottom sediments, these compounds partition out of the water column
onto suspended particulates and bottom sediments
through time (McElroy et al., 1989; Khodadoust et al.,
2005). They are assimilated by benthic organisms and
then pass through estuarine food webs. However, there
are different degrees of bioavailability of these contaminants, and there are variable capacities of the organisms
to metabolize them. Hence, uptake and concentrations of
PAHs in biotic tissue can be highly variable as well. The
concentrations of individual PAH contaminants measured
in aquatic organisms generally range from 0.01 to more
than 5,000 mg kg
À1 dry wt (Kennish, 1997).
Bibliography
Eisler, R., 1987. Polycyclic aromatic hydrocarbon hazards to fish,
wildlife, and invertebrates: a synoptic review. Biological Report
85 (1.11). Washington, DC: U.S. Fish and Wildlife Service.
Kennish, M. J., 1992. Ecology of Estuaries: Anthropogenic Effects.
Boca Raton, FL: CRC Press.
Kennish, M. J. (ed.), 1997. Practical Handbook of Estuarine and
Marine Pollution. Boca Raton, FL: CRC Press.
Kennish, M. J. (ed.), 2001. Practical Handbook Marine Science,
3rd edn. Boca Raton, FL: CRC Press.
Khodadoust, A., Lei, L., Antia, J., Bagchi, R., Suidan, M., and
Tabak, H., 2005. Adsorption of polycyclic aromatic hydrocarbons in aged harbor sediments. Journal of Environmental Engineering, 131, 403–409.
Lundstedt, S., White, P. A., Lemieux, C. L., Lynes, K. D.,
Lambert, I. B., Oberg, L., Haglund, P., and Tysklind, M., 2007.
Sources, fates, and toxic hazards of oxygenated polycyclic
aromatic hydrocarbons (PAHs) at PAH-contaminated sites.
Ambio, 36, 475–485.
McElroy, A. E., Farrington, J. W., and Teal, J. M., 1989. Bioavailability of polycyclic aromatic hydrocarbons in the aquatic environment. In Varanasi, U. (ed.), Metabolism of Polycyclic
Aromatic Hydrocarbons in the Aquatic Environment. Boca
Raton, FL: CRC Press.
Cross-references
Anthropogenic Impacts
Nonpoint Source Pollution
PRECAUTIONARY PRINCIPLE
Mafalda Marques Carapuço
Institute Dom Luiz, University of Lisbon, Lisbon,
Portugal
Synonyms
Precautionary approach; Preventive principle
Definition
The precautionary principle is an action or policy that
should not be implemented if, following the assessment
of the available information, it may represent a threat of
serious, irreversible, or unpredictable damage to the
environment or human health.
Precautionary risk management
The precautionary principle is an approach to risk management developed under circumstances of scientific
PRECAUTIONARY PRINCIPLE
495
Michael J. Kennish
Department of Marine and Coastal Sciences,
School of Environmental and Biological Sciences,
Rutgers University, New Brunswick, NJ, USA
Synonyms
PAHs; Polynuclear aromatic hydrocarbons; Poly-aromatic
hydrocarbons
Definition
Polycyclic aromatic hydrocarbons (PAHs) are a group of
widespread atmospheric and aquatic pollutants of major
concern because of their potential carcinogenicity, mutagenicity, and teratogenicity to a broad spectrum of organisms (Kennish, 1997). These organic xenobiotics consist
of hydrogen and carbon arranged in the form of two or
more fused aromatic (benzene) rings in linear, angular,
or cluster arrangements with unsubstituted groups possibly attached to one or more rings (Eisler, 1987).
