Concentrations Of PCBs Research Articles

Persistent organic pollutants and developmental trajectories of ADHD symptoms: The Rhea cohort study

Abstract Background Prenatal exposure to persistent organic pollutants (POPs) has been linked to elevated symptoms related to attention deficit hyperactivity disorder (ADHD) in a few studies, but findings remain inconclusive. We aimed to explore how prenatal exposure to POPs affects the developmental course of ADHD symptoms from early childhood to adolescence in the Rhea cohort in Crete, Greece. Methods We determined concentrations of HCB, DDE, and PCBs in first-trimester maternal serum. Child ADHD symptoms were reported by mothers using the ADHD Test at 4 years and the Conners’ Parent Rating Scale at 6, 11 and 15 years. Group-Based Trajectory Modeling was used to classify 551 participants into 4 distinct groups: Stable low (60.1%), Stable high (9.6%), Low-increasing (14.6%), and High-decreasing (15.7%) symptoms. Adjusted multinomial regression models were applied to assess the risk of being grouped into an adverse developmental trajectory as compared to the reference group (stable low), in relation to prenatal POP exposure in 465 children. The analyses were performed in sex-specific manner. Results Prenatal HCB exposure was associated with elevated risk of being grouped in the stable high ADHD symptoms trajectory only in girls (RRR [95%CI]: 2.0 [1.04, 3.82]). Overall, exposure to DDE and sum of PCBs was linked to decreased risk of membership in an adverse ADHD symptoms trajectory. More specifically, in utero exposure to DDE and sum of PCBs was associated with lower risk of being grouped in the low-increasing trajectory for boys (RRR [95%CI]: 0.7 [0.54, 0.95] and 0.5 [0.32, 0.88], respectively) and in the high-decreasing symptoms group for girls (RRR [95%CI]: 0.6 [0.44, 0.84] and 0.5 [0.30, 0.93], respectively). Conclusions The findings suggest that prenatal exposure to HCB is linked to increased risk of stable high ADHD symptoms from preschool age and up to adolescence. The association was pronounced only in girls, a group for which less is understood in relation to ADHD. Key messages • Prenatal exposure to HCB increases the risk of persistently high ADHD symptoms from preschool age to adolescence. • The impact of prenatal HCB exposure on ADHD symptoms is evident in girls.

Examining Bald Eagle Contaminant Exposure and Reproductive Risk Above and Below Dams on Great Lakes Tributaries

Removing lowermost dams can reestablish fish passage on Great Lakes tributaries. This can increase the transfer of contaminants from anadromous fish to piscivorous wildlife upstream; however, concentrations of bioaccumulative contaminants in Great Lakes fish have decreased over the last several decades. We analyzed concentrations of PCBs and the toxic equivalence (TEQs) calculated from PCBs, DDTs, other organochlorine pesticides, and PBDEs in the plasma of bald eagle nestlings above and below lowermost dams on five river systems in Michigan from 1999 to 2013. We examined relationships between contaminants and metrics of reproductive success from 1997 to 2018, including the effects of year and location relative to the lowermost dam. Σ20PCB and p,p’-DDE were important in characterizing differences in contaminant mixtures above and below dams. Concentrations of contaminants were generally greater below dams than above. There were generally greater nest success and more nestlings per nest below dams, but nest location explained little variability (R2 values = 0.03–0.15). Neither Σ20PCB nor p,p’-DDE was a significant predictor of 5-year productivity means by river reach despite concentrations exceeding previously established effects thresholds for healthy bald eagle populations in the Great Lakes (≥ 1 nestling/nest). Our study indicates that dams may continue to reduce the upstream movement of contaminants to bald eagles, but at the measured concentrations, contaminants did not impair productivity and reproductive success as indicated by nestlings per nest. Additional information about population dynamics could clarify population-level effects of contaminants on bald eagles and to what degree these populations are self-sustaining throughout the Great Lakes.

Application of 3D structure of carbon nanotube-interwoven metal–organic frameworks in solid-phase microextraction of trace polychlorinated biphenyls from tea beverages

A three-dimensional (3D) structure of multiwalled carbon nanotubes (MWCNTs) interwoven metal–organic frameworks (MOFs) was synthesized. The MWCNTs was utilized to bridge the neighboring MOF nanocrystals. The hybrid material MOFs/MWCNTs was used for SPME coating to extract six PCBS in tea beverages samples by gas chromatography coupled to tandem mass spectrometry. MOFs/MWCNTs coating materials were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and N2 adsorption–desorption analysis. The response surface method was utilized to systematically optimize the main extraction factors. Under the optimized conditions, the developed method demonstrated wide linear ranges (0.01–1000 ng·L−1), low limits of detection (0.003–0.009 ng·L−1) and high enrichment factors (701–2361) for extracting and determining six PCBS. The six PCBS concentration in environmental tea beverages samples was detected with this method. These results display that MOFs/MWCNTs hybrid materials are potential sorbents in the SPME of PCBS in environmental tea beverages samples.

