DDD), And Dichlorodiphenyldichloroethylene Research Articles

Dichlorodiphenyltrichloroethane (DDT) degradation by Streptomyces sp. isolated from DDT contaminated soil

Bioaccumulation, toxicity and long-range transport of persistent organic pollutants (POPs) is a threat to soil and other ecosystems, therefore removal of such pollutants from soil is required. This study thus aimed to isolate and identify bacteria capable of biodegrading a persistent organic pollutant; dichlorodiphenyltrichloroethane (DDT) from a former DDT production unit. The soil was sampled, transported to Japan through standard protocols and bacteria were isolated and assayed for dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) degradation. The concentration of DDTs in a composite soil sample was 0.7 mg kg−1. Twenty-four bacterial strains were isolated from DDT-contaminated soil, and one of them, strain 885, showed degradation of DDT but could not degrade DDE after 14 days of incubation. This strain also showed significant degradation of 15.6 µM DDD (degradation rate 55.9%) after 28 days incubation. Further metabolites of DDT including 2,2-bis(p-chlorophenyl) ethanol (DDOH) and 4,4-dichlorobenzophenone (DBP) were detected from a 14-day incubation culture with DDD as initial substrate. Strain 885 also showed degradation of metabolites of DDT including those of DDOH, and DBP. In conclusion, strain 885 successfully degraded DDT; therefore, it can be used for remediation of DDT-contaminated soil.

Distribution and sources of DDT and its metabolites in porewater and sediment from a typical tropical bay in the South China Sea

Dichlorodiphenyltrichloroethane (DDT) is well known for its harmful effects and has been banned around the world. However, DDT is still frequently detected in natural environments, particularly in aquaculture and harbor sediments. In this study, 15 surface sediment samples were collected from a typical tropical bay (Zhanjiang Bay) in the South China Sea, and the levels of DDT and its metabolites in sediment and porewater samples were investigated. The results showed that concentrations of DDXs (i.e., DDT and its metabolites) in bulk sediments were 1.58–51.0 ng g−1 (mean, 11.5 ng g−1). DDTs (DDT and its primary metabolites, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE)) were the most prominent, accounting for 73.2%–98.3% (86.1% ± 12.8%) of the DDXs. Additionally, high-order metabolites (i.e., 1-chloro-2,2-bis(4′-chlorophenyl)ethylene (p,p′-DDMU), 2,2-bis(p-chlorophenyl)ethylene (p,p′-DDNU), 2,2-bis(p-chlorophenyl)ethanol (p,p′-DDOH), 2,2-bis(p-chlorophenyl)methane (p,p′-DDM), and 4,4′-dichlorobenzophenone (p,p′-DBP)) were also detected in most of the sediment and porewater samples, with DDMU and DBP being predominant. The DDTs concentration differed among the sampling sites, with relatively high DDTs concentrations in the samples from the aquaculture zone and an area near the shipping channel and the Haibin shipyard. The DDD/DDE ratios indicated a reductive dichlorination of DDT to DDD under anaerobic conditions at most of the sampling sites of Zhanjiang Bay. The possible DDT degradation pathway in the surface sediments of Zhanjiang Bay was p,p′-DDT/p,p′-DDD(p,p′-DDE)/p,p′-DDMU/p,p′-DDNU/ … /p,p′-DBP. The DDXs in the sediments of Zhanjiang Bay were mainly introduced via mixed sources of industrial DDT and dicofol, including fresh input and historical residue. The concentrations of DDXs in porewater samples varied from 66.3 to 250 ng L−1, exhibiting a distribution similar to that in the accompanying sediments. However, the content of high-order metabolites was relatively lower in porewater than in sediment, indicating that high-order degradation mainly occurs in particles. Overall, this study helps in understanding the distribution, source, and degradation of DDT in a typical tropical bay.

Selenium status in lactating mothers-infants and its potential protective role against the neurotoxicity of methylmercury, lead, manganese, and DDT

