Informal E-waste dismantling activities accelerated the releasing of liquid crystal monomers (LCMs) in Pakistan: Occurrence, distribution, and exposure assessment.

Liquid crystal monomers (LCMs) are emerging contaminants characterized by their persistence, bioaccumulation potential, and toxicity. They have been observed in several environmental matrices associated with electronic waste (e-waste) dismantling activities, particularly in China. However, there is currently no information on the pollution caused by LCMs in other developing countries, such as Pakistan. In this study, we collected soil samples (n = 59) from e-waste dismantling areas with different functions in Pakistan for quantification analysis of 52 target LCMs. Thirty out of 52 LCMs were detected in the soil samples, with the concentrations ranging from 2.14 to 191 ng/g (median: 16.3 ng/g), suggesting widespread contamination by these emerging contaminants. Fluorinated LCMs (median: 10.4 ng/g, range: 1.27-116 ng/g) were frequently detected and their levels were significantly (P < 0.05) higher than those of non-fluorinated LCMs (median: 6.11 ng/g, range: not detected (ND)-76.7 ng/g). The concentrations and profiles of the observed LCMs in the soil samples from the four functional areas varied. The informal dismantling of e-waste poses a potential exposure risk to adults and infants, with median estimated daily intake (EDI, ng/kg bw/day) values of 0.0420 and 0.1013, respectively. Calculation of the hazard quotient (HQ) suggested that some LCMs (e.g., ETFMBC (1.374) and EDFPB (1.257)) may pose potential health risks to occupational workers and their families. Considering the widespread contamination and risks associated with LCMs, we strongly recommend enhancing e-waste management and regulation in Pakistan.

Spatial distribution and ecological risk assessment of short and medium chain chlorinated paraffins in water and sediments of river Ravi, Pakistan.

Short (SCCPs) and medium (MCCPs) chain chlorinated paraffins being the emerging organic pollutants have raised serious concerns due to their widespread use and related human health risks. However, their occurrence in aquatic bodies like rivers and associated damage to ecological integrity is yet unknown in some regions of the world. The current study is the first ever assessment of SCCPs and MCCPs in sediment and water of river Ravi, Pakistan. Spatial occurrence and associated ecological risks were investigated from sediments (n = 16) and composite water samples (n = 8) collected at eight locations along the stretch of river Ravi. The concentrations of SCCPs and MCCPs varied from below limit of detection (

Distribution, bioaccumulation, and health risk assessment of organochlorines across the riverine ecosystem of Punjab Province, Pakistan.

This study was designed to assess the distribution of organochlorines (OCs) in fish species, their spatio-temporal variations, bioaccumulation potential, and associated human health risks via dietary intake. The levels of twenty-three organochlorine pesticides (OCPs) and thirty-five polychlorinated biphenyls (PCBs) were analyzed in six fish species collected from the riverine ecosystem of Punjab Province, Pakistan. The results indicated that the mean levels of Σ23OCPs were 74.1 ng/g ww and 184 ng/g ww, and for Σ35PCBs the levels were 38.8 ng/g ww and 74.8 ng/g ww in herbivorous and carnivorous fish species, respectively. The most abundant contaminants in all fish species were DDTs (65%) and HCHs (14%) among OCPs and heavier PCB congeners (62%) among PCBs. As for dioxin-like PCBs, the WHO toxic equivalency values (ng TEQ/g ww) were in the range of 0.21 (Cyprinus Carpio) to 2.38 (Rita Rita), exceeding the maximum allowable limit of 0.004 ng TEQ/g, ww by the European Commission. Spatio-temporal analysis indicated relatively higher OC levels in winter season with elevated concentrations in fish samples from industrial zone. The bioconcentration factor (L/kg) values ranged from 723 to 2773 for PCBs and 315 to 923 for OCPs in all fish species, with higher levels were reported in carnivorous species. The human health risk assessment at both 50th and 95th percentiles revealed the absence of any significant non-carcinogenic risk as calculated HR was less than 1. However, the critical carcinogenic risk was found to be associated for most of the contaminants, signifying the dietary exposure to OCPs and PCBs might pose the public health concern.

Organochlorines in the riverine ecosystem of Punjab province, Pakistan: contamination status, seasonal variation, source apportionment, and ecological risk assessment.