Alterations in viscera histoarchitecture and organosomatic index as biomarkers of toxicity induced by Aba-Eku and Olusosun solid waste landfill leachates in Rattus norvegicus.

Solid waste disposal generates leachate, a mixture of deleterious chemical, physical and microbial contaminants, which poses risk to human and wildlife health. Leachate toxicity on relative organ weight and histopathology of important viscera in mammalian body is scarce. Leachate induced toxic effects on organosomatic indices and histopathology of vital mammalian organs were investigated. Wister rats were orally exposed to 1 - 25 % of raw and simulated leachates from Aba-Eku and Olusosun landfills for 30 days. At post-exposure, organosomatic index and histoarchitectural assessment of major viscera (heart, spleen, thymus and lungs) were conducted. The physico-chemical and organic compositions of the leachates were analysed using standard protocol. The tested leachates decreased weekly and terminal body weights, and altered organosomatic index of examined viscera in rats. The histoarchitecture of the investigated viscera revealed pathologies that ranged from mild to severe degeneration, cellular infiltration, haemorrhage, congestion, necrosis, disorganization of tissues and vacuolations. Others include increased histiocytes within the bronchial associated lymphoid, lymphoid depletions, haemosiderin deposits and apoptosis were observed in the examined viscera. Physico-chemical analysis of the leachates showed different concentrations of toxic metals, PAHs and PCBs that were higher than national and international permissible limits allowed in wastewaters. The physico-chemical compositions of the leachates are capable of eliciting the observed alterations in organosomatic indices and histopathological lesions in mammalian viscera. Xenobiotic components of the leachates possibly generated free radicals and/or directly disrupted the organ architectures. These findings suggest health risk to wildlife and human population exposed to emissions from waste landfills.

Characteristics of Anthropogenic Pollution in the Atmospheric Air of South-Western Svalbard (Hornsund, Spring 2019)

The character of atmospheric pollution and its impact on surface waters may vary substantially in space, and hence, we add a potentially important location for the studies of atmospheric air pollution to the map of the High Arctic. We have investigated the anthropogenic particle characteristics and selected persistent organic pollutant concentrations, in a priorly unmonitored location in the Arctic (Svalbard), exposed to a climatic gradient. Single-particle analysis of PM indicates that besides the prevailing natural aerosol particles, anthropogenic ones were present. The likely anthropogenic origin of some particles was established for spherical Fe-rich or aluminosilicate particles formed in high-temperature processes or metal-rich particles of the chemical composition corresponding to industrial products and atypical for natural minerals; soot, tar balls, and secondary sulfate were also likely of anthropogenic origin. Some of the observed anthropogenic particles could only come from remote industrial sources. POP concentrations indicated a background of LRAT, consistent with the ΣPCB concentrations and volatility profile. However, the ΣDDX composition indicating aged sources and an order of magnitude higher concentrations of both ΣDDXs and ΣHCHs than at other High Arctic monitoring stations indicate their potential source in two types of re-emission from secondary sources, i.e., from seawater and snowpack, respectively.

Investigation of organic micropollutant pollution in İzmit Bay: a comparative study of passive sampling and instantaneous sampling techniques.

In this study, we used a comprehensive array of sampling techniques to examine the pollution caused by organic micropollutants in İzmit Bay for the first time. Our methodology contains spot seawater sampling, semi-permeable membrane devices (SPMDs) passive samplers for time-weighted average (TWA), and sediment sampling for long-term pollution detection in İzmit Bay, together. Additionally, the analysis results obtained with these three sampling methods were compared in this study. Over the course of two seasons in 2020 and 2021, we deployed SPMDs for 21days in the first season and for 30days in the second season. This innovative approach allowed us to gather sea water samples and analyze them for the presence of polycyclic aromatic hydrocarbons (Σ15 PAHs), polychlorinated biphenyls (Σ7 PCBs), and organochlorine pesticides (Σ11 OCPs). Using SPMD-based passive sampling, we measured micropollutant concentrations: PAHs ranged from 1963 to 10342pg/L in 2020 and 1338 to 6373pg/L in 2021; PCBs from 17.46 to 61.90pg/L in 2020 and 8.37 to 78.10pg/L in 2021; and OCPs from 269.2 to 8868pg/L in 2020 and 141.7 to 1662pg/L in 2021. Our findings revealed parallels between the concentrations of PAHs, PCBs, and OCPs in both SPMDs and sediment samples, providing insights into the distribution patterns of these pollutants in the marine ecosystem. However, it is worth noting that due to limited data acquisition, the suitability of spot sampling in comparison to instantaneous sampling remains inconclusive, highlighting the need for further investigation and data collection.

