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Description of key information

Toxicokinetic analysis of Sodium O, O-bis(ethyl) dithiophosphate (EP1-Na)


Summary


No toxicokinetic study for EP1-Na itself is available. However the toxicokinetic behaviour can be predicted based on the available physico-chemical data and in vitro and in vivo studies.


Based on physicochemical characteristics, particularly water solubility, octanol-water partition coefficient (logPOW), and vapour pressure, no or only limited absorption by the dermal and inhalation routes is expected for the salt EP1-Na. For the oral route, uptake will strongly depend on the pH value and is more likely for the acidic pH environment of the stomach in which the free acid might (if at all, based on the logPOW data) be formed. However, even for the oral route limited absorption is expected, as the predominant effects in acute or repeated dose toxicity tests are disturbances of the gastro-intestinal tract due to the corrosive properties of the substances causing local tissue damage at high concentrations (doses). These strong alkaline conditions are however needed and the product is manufactured so, to stabilise the substance in the water phase.


Data on hydrolysis (none observed at any pH) and findings in vitro and in vivo experiments indicate that the substance is stable under biological conditions and excreted without significant metabolic changes. This is in line with the fact that this type of dithioesters are known as prominent urine metabolites from organophosphate type plant protection products. If a metabolic conversion at all is taking place and considering data from similar dialkyldithioester structures, the following metabolites after ester cleavage and/or oxidative desulfurization (conversion of thio to oxo) can be expected: dithiophosphate, thiophosphate and phosphate, monoesters (with two, one or no thio being present), as well as the respective alcohol (ethanol).


For the substance itself as well as for the potential metabolites a fast distribution and excretion (mainly via urine) is expected. Ethanol might also be exhaled.


Based on the physico-chemical properties neither for EP1-Na nor for its even more polar and high water soluble cleavage products bioaccumulation is expected. Respective experimental data for the alcohol (ethanol) also show that this metabolite is not bioaccumulative.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

For the full toxicokinetic analysis of Sodium O,O-bis(ethyl) dithiophosphate (EP1-Na) refer to Point 13.2 Other assessment reports,Toxicokinetic analysis