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Environmental fate & pathways

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DTDP has been shown to biodegrade to a high extent in an extended ready biodegradation test using a standard OECD test guideline and is expected to be inherently biodegradable. The principle transformation products (such as mono-isotridecyl phthalate) are likely to be biodegradable. 

DTDP has also demonstrated a moderate extent of biodegradability in a simulation test using river water, and moderate degree of removal in a wastewater treatability test based on a DT50of <1 day. These data are consistent with modelled data that suggest DTDP will be largely eliminated in a STP. 

Studies were not available to assess the biodegradability of DTDP in sediment. However, the monoester of DIDP (mono-isodecyl phthalate) demonstrated an average half-life of 25 hours in marine sediments. Because the formation of the monoester occurs as the first step in the biotic degradation of DIDP and because this step does not appear to be rate limiting, as evidenced by the high extent of biodegradation demonstrated by DIDP in a ready test, the degradation of the diester in sediment is expected to occur at a similar high rate. Because Di-isodecyl phthalate ester (DIDP) is an analog to DTDP, DTDP is expected to biodegrade in sediment at approximately the same rate as was exhibited by DIDP.

Studies are not available to assess the biodegradability of DTDP in soil. However, data for an earthworm toxicity test suggest DINP, an analog to DTDP, would have a half-life in soil of approximately 51 days. Based on the extent of biodegradability measured using various test procedures, DTDP and its degradation products are expected to biodegrade at a moderate rate under simulated conditions and in sediment and soil.