The aim of the present study was to determine the occurrence, spatio-temporal variations, source apportioning, and ecological risk assessment of selected PCBs and OCPs in surface water and sediments collected riverine environment of Punjab province, Pakistan. The concentration of ΣOCPs (water: 64-455 ng/L; sediments: 117-616 ng/g) and ΣPCBs (water: 2-132 ng/L; sediments: 3.27-200 ng/g) was found comparatively higher than the levels reported from other parts of the world. The higher concentrations of DDTs and HCHs were detected in both studied matrices, whereas among PCBs, CB-28, 49 and CB-37, 82 were dominant in water and sediments, respectively. The isomeric ratios including α-HCH/γ-HCH, (DDE + DDD) / DDTs, and α /ß-endosulfan reflected the recent use of lindane, technical DDT, and endosulfan in the study area. The WHO-TEQ values of DL-PCBs ranged from 3.6 × 10-6 to 0.115 ng/L and 8.7 × 10-6 to 0.157 ng/g in surface water and sediments in both seasons, respectively. The spatial variation analysis revealed that the sites in the industrial and agricultural zones were highly contaminated. The OCPs and PCBs fluxes to downstream areas were estimated to be 12.4 tons/year and 1.9 tons/year, respectively. The significant ecological risks were estimated to be posed by OCPs and PCBs, as their levels in 67% and 62% of surface water and sediment samples were exceeding the threshold limits, highlighting effects to ecological integrities.

Source identification and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in air and dust samples of Lahore City.

During two consecutive summer and winter seasons in Lahore, the health risk of air and dust-borne polycyclic aromatic hydrocarbons (PAHs) was evaluated. Gas chromatography/mass spectrometry (GS/MS) was used to determine air and dust samples from various functional areas across the city. The mean ∑16PAHs were higher in air 1035.8 ± 310.7 (pg m-3) and dust 963.4 ± 289.0 (ng g-1 d.w.) during winter seasons as compared to summer seasons in air 1010.9 ± 303.3 (pg m-3) and dust matrices 945.2 ± 283.6 (ng g-1 d.w.), respectively. PAHs ring profile recognized 3 and 4 rings PAHs as most dominant in air and dust samples. Estimated results of incremental lifetime cancer risk (ILCR) highlighted high carcinogenic risk among the residents of Lahore via ingestion and dermal contact on exposure to atmospheric PAHs. The total ILCR values in air among children (summer: 9.61E - 02, winter: 2.09E - 02) and adults (summer: 1.45E - 01, winter: 3.14E - 02) and in dust, children (summer: 9.16E - 03, winter: 8.80E - 03) and adults (summer: 1.38E - 02, winter: 1.33E - 02) during the study period. The isomeric ratios in the study area revealed mixed PAH sources, including vehicular emission, petroleum, diesel and biomass combustion. As a result, it is advised that atmospheric PAHs should be monitored throughout the year and the ecologically friendly fuels be used to prevent PAHs pollution and health concerns in the city. The findings of this study are beneficial to the local regulating bodies in terms of controlling the exposure and promoting steps to reduce PAHs pollution and manage health in Lahore.

Assessment of organochlorine pesticides and health risk in tobacco farming associated with River Barandu of Pakistan.

Diffuse pesticide pollution through tobacco fields is a serious threat to both natural integrities and living beings because tobacco is known as a pesticide-intensive crop. Upsurge in the knowledge of detrimental impacts caused by organochlorine pesticides (OCPs) has made them a burning issue particularly in developing countries. Pakistan is a country famous for its agro-based economy and simultaneously is the second most significant pesticide consumer in South Asian countries. The studied area is tobacco hub of the country. Thus, the present work is aimed to investigate the contamination profile that highlights the ecological and health risk posed by OCPs in River Barandu, located in the proximity of tobacco farming region. ΣOCP levels in sediments ranged between 32.918 and 98.810 ng/g and in water between 0.340 and 0.935 µg/L. Hexachlorocyclohexanes (HCHs) and heptachlor were the most prevailing pesticides in both matrices of the river. Isomeric composition of DDTs and HCHs highlighted that the ß-HCH and p,p'-DDT were dominant isomers in water, while α-HCH and p,p'-DDT in sediment compartment. Enantiomeric compositions of HCH and DDT indicate both recent and historic uses of these compounds in the area. Indirect contamination through nearby tobacco clusters has been depicted through spatial analysis. Ecological risk assessment based upon the risk quotient (RQ) method revealed that α-endosulfan, dieldrin, heptachlor, and ∑HCHs represent a very high level of ecological risks. The OCPs' lifetime carcinogenic and non-carcinogenic health risks associated with dermal exposure to river's water were considered nominal for surrounding populations. However, detailed ecological and health risk studies are recommended considering the bio-accumulating nature of these contaminants in the food chain.

