Relation of DDT residues to plasma retinol, α-tocopherol, and β-carotene during pregnancy and malaria infection: A case–control study in Karen women in northern Thailand

Populations living in endemic malaria areas maybe exposed simultaneously to DDT and malaria infection. DDT may impair status of vitamins, which are implicated in the immunity and pathophysiology of malaria. To explore possible interactions, DDT residues, retinol, α-tocopherol, β-carotene and cholesterol were measured in plasma samples of malaria-infected pregnant women (cases, n = 50) and age matched malaria-free controls (n = 58). DDT residues were found in all samples: mean (sd) total DDT levels of 29.7 and 32.7 ng/ml in cases and controls, respectively. Mean (sd) p,p′-DDT was higher in the controls than the cases (13.5 vs. 9.5 ng/ml, p = 0.006). Malaria infection was associated with lower mean (sd) plasma retinol (0.69 vs. 1.23 μmol/L) and cholesterol (2.62 vs. 3.48 mmol/L) compared to controls (p < 0.001). Mean (sd) plasma α-tocopherol (7.65 vs. 15.58 μmol/L) and α-tocopherol / cholesterol ratio (2.3 vs. 6.7 μmol/L/mmol/L) were significantly lower among the controls (p < 0.001). Mean (sd) plasma β-carotene was low (< 0.3 μmol/L) in both groups, but higher among malaria cases (0.19 vs. 0.15 μmol/L).Plasma retinol among the controls showed highly significant positive correlations with individual DDT compounds, particularly with p,p′-DDT (r = 0.51, p < 0.001). Plasma α-tocopherol and β-carotene seemed not to be affected by DDT residues.