DDT residue in soil and water in and around abandoned DDT manufacturing factory

Contaminants of Emerging Concern (CECs): Assessment of health and dietary risk in the consumption of Plagioscion squamosissimus in one of the largest rivers in a semi-arid region (Rio São Francisco, Brazil)

The São Francisco River, significant in semi-arid areas, faces impacts from hydroelectric plants and agricultural pesticides. Despite extensive research on its aquatic life, especially fish reproductive biology, there's a notable lack of studies on toxicity and its human health implications. This gap highlights the need for targeted research in this vital ecological zone. Consequently, this study aimed to scrutinize the concentrations of Contaminants of Emerging Concern (CECs), including Polychlorinated Biphenyls (PCBs), Polybrominated Diphenyl Ethers (PBDEs), Organochlorine Pesticides (OCPs), pyrethroid pesticides (PPs), triazine pesticides (TPs), and Organophosphorus Pesticides (OPPs) in the water, sediment, and fish (Plagioscion squamosissimus). The findings revealed the presence of all compound classes in sediment, albeit in limited quantities in water. Biotic components exhibited higher concentrations in nerve tissue, followed by the liver and muscle, indicative of a bioaccumulation trend. It is noteworthy that more concerning levels were observed in both water and sediments. In particular, Fenvalerate in water and Prometon in sediments demonstrated the highest Bioaccumulation Factor (BAF) values. While for non-carcinogenic effects and Cancer Risk (CR), the parameters were calculated and all classified in the areas of acceptable or insignificant according to chemical safety agencies. However, the compounds under scrutiny demand vigilant attention, given their nearly ubiquitous presence across various matrices and demonstrated bioaccumulative capacity, potentially posing future repercussions for human health.

Determination of lindane in surface water samples and its degradation by hydrogen peroxide and persulfate assisted TiO2-based photocatalysis

Organochlorine pesticides (OCPs) have been used extensively as insecticides and herbicides. This study investigates the occurrence of lindane in surface water from the Peshawar valley (i.e., Peshawar, Charsadda, Nowshera, Mardan and Swabi districts of Khyber Pakhtunkhwa, Pakistan). Out of 75 samples tested (i.e., 15 samples from each district), 13 samples (including 2 from Peshawar, 3 from Charsadda, 4 from Nowshera, 1 from Mardan, and 3 from Swabi) are found to be contaminated with lindane. Overall, the detection frequency is 17.3%. The maximum concentration of lindane is detected in a water sample from Nowshera and found to be 2.60 μg L^-1. Furthermore, the degradation of lindane in the water sample from Nowshera, containing the maximum concentration, is investigated by simulated solar-light/TiO₂ (solar/TiO₂), solar/H₂O₂/TiO₂ and solar/persulfate/TiO₂ photocatalysis. The degradation of lindane by solar/TiO₂ photocatalysis is 25.77% after 10 h of irradiation. The efficiency of the solar/TiO₂ process is significantly increased in the presence of 500 μM H₂O₂ and 500 μM persulfate (PS) (separately), represented by 93.85 and 100.00% lindane removal, respectively. The degradation efficiency of lindane is lower in natural water samples as compared to Milli-Q water, attributed to water matrix effect. Moreover, the identification of degradation products (DPs) shows that lindane follows similar degradation pathways in natural water samples as the one in Milli-Q water. The results show that the occurrence of lindane in surface waters of Peshawar valley is a matter of great concern for human beings and the environment. Interestingly, H₂O₂ and PS assisted solar/TiO₂ photocatalysis is an effective method for the removal of lindane from natural water.

Target and non-target analysis of organochlorine pesticides and their transformation products in an agrochemical-contaminated area