Back on top: Resuspended by dredging and other environmental disturbances, organochlorine compounds may affect the health of a dolphin population in a tropical estuary, Sepetiba Bay

Organochlorine compounds (OCs) are persistent organic pollutants linked to damaging the immune and endocrine systems, leading to a greater susceptibility to infectious diseases at high concentrations. Sepetiba Bay, in the Southeastern Brazilian coast, historically presents anthropogenic activities and environmental contamination that could negatively impact resident populations. In this context, this study aimed to investigate the temporal trends in the accumulation of organochlorine compounds over a 12-year database in the Guiana dolphins’ (Sotalia guianensis) resident population from Sepetiba Bay, including individuals collected before, during, and after an unusual mortality event triggered by morbillivirus (n = 85). The influence of biological parameters was also evaluated. The OCs concentrations in the blubber ranged from 0.98 to 739 μg/g of ΣPCB; 0.08–130 μg/g of ΣDDT; <0.002–4.56 μg/g of mirex; <0.002–1.84 μg/g of ΣHCH and <0.001–0.16 μg/g of HCB in lipid weight. Increased temporal trends were found for OCs in Guiana dolphins coinciding with periods of large events of dredging in the region. In this way, our findings suggest that the constant high OCs concentrations throughout the years in this Guiana dolphin population are a result of the constant environmental disturbance in the area, such as dredging. These elevated OCs levels, e.g., ΣPCB concentrations found above the known thresholds, may impair the response of the immune system during outbreak periods, which could lead the population to a progressive decline.

Linking contaminant exposure to embryo aberrations in sediment-dwelling amphipods: a multi-basin field study in the Baltic Sea

Embryo development of sediment-dwelling amphipod Monoporeia affinis is sensitive to contaminant exposure. Therefore, embryo aberrations in gravid females are used to detect the biological effects of contaminant exposure in the Baltic Sea benthic habitats. The indicator based on the aberration frequencies in wild populations (ReproIND) is currently used for environmental status assessment within the Marine Strategy Framework Directive, Descriptor 8.2. However, so far, it has mainly been applied in the Bothnian Sea (BoS) and the Western Gotland Basin (WGB), where it was found to respond to contaminant pressure and non-chemical environmental factors, such as temperature.To expand the applicability of the indicator to other Baltic Sea basins, we used field data from the gulfs of Finland and Riga, BoS, and WGB to investigate the relationships between reproductive disorders and contaminants and environmental factors, thus evaluating the indicator suitability in these areas. Despite the natural variability of the environments and contaminant distribution across and within the basins, we found that high concentrations of contaminants, e.g. metals, PAHs, and PCBs, contribute significantly to the embryo aberrations in M. affinis. These findings support ReproIND applicability in the Baltic Sea and, perhaps, in other marine areas.

Study the regional and seasonal variation of polychlorinated biphenyl in sediments of the Eastern AL-Hammar Marshes, Iraq

Wetland sediments can become contaminated with contaminants that pose a risk to plants and animals and are present in groundwater and fresh surface water entering the wetland. The current study aims to detect PCB contaminants in the sediments of the Al-Hamar Marsh in southern Iraq from the winter season of 2021 until the fall season of 2022 during the day from five stations in the Al-Hamar Marsh, which are (1 - Al-Harir, 2 - Al-Mashab 3 - Al-Nakara, 4 - Baraka 1, 5 - Baraka 2). PCBs were analyzed by GC-MASS. The results showed that the highest rate of PCBs concentrations was (2.84) in the winter season and the lowest rate was (0.14 ng/g d. w). The concentrations of PCBs at the study stations ranged (2.34 ng/g d.w - 3.9 ng/g d.w) during the winter season. (0.01 ng/g d.w-3.7 ng/g d.w) during the spring, (0.01 ng/g d.w- 1.46 ng/g d.w) in the summer, and (0.02 ng/g d.w -5.78 ng/g d.w) during the summer. In the fall, the soil texture was measured and the results showed that the sediments of the Al-hammar marsh were silty clay deposits. This study is a first of its kind in the region and could be give available information and used as a baseline study in the futures.

