Pyrasulfotole

Endpoint summary

Additional information

Experimental studies are available investigating the short- and long-term effects of the test item on aquatic organisms from three different trophic levels. The studies were performed according to internationally accepted guidelines in accordance with GLP. For all trophic levels freshwater and marine studies are available.
The short-term toxicity fish was investigated using the freshwater fish Oncorhynchus mykiss as well as Lepomis macrochirus (M-103513-02-2 and M-103514-02-2). Both studies were performed according to OECD 203 as a limit test with a concentration of 100 mg test item/L. No effects were observed and a LC50 (96 h) of > 100 mg test item/L (nominal) was derived in both studies. The study with the marine species Cyprinodon variegatus (M-076735-01-1) was performed under comparable conditions to the freshwater study (OECD 203, GLP). The test organism was exposed to 100 mg a.i./L. No mortality was recorded and a LC50 (96 h) of > 100 mg a.i./L (nominal) was derived. In all studies the test substance was shown to be stable by suitable analytical methods.
In order to assess the chronic toxicity of the test item to fish one experimental study was performed according to OECD 210 (GLP) with the freshwater fish Pimephales promelas (M-123221-01-1). Early life stages of P. promelas were exposed under flow-through conditions to 0.63, 1.25, 2.50, 5.00 and 10.0 mg a.i./L. Hatching rates, sub-lethal symptoms, fry survival and growth (length and wet and dry weight) were recorded. After 35 d of exposure (29 d post-hatch) an overall NOEC (35 d) of 0.58 mg a.i./L (measured) was derived based on growth rate (length and weight).
The short-term toxicity to aquatic invertebrates was assessed in three experimental studies. One was performed with the freshwater organism Daphnia magna (M-103462-02-2). Two of the available studies were performed with the marine species Crassostrea virginica (M-122204-01-1) and Americamysis bahia (M-122206-01-1). The study with Daphnia magna was performed according to OECD 202 (GLP) and exposed to a limit concentration of 100 mg test item/L under static conditions. The mobility of D. magna was not affected and an EC50 (48 h) of > 100 mg test item/L (nominal) was derived. The key study with the marine species Americamysis bahia was exposed to the nominal (mean measured) concentrations of 0 (control). 0.10 (0.093), 0.20 (0.20), 0.40 (0.37), 0.80 (0.75), 1.6 (1.5), 3.2 (2.9), 6.4 (6.2) and 13 (12) mg a.i./L in natural filtered seawater (pH at 7.9-8.0, salinity at 32‰) for a 96 hour period. to the control. The LC50 (96 h) was determined by probit analysis to be 1.1 mg a.i./L (95% confidence interval: 0.84 - 1.5 mg a.i./L). The NOEC was determined to be 0.37 mg a.i./L. No mortality or adverse effects were observed among mysids exposed. In the supporting study the effects of the test item on shell deposition of Crassostrea virginica was investigated for 96 h. It was performed according to EPA OPPTS 850.1025 (GLP) and the shells were exposed to a limit concentration of 100 mg a.i./L (nominal). After 96 h an EC50 of > 100 mg a.i./L was derived. In conclusion it was shown that the marine species (A. bahia) were more sensitive to the test item compared freshwater results.
In a long-term study with Daphnia magna according to OECD 211 (GLP) the test species were exposed to concentrations up to 50 mg a.i./L (nominal) under semi-static conditions. The reproduction of Daphnids was inhibited and a NOEC (21 d) of 25.5 mg a.i./L was derived based on arithmetic mean measured concentrations.
The toxicity to aquatic algae was investigated in four experimental studies (M-001513-01-1, M-062300-01-1, M-107701-01-1, M-122128-01-2). Three studies were performed with freshwater organisms whereas one was performed with a marine diatom species. The key study with the freshwater species Pseudokirchneriella subcapitata was performed according to OECD 201 (GLP). P. subcapitata was exposed to five nominal concentrations up to 100 mg a.i./L under static conditions for up to 96 h. The growth was inhibited allowing the derivation of a NOErC (96 h) of 6.4 mg a.i./L (measured) an ErC50 (96 h) of 29.8 mg a.i./L. In the supporting study with Navicula pelliculosa which was performed according to OECD 201 (GLP), an ErC50 (96 h) of 87.8 mg a.i./L and a NOErC (96 h) of 51.4 mg a.i./L were derived. The third study with Anabaena flos-aquae resulted in the same order of magnitude with an ErC50 (96 h) of 48.8 mg a.i./L and a NOErC (96 h) of 40.1 mg a.i./L. The study with the marine species Skeletonema costatum was performed according to OECD 201 (GLP). Inhibition of growth was measured and an EC50 (72 h) of 15.7 mg a.i./L and a NOEC (72 h) of 6.4 mg a.i./L were calculated. The toxicity of the test item to aquatic plants was studied in a GLP guideline study according to OECD 221 with Lemna minor (M-107686-01-1). Duckweed was exposed to nominal concentrations up to 150 µg a.i./L. Total frond area as well as total frond number were investigated for 7 d in a static test system. After 7 d an EC50 of 110 µg a.i./L (measured, arithmetic mean) was calculated and a NOEC (7 d) of 9.57 µg/L (measured, arithmetic mean) was derived based on growth rate.

In conclusion aquatic plants were the most sensitive taxonomic group in acute studies and chronic studies with freshwater organisms. Aquatic invertebrates were the most sensitive species in acute studies for the marine compartment.
The toxicity to the microbial community was studied in a GLP guideline study according to OECD Guideline 209 (M-566988-01-1). The activated sludge was exposed to the test item at a limit test item concentration of 100 mg/L. The respiration rate of each mixture was determined after aeration periods of 3 hours (no nitrification set up was performed). The test item showed 1.4% respiration inhibition of activated sludge at a test item concentration of 100 mg/L. The EC50 (3 h) is higher than 100 mg/L. The NOEC (3 h) is equal or higher than 100 mg/L. The effect value relates to a nominal concentration, since no analytical monitoring was performed. No inhibition of the degradation process in sewage treatment plants is expected.