Detection of health hazard insecticide dichlorodiphenyltrichloroethane (DDT) in some common marine dry fish samples from Bangladesh

Objectives: The general purpose of this study is to detection and determination of the concentration level of dichlorodiphenyltrichloroethane (DDT) in some commercially available marine dry fishes and to investigate the contamination status of dichlorodiphenyltrichloroethane (DDT) of these dry fishes. Methods: Samples were collected from six largest dry fish markets (three from Chittagong district and three from Cox’s Bazar district) and four types of dry fishes were taken in this study are Ribbon fish (Lepturacanthus savala), Sin Croaker (Johnius dussumieri), Bombay duck (Harpodon nehereus) and Shrimp (mixed species). Total numbers of samples were 24 that were analyzed in the laboratory. Results: The results of the study show that the mean concentrations of dichlorodiphenyltrichloroethane (DDT) in the samples of Ribbon fish, Bombay duck and Sin croaker were ranged between 130.85 - 153.47ppb, 125.21 - 181.4ppb and 119.86 – 208.65ppb respectively. The mean concentrations of dichlorodiphenyltrichloroethane (DDT) were found at a lower amount in shrimp sp. than the other. Conclusions: This result indicates that the concentration of dichlorodiphenyltrichloroethane (DDT) in dry fish samples from Bangladesh are higher and may causes chronic disease and potential long-term risk for human health.

Distribution and health risk assessment of organochlorine pesticides(OCPs) in industrial site soils:A case study of urban renewal in Beijing,China

A field survey was conducted in a contaminated industrial site of southern Beijing, China to investigate the contents and distribution of the organochlorine pesticides （α-, β-, y-, δ-HCH, p,p＇-DDT, p,p＇-DDE, p,p＇-DDD and o,p＇-DDT） in the profiles of soil, and a health risk assessment was carded out with CalTOX multimedia exposure model. Results showed that mean concentrations of total hexachlorocyclohexane isomers （HCHs） and total dichlorodiphenyltrichloroethane isomers （DDXs） in soils were in the range of 13.20- 148.71 mg/kg, and 3.02-67.43 mg/kg, respectively. Organochlorine pesticides （OCPs） content peaked in the surface and declined in soil profile with depth. The amounts of HCHs in three profiles of soil were larger than DDXs. Composition analysis indicated that there was a trend of degradation of OCPs in the site, but the mean of HCHs and DDXs concentration were over the state warning standard limit （HCHs, 0.50 mg/kg; DDXs, 0.50 mg/kg）. According to current land use development, health risk assessment with CalTOX and Monte Carlo analysis showed that health risks mainly came from two exposure pathways： dermal uptake and inhalation, and the total risk values all exceeded the general acceptable health risk value （10-6）. The sensitivity analysis indicated that five parameters significantly contributed to total risk.

Chlorobenzenes and organochlorinated pesticides in vegetable soils from an industrial site, China

Organochlorinated compounds are ubiquitous contaminants in the environment, especially in industrial sites. The objective of the work was to investigate whether a vegetable field near an industrial site is safe for vegetable production. The residues of chlorobenzenes （CBs）, hexachlorocyclohexanes （HCHs） and dichlorodiphenyltrichloroethanes （DDTs） in a vegetable field which was near a chemical plant in China were characterized. Point estimate quotient was used for ecological risk assessment of the investigated site. The results showed that all CBs except monochlorobenzene （MCB） were detected in soils. The total concentrations of ∑ CBs ranged from 71.06 to 716.57 ng/g, with a mean concentration of 434.93 ng/g. The main components of CBs in soil samples were dichlorobenzenes （DCBs）, trichlorobenzenes （TCBs） and tetrachlorobenzenes （TeCBs）, while for single congeners, 1,2,4-TCB had the highest concentration, which ranged from 13.21 to 210.35 ng/g with a mean concentration of 111.89 ng/g. Residues of hexachlorobenzene （HCB） in soil samples ranged from 0.9 to 11.79 ng/g, significantly lower than ∑ DCB, ∑ TCB and ∑ TeCB. Concentrations of ∑ HCHs and ∑ DDTs in soils ranged from 11.32 to 55.24 ng/g and from 195.63 to 465.58 ng/g, respectively, of which the main components were α-HCH and p,p＇-dichlorodiphenyldichloroethylene （p,p＇-DDE）. Ecological risk assessment for the investigated site showed that the most potential risks were from TCBs and TeCBs, based on the hazard quotients. The higher residues of CBs and DDTs compared to the target values and the higher than 1 hazard quotients indicated that this area is not safe for vegetable production and thus soil remediation is needed.