Balancing conservation, traditional cuisine and pollution: case study of the stingray Hypanus berthalutzae in Pernambuco, Brazil.

Fish is an important food item in the diet of humans, whereas it is also a major source of exposure to toxic chemicals. Persistent organic pollutants (POPs) and mercury (Hg) are known to have hotspots of contamination across the coast of Pernambuco, Brazil. This study investigated organochlorines and Hg in muscle samples from respectively 17 and 14 individuals of the stingray Hypanus berthalutzae - a fishing resource used to prepare a traditional dish in the local cuisine. DDTs, HCHs and mirex were not detected in the samples. Mean concentrations of PCBs, CHLs and total Hg were 0.032, 0.004 and 60 ng g-1 wet weight (ww), respectively. Ecological and biological parameters are important factors in the bioaccumulation of pollutants in fish. Although the concentrations of POPs and Hg do not present a health risk to consumers in general, they may pose a health risk to certain groups such as children and people who eat H. berthalutzae daily. This paper is relevant for the conservation of an endemic stingray species widely consumed in northeastern Brazil and classified as vulnerable in terms of risk of extinction.

Influence of former industrial waste landfill in central Poland on PCBs content in the environment

Influence of former industrial waste landfill in central Poland on PCBs content in the environment

A comparison of stable isotopes and polychlorinated biphenyls among genetic strains of Lake Ontario lake trout (Salvelinus namaycush)

This study quantified stable carbon (δ13C) and nitrogen (δ15N) isotopes, polychlorinated biphenyl (PCB) concentrations and growth rates among multiple genetic strains of Lake Ontario lake trout (Salvelinus namaycush) to evaluate the potential role of genetics in these parameters. Fish ranging in age from 1 to 31 years (n = 72) and representing nine genetic strains including wild-recruits to hatchery fish derived from Lakes Ontario, Superior and Champlain watersheds, and individuals of unknown hatchery origin. Carbon (δ13C) and nitrogen (δ15N) stable isotope values averaged −22.2 ‰ and 17.4 ‰, respectively, but did not differ significantly among genetic strains. ΣPCB concentrations ranged from 42 to 1820 ng/g and varied significantly among individuals including those of similar age and genetic strain. For example, Sum PCB (ΣPCB) concentrations among 7-year-old fish (n = 16) ranged from 159 to 607 ng/g, which compares to growth rates of 3.5 – 32.9 %/yr for these same fish. Multivariate analysis of stable isotope and PCB profiles, however, provided considerable resolution among the strains. For example, fish of unknown hatchery origin ordinated most similar to Seneca Lake fish, the predominant strain stocked in Lake Ontario. Wild fish had a unique ordination with only Lake Superior Klondike strain fish overlapping into their ordination space. Lakes Champlain and Superior strain individuals had similar ordinations but did not overlap substantially with wild or Klondike strain fish. Combined, these differences agree with the ecologies described for these strains in their native ecosystems suggesting that insight can be gained from strain specific evaluations of ecological tracers and these pollutants among Great Lakes lake trout.

Nonlinear-optical piezoelectric electrospun nanofibers

This paper presents a nonlinear optical piezoelectric electrospun nanocomposite of polyvinylidene fluoride (PVDF) nanofibers with embedded nanomaterial of poly {1-[p-(3’-carboxy-4’- hydroxyphenylazo) benzenesulfonamido]-1, 2-ethandiyl} (PCBS). PCBS of different weight ratios are added in-situ to the synthesized PVDF nanofibers. The generated nanofibers mats have been proved to possess both properties of piezoelectric response and nonlinear optical conversion due to the presence of both PVDF and PCBS, respectively. Innovatively, embedding PCBS within the PVDF nanofibers increases the piezoelectric response of the nanocomposite, compared to the case of neat PVDF nanofibers, at certain optimum weight concentrations of PCBS. This has been proved by different piezoelectric measurements at different applied forces and vibration frequencies, along with d33 coefficient measurements and supported by FTIR analysis of beta-sheets. Our results support the evidence of the coupling between the polarized diploes of PCBS and PVDF, which can enhance the overall piezoelectric response. Furthermore, the synthesized nanocomposite shows an optical second harmonic generation (SHG) at optimum concentration of added PCBS within the PVDF nanofibers of around 1 wt.%. The synthesized nonlinear optical nanocomposite of PVDF/PCBS can be multi-functionalized sensors/transducer membranes for biomedical and sensing applications.

