Terphenyl, hydrogenated

Endpoint summary

Additional information

The information provided in the summaries in Section 7 are those studies, pieces of information, relevant for risk assessment purposes. More specifically, this information is considered relevant for classification and labeling purposes of the substance and PNEC derivation. Additional studies were included in the iuclid for PBT purposes. However, these studies are not dealt with in detail in section 7, but instead are discussed in Section 8 of this CSR.

Summary on aquatic toxicity:

Aquatic toxicity related to hydrogenated terphenyls has been assessed both in acute and chronic toxicity tests. These tests however cover different trophic levels (fish, invertebrate, algae) and among the fish and invertebrates, different species were used.

FISH:

From the fish tests (all acute 96h tests) (Griffin, 1979; Thompson, 1979; John O’H. Rice, 1972 a&b; Adams 1979 a&b; BTL 1972 a&b), it was concluded that the substance is not acutely toxic towards fish at concentrations well above the water solubility. In four out of five tests, the LC₅₀(96h) was reported to be > 1000 mg/L test substance. The fifth, remaining test yielded a LC₅₀(96h) > 10 - < 100 ppm. It should be noted however that this fifth test was the only one that was not carried out with the primary test substance with 40 % hydrogenated terphenyls, but with a substance containing 30 % hydrogenated terphenyls, which thereby has a slightly different composition compared to the primary test substance.

INVERTEBRATES

The acute toxicity towards aquatic invertebrates for the primary test substance was evaluated for multiple species:Daphnia magna (Forbis, 1979; Powel and Moser, 1996; Adams, 1979; Renaudette, 1984),Mysidopsis bahia (Gledhill, 1984),Gammarus fasciatus (Hoberg, 1984a)andParatanytarsus parthenogenetica (Hoberg, 1984b).Based on the results reported in all these studies, no toxicity was observed up to water solubility levels (approximately 0.06 mg/L).

The most recently performed study (Powell and Moser, 1996) was the only study reporting measured exposure concentrations. This limit test with Terphenyl, hydrogenated indicated that the EC₅₀(48h) is > 1.34 mg/L (measured concentration). It should be noted however that a dispersant was used to dissolve the test substance. The other EC₅₀(48h) values for freshwater invertebrates reported for Terphenyl, hydrogenated ranged from 0.1 mg/L to > 1.5 mg/L, all based on nominal concentrations in the presence of a solvent. Additional tests performed with a "read-across" substance (substance containing 40 % hydrogenated polyphenyls) onDaphnia magna(Monsanto Report, 1980; Calvert 1982) andChironomus tentans(Renaudette, 1984), generally indicated a higher toxicity of this substance with EC₅₀48h values ranging from 0.011 to 0.52 mg/L. However, due to the difference in chemical composition of the substance (which contains a larger fraction of hydrogenated quaterphenyls in comparison to the primary test substance), these values were not taken into account further in the risk assessment. To conclude, although the lowest EC50 (48h) is 0.1 mg/L, the test reporting an EC50 (48h) > 1.34 mg/L is considered the most relevant and reliable study. For risk assessment purposes this result is taken into account.

The determined chronic toxicity towards aquatic invertebrates is based on the 21 -reproduction study performed with Daphnia magna on Water Accommodated Fractions of 1 and 5 mg/L hydrogenated terphenyl (Tobor-Kaplon, 2014). This test resulted in a NOELR for reproduction < 1 mg/L, a NOELR for mortality of 1 mg/L and a NOELR for growth < 1 mg/L.At the Loading Rate of 1 mg/L, a 32% reduction of the reproduction was observed. As the test design did not include lower concentrations, this due to technical reasons, no exact NOELR could be determined.

 

ALGAE:

Two phytotoxicity studies (K1 & K2) are available, evaluating the effect of hydrogenated terphenyls on the freshwater algaSelenastrum capricornutum (new name is P. subcapitata) (Hollister, 1979; Weltens, 2010).In the oldest study (K2), only nominal concentrations were reported (10, 32, 56, 100 and 320 mg/L). The basis of the reported effects was in vivo chlorophyll a (for all time points) and cell numbers (96h). Based on the decrease of in vivo chlorophyll a, the calculated 96 hour EC₅₀was 44 ppm (95% CL 1 - 1586 ppm). The calculated 96 hour EC₅₀based on cell number decrease was 56 ppm (CL 95% of 4 -743 ppm). In the most recent study (K1), algae were exposed to water soluble fractions of hydrogenated terphenyls. The presense of the hydrogenated terphenyl in these WAFs could be measured with HPLC when solutions were freshly prepared. This soluble fraction however disappeared during the exposure time both in filtered and unfiltered WAFs and it was not clear from the results how fast the test substance disappears. The initial presence of these soluble compounds in the WAFs however does not interfere with normal algal growth rate for WAFs produced with nominal concentrations up to 100 mg/L hydrogenated terphenyl. As no effects were seen in the test range, no effect values could be defined either.

CONCLUSION:

Based on the available data, it can be concluded that invertebrates (more specifically Daphnia magna) are the most sensitive species. As both acute and long term toxicity information is available covering that species there is no need to collect more ecotoxicology related information on other (vertebrate) organisms.