Antioxidative enzyme activities in the Rhodeinae sinensis Gunther and Macrobrachium nipponense and multi-endpoint assessment under tonalide exposure.

Tonalide or acetyl hexamethyl tetralin (AHTN) is used as a fragrance additive in various household products. Recently, AHTN has drawn attention owing to its negative health effects on aquatic organisms. Data on AHTN toxicity toward aquatic species are limited. Therefore, this study tested the oxidative stress induced by AHTN exposure on the Rhodeinae sinensis Gunther and Macrobrachium nipponense. In this study, malonaldehyde (MDA) content and the activities of acetyl cholinesterase (AchE), superoxide dismutase (SOD), glutathione S-transferase (GST), and catalase (CAT) in R. sinensis Gunther were tested after 30 days of exposure to 30.093, 34.005, 38.426, 43.421, 49.067, 55.444, 62.652, 70.800, and 80.000 µg/L AHTN, respectively. The MDA, AchE, SOD, GST and CAT in M. nipponense were tested after 40 days of exposure to 60.000, 72.000, 86.400, 103.680, 124.416, 149.299, 179.159, 214.991, and 257.989 µg/L AHTN, respectively. In addition, an integrated biomarker response (IBR) index was utilised to evaluate the integrated toxic effects of AHTN on R. sinensis Gunther and M. nipponense. Finally, the predicted no-effect concentrations (PNECs) of AHTN, based on reproduction, biochemistry, survival, chronic toxicity, and acute toxicity endpoints were derived. The results indicated that low concentrations of AHTN can induce significant changes of oxidative stress biomarkers. The no observed effect concentrations (NOECs) of SOD, GST, AchE, CAT, and MDA were 103.680, 72.000, <60.000, 72.000, and <60.000 µg/L for R. sinensis Gunther and 38.426, 43.421, 30.093, 30.093, and 38.426 µg/L for M. nipponense, respectively. The IBR calculation results showed that 149.299 µg/L AHTN caused the highest toxic effect on R. sinensis Gunther after 30 days of exposure, whereas 70.797 µg/L AHTN caused the greatest damage to M. nipponense after 40 days of exposure. The PNECs of AHTN based on the non-traditional endpoints of biochemistry and reproduction were 0.00145 µg/L and 0.000395 µg/L, respectively, which were significantly lower than the PNEC of 2.636 µg/L for traditional endpoint survival. Therefore, the protection of aquatic organisms based on non-traditional toxicity endpoints should be considered in ecological risk assessment.

Development of aquatic life criteria for tonalide (AHTN) and the ecological risk assessment.

AHTN (tonalide) is a polycyclic musk that is widely used as fragrance additive in numerous consumer products. AHTN is of great worldwide concern owing to its adverse effects on aquatic organisms and frequent detection in both domestic and foreign aquatic environments. Therefore, derivation of the aquatic life criteria for AHTN exposure is urgently needed. In this work, AHTN toxicity data for eight Chinese native freshwater organisms were used to derive a criterion maximum concentration of 59.39 µg/L and a criterion continuous concentration of 22.43 µg/L using United States Environmental Protection Agency guidelines. Toxicity tests showed that the annelid L. hoffmeisteri and the amphibian R. nigromaculata were the least and most sensitive species to AHTN, respectively. The sensitivity of the planktonic crustacean D. magna to AHTN obviously differed from that of the benthic crustacean M. nipponense. The AHTN and HHCB correlation analysis exhibited a strong positive linear correlation (R2 = 0.8622) in water. The ecological risk assessment showed that AHTN and HHCB posed a higher risk in foreign surface waters than Chinese waters, but a lower risk in foreign wastewater treatment plant effluent than in China. The ecological risks of AHTN and HHCB in most surveyed water bodies of various countries were at acceptable levels, with a few exceptions.