Thiram

Short-term toxicity to fish

Description of key information

LC50 (96 h): 0.046 mg/L (meas. initial, OECD 203, static, Oncorhynchus mykiss)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

0.046 mg/L

Additional information

One key study and seven supporting studies on the short-term toxicity of tetramethylthiuram disulfide (CAS No. 137-26-8) to five different freshwater and one marine fish species are available. Two further studies on the short-term toxicity of tetramethylthiuram disulfide (CAS No. 137-26-8) to fish, with minor reliability (RL 3) are available.

 

The available key study (2000) on short-term toxicity of tetramethylthiuram disulfide (CAS No. 137-26-8) to the freshwater fish Oncorhynchus mykiss was performed according to the OECD Guideline 203 (GLP). Fish were exposed to 0, 0.0032, 0.010, 0.032, 0.10, 0.32 and 1.0 mg/L tetramethylthiuram disulfide (CAS No. 137-26-8; nominal) under static conditions for 96 h. Tetramethylthiuram disulfide (CAS No. 137-26-8) water concentrations were analyzed at 0, 48, and 96 h of exposure. Chemical analysis revealed tetramethylthiuram disulfide (CAS No. 137-26-8) water concentrations of 0, 0.0032, 0.011, 0.031, 0.089, 0.300 and 1.05 mg a.i./L. at test initiation, < 0.001, < 0.001, < 0.001, < 0.001, 0.00227, 0.0120, 0.0788, n.a. (0.722 at 24 h) mg/L at 48 h and < 0.001, < 0.001, < 0.001, < 0.001, 0.00519, n.a., n.a. mg/L at test termination (96 h). Since the test substance concentration declined extensively in the first 48 h (< 0.001 mg/L to 25% of nominal concentration), effects were based on initial measured concentrations of tetramethylthiuram disulfide (CAS No. 137-26-8). Concentration dependent effects on survival were observed after 96 h, resulting in an LC50 (96 h) of 0.046 mg a.i./L (meas. initial) and a NOEC (96 h) of 0.010 mg a.i./L (meas. initial).

 

Furthermore, five additional reliable supporting freshwater studies are available. These studies on the short-term toxicity of tetramethylthiuram disulfide (CAS No. 137-26-8) to five different freshwater fish species were performed according to the OECD Guideline 203 (GLP). Fish were exposed to tetramethylthiuram disulfide (CAS No. 137-26-8) under flow through conditions for 96 h. Water sample analysis revealed that stable water concentrations of tetramethylthiuram disulfide (CAS No. 137-26-8) were maintained throughout all tests. Concentration dependent effects on survival were observed after 96 h. LC50 values (96 h) were in the same range of magnitude and laid between 89 – 233 µg a.i./L (geometric mean measured). Upon these five species, Oncorhynchus mykiss represents the most sensitive species.

 

The 96 h LC50 values (geometric mean measured) determined in the supporting studies are all higher than the 96 h LC50 value of the key study. This confirms that it is appropriate to base the observed effects of the key study on initial measured concentrations. Since, effect values in the key study are based on initial measured concentrations and exposure concentrations were not maintained within 80-120% of nominal throughout the test, the supporting studies are rated with a higher reliability than the key study. In order to consider the lower effect value determined in the static short-term test, this study was chosen as key study.

 

One further short term study according to EPA OPP 72-3 is available with the marine species Cyprinodon variegatus. After 96 h of exposure to tetramethylthiuram disulfide (CAS No. 137-26-8) in a flow-through test system, concentration dependent effect on survival were observed, resulting in a LC50 (96 h) value of 540 µg/L (meas., arith. mean). This test implies that compared to freshwater species, marine species are less sensitive to tetramethylthiuram disulfide (CAS No. 137-26-8).