Detection Of DDT Research Articles

Catching flame retardants and pesticides in silicone wristbands: Evidence of exposure to current and legacy pollutants in Uruguayan children

Children are exposed to many potentially toxic compounds in their daily lives and are vulnerable to the harmful effects. To date, very few non-invasive methods are available to quantify children's exposure to environmental chemicals. Due to their ease of implementation, silicone wristbands have emerged as passive samplers to study personal environmental exposures and have the potential to greatly increase our knowledge of chemical exposures in vulnerable population groups. Nevertheless, there is a limited number of studies monitoring children's exposures via silicone wristbands. In this study, we implemented this sampling technique in ongoing research activities in Montevideo, Uruguay which aim to monitor chemical exposures in a cohort of elementary school children. The silicone wristbands were worn by 24 children for 7 days; they were quantitatively analyzed using gas chromatography with tandem mass spectrometry for 45 chemical pollutants, including polychlorinated biphenyls (PCBs), pesticides, polybrominated diphenyl ethers (PBDEs), organophosphorus flame retardants (OPFRs), and novel halogenated flame-retardant chemicals (NHFRs). All classes of chemicals, except NHFRs, were identified in the passive samplers. The average number of analytes detected in each wristband was 13 ±3. OPFRs were consistently the most abundant class of analytes detected. Median concentrations of ΣOPFRs, ΣPBDEs, ΣPCBs, and dichlorodiphenyltrichloroethane (DDT) and its metabolites (dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD)) were 1020, 3.00, 0.52 and 3.79 ng/g wristband, respectively. Two major findings result from this research; differences in trends of two OPFRs (TCPP and TDCPP) are observed between studies in Uruguay and the United States, and the detection of DDT, a chemical banned in several countries, suggests that children's exposure profiles in these settings may differ from other parts of the world. This was the first study to examine children's exposome in South America using silicone wristbands and clearly points to a need for further studies.

Detection of DDT and carbaryl pesticides in honey by means of immunosensors based on high fundamental frequency quartz crystal microbalance (HFF-QCM).

In recent years there has been a concern about the presence of pesticides in honey because residues of DDT and carbaryl were found in honey samples. Traditional techniques, such as chromatography, reach the required limits of detection (LOD) but are not suitable for in situ implementation in the honey-packaging industry due to their high cost and the need for highly qualified staff for routine operation. Biosensors offer simplicity, low cost, and easy handling for analytical purposes in food applications. Piezoelectric immunosensors based on high fundamental frequency quartz crystal microbalance (HFF-QCM) have been developed for the detection of carbaryl and DDT in honey. Biorecognition was based on competitive immunoassays in the conjugate-coated format, using monoclonal antibodies as specific immunoreagents. The assay LODs attained by the HFF-QCM immunosensors were 0.05 μg L-1 for carbaryl and 0.24 μg L-1 for DDT, reaching a similar level of detectability to that of the usual reference techniques. The practical LODs in honey samples were 8 μg kg-1 for carbaryl and 24 μg kg-1 for DDT. The immunosensors' analytical performance allow the detection of these pesticides in honey at EU regulatory levels with good accuracy (recovery percentages ranging from 94% to 130% within the working range of each pesticide standard curve) and precision (coefficients of variation in the 9-36% range). The proposed immunosensor is a promising analytical tool that could be implemented for quality control in the honey packaging industry, to simplify and to reduce the cost of the routine pesticide analysis in this appreciated natural food. © 2020 Society of Chemical Industry.

Integrating bioavailability and soil aging in the derivation of DDT criteria for agricultural soils using crop species sensitivity distributions

Although the agricultural use of dichlorodiphenyltrichloroethane (DDT) has been banned for decades in many countries around the world, the detection of DDT and its metabolites in soils is very common due to their persistence. DDTs (sum of DDT and its metabolites) in farmland soils can be absorbed by crops at different levels and accumulate in the edible parts of agricultural products, posing threats to the health of human being. However, no information on the species sensitivity distribution (SSD) of crops with regard to DDTs has been reported due to the lack of enough bioavailability data and models to normalize the bioavailability data from different sources. Based on the bioconcentration factors of 17 crop species in Chinese soils obtained from previous studies, the criteria of DDTs in soils was derived according to the quality standard of agricultural products using the SSD method. Corrections for water content and aging time were conducted to normalize the data from different sources. The risk values of agricultural products at different concentration levels of DDTs in soils were also evaluated. It was found that oil crops are able to take up more DDTs than non-oil crops, so the soil criteria were calculated separately for oil crops and non-oil crops, which were 0.083 mg/kg and 0.29 mg/kg, respectively. With the residual concentrations of DDTs in soils at the range of 0.01–0.5 mg/kg, 0–8% of the agricultural products exceeded the permissible limits for DDTs which were set in the National Food Safety Standard of China. The results also demonstrated the feasibility for applying SSDs to derive the soil criteria of DDTs in order to ensure the safety of agricultural products. This work will provide information for the risk assessment and the establishment of soil environmental quality standards to ensure safe agricultural production.