Organochlorine pesticides show biological toxicity and their degradation typically takes many years. Previous studies of agrochemical-contaminated areas have mainly focused on limited target compounds, and emerging pollutants in soil have been overlooked. In this study, we collected soil samples from an abandoned agrochemical-contaminated area. Target analysis and non-target suspect screening by gas chromatography coupled with time-of-flight mass spectrometry were combined for qualitative and quantitative analysis of organochlorine pollutants. Target analysis showed that dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), and dichlorodiphenyldichloroethane (DDD) were the main pollutants. With concentrations between 3.96 × 10⁶ and 1.38 × 10⁷ ng/g, these compounds posed significant health risks at the contaminated site. Non-target suspect screening identified 126 organochlorine compounds, most of which were chlorinated hydrocarbons and 90% of the compounds contained a benzene ring structure. The possible transformation pathways of DDT were inferred from proven pathways and the compounds identified by non-target suspect screening that had similar structures to DDT. This study will be useful for studies of the degradation mechanism of DDT. Semi-quantitative and hierarchical cluster analysis of compounds in soil showed that the distribution of contaminants in soil was influenced by the types of pollution sources and distance to them. Twenty-two contaminants were found in the soil at relatively high concentrations. The toxicities of 17 of these compounds are currently not known. These results improve our understanding of the environmental behavior of organochlorine contaminants in soil and are useful for further risk assessments of agrochemical-contaminated areas.

Use, exposure, and environmental impacts of pesticides in Pakistan: a critical review

The excessive use of pesticides is posing major threats to humans and the environment. However, the environmental exposure and impact of pesticides in Pakistan have yet been systematically reviewed, despite the country's leading role in pesticide use. Therefore, this study identified and then reviewed 85 peer-reviewed scientific publications on the topic. It was found that, compared to the worldwide average, Pakistan had high consumptions of pesticides, with an alarming increase of 1169% in the last two decades. The quantities of pesticides used followed an order of pyrethroids > organophosphates > organochlorines > carbamates, but organochlorines were the most problematic due to their environmental occurrence, the ability to transport across the media, and identified human and ecological toxicities. Additionally, the misuse or overuse of pesticides by farmers is prevailing due to insufficient knowledge about the risks, which leads to high risks in occupational exposure. These issues are further aggravated by the illegal use or continuous impacts of banned organochlorine pesticides. For the future, we suggested the establishment of organized monitoring, assessment, and reporting program based on environmental laws to minimize contamination and exposure to pesticides in Pakistan. Remediation of the contaminated areas to mitigate the adverse environmental-cum-health impacts are recommended in the most affected regions.

An efficient nanofiltration system containing mixture of rice husk ash and Fe/CeO2–SiO2 nanocomposite for the removal of azo dye and pesticide

Fe/CeO2–SiO2 nanocomposite was synthesized by using zwitterionic surfactant 3-(N,N-dimethyloctadecylammonio) propane sulfonate (SB3-18) by sol–gel and hydrothermal methods. The nanocomposite was well characterized before its use. X-ray diffraction (XRD) results confirmed the synthesis of the Fe/CeO2–SiO2 nanocomposite. Crystallite size calculated by using Scherrer equation was 5.33 nm while it was found 5.26 nm by Williamson–Hall equation. Bandgap of Fe/CeO2–SiO2 nanocomposite shows redshift after the doping of Fe. Degradation studies of methylene blue (MB) and chlorpyrifos (CP) were investigated by nanofiltration (NF) column under visible light irradiation. Degradation and adsorption of MB was investigated by three different types of columns under visible light irradiation. It was observed to achieve 100 % removal of MB and 91 % of CP through column in which rice husk ash (RHA) slurry was mixed with the nanocomposite.

Organochlorine pesticides across the tributaries of River Ravi, Pakistan: Human health risk assessment through dermal exposure, ecological risks, source fingerprints and spatio-temporal distribution

This study monitored the human health risks through dermal exposure, hazardous risks to ecological integrity, contamination levels, spatio-temporal distribution, and congener specific analysis of organochlorine pesticides (OCPs) across River Ravi and its three northern tributaries (Nullah Bein, Nullah Basanter and Nullah Deg). The residual levels of OCPs isomers were screened for water (n=54) and surface sediment (n=54) samples from twenty seven sampling sites in two alternate seasons (pre-monsoon and post-monsoon). The ∑OCPs concentrations ranged from 13.61 to 1992.18ng/g dry weight and 12.89 to 128.16ng/L with predominance of β-endosulfan and p,p'-DDT in sediment and water matrixes, respectively. Distribution pattern revealed significantly higher concentrations in upstream and midstream, suggesting considerable transboundary OCPs pollution. Calculated ratios of α-HCH/γ-HCH, o,p'-DDT/p,p'-DDT, (DDE+DDD)/∑DDTs and cis/trans-chlordane for water and sediments identified the fresh addition of lindane, technical DDTs and chlordane in the study area. Risk quotient (RQ) based ecological risk was found to be >1 at all studied streams during both seasons and elucidates higher risks for endosulfan (α-endosulfan) and endrin. Human health risk assessment indicated absence of hazardous (non-carcinogenic) risk through bathing in studied streams; as the hazard index values ranged from 1.09E-05 to 2.48E-02 (acceptable limit; <1). However, the calculated carcinogenic risk possessed by OCPs through dermal exposure ranged from 1.39E-10 to 1.98E-05 that highlighted the considerable carcinogenic risk associated to aldrin, dieldrin, p,p'-DDT and β-endosulfan at certain studied sites. Therefore, the high levels of ecological risk and carcinogenic human health risk had emphasized an immediate elimination of ongoing OCPs addition in the studied area.

