Fate of bis(2-ethylhexyl) [14C]phthalate in laboratory and outdoor soil-plant systems

Fate and degradation of bis(2-ethylhexyl) [carooxyl-14C]phthalate ([14C]DEHP) were studied in various soil and soil-plant systems. In suspended soil, degradation rates to 14CO2 were 9.5% after 9 days at room temperature under aerobic conditions; in a closed aerated laboratory soil-barley system, they were 8.2% after 7 days. In a lysimeter under outdoor conditions, total recovery of radioactivity in soil was 6.9%, in potatoes 0.11%, and in leached water 0.51% after one growing period. After two growing periods, recovery in soil was 1.7%, in barley 0.005%, and in leachate 0.01%. The radioactivity in the top soil layer (0-20-cm depth), after one growing period, consisted of DEHP (3% of applied 14C), mono(2-ethylhexyl) phthalate (0.14%), phthalic acid (0.35%), unidentified soluble metabolites (1.29%), and unextractable residues (1.84%). Uptake by plants was low; most of the radioactivity absorbed was very polar or unextractable.