A total of 206 lactating mothers and their infants (3-12 months) were included in this study to evaluate postnatal exposure to neurotoxic pollutants such as methylmercury (MeHg), lead (Pb), manganese (Mn), dichlorodiphenyltrichloroethane (DDT) and its metabolites [dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE)] and their association with delayed neurological development and to explore the protective role of selenium (Se) against chemical neurotoxicity. Neurodevelopmental performance was evaluated using Denver Developmental Screening Test II and Parents' Evaluation of Developmental Status (PEDS). Multivariate log-binomial regression modeling was applied for both single and multiple exposures to chemicals using a principal component analysis that generated six principal components. Both mothers and their infants had been exposed to metals and DDT metabolites, with some exceeding the accepted permissible limits. The geometric means of MeHg, Pb, Mn, DDD, DDE and DDT levels in breast milk were 1.333, 45.327, 15.576, 0.069, 0.542 and 1.08 μg/l, respectively. A single-exposure model identified a high risk of reduced PEDS performance significantly associated with DDD in breast milk [relative risk (RR) = 1.484; 95% confidence interval (95%CI) = 1.091-2.019] and marginally significantly associated with Pb in the mothers' blood (RR = 2.164; 95%CI = 0.87-5.382). We did not find a protective role of Se in neurodevelopment due to its high levels in the mothers. Models of multi-chemical exposure indicated that Mn in blood and breast milk, Se in blood and Pb in the mothers' urine were marginally significantly associated with a high risk of reduced PEDS performance (RR = 0.424; 95%CI = 0.176-1.022). The use of multi-chemical exposure approach in early life risk assessments is important because it indicates real-world exposure. Our results were not conclusive because the sample size was small, so future studies examining the implications to health of the impact of prenatal/postnatal exposure to a mixture of chemicals in the Saudi population are merited.

DDT, DDD, and DDE in soil of Xiangfen County, China: Residues, sources, spatial distribution, and health risks

We collected and analyzed 128 surface soil samples from Xiangfen County for dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE). Total DDT concentrations (DDTs; sum of p,p′-DDD, p,p′-DDE, and p,p′-DDT) ranged from ND to 427.81 ng g−1 (dry weight, dw), with a mean of 40.26 ng g−1 (dw). Among the three compounds, p,p′-DDD was the most dominant. The DDTs in Xiangfen County soils mainly originated from historical DDT use, but there were also new inputs likely related to dicofol use. The DDTs in Xiangfen County soils were mainly degraded under anaerobic conditions, and direct degradation to DDD was the main degradation route. Regions with relatively high concentrations of DDTs were mainly located in North and South Xiangfen County. In these regions, many soil samples contained p,p′-DDT as the predominant pollutant, suggestive of extensive new inputs of DDT. A health risk assessment revealed that there are no serious long-term health impacts of exposure to DDTs in soil, for adults or children.

Bioaccumulation of HCHs and DDTs in organs of Pacific salmon (genus Oncorhynchus) from the Sea of Okhotsk and the Bering Sea

Concentrations of isomers of hexachlorocyclohexane (α-, β-, γ-HCH) and dichlorodiphenyltrichloroethane (DDT) and its metabolites (dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) were assessed in organs of the pink (Oncorhynchus gorbuscha), chum (Oncorhynchus keta), chinook (Oncorhynchus tshawytscha), and sockeye salmon (Oncorhynchus nerka), caught near the Kuril Islands (the northern-western part of the Pacific Ocean), in the Sea of Okhotsk and the Bering Sea. Pesticides have been found to accumulate in fish organs in the following: muscles < liver < eggs < male gonads. The highest concentrations in muscles and liver have been recorded from sockeye. Of the DDT group, only DDE has been detected. The average concentration of HCHs + DDE in the muscles of pink, chum, chinook, and sockeye was 141, 125, 1241, 1641 ng/g lipids, respectively; and in the liver, 279, 183, 1305, 3805 ng/g lipids, respectively. The total concentration of HCHs isomers was higher than that of DDE. Average HCHs + DDE concentration in organs of salmon from study area is lower than that in salmon from Pacific coast of North America.

The Kuril Islands as a Potential Region for Aquaculture: Organochlorine Pesticides in Pink and Chum Salmon

The Kuril Islands region is considered promising for development of salmon aquaculture. There are 41 salmon fish hatcheries in the Sakhalin Island and the Kuril Islands, 38 of them are hatcheries of the pink and chum. Food safety of products is an important task of aquaculture. Therefore, concentrations of isomers of hexachlorocyclohexane (α-, β-, γ-HCH) and dichlorodiphenyltrichloroethane (DDT) and its metabolites (dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) were determined in pink and chum salmon were caught in this region. The contents of toxic substances don’t exceed the maximum permissible concentrations (MPC) according to the Russian sanitary standards. The average total concentration of pesticides in organs of salmon from the Kuril Islands is lower than that in salmon from the North Pacific American coast and the Atlantic Ocean. The region can be used to grow smolts, which will be later released into the ocean.