Using Isomeric and Metabolic Ratios of DDT To Identify the Sources and Fate of DDT in Chinese Agricultural Topsoil

The metabolic ratio of (p,p'-DDE + p,p'-DDD)/p,p'-DDT or p,p'-DDE/p,p'-DDT has been used previously to estimate the approximate half-life of p,p'-DDT, with a relatively unclear concept of "old" and "new" sources of p,p'-DDT and without paying attention to the influence by dicofol-type DDT contributed from the more recent usage of dicofol. Based on the isomeric ratio of o,p'-DDT/p,p'-DDT to distinguish the sources of DDT, this study used the corrected metabolic ratio of (p,p'-DDE + p,p'-DDD)/p,p'-DDT to estimate a more accurate half-life of p,p'-DDT using a model-based approach. This indicates the average half-life of p,p'-DDT in Chinese topsoils was 14.2 ± 0.9 years with dicofol-type DDT input considered. In deeper soil, the half-life was >30 years and the metabolic pathway of p,p'-DDT was significantly different with topsoil's. Further analysis on the fraction of DDT from technical DDT suggested that a region that had been sprayed with technical DDT was likely to have been sprayed with dicofol as well, but the monitoring residues of DDT in topsoil mainly derive from historical use of technical DDT.

Time matters: A stock-pollution approach to authorisation decision-making for PBT/vPvB chemicals under REACH

A core aim of the European chemicals legislation REACH is to ensure that the risks caused by substances of very high concern (SVHC) are adequately controlled. Authorisation - i.e. the formal approval of certain uses of SVHC for a limited time - is a key regulatory instrument in order to achieve this goal. For SVHC which are, in addition to their toxicity, (very) persistent and/or (very) bioaccumulative (PBT/vPvB chemicals), decision-making on the authorisation is conditional on a socio-economic analysis (SEA). In a SEA companies must demonstrate that the gains from keeping a chemical in use outweigh expected damage costs for society. The current setup of the REACH authorisation process, including existing guidance on performing a SEA, ignores that PBT/vPvB chemicals are stock pollutants. This paper explores the implications of incorporating stock pollution effects of these chemicals into a SEA on authorisation decision-making. We develop a cost-benefit approach which includes stock dynamics of PBT/vPvB chemicals. This allows identifying the decision rules for granting or refusing an authorisation. Furthermore, we generalize the model to an entire set of damage functions. We show that ignoring stock pollution effects in a SEA may lead to erroneous decisions on the use of PBT/vPvB chemicals because long-term impacts are not adequately captured. Using a historic case of DDT soil contamination as an illustrative example we discuss information requirements and challenges for authorisation decisions on the use of PBT/vPvB chemicals under REACH.

Concentrations and patterns of organochlorines (OCs) in various fish species from the Indus River, Pakistan: A human health risk assessment

The present study was conducted to reveal the concentrations and patterns of organochlorines [i.e., organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs)] in freshwater fish species collected from four ecologically important sites of the Indus River i.e., Taunsa (TAU), Rahim Yar Khan (RYK), Guddu (GUD) and Sukkur (SUK). In the fish muscle tissues, concentrations of 15 OCPs (∑15OCPs) and 29 PCBs (∑29PCBs) varied between 1.93-61.9 and 0.81-44.2 ng/g wet weight (ww), respectively. Overall, the rank order of OCs was DDTs>PCBs>hexachlorocyclohexanes (HCHs)>chlordanes (CHLs). The patterns of PCBs showed maximum contribution of tri-CBs (59%). Ratios of individual HCH and DDT analytes contributing to the summed values indicated both recent and past use of these chemicals in the region, depending upon fish species. To assess the associated health risks, carcinogenic and non-carcinogenic risks were calculated through hazard ratios (HRs). For carcinogenic risk, HR was >1 at both 50th and 95th percentile concentrations, suggesting that the daily exposure to OCPs and PCBs yields a lifetime cancer risk of 1 in a million. HR for non-cancerous risk was <1 at both the percentiles, signifying no adverse effect by OCs exposure in native population.

