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[en] The leaf-air transfer of organochlorine pesticides (OCPs) in three kinds of vegetables, namely lettuce, romaine and garlic leaves was investigated. It was found that although the uptake of OCPs by the three selected vegetables was similar under controlled conditions, the depuration varied significantly among chemicals and plant species in terms of elimination rate, final residue of each OCPs, as well as the effect of temperature on the residue of OCPs in the vegetables. The results indicated that neither QCB nor HCB could be trapped tightly by any of the three selected vegetables, in contrast, p,p'-DDT could be retained effectively by all of them; the retainment of α-HCH, γ-HCH, p,p'-DDE, was dependent on the vegetable species, of which the garlic leaf had the biggest ability to trap them. Our work provided insight into the behavior of OCPs in the agroecosystem. - The leaf-air transfer of OCPs varied significantly among chemicals and the three selected vegetables
[en] The influence of moisture on persistence and degradation of 14C-DDT in a soil under 'cerrado' is studied under laboratory conditions. The persistence of DDT in the Dark Red Latosol medium texture after one year, in spite of a tendency to be more persistente at 1/3 field capacity and less persistent at higher levels of moisture, is related. (Author)
[pt]Estuda-se em condicoes de laboratorio, a influencia da umidade na persistencia e degradacao do DDT-14C em solo sob cerrado. Relata-se que o DDT ainda persistiu no latossolo Vermelho Escuro textura media apos um ano, a despeito da tendencia maior da persistencia a 1/3 da capacidade de campo e menor a niveis maiores de umidade. (Autor)
[en] The main objective of this study was to investigate possible temporal trends of persistent organic pollutants (POPs) and mercury in eggs of herring gulls (Larus argentatus), black-legged kittiwakes (Rissa tridactyla), common guillemots (Uria aalge) and Atlantic puffins (Fratercula arctica) in Northern Norway. Eggs were collected in 1983, 1993 and 2003. Egg concentrations of POPs (PCB congeners IUPAC numbers: CB-28, 74, 66, 101, 99, 110, 149, 118, 153, 105, 141, 138, 187, 128, 156, 157, 180, 170, 194, 206, HCB, α-HCH, β-HCH, γ-HCH, oxychlordane, trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT and p,p'-DDT) and mercury were quantified. Generally, POP levels decreased between 1983 and 2003 in all species. No significant temporal trend in mercury levels was found between 1983 and 2003. - POP levels decreased between 1983 and 2003 in seabird eggs from Northern Norway
[en] Concentrations of the pesticide DDT (dichlorodiphenyltrichloroethane) and its metabolite DDE (dichlorodiphenyldichloroethylene), in the blood of Mexican Americans, were evaluated to determine their relationships with diabetes and diabetic nephropathy. The data were derived from the National Health and Nutrition Examination Survey (NHANES) 1999–2004 (unweighted N = 1,411, population estimate = 13,760,609). The sample included teens, 12–19 years old, which accounted for 19.8% of the data. The time of the study overlapped the banning of DDT in Mexico in the year 2000, and those participants born in Mexico were exposed to DDT before they immigrated to the US. We sought to better understand the relationship of DDT with diabetes in a race/ethnicity group prone to develop diabetes and exposed to DDT. In this study, nephropathy was defined as urinary albumin to creatinine ratio >30 mg/g, representing microalbuminuria and macroalbuminuria, and total diabetes was defined as diagnosed and undiagnosed diabetes (glycohemoglobin, A1c ≥ 6.5%). The proportion with the isomer p,p′-DDT >0.086 ng/g (above the maximum limit of detection) was 13.3% for Mexican Americans born in the US, and 36.9% for those born in Mexico. Levels of p,p′-DDT >0.086 ng/g were associated with total diabetes with nephropathy (odds ratio = 4.42, 95% CI 2.23–8.76), and with total diabetes without nephropathy (odds ratio = 2.02, 95% CI 1.19–3.44). The third quartile of p,p′-DDE (2.99–7.67 ng/g) and the fourth quartile of p,p′-DDE (≥7.68 ng/g) were associated with diabetic nephropathy and had odds ratios of 5.32 (95% CI 1.05–26.87) and 14.95 (95% CI 2.96–75.48) compared to less than the median, respectively, whereas p,p′-DDE was not associated with total diabetes without nephropathy. The findings of this study differ from those of a prior investigation of the general adult US population in that there were more associations found with the Mexican Americans sample. - Highlights: • Persons born in Mexico were exposed to DDT before the year 2000. • p,p′-DDT and p,p′-DDE in blood differed by country of birth. • p,p′-DDT was associated with diabetic nephropathy among Mexican Americans. • p,p′-DDT was also associated with diabetes without nephropathy. • Relationships with p,p′-DDE may be due to a gene × environment interaction.