Organochlorine pesticide levels in maternal blood and placental tissue with reference to preterm birth: a recent trend in North Indian population.

Organochlorine pesticides (OCPs) have been widely used in public health and agriculture programs in developed as well as developing countries, including India. Being xenoestrogenic in nature, OCPs may act as endocrine disruptors leading to preterm birth (PTB) through disturbance of normal estrogen-progesterone ratio. PTB is the leading cause of neonatal deaths worldwide. Therefore, the present study is aimed to determine the extent to which persistent environmental chemicals may accumulate in pregnant women and placenta and ascertain possible associations between exposure level and period of gestation (POG), baby weight, and/or placental weight in PTB cases. Maternal blood and placenta samples of PTB cases (n = 50) and subjects of term delivery as controls (n = 50) were collected. OCP residue levels were estimated by the gas chromatography system equipped with an electron capture detector. Significantly higher levels of α-hexachlorocyclohexane (α-HCH), β-hexachlorocyclohexane (β-HCH), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE) were found in maternal blood of PTB cases as compared to control. Significantly higher levels of DDE and dichlorodiphenyltrichloroethane (DDT) were also found in placental tissue of PTB cases as compared to control group. There was a statistically significant negative correlation between maternal blood level of α-HCH and birth-weight (r = -0.299) and POG (r = -0.234). γ-Hexachlorocyclohexane (γ-HCH) and dieldrin had a negative correlation with placental weight (r = -0.401 and -0.256, respectively), and DDE and β-HCH had a negative correlation with POG (r = -0.251 and -0.229, respectively). The presence of OCPs in maternal blood and placental tissue represents prenatal exposure hazard for fetuses due to chronic bioaccumulation and poor elimination with possible deleterious effect on health.

Influence of Hydroxypropyl-β-cyclodextrin on the Extraction and Biodegradation of p,p′-DDT, o,p′-DDT, p,p′-DDD, and p,p′-DDE in Soils

Dichlorodiphenyltrichloroethane (DDT) is one of the persistent organic pollutants (POPs) that are highly toxic to the environment. Effective evalu- ation on the bioavailability of DDTs in soils is essen- tial for risk assessment and soil remediation. The aims of this study were to verify the feasibility of the hydroxypropyl-β-cyclodextrin (HPCD) extraction method for predicting the bioavailability of DDT, dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE) in soils, and to examine the effect of HPCD on their biodeg- radation in different soils. Four soils were aged with a mixture of p,p'-DDT, o,p'-DDT, p,p'-DDD and p,p'- DDE (0.25 μ gg −1 for each compound) for 20 and 100 days, respectively. For each of the DDTs, a sig- nificant positive correlation between HPCD- extractable fraction and biodegradable fraction in each soil was observed. It was demonstrated that the amounts of HPCD-extractable p,p'-DDT and o,p'- DDT were not significantly different from the amounts that were degradable as assessed from their degradation by Enterobacter sp. LY402 (p>0.05). Such 1:1 relationship between extraction and degra- dation was not obtained in the cases of p,p'-DDD and p,p'-DDE, as the amounts of degradable p,p'-DDD and p,p'-DDE were lower than the amounts that were extractable with HPCD. Additionally, the biodegra- dation of p,p'-DDT, o,p'-DDT, p,p'-DDD, and p,p'- DDE was inhibited in the presence of HPCD, which could be due to the binding of the compounds to HPCD, making them less available to access the bac- teria for degradation. This study provides the possi- bility of using the HPCD extraction method to predict the bioavailability of p,p'-DDTand o,p'-DDTin soils. But when HPCD was used as an additive in the bioremediation of DDT-contaminated soils, it might have a negative effect on biodegradation.

Sample Preparation Method for the Determination of Organochlorine Pesticides in Aquatic Organisms by Gas Chromatography

Sample preparation can be used in biology and ecology for gas chromatographic determination of organochlorine pesticides (OCP), namely, α-, β- and γ-isomers of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) in various aquatic organisms (molluscs, fish, birds and mammals) containing lipids (because organochlorine pesticides are lipophilic) in the internal organs and tissues, fat, skin and feather cover. The method is easy to implement and economically profitable; it can be used in laboratories without special extraction equipment, as well as in the field, with a minimum set of glassware and reagents. The result of this process is an increase of efficiency and precision of research through a more complete extraction of pesticides chemically bonded with lipids using n-hexane and a reduction of the number of steps needed for the extraction and purification of co-extrusive substances with concentrated sulphuric acid.