Organochlorine pesticides in the surrounding soils of POPs destruction facility: source fingerprinting, human health, and ecological risks assessment.

The elimination of persistent organic pollutants (POPs) obsolete pesticides stockpiles, particularly the organochlorine pesticides (OCPs), is one of the critical environmental issues faced by many developing countries. This pioneering study aimed to investigate the occurrence, source fingerprinting, human health, and ecological risks of OCPs in the surroundings of the lone POPs pesticide destruction facility in Pakistan. The ΣOCPs residual levels in soil ranged from 35.98 to 566.77 ng/g dry weight (dw), with a mean concentration of 174.42 + 111.62 ng/g (dw). The OCPs contamination levels in the soil followed the pattern as ΣHCHs > Σendrins > Σendosulfans > dieldrin > Σheptachlors > ΣDDTs > Σchlordanes > methoxychlor. The ΣHCHs residual concentrations were comparatively higher than the previous national and global soil studies. The recent accumulation of HCHs, DDTs, and heptachlor was observed in the study area as identified by ß-HCH/∑HCHs, (DDE + DDD)/ΣDDTs, heptachlor/Σheptachlor, and heptachlor exo-epoxide/heptachlor ratios. The OCPs' lifetime carcinogenic risk through ingestion, dermal, and inhalation exposure routes ranged from 1.65E-08 to 2.91E-07, whereas the noncarcinogenic hazard quotient (HQ) ranged from 9.12E-05 to 1.61E-03. The risk vulnerability among age groups was in the order: adult > toddler > child > teen > infant. The calculated risk levels were within an acceptable limit of one in a million (1 × 10-6) for carcinogenic risk and HQ < 1 for noncarcinogenic risk. The current OCPs residual levels, especially dieldrin and endrin, exhibited low to medium ecological risks when compared to various worldwide limits. The upsurge of the OCPs' environmental contamination levels over the years and consideration of the food chain transfer might amplify the human health and ecological risks intensities.

Assessment of polychlorinated biphenyls (PCBs) in the Himalayan Riverine Network of Azad Jammu and Kashmir.

The emission of polychlorinated biphenyls (PCBs) in South Asian countries is one of the great environmental concerns and has resulted in the contamination of surrounding high altitude regions such as Azad Jammu and Kashmir (AJK), Pakistan. This first investigation of Polychlorinated Biphenyl (PCBs) concentrations in the ambient air, water and surface soil was conducted along the extensive stream network in the AJK valley of the Himalayan Region. In 2014, surface soil samples were taken and passive air and water samplers were deployed along the four main rivers, namely Jhelum, Neelum, Poonch and Kunhar, and analysed for PCBs (33 congeners) using GC-MS/MS. The ∑33PCBs concentrations ranged from 31.17 to 175.2 (mean ±â€¯SD: 81 ±â€¯46.4 pg/L), ND to 1908 (1054 ±â€¯588.5 pg/g), and 29.8 to 94.4 (52.9 ±â€¯22.7 pg/m3) in surface water, soil and air matrices, respectively. The levels of dioxin-like PCBs (∑8DL-PCBs) contributed considerably towards the total PCBs concentrations: 60.63% (water), 43.87% (air) and 13.76% (soil). The log transformed air-water fugacity (log fa/fw) ratios ranged from -9.37 to 2.58; with 86.3% of the sampling sites showing net volatilization of selected PCB congeners. Similarly, the fugacity fractions for air-soil exchange exhibited narrow variation (0.8 to < 1) indicating net volatilization of PCBs. The ecological risk assessment showed low potential ecological risks (Eri  = 1.58-7.63) associated with PCB contamination. The present findings provide baseline data that suggest cold trapping of POPs in the remote mountainous areas of Pakistan and can support environmental management of POPs at the regional level. This pioneer investigation campaign to assess the PCBs concentrations in Himalayan Riverine Network of Azad Jammu and Kashmir, Pakistan helps to develop baseline data of PCBs from the strategically important riverine environment that would help in future regional as well as global ecological studies. However, the effects of temperature variations on the sampling rates of chemicals across a wide spectrum of volatility along the elevation gradient were not taken under consideration for PCBs atmospheric concentrations.

Assessment of organochlorine pesticides in the Himalayan riverine ecosystems from Pakistan using passive sampling techniques.

