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Short-term toxicity to fish

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Description of key information

No data on short-term toxicity of ATMP-xK (CAS 27794-93-0, where x = 5), to fish are available. A 96-h LC50 value of 260 mg/L has however been determined for the effects of the substance on mortality of Salmo gairdneri (now known as Onychorhynchus mykiss) based on the results of a test with ATMP acid (CAS 6419-19-8).

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Additional information

No data on short-term toxicity of ATMP xK salts, 27794-93-0, to fish are available.

Freshwater

However, areliable 96 h LC50 value of 160 mg/L (as active acid) has been determined for the effects of ATMP acid (CAS 6419-19-8) on mortality ofSalmo gairdneri(now known as Onychorhynchusmykiss). This value is taken from a 14-day study, where the 96 h LC50 was reported. The same study determined a 14-day NOEC of 47 mg active acid/L and a 14-day LC50 of 150 mg active acid/L withS. gairdneri(now known asO. mykiss) and ATMP acid 6419-19-8.

The results of tests conducted on ATMP and its salts are directly comparable, because the ionisation state will depend only on the pH of the test medium. The counterion is not considered to contribute to effects in fish. At environmentally-relevant pH values, ATMP will be ionised typically four or five times, and will form stable complexes with metal ions.

Here, the value of 160 mg equivalent active acid/L may be directly read-across. It is convenient to convert the result into units of mg ATMP xK salt/L at relevant conditions of pH by considering the ionisation state of ATMP 6419-19-8 at the 160 mg/L concentration.

The pH of the test medium at concentration 160 mg/L on day 5 was 6.8. At this pH ATMP is ionised 5 times (pKa5= pH 6.6), hence the calculation is to determine the concentration of ATMP-xK (where x = 5) which would be equivalent to 160 mg active acid/L. In the calculation we also remove the number of hydrogen atoms substituted by the potassium salt from the MW of ATMP, in this case 5.

The 96 h LC50 for ATMP 6419-19-8 is 160 mg/L, which is equivalent to a 96 h LC50 value of 160 * 1.64 = 260 mg/L ATMP-xK (CAS 27794-93-0, where x = 5) [using MW(ATMP-5K)/MW(ATMP) = 299.05+((39.098-1.008)*5)/299.05 = 1.64]

Marine

A 96 h LC50 value of >400-500 mg/L has been determined for the effects of ATMP-xNa salt on the mortality of the marine fishCyprinodon variegatus. This corresponds to a 96 h LC50 value of >282 mg/L (as active ATMP acid) based on the active acid content (28.2%) reported in the test report. The study was conducted with ATMP-xNa (CAS 20592-85-2).

The results of tests conducted on ATMP and its salts are directly comparable, because the ionisation state will depend only on the pH of the test medium. The counterion is not considered to contribute to effects in fish. ATMP will be ionised typically four or five times at environmentally-relevant pH values and will form stable complexes with metal ions.

Here, the value of >282 mg equivalent active acid/L may be directly read-across. It is convenient to convert the result into units of mg ATMP xK salt/L at relevant conditions of pH by considering the ionisation state of ATMP 6419-19-8 at the >282 mg/L concentration.

The pH of the test medium at concentration >282 mg/L on day 4 was ca.8. At this pH ATMP is ionised mostly 5 times (pKa5= pH 6.6), hence the calculation is to determine the concentration of ATMP-xK (where x = 5) which would be equivalent to >282 mg active acid/L. In the calculation we also remove the number of hydrogen atoms substituted by the potassium salt from the MW of ATMP, in this case 5.

The 96 h LC50 for ATMP-xNa (CAS 20592-85-2)is >282 mg/L, which is equivalent to a 96 h LC50 value of 282 * 1.64 = >465 mg/L ATMP-xK (CAS 27794-93-0, where x = 5) [using MW (ATMP-5K)/ MW(ATMP) = 299.05+((39.098-1.008)*5)/299.05 = 1.64]

 

The results reflect the lowest values that are available for this endpoint.