Polycyclic aromatic hydrocarbons (PAHs) are organic compounds that are widely distributed in the air, water, and soil. Recently, the amount of PAHs derived from fuels and from incomplete combustion processes is increasing. In the aquatic environment, oil spills directly cause PAH pollution and affect marine organisms. Oil spills correlate very well with the major shipping routes. Furthermore, accidental oil spills can seriously impact the marine environment toxicologically. Here, we describe PAH toxicities and related bioaccumulation properties in aquatic animals, including invertebrates. Recent studies have revealed the toxicity of PAHs, including endocrine disruption and tissue-specific toxicity, although researchers have mainly focused on the carcinogenic toxicity of PAHs. We summarize the toxicity of PAHs regarding these aspects. Additionally, the bioaccumulation properties of PAHs for organisms, including invertebrates, are important factors when considering PAH toxicity. In this review, we describe the bioaccumulation properties of PAHs in aquatic animals. Recently, microplastics have been the most concerning environmental problem in the aquatic ecosystem, and the vector effect of microplastics for lipophilic compounds is an emerging environmental issue. Here, we describe the correlation between PAHs and microplastics. Thus, we concluded that PAHs have a toxicity for aquatic animals, indicating that we should emphasize the prevention of aquatic PAH pollution.

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Toxicities of Polycyclic Aromatic Hydrocarbons for Aquatic Animals.

Chemicals are a vital part of everyday life. They come in the form of fuels, antibiotics, pesticides, plastic containers, agricultural fertilizers, photocopying compounds, and so on. Society cannot survive in its present form without them. Growth in the numbers of chemicals used during recent decades has been extraordinary. In 1980 the total number of substances commercially available was estimated at 40,000 with about 2000 new ones being placed on the market each year (Schmidt-Bleek and Haberland 1980).

Bioaccumulation behavior of persistent organic chemicals with aquatic organisms.

The U.S. Fish and Wildlife Service analyzed residues of organochlorine chemicals in 315 composite samples of whole fish collected in 1980–81 from 107 stations nationwide as part of the National Pesticide Monitoring Program (NPMP). The mean concentrations of total DDT and allp,p′-ho-mologs exceptp,p′-DDT showed significant but small declines relative to mean concentrations before 1978–79. The mean concentration ofp,p′-DDT did not change. The most persistent DDT homolog (p,p′-DDE) continued to constitute about 70% of total DDT residues, as it did in 1974–79. DDT contamination attributable to former DDT manufacturing facilities remained evident at sites in Alabama and Arkansas, and high concentrations at one site in Hawaii suggested that input to the environment was continuing. Conversely, the data do not support the contention of others that DDT was still being used in the Southwest. Residues of polychlorinated biphenyls (PCBs) remained widespread, but a significant downward trend in total PCBs was evident, especially in areas that the NPMP has previously shown to be the most heavily contaminated. Mean concentrations of dieldrin had not changed since 1978–79, and levels remained highest in Hawaii and in the Great Lakes. Toxaphene concentrations plateaued after a period of steady increase through the 1970's, but the incidence of toxaphene continued to increase; residues were present at 88% of the stations sampled in 1980–81, including one in Alaska (most likely as a consequence of atmospheric transport). Mean chlordane concentrations were slightly lower than in 1978–79, and residues were detected at fewer stations in 1980–81 than in 1978–79. Residues of other organochlorines [e.g., mirex, pentachloroanisole (PCA), benzene hexachloride (BHC) isomers, endrin, heptachlor, hexachlorobenzene (HCB), Dacthal® (DCPA)2, and methoxychlor] were either found at relatively few (<25%) of the stations sampled in 1980–81 or were characterized by relatively low concentrations.

National Pesticide Monitoring Program: Residues of organochlorine chemicals in freshwater fish, 1980–81

Use of biological indicator organisms to quantitate organochlorine pollutants in aquatic environments—A review

The biological half-life of a chemical is the time required for its concentration in an organism to decline by 50%. This value is described in the relationship: 

$$ {{T}_{{1/2}}} = \frac{{0.693}}{{{{K}_{e}}}} $$

where T 1/2 is the biological half-life, and K e the clearance coefficient. Both T 1/2 and K e have important applications in chemical hazard assessments. Contaminant dynamics models generally include a coefficient to describe the clearance rate of a chemical (Thomann 1981; Bruggeman 1982). K e can be used to estimate the bioconcentration factor (BCF) of a persistent chemical that does not attain steady-state concentration in fish during a study. Using the kinetics approach, another experiment could determine the chemical uptake coefficient (K 1) by exposing fish to a constant chemical concentration, and this factor can be estimated as BCF = K 1/K e (Oliver and Niimi 1985). Half-lives can also be used to assess the relative importance of the bioconcentration and biomagnification pathways for accumulation of contaminants by fish (Niimi 1985).

Biological half-lives of chemicals in fishes

The rate and efficiency of uptake from food, the distribution in selected tissues, and the rate of elimination, of 14C-p,p' DDT and 14C-dieldrin in rainbow trout were investigated during and after a minimum of 140 days of exposure. Growth of fish during 140 days of exposure was not affected by insecticide exposure. However, both DDT and dieldrin significantly increased lipogenesis during this period. Total residue accumulation was dose-dependent, and those fish exposed to 0.2 mg/kg per week of either DDT or dieldrin, or to 1.0 mg/kg per week dieldrin apparently had reached the equilibrimn state after 140 days of exposure. Fish accumulated 20–24% of the available dietary DDT and 9–11% of the available dietary dieldrin. Generally, there was an approximately linear increase in the residue concentration of a tissue, followed by an equilibrium state during which the residue content remained virtually constant with continued exposure to the insecticide. The predicted time required for rainbow trout to ...

Charles R. Rodgers

Papers

The Uptake, Distribution and Elimination of Dietary 14C-DDT and 14C-Dieldrin in Rainbow Trout