Quantification of penoxsulam in soil and rice samples by matrix solid phase extraction and liquid-liquid extraction followed by HPLC-UV method

The paper exploits the development of novel, simple and sensitive methodology involving matrix solid phase dispersion (MSPD) and the comparison of MSPD with liquid-liquid extraction (LLE) for the evaluation of residual penoxsulam in soil and rice samples. Extracted samples were analyzed by high-performance liquid chromatography (HPLC) with ultraviolet detector at 230 nm. Both methods were optimized, considering different parameters, and under optimum conditions, the mean recoveries obtained were in the range of 85-104 % for MSPD and 78.8-90.7 % for LLE. Precision values expressed as relative standard deviation (RSD) were ≤10 for MSPD and ≤15 for LLE. Linearity for penoxsulam was in the range of 0.01-20 μg mL(-1) with limits of detection and limits of quantification of 0.01 and 0.03 mg kg(-1), respectively.

Levels, distribution pattern and ecological risk assessment of organochlorines pesticides (OCPs) in water and sediments from two tributaries of the Chenab River, Pakistan

Residue levels, distribution patterns and ecological risk assessment of OCPs in water and sediment samples collected from two upstream feeding tributaries of the River Chenab, Pakistan were monitored. ΣOCPs levels in water and sediment ranged between 8 and 76 ng L(-1) and 17 and 224 ng g(-1), respectively. The mean concentration of ΣHCH (hexachlorocyclohexane) was 3.3 ± 3.2 ng L(-1) and 8.4 ± 9 ng g(-1) for water and sediment samples, respectively, while ΣDDT (dichlorodiphenyltrichloroethane) exhibited the average concentration of 9.07 ± 6.15 ng L(-1) and 40.3 ± 26.2 ng g(-1) for water and sediment samples, respectively. The concentration of DDT and HCHs in both water and sediment samples were about 80 % of total OCPs and DDTs were the predominant organochlorines in the investigated matrix. DDTs and HCHs in sediment samples posed higher ecotoxicological risk and results were significant when compared with the quality guidelines. Results of the present study should be taken seriously by higher authorities as there is a serious threat to ecological integrities by OCPs exposure.

Human health risk assessment and dietary intake of organochlorine pesticides through air, soil and food crops (wheat and rice) along two tributaries of river Chenab, Pakistan

To assess the organochlorine pesticides (OCPs) contamination and their probable hazardous effects on human health; cereal crops (wheat and rice; n=28) agricultural soil (n=28) and air (n=6) samples were collected from Gujranwala division, Punjab Province, Pakistan. ∑OCPs concentration ranged between 123 and 635 pg m(-3), 31 and 365 ng g(-1) (dw), 2.72 and 36.6 ng g(-1) (dw), 0.55 and 15.2 ng g(-1) (dw) for air, soil, rice and wheat samples, respectively. DDTs were the predominant over other OCPSs detected from screened samples while the source apportionment analysis suggested the new inputs of DDTs in the study area. EDI (estimated daily intake) of ∑OCPs through rice and wheat was found 39 and 40 ng kg(-1) day(-1), respectively. Hazard ratios (HRs) on the basis 95th percentile concentrations were exceeding the integrity for most of the investigated OCP in rice and wheat. The results revealed that there is a severe risk to the human population of the study area through consumption of contaminated cereal crops.