Application of sewage sludge and intermittent aeration strategy to the bioremediation of DDT- and HCH-contaminated soil

Adding organic amendments to stimulate the biodegradation of pesticides is a subject of ongoing interest. The effect of sewage sludge on the bioremediation of dichlorodiphenyltrichloroethane（DDT） and hexachlorocyclohexane（HCH） contaminated soil was investigated in bench scale experiments,and intermittent aeration strategy was also used in this study to form an anaerobic–aerobic cycle. Bioremediation of DDT and HCH was enhanced with the addition of sewage sludge and the intermittent aeration. The removal rates of HCH and DDT were raised by 16.8%–80.8% in 10 days. Sewage sludge increased the organic carbon content from 6.2 to218 g/kg,and it could also introduce efficient degradation microbes to soil,including Pseudomonas sp.,Bacillus sp. and Sphingomonas sp. The unaerated phase enhanced the anaerobic dechlorination of DDT and HCH,and anaerobic removal rates of β-HCH,o,p′-DDT and p,p′-DDT accounted for more than 50% of the total removal rates,but the content of α-HCH declined more in the aerobic phase.

Bioaugmentation of DDT-contaminated soil by dissemination of the catabolic plasmid pDOD

A plasmid transfer-mediated bioaugmentation method for the enhancement of dichlorodiphenyltrichloroethane（DDT） degradation in soil was developed using the catabolic plasmid pDOD from Sphingobacterium sp. D-6. The p DOD plasmid could be transferred to soil bacteria, such as members of Cellulomonas, to form DDT degraders and thus accelerate DDT degradation. The transfer efficiency of pDOD was affected by the donor, temperature,moisture, and soil type. Approximately 50.7% of the DDT in the contaminated field was removed 210 days after the application of Escherichia coli TG I（pDOD-gfp）. The results suggested that seeding p DOD into soil is an effective bioaugmentation method for enhancing the degradation of DDT.

Remediation of Organochlorine Pesticide-Contaminated Soils by Surfactant-Enhanced Washing Combined with Activated Carbon Selective Adsorption

Remediation of organochlorine pesticide (OCP)-contaminated soils is urgently required especially in China. The present study investigated the removal of OCPs from two soils by triton X-100 (TX- 100)-enhanced washing coupled with powdered activated carbon (PAC) adsorption treatment of the solution. Two contaminated soils, including a silt clay contaminated w计h chlordene, dichloro- 2,2-6is(p-chlorophenyl)ethanes (DDDs), and dichlorodiphenyltrichloroethane (DDT) and a sandy loam containing chlordanes and mirex, were selected. Effects of varied operating parameters, including TX-100 dosage, liquid/soil (L/S) ratio, and extraction time, on the contaminant removal were examined. For both soils, OCP removal was clearly enhanced with increasing TX-100 in extraction solution and L/S ratio. Meanwhile, the removal efficacy was also impacted by soil texture and characteristics and contents of the contaminants. Moreover, by using PAC as an absorbent, a significant decrease in the contaminants in the extraction solutions was detected, and TX-100 could be further reused. Our investigation suggests that surfactant-enhanced washing combined with activated carbon selective adsorption would be an alternative to remediate OCP-contaminated soils.