Organochlorine pesticides (OCPs) pose a considerable threat to human and environmental health. Despite most OCPs have been banned, they are still reported to be used in developing countries, including Pakistan. We aimed to identify the distribution, origin, mobility, and potential risks from OCPs in three major environmental compartments, i.e., air, water, and soil, across Azad Jammu and Kashmir valley, Pakistan. The sums of OCPs ranged between 66 and 530 pg/g in soil, 5 and 13 pg/L in surface water, and 14 and 191 pg/m3 in air, respectively. The highest sum of OCPs was observed in the downstream zone of a river that was predominantly influenced by peri-urban and urban areas. The OCP isomers ratios (α-HCH/γ-HCH and o,p'-DDT/p,p'-DDT) indicate use of lindane and technical DDTs mixture as a source of HCH and DDT in the riverine environment. Similarly, the ratios of DDE and DDD/the sum of DDTs, α-endosulfan/ß-endosulfan, and cis-chlordane/trans-chlordane indicate recent use of DDTs, endosulfan, and chlordane in the region. The air-water exchange fugacity ratios indicate net volatilization (fw/fa > 1) of α-endosulfan and trans-chlordane, and net deposition (fw/fa < 1) of ß-endosulfan, α-HCH, γ-HCH p,p'-DDD, p,p'-DDE, and p,p'-DDT. Based on the risk quotient (RQ) method, we consider the acute ecological risks for fish associated with the levels of OCPs as negligible. However, more studies are recommended to evaluate the chronic ecological risks to other riverine-associated aquatic and terrestrial species as well as human health risks to the POPs exposure through food chain transfer in forthcoming years.

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 ß-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 ß-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.

Occurrence, ecological risk assessment, and spatio-temporal variation of polychlorinated biphenyls (PCBs) in water and sediments along River Ravi and its northern tributaries, Pakistan.

Ecological risk assessment, spatio-temporal variation, and source apportionment of polychlorinated biphenyls (PCBs) were studied in surface sediments and water from River Ravi and its three northern tributaries (Nullah Deg, Nullah Basantar, and Nullah Bein) in Pakistan. In total, 35 PCB congeners were analyzed along 27 sampling stations in pre-monsoon and post-monsoon seasons. The ∑35PCB concentration ranged from 1.06 to 95.76 ng/g (dw) in sediments and 1.94 to 11.66 ng/L in water samples, with hexa-CBs and tetra-CBs as most dominant homologs in sediments and water matrixes, respectively. The ∑8DL-PCB levels were 0.33-22.13 ng/g (dw) and 0.16-1.95 ng/L in sediments and water samples, respectively. The WHO-toxic equivalent values were ranged from 1.18 × 10-6 to 0.012 ng/L and 1.8 × 10-6 to 0.031 ng/g in water and sediments matrixes, respectively. The ecological risk assessment indicates considerable potential ecological risk during pre-monsoon season ([Formula: see text] = 95.17) and moderate potential ecological risk during post-monsoon season ([Formula: see text] = 49.11). The industrial and urban releases were recognized as key ongoing sources for high PCB levels in environment. Therefore, we recommend more freshwater ecological studies to be conducted in the study area and firm regulatory initiatives are required to be taken in debt to the Stockholm Convention, 2001 to cop up with PCB contamination on emergency basis.

Use of Mercury in Dental Silver Amalgam: An Occupational and Environmental Assessment.

The objective of this study was to assess the occupational exposure to mercury in dentistry and associated environmental emission in wastewater of Lahore, Pakistan. A total of ninety-eight blood samples were collected comprising 37 dentists, 31 dental assistants, and 30 controls. Results demonstrate that the dentistry personnel contained significantly higher mean concentration of mercury in their blood samples (dentists: 29.835 µg/L and dental assistants: 22.798 µg/L) compared to that of the controls (3.2769 µg/L). The mean concentration of mercury was found maximum in the blood samples of older age group (62.8 µg/L) in dentists and (44.3 µg/L) in dental assistants. The comparison of mercury concentration among dentists, dental assistants, and controls (pairing based on their ages) revealed that the concentration increased with the age and experience among the dentists and dental assistants. Moreover, the mercury concentration in all the studied dental wastewater samples, collected from twenty-two dental clinics, was found to be exceeding the recommended discharge limit of 0.01 mg/L. Therefore, we recommend that immediate steps must be taken to ensure appropriate preventive measures to avoid mercury vapors in order to prevent potential health hazards to dentistry personnel. Strong regulatory and administrative measures are needed to deal with mercury pollution on emergency basis.