Cattle egrets as a biosentinels of persistent organic pollutants exposure

We investigated selected chlorinated pollutants (β-HCH, γ-HCH, DDDs, DDEs, o,p'-DDT, p,p'-DDT, heptachlor, aldrin, dieldrin, and endrin) in the Lahore and the Sialkot districts of Pakistan, using eggs of cattle egret (Bubulcus ibis) collected during May and June 2007. The pollutant with highest level and frequency was ΣDDT, followed by β-HCH, γ-HCH, heptachlor, aldrin, dieldrin, and endrin in descending order. The concentration(s) were significantly higher in Sialkot heronry for all the pollutants (except p,p'-DDT) than in Lahore. The values for DDTs, β-HCH, γ-HCH, and heptachlor were significantly higher (p < 0.05) in the egg(s) than in sediment(s) and in the chicks' diet, due to biomagnification. Among DDTs analogues, p,p'-DDD was the major contaminant with >60 % of total DDT burden, reflecting the widespread aged as well as recent use of DDT as well as anaerobic degradation (DDD/DDE > 1 in many cases) in the nearby paddy soils. In few samples, p,p'-DDT/(DDD + DDE) > 0.5 suggested the recent emission patterns from surrounding contaminated areas of demolished DDT units and obsolete pesticide stores. The higher levels of HCHs (i.e., β-HCH) in the samples collected from Sialkot indicate exposure from long-term agricultural use. Overall, concentrations of all studied POPs were less than the threshold levels known to affect reproduction. Nevertheless, total DDTs and/or HCHs burdens in some eggs contained concentrations of greater than what would educe adverse effects on birds. This is among few studies on OCPs exposure to avian species, which provide the evidence of Pakistan's contribution toward the Global POPs emission.

Organochlorine pesticides (OCPs) in South Asian region: a review

Organochlorine pesticides (OCPs) are semi volatile organic compounds of global concern. During the last decades, their distribution, sources, transformation, toxicity and accumulation in the terrestrial and aquatic ecosystems have gained significant attention. Many of these chemicals are characterized by long range atmospheric transport potential, and their occurrence in remote areas is attributed to transport of chemicals from places where OCPs are still in use. The South Asia region is a place where primarily emissions are still taking place and thus it is important to assess the status of OCPs pollution. This document provides the historical overview and country specific environmental legislation of OCPs from the South Asian region in the context of their illegal use and storage for extended periods and still until to date. In addition, the current review discusses the existing knowledge on the levels and distribution of OCPs in different environmental compartments of South Asian region. Data on OCPs also highlights the risk assessment of these organic contaminants in the regional environment and spans the long range atmospheric transport phenomena based on Himalayas and Northern mountainous glaciers. Paradoxically in the scientific literature sources, distribution and transport of these organic pollutants in South Asian region are very limited compared to the rest of the world.

Organochlorine pesticides in surface soils from obsolete pesticide dumping ground in Hyderabad City, Pakistan: contamination levels and their potential for air-soil exchange

This study was conducted to examine organochlorine pesticides (OCPs) contamination levels in the surface soil and air samples together with air-soil exchange fluxes at an obsolete pesticide dumping ground and the associated areas from Hyderabad City, Pakistan. Among all the sampling sites, concentrations of OCPs in the soil and air samples were found highest in obsolete pesticide dumping ground, whereas dominant contaminants were dichlorodiphenyltrichloroethane (DDTs) (soil: 77-212,200 ng g(-1); air: 90,700 pg m(-3)) and hexachlorocyclohexane (HCHs) (soil: 43-4,090 ng g(-1); air: 97,400 pg m(-3)) followed by chlordane, heptachlor and hexachlorobenzene (HCB). OCPs diagnostic indicative ratios reflect historical use as well as fresh input in the study area. Moreover, the air and soil fugacity ratios (0.9-1.0) at the dumping ground reflecting a tendency towards net volatilization of OCPs, while at the other sampling sites, the fugacity ratios indicate in some cases deposition and in other cases volatilization. Elevated concentrations of DDTs and HCHs at pesticide dumping ground and its surroundings pose potential exposure risk to biological organisms, to the safety of agricultural products and to the human health. Our study thus emphasizes the need of spatio-temporal monitoring of OCPs at local and regional scale to assess and remediate the future adverse implications.