Persistent toxic substances in the muscles and liver of the pacific walrus Odobenus rosmarus divergens Illiger, 1815 from the Bering Sea

This study reports data on the contents of organochlorine pesticides and heavy metals in the muscles and livers of eight individuals (five males and three females) of the Pacific walrus Odobenus rosmarus divergens Illiger, 1815, which were captured in the summer of 2011 in Mechigmensky Bay of the Bering Sea. Pesticides, namely α-, β-, and γ-isomers of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), as well as the heavy metals Cd, Pb, and Hg were found in all samples studied. The total concentration of organochlorine pesticides in the muscles varied from 200 to 5700 ng/g lipid weight and in the liver from 4900 to 90300 ng/g lipid weight. The concentrations of cadmium, lead, and mercury were 0.04–6.7, 0.13–0.76, and 0.03–0.40 μg/g dry weight, respectively. On the whole, the contents of organochlorine pesticides and heavy metals in the organs of the Pacific walrus were lower compared to those in marine mammals from other regions of the World Ocean.

Effects of skin removal on contaminant levels in salmon and trout filets

Skin removal is a generally accepted method to reduce exposure to contaminants through fish consumption. However, inconsistent results from studies on the effectiveness of this method suggest influence of other factors such as characteristics of contaminants and fish species. This study investigated the effects of skin removal on the lipid contents and concentrations of total mercury, α-chlordane, hexachlorobenzene, mirex, octachlorosytrene, polychlorinated biphenyls (PCB), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE). Four fish species namely brown trout (Salmo trutta), Chinook salmon (Oncorhynchus tschawytscha), coho salmon (Oncorhynchus kisutch) and rainbow trout (Oncorhynchus mykiss) sampled from the Credit River, Ontario, Canada were considered. Concentrations of all the lipophilic organic contaminants decreased significantly (median 17–37%) after removing skins from filets of brown trout, Chinook salmon and coho salmon, but not of rainbow trout. In contrast, the concentrations of mercury tended to be either similar or marginally higher after removing skins from filets of all four species; however, the amount of mercury would have likely declined or remained unchanged. Overall, removal of skin before consuming a fish filet is recommended to reduce exposure to contaminants widely found in Ontario fish.

Occurrence and profiles of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in soils from a typical e-waste recycling area in Southeast China

Surface soils collected from Taizhou, a typical e-waste recycling area in Southeast China, were analyzed for the residues of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) by using microwave-assisted extraction and gas chromatography -mass spectrometry (GC-MS). The total concentrations of 16 PAHs in US EPA's priority list (ΣPAHs), six indicator PCBs (ΣPCBs), 15 OCPs widely used in China (ΣOCPs) in soils ranged from 125 to 4737 ng/g (average: 854 ng/g), from not detected to 55.4 ng/g (3.16 ng/g), and from 47.9 to 820 ng/g (276 ng/g), respectively. Individual PAHs were ubiquitously found in soil samples with detected ratio of 96% and their residual levels were comparable with those of serious polluted sites. Principal component analysis in combination with diagnostic ratios suggested that the combustion of coal, wood, and plastic wastes that are closely associated with illegal and unsafe recycling operations of e-wastes was the main source of PAHs in this area. Compared with other polluted sites, the PCBs residues in soils were generally low except for those in the major recycling site. The residual levels of OCPs in this region were also relatively higher and hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolite forms including dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), and dicofol were dominant species. The composition analysis indicated that the HCHs residues in soils might originate from the application of lindane (pure γ-HCH) and parts of DDTs possibly from the wide use of dicofol with high impurity of DDT compounds in this region.

Input pathways of organochlorine pesticides to typical freshwater cultured fish ponds of South China: Hints for pollution control

Air, rain, pond water, bank soil, pond sediment, fish feed, and fish were sampled from four freshwater cultured fish ponds (FWCFPs) in rural areas within the Pearl River Delta (PRD) of South China. Compositional analyses indicated that historical residues were the main sources of DDXs (defined as the sum of dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE) and 1-chloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDMU)), and hexachlorocyclohexanes (HCHs) in the FWCFPs. The input fluxes to the FWCFPs were estimated at 4.0, 1.6, 15, and -0.92 µg/m(2) ·year for DDXs and 3.8, 0.92, 2.9, and -1.4 µg/m(2) ·year for HCHs for dry deposition, wet deposition, feeding, and net air-water exchange in Dongguan, and 3.8, 1.2, 137, and -1.2 µg/m(2) ·year for DDXs and 3.6, 0.66, 5.0, and -1.0 µg/m(2) ·year for HCHs in Shunde, respectively. These results indicated that fish feed was the dominant input source of DDXs to the FWCFPs. As for HCHs, fluxes via dry deposition and feeding were similar and slightly higher than those via wet deposition. Biological effects due to the occurrence of DDXs in the FWCFPs were minimal, and consumption of freshwater fish from the PRD appeared to pose insignificant risk to human health based on some existing regulations and guidelines.