Description
PAH compounds range from naphthalene (two rings) to
coronene (seven rings); the low-molecular-weight PAH
compounds containing two or three rings are
noncarcinogenic but acutely toxic to many estuarine and
marine organisms, whereas the high-molecular-weight
PAH compounds containing four or more rings have greater
carcinogenic potential but are less toxic. Anthracene,
fluorene, naphthalene, and phenanthrene are examples of
low-molecular-weight PAH compounds that tend to be
toxic; benzo(a)pyrene, benzo(c)phenanthrene, dibenzo(a,i)
pyrene, and 3-methylcholanthrene are examples of highmolecular-weight, carcinogenic compounds. While some
PAH compounds are synthesized by bacteria, fungi, and
plants or are derived from natural fires, marine seeps, and
volcanic emissions, most PAHs released to the environment
originate from human activities (Kennish, 1992).
Highest levels of PAHs typically occur in urbanized estuaries and nearby coastal marine waters in close proximity to
highly populated metropolitan centers. PAH-contaminated
sites are often problematic sources of PAHs to local waterways (Lundstedt et al., 2007). The pyrolysis of organic matter, notably fossil fuels, is a primary delivery system of PAH
compounds to estuarine environments. Other important
delivery pathways include sewage releases, storm sewer
runoff, oil refinery wastewaters, and oil spills. Urban and
agricultural runoff and municipal and industrial discharges,
therefore, play a major role in transporting PAH compounds
to estuarine and coastal marine systems (Kennish, 2001).
PAHs are hydrophobic. Because they readily sorb to
particulate matter in the water column and bottom sediments, these compounds partition out of the water column
onto suspended particulates and bottom sediments
through time (McElroy et al., 1989; Khodadoust et al.,
2005). They are assimilated by benthic organisms and
then pass through estuarine food webs. However, there
are different degrees of bioavailability of these contaminants, and there are variable capacities of the organisms
to metabolize them. Hence, uptake and concentrations of
PAHs in biotic tissue can be highly variable as well. The
concentrations of individual PAH contaminants measured
in aquatic organisms generally range from 0.01 to more
than 5,000 mg kg
À1 dry wt (Kennish, 1997).
Bibliography
Eisler, R., 1987. Polycyclic aromatic hydrocarbon hazards to fish,
wildlife, and invertebrates: a synoptic review. Biological Report
85 (1.11). Washington, DC: U.S. Fish and Wildlife Service.
Kennish, M. J., 1992. Ecology of Estuaries: Anthropogenic Effects.
Boca Raton, FL: CRC Press.
Kennish, M. J. (ed.), 1997. Practical Handbook of Estuarine and
Marine Pollution. Boca Raton, FL: CRC Press.
Kennish, M. J. (ed.), 2001. Practical Handbook Marine Science,
3rd edn. Boca Raton, FL: CRC Press.
Khodadoust, A., Lei, L., Antia, J., Bagchi, R., Suidan, M., and
Tabak, H., 2005. Adsorption of polycyclic aromatic hydrocarbons in aged harbor sediments. Journal of Environmental Engineering, 131, 403–409.
Lundstedt, S., White, P. A., Lemieux, C. L., Lynes, K. D.,
Lambert, I. B., Oberg, L., Haglund, P., and Tysklind, M., 2007.
Sources, fates, and toxic hazards of oxygenated polycyclic
aromatic hydrocarbons (PAHs) at PAH-contaminated sites.
Ambio, 36, 475–485.
McElroy, A. E., Farrington, J. W., and Teal, J. M., 1989. Bioavailability of polycyclic aromatic hydrocarbons in the aquatic environment. In Varanasi, U. (ed.), Metabolism of Polycyclic
Aromatic Hydrocarbons in the Aquatic Environment. Boca
Raton, FL: CRC Press.
Cross-references
Anthropogenic Impacts
Nonpoint Source Pollution
PRECAUTIONARY PRINCIPLE
Mafalda Marques Carapuço
Institute Dom Luiz, University of Lisbon, Lisbon,
Portugal
Synonyms
Precautionary approach; Preventive principle
Definition
The precautionary principle is an action or policy that
should not be implemented if, following the assessment
of the available information, it may represent a threat of
serious, irreversible, or unpredictable damage to the
environment or human health.
Precautionary risk management
The precautionary principle is an approach to risk management developed under circumstances of scientific
PRECAUTIONARY PRINCIPLE
495