Organohalogenated contaminants (OHCs) in human serum of mothers and children from Pakistan with urban and rural residential settings

This study aimed to provide first data on the concentrations of different classes of organohalogenated contaminants (OHCs) in human serum from Pakistan, an area with limited information on environmental pollution. Serum samples (N=85) were collected from mothers (N=34; age ranged 23-51 years), their children (N=34; age 3-10 years) and general group (N=17; age 13-65 years) with rural and urban residential settings. The concentrations of studied OHCs in serum decreased as follows: organochlorinated pesticides (OCPs)>polychlorinated biphenyls (PCBs)>polybrominated diphenyl ethers (PBDEs). Novel brominated flame retardants (NBFRs) were not detected, except for 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE)<0.2-8 ng/g lipid weight (lw). Low levels of HO-PCBs (<0.2-20 ng/g lw) were detected, while HO-PBDEs were <0.2 ng/g lw. ∑PCBs (2-105 ng/g lw) together with ∑PBDEs (0.2-6.7 ng/g lw) contributed ~5% of the total OHCs body burden. The concentration(s) of major contributors (>80%) of OCPs ranged from <1-3645 ng/g lw for 1,1'-bis-(4-chlorophenyl)-2,2-dichloroethene (p,p'-DDE), <1-445 ng/g lw for β-hexachlorocyclohexane (β-HCH) and from 5 to 200 ng/g lw for pentachlorophenol (PCP). p,p'-DDE, the major OHC, was significantly higher (p<0.05) in rural children than in all other groups. In serum of rural children, the major OHCs were significantly higher (p<0.05) than the mothers. The current study indicates continuous exposure to humans with already regulated OHCs and highlights the need for further monitoring of these OHCs in the region.

Uptake of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) by river water fish: the case of River Chenab

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in eleven edible fish species (5 herbivorous and 6 carnivorous) collected from the River Chenab, Pakistan, during 2007-2009. Total OCP and PCB concentrations (ng g(-1) wet weight, ww) ranged between 13-107 (mean: 38) and 3.1-93.7 (mean: 20) for five herbivorous fish species and 21.6-365 (mean: 148) and 2.5-108 (mean: 30) for six carnivorous species, respectively. The trends of detected organochlorine pesticides (OCPs) in fish samples were: DDTs>PCBs>chlordanes>HCHs. The mean concentration(s) (ng g(-1) ww) of OCPs were relatively higher in all fish species collected near industrial areas followed by urban and agricultural areas. Risk assessment of OCPs and PCBs indicated that fish intake may pose health risk to humans with a consumption rate of >8 g/person/day. The hazardous ratios for the 50th and 95th percentile data of OCPs and PCBs in fish exceeded the value of 1, suggesting that the daily exposure to OCPs and PCBs yield a lifetime cancer risk greater than 1 in 10,000.

The source of DDT and its metabolites contamination in Turkish agricultural soils

The concentration and impact of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)-ethane (DDT) and its metabolites (DDE: 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene) on the environment was expected to decrease after its ban in the mid-1980s. Unfortunately, DDT contamination via its presence as an impurity in dicofol (2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol) has led to a new source of contamination. This is particularly true especially in cotton production in Söke Plain, Turkey, where difocol-based pesticides are being used. The aim of this research was to investigate the extent and source of DDT contamination in cotton soils. Söke Plain soil samples were collected from 0-30, 30-60, and 60-90-cm depth and analyzed by GC/MS/MS. o,p'-DDT and p, p'-DDE were detected at 16.2 % and 17.6 % of the sites in the 0-30-cm depth of soils. In the 30-60 cm, p, p'-DDT (14.9 %), o, p'-DDE (8.1 %) and p, p'-DDE (2.7 %) were found in soil samples, and p, p'-DDT was the most prevalent with 9.5 % of the sampling sites. The dominant source of DDT particularly in the 60-90-cm depth was due to historic use of DDT. The presence of p, p'-DDE, o, p'-DDE and p,p'-DDT in the topsoil was attributed to recent dicofol applications.

Organochlorine pesticides in air and soil and estimated air-soil exchange in Punjab, Pakistan

This study provides the first systematic data on the distribution of organochlorine pesticides (OCPs) in the soils and atmosphere of the Punjab province, Pakistan. Atmospheric concentrations of OCPs were estimated by using the polyurethane foam passive air sampling (PUF-PAS) technique. DDTs (dichlorodiphenyltrichloroethane), HCHs (hexachlorocyclohexane) and chlordane were the dominant OCPs found in both soil and air samples. The average concentrations of DDTs, HCHs and chlordane were 350, 55 and 99 pg m(-3) in air and 40, 7.8 and 3.8 ng g(-1) in soils, respectively. Air-soil exchange of OCPs was estimated by calculating the fugacities in soil and air. Fugacity fraction (ff) values indicate that soils are acting as a secondary source to contaminate the atmosphere at certain sampling stations.

