Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability

Stability for DMBPC was determined in a five day study according to OECD Guideline 111 (Hydrolysis as a function of pH) at pH 4, 7, and 9 at 50 °C (Lockwood SH, 2001a). The initial concentrations of DMBPC were 345, 340 and 480 µg/L at pH 4, 7 and 9, respectively. There was no loss of the test substance after 5 d. Therefore, no value could be determined for half-life. DMBPC as a saturated solution in aqueous buffers at pH 4.0, 7.0 and 9.0 was found to be hydrolytically stable after 5.0 d at 50 °C. At pH 4, 7 and 9, the percent recovery values were 104.1, 103.5 and 100.2, respectively. There are no stability data available regarding photo transformation in air, water or soil for DMBPC.

 

Biodegradability

Three studies are available investigating the biodegradability of DMBPC in aquatic environments, all of which demonstrate that DMBPC is not readily biodegradable; however, all of these studies possess deficiencies preventing their selection as a key study. For this reason, the conclusion that DMBPC is not readily biodegradable is supported by the weight-of-evidence.

In a study performed according to OECD Test Guideline 301 F, the aerobic biodegradability of DMBPC was examined, testing two types of domestic activated sludge for a contact period of 800 h (approximately 33.3 d) (Lockwood SH, 2001b). In these tests, a maximum of 38 % degradation (measured by O₂ consumption) was observed after 800 h.

In a study performed according to OECD Test Guideline 301 C, the ready biodegradability of DMBPC was investigated (Institute of Ecotoxicology, Ltd., 2002). After a contact period of 28 d, 0 % degradation was observed (measured by O₂ consumption) in all three replicate samples.

In a third study, the biodegradability of DMBPC was investigated by High Performance Liquid Chromatography (HPLC) and Total Organic Carbon (TOC) analysis; no biodegradation was observed using either analytical method (Kurume Laboratory, 2001).

Based on this evidence, it is concluded that DMBPC is not readily biodegradable.

 

Bioconcentration

In accordance with section 9.3.2 of Column 2 of Annex IX of Regulation (EC) No 1907/2006, it is considered justified to omit the bioaccumulation in aquatic species study on the basis that the substance has a low potential for bioaccumulation and direct and indirect exposure of the aquatic compartment is unlikely. The use of vertebrate animals to further investigate this endpoint is therefore not considered to be ethical.

Furthermore, in a supporting study performed according to OECD Test Guideline 305 C testing common carp (Cyprinus carpio), 28-d bioconcentration factors (BCFs) of 86 and 73 L/kg were reported when DMBPC was tested at initial aqueous concentrations of 0.01 and 0.001 mg/L, respectively (Institute of Ecotoxicology, Ltd., 2003). These BCFs indicate that DMBPC has a low potential to bioaccumulate/ bioconcentrate. However, the original study report is in Japanese and only the abstract has been provided in English; therefore, a thorough assessment of study reliability could not be completed. An experimentally-determined log Kow of 3.1 (RCC Ltd., 2001g) supports the conclusion that DMBPC has low potential to bioaccumulate/bioconcentrate.

Taken together, these data support the argument that DMBPC is not bioaccumulative in aquatic/benthic species.

 

Transportation and Distribution

The organic carbon normalised adsorption coefficient (Koc) was estimated by calculation using KOCWIN Program (v2.00) found in EPI Suite and was found to be 940.8 L/kg (log Koc = 2.97) (ARCADIS US, Inc., 2012b). The Koc was also estimated using the Gerstl correlation, as described in ECHA REACH Guidance Document R.7a (ECHA, 2008a), and found to be 158 L/kg at 25 °C (ARCADIS US, Inc., 2012c). A substance is considered weakly sorbing by ECHA if the Koc is less than about 25 L/kg. Based on the estimated Koc values (158 L/kg and 940.8 L/kg) it is estimated that DMBPC is likely to adsorb to soil and has low to moderate mobility. Based on estimated data, there is a slight potential for groundwater leaching if the soil conditions are optimum to decrease the Koc of the substance (e.g. soil type, moisture content, organic matter content or pH), however there are no experimental absorption/desorption data available to validate this.