Aquatic Toxicity

Risk assessments for high phthalates DINP and DIDP, as well as for the low phthalate DEHP, show that, at concentrations up to their water solubility, they produce no acute or chronic toxic effects in aquatic organisms. However, in order to make risk assessments as concrete as possible, multigeneration studies have been carried out in which fish are exposed to phthalates via food rather than in the usual way via water.

Low phthalates, DBP and BBP, have been classified as toxic to aquatic organisms but their EU risk assessments demonstrate that there is no cause for concern at the low levels in which they are present in the environment.

Conflicting data
There are some reports of effects of some phthalates at concentrations in excess of their water solubility. The conflicting data found in some chronic daphnia studies are attributed to surface entrapment which causes stress and in many cases the daphnia die. This conclusion is supported by the studies carried out on a number of phthalate esters in the presence of a non-toxic dispersant at nominal concentrations greatly in excess of water solubility of most of the test compounds. Using a dispersant, 13 high and low phthalates showed no significant effects at a concentration of 1 mg/L(1). No surface entrapment was observed.

Eighteen individual chronic fish toxicity tests from eight independent studies are available. These studies include data for phthalates ranging from dihexyl to diundecyl across nine fish species(2). One early study by Mehrle & Mayer(3), which appears to be an outlier, has been considered by US EPA scientists to be invalid due to unacceptable test conditions(4). Discounting these results, the chronic fish NOEC (no observed effect concentration) for high phthalates ranges from > 52 to 23,800 µg/l. The large variations in reported NOEC values between studies reflect the different experimental techniques that were used to obtain maximum exposure concentrations (i.e. emulsions).

These studies indicate that phthalates are not chronically toxic to fish at the maximum concentrations that could be maintained as stable emulsions. A recent review(5) of the available chronic aquatic toxicity of phthalates confirms this and other conclusions that, for most phthalates, there are no, or minimal risks to aquatic organisms.