Knockdown Resistance, rdl Alleles, and the Annual Entomological Inoculation Rate of Wild Mosquito Populations from Lower Moshi, Northern Tanzania

Aim:

Understanding vector behavioral response due to ecological factors is important in the control of disease vectors. This study was conducted to determine the knockdown resistance (kdr) alleles, dieldrin resistance alleles, and entomological inoculation rates (EIRs) of malaria vectors in lower Moshi irrigation schemes for the mitigation of disease transmission.

Materials and Methods:

The study was longitudinal design conducted for 14 months. Mosquitoes were collected fortnightly by using a CDC miniature light trap in 20 houses. Mosquitoes were identified morphologically in the field, of which 10% of this population was identified to species level by using molecular techniques. Samples from this study population were taken for kdr and resistance to dieldrin (rdl) genes detection.

Results:

A total of 6220 mosquitoes were collected by using a light trap, of which 86.0% (n=5350) were Anopheles gambiae sensu lato and 14.0% (n=870) were Culex quinquefasciatus. Ten percent of the An. gambiae s.l. (n=535) collected were taken for species identification, of which 99.8% (n=534) were identified as An. arabiensis while 0.2% (n=1) were An. gambiae sensu stricto. Of the selected mosquitoes, 3.5% (n=19) were sporozoite positive. None of the mosquitoes tested had the kdr gene. The rdl resistant allele was detected at a frequency of 0.48 throughout the year. EIR was determined to be 0.54 ib/trap/year.

Conclusion:

The findings of this study suggest that the homozygous and the heterozygous resistance present in rdl genes demonstrated the effect of pesticide residues on resistance selection pressure in mosquitoes. A better insecticide usage protocol needs to be developed for farmers to use in order to avoid excessive use of pesticides.

Assessment of human exposure to indoor organic contaminants via dust ingestion in Pakistan

  Ingestion of indoor dust has been acknowledged as an important route of exposure to organic contaminants (OCs). We investigated the presence of polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), organophosphate flame retardants (OPFRs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in indoor floor dust from rural homes (N=31) and mosques (N=12) in Gujrat, Pakistan. Low concentrations were observed for most contaminants. OPFRs were the principle contaminants, with tri-(2-butoxyethyl)-phosphate (TBEP) and tri-phenyl-phosphate (TPP) having medians of 66 and 109 ng/g, respectively. PBDEs were only minor constituents in the investigated samples, with BDE 209 (median 40 ng/g) being the most important congener. Levels and profile of ∑PBDEs, ∑NBFRs, ∑HCHs, ∑DDTs, and ∑PCBs revealed no difference (P<0.05) between samples of dust from homes and mosques, indicating similar emission sources. Exposure scenarios using 5th percentile, median, mean, and 95th percentile levels were estimated for both adult and toddlers. Typical high-end, using median levels and high dust ingestion, exposure for adults were 0.02, 0.02, 0.03, <0.01, and 0.65 ng/kg bw/day and for toddlers 0.39, 0.45, 0.69, 0.01, and 15.2 ng/kg bw/day for ∑PBDEs, ∑NBFRs, ∑OCPs, ∑PCBs, and ∑OPFRs, respectively. To the authors' knowledge, this is the first study to document the presence of indoor OCs in Pakistani dust.

PRACTICAL IMPLICATIONS

This is the first report on the analysis of various contaminants in indoor dust from Pakistan. Some of these chemicals are currently being used in different consumer products. The study will help to further an understanding of the levels of different organic contaminants (OCs) in Pakistani indoor environments and will enlighten the generally ignored area of environmental pollution in Pakistan. Furthermore, studies based on animal models have shown that some of the analyzed chemicals can cause different types of chronic toxicities. However, our results showed that the levels of estimated exposure via dust ingestion for all chemicals were several orders of magnitude lower than their reference dose (RfD) values or than those reported in studies from Belgium, China, Singapore, and the UK (Ali et al., 2011a; Harrad et al., 2008; Tan et al., 2007a,b; Van den Eede et al., 2011a; Wang et al., 2010).

