New DDT inputs after 30 years of prohibition in Spain. A case study in agricultural soils from south-western Spain

This study provides information on the current status of contamination by DDT in agricultural soils in south-western Spain. A recent use of technical DDT in at least 17% of the soils was found based on the values (<1) of the ratio Rp,p′/p,p′=[p,p′-DDE+p,p′-DDD]/[p,p′-DDT]Rp,p′/p,p′=[p,p′-DDE+p,p′-DDD]/[p,p′-DDT]. According to the ratio Ro,p′/p,p′=[o,p′-DDT]/[p,p′-DDT]Ro,p′/p,p′=[o,p′-DDT]/[p,p′-DDT], a dicofol type contamination was detected in about 27% of the soils. A wide range of concentrations was observed (0.08–11.1 ng/g d.w.) regardless of the type of crop soil. Enantiomeric fractions (EFs), based on the chiral analysis of o,p  ′-DDT residues differed from the racemic value (0.500) in most soils but they were not correlated with the study variables [DDTs], SOM, Rp,p′/p,p′Rp,p′/p,p′ and Ro,p′/p,p′Ro,p′/p,p′. Given the health risks posed by DDT, our findings support how the environmental control of legacy pollutants such as DDT cannot be neglected.

► Fresh technical DDT inputs detected in agricultural soils. ► A Dicofol type contamination was found in agricultural soils from south-western Spain. ► EFs of o,p′-DDT do not provide a good measure for overall DDT degradation.