(1-methylethylidene)di-4,1-phenylenetetraphenyl diphosphate

Endpoint summary

Additional information

A test for ready biodegradability conducted according to the Modified MITI (OECD Test Guideline 301C) indicated that the chemical only very slowly degraded under the conditions of the test (Iwami S, 1994). The result of this test indicates that the BDP is not readily biodegradable. The eventual fate of the majority of the imported chemical will be strongly linked to that of discarded plastic articles, and this is likely to be either placed into landfill or be incinerated. The chemical to be disposed of to landfill will be incorporated and immobilised in a solid resin matrix (ie the plastic article). However, the resin matrix will be slowly degraded through the biological and abiotic processes operative in landfills, to release the BDP. The compound has a large Koc (log Koc > 4.53), indicating strong affinity for the organic component of soils and sediments, and low mobility in these media. The chemical is not readily biodegradable, but when bound to, or otherwise associated with soils and sediments, it could be expected to be slowly degraded through the agency of biological and abiotic processes operative within landfills.The high log Pow (> 6), relatively low molecular weight (693 g/mol) and low water solubility (0.4 mg/L) indicate large potential for bioaccumulation (Connell, 1990).

Hydrolytic degradation of the compound was studied as a function of pH by incubating stoppered flasks containing (nominally) 0.25 mg/L in buffer solutions at pH 4, 7 and 9 for 5 days. The concentration of the compound in the solutions was determined using HPLC at various times over the 5 day (120 hour) test period. Very little degradation was observed in any of the buffers over the 5 day test period, with the maximum loss of 5% of initial concentration observed in the pH 9 buffer. These data indicate that the phosphate ester linkages within the molecules are stable to hydrolysis at 50°C. The small extent of observed degradation extrapolated to 25 °C indicates a half life of greater than 1 year at environmental pH 4-9.