Chemical and geochemical characterisation of a disused red brick factory area of central Italy

Characterisation and remedial actions are proposed for a polluted site enclosed within a red brick factory, located in central Italy. Approximately 22,000 t of chromium containing tannery sludge were introduced as ‘secondary raw materials’ for reuse in red brick manufacture. Preliminary geo-electric tomography was carried out on the waste bank, followed by the perforation of 14 boreholes into the bottom geological stratum. Heavy metals [B, Crtot, Cr(VI), Hg, Pb, Cu, Sn, V, Zn] and polycyclic aromatic hydrocarbons [benzo(a)pyrene; phenanthrene; dibenzo(a,h)pyrene; pyrene] were determined on solid samples. Carrots were sliced to give samples from different depths in the waste bank. The following samples were determined in the waste leachate: 1,1,2trichlorethane, phenol, 2,4,6trichlorphenol, hexachlorhexane, dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE). During characterisation, laboratory experiments were also carried out on lime-treated and untreated carrot sections to evaluate heavy metal release and potential migration in the subsoil. Pollutant exposure pathways were set up, based on application of the Risk-Based Corrective Action (RBCA) model, followed by the evaluation of potential environmental and sanitary targets for site-specific risk evaluation and the proposition of scientifically based restoration scenarios. Surface capping, coupled with lateral belting of the site, were selected for the site recovery operations after extensive cost–benefit evaluations.

Characterization of a bacterial strain capable of degrading DDT congeners and its use in bioremediation of contaminated soil

A bacterial strain DDT-6 (D6) capable of utilizing dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE) (DDTs) as its sole carbon and energy source was isolated and identified as Sphingobacterium sp. The degradation of DDTs by strain D6 in mineral salt medium and in field soil was investigated. The half-lives of the degradation of DDTs increased with increasing concentration ranging from 1 to 50mgL−1. Favorable degradation conditions for DDTs by strain D6 were found to be pH 7.0 and 30°C. The degradation of DDTs by strain D6 was found to be statistically significantly enhanced (p≤0.05) by the addition of glucose. Based on the metabolites detected, a pathway was proposed for DDT degradation in which it undergoes dechlorination, hydrogenation, dioxygenation, decarboxylation, hydroxylation, and phenyl ring-cleavage reactions to complete the mineralization process. The addition of strain D6 into the contaminated soils was found to statistically significantly enhance (p≤0.05) the degradation of DDTs. The results indicate that the isolate D6 can be used successfully for the removal or detoxification of residues of DDTs in contaminated soil.

Uptake and depuration of nonionic organic contaminants from sediment by the oligochaete, Lumbriculus variegatus

Uptake of sediment-associated contaminants by the oligochaete Lumbriculus variegatus was evaluated after 1, 3, 7, 14, 28, and 56 d of exposure to a field-collected sediment contaminated with DDT and its metabolites, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), or to a field-collected sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Depuration of contaminants by oligochaetes in a control sediment or in water was also evaluated over a 7-d period after 28 d of exposure to the field-collected sediments. Accumulation of PAHs with a log octanol-water partitioning coefficient (log Kow) <5.6 typically reached a peak at day 3, followed by a lower plateau between days 7 and 56 of the sediment exposure. Similarly, 4,4'-DDT exhibited a peak in accumulation at day 14 followed by a decline at days 28 and 56. In contrast, accumulation of PAHs with a log Kow >5.6 or DDD and DDE typically exhibited a steady increase from day 1 to about day 14 or 28, followed by a plateau. Therefore, exposures conducted for a minimum of 14 to 28 d better reflected steady-state concentrations for DDT and its metabolites and for PAHs. Depuration rates for DDT and its metabolites and high-Kow PAHs were much higher in organisms held in clean sediment relative to both water-only depuration and model predictions. This suggests that depuration in clean sediment may artificially accelerate depuration of hydrophobic compounds. Comparisons between laboratory-exposed L. variegatus and oligochaetes collected in the field from these sediments indicate that results of laboratory tests can be extrapolated to the field with a reasonable degree of certainty.