Status of organochlorine contaminants in the different environmental compartments of Pakistan: a review on occurrence and levels

This review evaluates and summarizes the results of the studies of organochlorines-contaminated water, sediment/soil and biota in Pakistan. Pattern of occurrence of each contaminant class from different study sites is followed as DDTs > Cyclodiens > HCHs > PCBs. The studies conducted in the surrounding areas of the demolished DDT manufacturing units and obsolete pesticides stores of country showed extremely highest values of ∑DDTs, which differ significantly (p < 0.05) than those reported from the agricultural areas and fresh water bodies of the country. HCHs, heptachlor, dieldrin, and HCB were also reported in many studies, but the concentrations are comparable among all the locations in the country. The authors suggested surface run-off, dumping of waste from industries and contamination from obsolete pesticides and demolished OCPs manufacturing units as the major sources in Pakistan. Information on PCBs is scares and studies on assessment of PCBs occurrence, and spatial trends in various environmental matrices needs special attention to produce the scientific publication. The results draw attention that POPs contamination must be considered as a priority environmental concern due to their use in agricultural and industrial sector.

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 sigmaCBs 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 sigmaDCB, sigmaTCB and sigmaTeCB. Concentrations of sigmaHCHs and sigmaDDTs 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 alpha-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.

Organochlorine pesticide residues in sediments from coastal environment of Cantabria (northern Spain) and evaluation of the Atlantic Ocean

This paper documents levels of organochlorine pesticides (OCs) in coastal surface sediments from selected reference sites on the northern Atlantic Spanish coast. One hundred eight samples covering three estuaries in the Cantabrian Coast were sampled in 2006 and analyzed in the finer fraction (<63 μm) for 19 OCs by gas chromatography with electron capture detector after confirmation by mass spectrometry. Detected organochlorine pesticides were endosulfan α, endosulfan β, endosulfan sulfate, hexachlorobenzene (HCB), aldrin, dieldrin, methoxychlor, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4'-DDE) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (4,4'-DDD). Total OCs concentrations ranged from 1.8 ng g(-1) dry weight (dw) to 3.9 ng g(-1) dw, showing a uniform distribution along the studied area, and being consistent with recorded levels in the literature for coastal sediments in other reference sites with low levels of pollution by OCs along the Atlantic Ocean. Endosulfan, 4,4'-DDD, HCB, aldrin, and dieldrin seemed to be ubiquitous as the legacy of past uses and deposition. OCs concentrations were significantly correlated to organic matter content and particle size distribution. No adverse biological effects derived from these pollutants are expected to take place as it can be concluded from the comparison with the existent marine sediment quality guidelines.

The level and distribution of selected organochlorine pesticides in sediments from River Chenab, Pakistan

Organochlorine pesticides (OCPs), viz. β-hexachlorocyclohexane (β-HCH), γ-HCH, aldrin, dieldrin, endrin, heptachlor, endosulfan-I, endosulfan-II, heptachlor endoepoxide, heptachlor exoepoxide, mirex, dicofol, o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT), p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyltrichloroethylene (DDE) and 12 other physicochemical parameters were measured in surface sediments from River Chenab during two sampling seasons (summer and winter, 2007) to evaluate spatial and temporal trends of sediment pollution. Hierarchical agglomerative cluster analysis identified three groups of sites based on spatial similarities in physicochemical parameters and OCP residual concentrations. Spatial discriminant function analysis (DFA) segregated 14 parameters, viz. dicofol, endosulfan-I, heptachlor endoepoxide, dieldrin, DDD, DDE, endosulfan-II, o,p'-DDT, p,p'-DDT, pH, electrical conductivity (EC), Cl⁻¹, total P (%), and silt, which explained 96% of total variance between spatial groups. γ-HCH was the most frequently detected (63%) pesticide, followed by DDD (56%). The ratio of DDTs to their metabolites indicated current input and anaerobic biodegradation. Temporal DFA highlighted aldrin, heptachlor endoepoxide, Cl⁻¹, total P, and EC as important variables which caused variations between summer and winter. DDTs were relatively more prevalent as compared to other OCPs in the sediments samples during both seasons. DDT metabolites were detected at greater frequencies and concentrations in winter, whereas DDT isomers were more prevalent in summer sediment samples. Factor analysis identified agricultural and industrial activities as major sources of sediment OCP contamination. Concentrations of γ-HCH, heptachlor endoepoxide, dieldrin, and DDTs (isomers and metabolites) in all sediment samples were well above interim sediment quality guidelines (ISQGs) and probable effect limits (PEL) given by Canadian Sediment Quality Guidelines (CSQGs).