By-products or contaminants :: freshwater ecosystems

Ecosystems: 

Key Concerns:

PAHs are acutely toxic to aquatic organisms due to the formation of toxic metabolites. The PAHs which are most toxic to algae are benz(a)anthracene and benzo(a)pyrene, with EC50 values ranging from 1 to 29 µg/l and 5 to 15 µg/l, respectively (WHO 1998). Corresponding EC50 values for 3 ring PAHs range from 240 to 940 µg/l. Naphthalene is less toxic than other PAHs, with EC50 values in algae ranging from 2800 to 34 000 µg/l.

PAHs have been shown to be toxic to various taxonomic groups of invertebrates, including crustaceans, insects, molluscs, polychaetes and echinoderms. No clear difference in sensitivity between these groups was reported. Naphthalene was the least toxic, with LC50 values ranging from 100 to 2300 µg/l. Anthracene was the most toxic, with LC50 values ranging from <1 to 260 µg/l (Borovsky et al, 1987). Corresponding values for other PAHs range from <1 to 325 000 µg/l (WHO 1998).

The toxicity of PAHs to fish is also variable. Naphthalene the least toxic, with LC50 values ranging from 110 to >10 000 µg/l, and anthracene the most toxic, with LC50 values ranging from 2.8 to 360 µg/l (Oris, 1986; Kagan et al, 1985). Corresponding LC50 values for other PAHs range from 0.7 to 22 400 µg/l (WHO 1998). Fish exposed to PAHs have also demonstrated physiological changes with effects on growth, reproduction, swimming performance and reproduction (WHO 1998).

Environmental limit: 

Critical Load/ Level

No estimate available