An analytical device for on-sight immunoassay: demonstration of its applicability in detection of DDT in food samples

A simple analytical device was developed for performing non-instrumental immunoassay. The device consists of membrane with antibody-coated zones and filter pad acting as an absorbent body. Very low concentrations of DDT in food samples were estimated by using an improved catalysed reporter deposition I-CARD method. The signal amplification involved biotinylated tyramine and avidin–alkaline phosphatase (ALP) conjugate. 5-Bromo-4-chloro-3-indolyl-phosphate in conjunction with nitro blue tetrazolium was used for colour visualisation. Semi-quantitative results were obtained by visual comparison of the colour intensity of the sample spot with those of reference standards. Quantitative estimation is possible by densitometry using CCD camera. A batch of five extracted samples could be analysed in a single kit within 30 minutes. Spiked samples were analysed without sample cleanup. The possible matrix interference was analysed. The results were comparable with gas chromatography and CCD analyses. The method is well suited for visual screening of food samples for DDT under field conditions.

Detection of DDT and its metabolites in two estuaries of South China using a SPME-based device: First report of p, p′-DDMU in water column

A solid-phase microextration-based sampling method was employed to determine the concentrations of 1,1,1-trichloro-2,2- bis( p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dichloro-2,2- bis( p-chlorophenyl)ethane (DDD), 1,1-dichloro-2,2- bis( p-chlorophenyl)ethene (DDE) and 1-chloro-2,2- bis( p-chlorophenyl)ethene (DDMU), in two estuarine bays, Daya Bay and Hailing Bay, of South China. Six DDT components including p, p′-DDT, o, p′-DDD, p, p′-DDD, o, p′-DDE, p, p′-DDE, and p, p′-DDMU were detected in Hailing Bay, while only p, p′-DDD was found in Daya Bay. p, p′-DDD was the most abundant DDT component in both bays, sharply different from the previous finding in the water column of the Palos Verdes Shelf, California, USA that p, p′-DDE was prevalent. In addition, the occurrence of p, p′-DDMU (with a range of 0.047–0.21 ng/L in Hailing Bay) has not been reported around the globe, and its presence in our study region appeared to stem from dehydrochlorination of p, p′-DDD, favored under aerobic conditions, but further investigations are clearly needed to confirm the mechanism for generation of DDMU in estuarine environments.

Development of enzyme immunoassay for detection of DDT

Dichlorodiphenyltrichloroethane (DDT) is one of the persistent organic pollutants (POPs) widely found in the environment and in the general population. In this study, a direct competitive enzyme immunoassay (EIA) has been developed for the quantitative analysis of DDT. To generate a specific polyclonal antibody for EIA, p, p′-DDT was conjugated to porcine thyroglobulin for rabbit immunization. At optimized EIA conditions, the standard curves ranged from 0.137 to 100 ng/mL with the quantification limit of 0.41 ng/mL. The coefficients of variation (CV%) were 5.42–10.53% for intra-assay and 6.04–7.26% for inter-assay. Cross-reactivities with DDT metabolites (DDTs, including o, p′-DDT, p, p′-DDD, o, p′-DDD, p, p′-DDE, o, p′-DDE, p, p′-dichlorobenzophenone (DCBP), o, p′-DCBP) were investigated. The polyclonal antibody showed relatively low and/or no cross-reactivity with these compounds, and the assay was seen to be highly selective for p, p′-DDT. Moreover, the DDTs could be ranked by their reactivity: DDT > DDD > DDE > DCBP. In addition, the characterization of the polyclonal antibody indicated that the antiserum possesses a high specificity for p, p′-isomers. The results indicated that the developed EIA using this antibody could be a convenient and supplemental analytical tool for monitoring DDT.

Distribution of DDTs in the Sediment of Lake Biwa

An investigation was carried out to determine the residual tendency of DDT and its derivatives in the sediment of Lake Biwa, Japan, where the banning of DDT took effect some 15 years ago. Of the two basins shaping Lake Biwa, the frequency of detection of DDT was higher in the Northern Basin than in the Southern Basin. In the Southern Basin, the area of DDT detection was more confined than that of DDE detection. Therefore, it is reasonable to assume that DDT has been decomposing more rapidly in the Southern Basin than in the Northern Basin. Based on the profile obtained for the vertical distribution of DDTs, it can be inferred also that the amount of DDT and DDE flowing in from land has been decreasing in the past years. DDT has hardly been decomposing into DDE at the deeper part of the Lake.