[en] In the present study, five soil samples with organic carbon contents ranging from 0.23% to 7.1% and aged with technical dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) for 15 months were incubated in a sealed chamber to investigate the dynamic changes of the OCP residues. The residues in the soils decreased over the incubation period and finally reached a plateau. Regression analysis showed that degradable fractions of OCPs were negatively correlated with soil organic carbon (SOC) except for α-HCH, while no correlation was found between degradation rate and SOC, which demonstrated that SOC content determines the OCP sequestration fraction in soil. Analysis of the ratio of DDT and its primary metabolites showed that, since it depends on differential sequestration among them, magnitude of (p,p'-DDE + p,p'-DDD)/p,p'-DDT is not a reliable criterion for the identification of new DDT sources. - Research highlights: → Soil organic carbon content determines the OCP sequestration fraction in soil. → Magnitude of (p,p'-DDE + p,p'-DDD)/p,p'-DDT is not a reliable criterion for the identification of new DDT sources. → The more hydrophobic compounds have relatively higher sequestration fractions in soils with SOC contents >2%. → DDD may have higher sorption by soil organic matter than DDE. - The effect of soil organic matter on the sequestration of organochlorine pesticides (HCHs and DDTs) in soils was investigated in an innovative microcosm chamber.
[en] In this study, the bioavailability of DDTr (sum of DDT, DDD and DDE isomers) in pesticide-contaminated soil was assessed using an in vivo mouse model. DDTr relative bioavailability (RBA) ranged from 18.7±0.9 (As35) to 60.8±7.8% (As36) indicating that a significant portion of soil-bound DDTr was not available for absorption following ingestion. When DDTr bioaccessibility was assessed using the organic Physiologically Based Extraction Test (org-PBET), the inclusion of a sorption sink (silicone cord) enhanced DDTr desorption by up to 20-fold (1.6–3.8% versus 18.9–56.3%) compared to DDTr partitioning into gastrointestinal fluid alone. Enhanced desorption occurred as a result of the silicone cord acting as a reservoir for solubilized DDTr to partition into, thereby creating a flux for further desorption until equilibrium was achieved. When the relationship between in vivo and in vitro data was assessed, a strong correlation was observed between the mouse bioassay and the org-PBET+silicone cord (slope=0.94, y-intercept=3.5, r2=0.72) suggesting that the in vitro approach may provide a robust surrogate measure for the prediction of DDTr RBA in contaminated soil. - Highlights: • An optimised mouse assay was used to quantify DDTr relative bioavailability in soil. • DDTr bioaccessibility was also determined using an in vitro sorption sink approach. • A strong correlation was observed between in vivo and in vitro data. • The sorption sink approach may be used to predict DDTr relative bioavailability.
[en] We investigated the association between diabetes and p,p′-DDT (dichlorodiphenyltrichloroethane) in blood of Mexican Americans who participated in the 1999–2004 National Health and Nutrition Examination Survey (NHANES). In this sample, p,p′-DDT were missing in 50% of subjects and we used multiple imputation (MI) to address the problem. Compared to ignoring the missing data, MI led to a more robust threshold for the p,p′-DDT reference category. Whereas previously p,p′-DDT ≤ 0.0860 ng/g was used as the reference category, using MI, we were able to use p,p′-DDT < 0.0574 ng/g as the reference category to study the association between p,p′-DDT and diabetes via logistic regression. In this analysis, p,p′-DDT ≥ 0.0750 ng/g was associated with an odds ratio of 1.99 (95% CI 1.09–3.61) for diabetes and 4.20 (95% CI 1.93–9.12) for diabetic nephropathy. The reference category for diabetes without nephropathy outcome stayed consistent after MI but our analysis confirmed that p,p′-DDT > 0.0860 ng/g was associated with diabetes without nephropathy with an odds ratio of 1.89 (95% CI 1.09–3.27). Our study showed that MI can be effectively used to deal with missing at random data in persistent organic pollutants measured in the 1999–2004 NHANES.
[en] The fate, dissipation and degradation of DDT in soil under tropical condition was studied in the field. The dissipation of DDT was characterized by a rapid decline during the first four weeks which then gradually slowed down with time. Extractable radioactivity decreased with time while bound activity increased. p,p-DDE was the major metabolite of DDT and DDD was formed only after 120 days from date of application. The half-life of DDT including its metabolic products in soil was 235 days. 14C-DDE dissipated with a half-life of 151 days which is comparable with half-life of 105 days for extracted DDT. Unchanged accounted for the bulk of the residues following DDE treatment in soil. In water, DDT declined rapidly compared to its dissipation in soil with a half-life of 31 days. Decline of DDT on wood surface was gradual with a half-life of 60 days. The result indicates that DDT and its metabolite DDE dissipate from Philippine soil at a rate faster than that reported from temperate countries. (author)