Reaction mass of Disodium decyl(sulphonatophenoxy)benzenesulphonate and Disodium oxybis[decylbenzenesulphonate]

PBT assessment

PBT assessment: overall result

Reference

Name:

Boundary Composition - Reaction mass of Disodium decyl(sulphonatophenoxy)benzenesulphonate and Disodium oxybis[decylbenzenesulphonate]

Type of composition:

boundary composition of the substance

State / form:

solid: particulate/powder

Reference substance:

Boundary Composition - Reaction mass of Disodium decyl(sulphonatophenoxy)benzenesulphonate and Disodium oxybis[decylbenzenesulphonate]

Reference substance:

Boundary Composition - Reaction mass of Disodium decyl(sulphonatophenoxy)benzenesulphonate and Disodium oxybis[decylbenzenesulphonate]

Reference substance:

Boundary Composition - Reaction mass of Disodium decyl(sulphonatophenoxy)benzenesulphonate and Disodium oxybis[decylbenzenesulphonate]

Reference substance:

Boundary Composition - Reaction mass of Disodium decyl(sulphonatophenoxy)benzenesulphonate and Disodium oxybis[decylbenzenesulphonate]

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence Assessment

The biodegradability of DOWFAX 3B2 Surfactant in water was investigated in several studies of ready and inherent biodegradation. Consistent with the findings with other category members, DOWFAX 3B2 did not meet the criteria for classification as readily biodegradable, showing little DOC removal in two OECD TG 301E studies. In two older but reliable biodegradability studies according to the Soap & Detergent Association semi-continuous activation sludge method, DOWFAX 3B2 demonstrated a high degree (at least 97%) of reduction in methylene blue active substance (MBAS), an indicator of primary degradation of the surfactant. An additional study of the biodegradability of DOWFAX 3B2 under conditions simulating aerobic sewage treatment, according to OECD TG 303A, demonstrated complete removal of the parent substance within the first 15 days of operation; however, the extent of ultimate biodegradation based on DOC removal was limited (7.4%). Together, the available studies support the conclusion that DOWFAX 3B2 is inherently (primary) biodegradable. This conclusion is supported by studies on other category members, including OECD TG 302B tests of the inherent biodegradability of DOWFAX 2A1 and DOWFAX 8390 indicating the inherent primary biodegradability of these substances. Overall, since DOWFAX 3B2 is not readily biodegradable and the rate/extent of ultimate biodegradation (i.e., mineralization) in inherent tests with other category members do not meet specific criteria, DOWFAX 3B2 is considered to meet the screening level criteria for persistence (P).

Bioaccumulation Assessment

There are no empirical bioaccumulation data available for DOWFAX 3B2 from studies with fish or other biota. From a screening standpoint, the log Pow for DOWFAX 3B2 was determined by the HPLC method described in the OECD Test Guideline 117. The log Pow value for the main component was determined to be <1.0, based on the smallest log Pow value for the reference substances used to calibrate the method. Several smaller peaks corresponding to less abundant components were observed, with the longest retained component having a log Pow value of 4.0. These values are all less than the screening level bioaccumulation criterion of log Pow≥4.5. In addition, QSAR predictions of the ADME behavior or DOWFAX 3B2 indicate that based on low volume of distribution, and predicted metabolism and excretion, DOWFAX 3B2 is not expected to bioaccumulate in humans. Therefore, DOWFAX 3B2 does NOT meet the screening criterion for classification as bioaccumulative (B).

Toxicity Assessment

The available aquatic toxicity data from testing with DOWFAX 3B2 were all short-term studies in three species of freshwater fishes and an aquatic invertebrate. The key parameters for acute toxicity tests with fish and daphnids were 3.7 mg/L (lowest 96 -hour LC50 value for fish), and 1.5 mg/L (48 -hour EC50 value forD. magna). With one exception, LC50/EC50 values for short-term testing on fish and invertebrates with DOWFAX 2A1, the ADPODS category member most structurally similar to DOWFAX 3B2, were also in the 1 to 10 mg/L range.

Studies with freshwater algae were available from testing with ADPODS category members DOWFAX 2A1 and DOWFAX 8390. For DOWFAX 2A1, a 96 -hour EC50 of 840 mg/L was reported based on cell counts, with a corresponding NOEC of 298 mg/L. In the case of DOWFAX 8390, the 72 -hour EC50 and NOEC values were > 100 mg/L and 10 mg/L, respectively, based on growth rate inhibition. These studies demonstrated that members of the ADPODS category are not toxic to aquatic algae.

Long-term aquatic toxicity data for ADPODS category members DOWFAX 2A1 and DOWFAX 8390 were available from testing with the freshwater invertebrates. For DOWFAX 2A1, the 168 -hour NOEC values for mortality and reproduction ofC. dubiawere 0.65 mg/L and 1.08 mg/L, respectively. In the case of DOWFAX 8390, the reported 21 -day NOEC values withD. magnawere 0.7 mg/L for both mortality and reproduction. Based on similar chemistry and short-term toxicity, the long-term toxicity of DOWFAX 3B2 to aquatic invertebrates was well-represented by the NOEC value for DOWFAX 2A1, 0.65 mg/L.

Based on this data set, Dowfax 3B2 does not meet the criteria for toxicity (T) according to REACH Annex XIII.