Contaminants from dredged sediments alter the transcriptome of Manila clam and induce shifts in microbiota composition

BackgroundThe reuse of dredged sediments in ports and lagoons is a big issue as it should not affect the quality and the equilibrium of ecosystems. In the lagoon of Venice, sediment management is of crucial importance as sediments are often utilized to built-up structures necessary to limit erosion. However, the impact of sediment reuse on organisms inhabiting this delicate area is poorly known. The Manila clam is a filter-feeding species of high economic and ecological value for the Venice lagoon experiencing a drastic decline in the last decades. In order to define the molecular mechanisms behind sediment toxicity, we exposed clams to sediments sampled from different sites within one of the Venice lagoon navigable canals close to the industrial area. Moreover, we investigated the impacts of dredged sediments on clam’s microbial communities.ResultsConcentrations of the trace elements and organic chemicals showed increasing concentrations from the city of Venice to sites close to the industrial area of Porto Marghera, where PCDD/Fs and PCBs concentrations were up to 120 times higher than the southern lagoon. While bioaccumulation of organic contaminants of industrial origin reflected sediments’ chemical concentrations, metal bioaccumulation was not consistent with metal concentrations measured in sediments probably due to the activation of ABC transporters. At the transcriptional level, we found a persistent activation of the mTORC1 signalling pathway, which is central in the coordination of cellular responses to chemical stress. Microbiota characterization showed the over-representation of potential opportunistic pathogens following exposure to the most contaminated sediments, leading to host immune response activation. Despite the limited acquisition of new microbial species from sediments, the latter play an important role in shaping Manila clam microbial communities.ConclusionsSediment management in the Venice lagoon will increase in the next years to maintain and create new canals as well as to allow the operation of the new mobile gates at the three Venice lagoon inlets. Our data reveal important transcriptional and microbial changes of Manila clams after exposure to sediments, therefore reuse of dredged sediments represents a potential risk for the conservation of this species and possibly for other organisms inhabiting the Venice lagoon.

Source characteristics of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in surface soils of Shenyang, China: A comparison of two receptor models combined with Monte Carlo simulation

The surface soil concentrations of 16 PAHs and 15 PCBs were simultaneously determined by gas chromatography-tandem mass spectrometry in 21 locations of urban areas of Shenyang. The average concentrations of PAHs and PCBs were 26.40 ± 34.68 mg/kg and 48.03 ± 27.47 μg/kg, respectively. Factor analysis with nonnegative constraints (FA-NNC) and absolute principal component score with multiple linear regression (APCS-MLR) model were used to explore and evaluate the sources of PAHs and PCBs in the study area. The results of FA-NNC showed that PAHs in soils were mainly from traffic emissions (49.64%), coal combustion (46.88%) and petrogenic source (3.49%). The PCBs in soils were mainly from commercial and high temperature combustion mixed sources (20.3%), combustion and industry emission mixed sources (21.1%), electrical equipment sources (22.2%) and traffic emission sources (36.4%). The results of APCS-MLR were consistent with those of FA-NNC. The uncertainty of FA-NNC and APCS-MLR model was analyzed by Monte Carlo simulation method. The results revealed the reliability of the two receptor models on source apportionment. The estimated carcinogenic risks indicated that the risks of PAHs in soils exceed the acceptable range (10−6-10−4), while the risks of PCBs were below the acceptable risk level of 10−6.

Ecotoxicity of sediments in Ho Chi Minh city’s canals

For an ecotoxicological screening of recently deposited sediments, samples were collected from Ho Chi Minh City’s canals in August 2015. The sediments were characterized by physico-chemical analysis of metals, PAHs, PCBs, and other organic micropollutants, and standard sediment toxicity testing. The results showed that the sediments from the canals from both the urban and suburban areas contained a mixture of contaminants with concentrations of several metals, PAHs, PCBs and OCs being above thresholds for effects to benthic organisms. The results of the chemical analyses were corroborated by toxicity detected in standard laboratory tests with crustaceans (ostracods) and insect (midge) larvae. Conspicuous concentrations at the μg/g level were found for the fragrances galaxolide and OTNE, and nonylphenol, triclosan and the UV filters octocrylene, 2-EHDP and EHMC were measured at all sampling sites at concentrations of several tens and even hundreds ng/g. Highest concentrations were measured for the pyrethroid insecticide permethrin in sediments from the urban area and for the pyrethroid insecticide bifenthrin in sediments from suburban areas (3692.9 ng/g dw and 477.6 ng/g dw, respectively). Insecticides were identified as the most probable contributors to the observed toxicity.

Chlorinated pesticides and PCB residues in the Egyptian Western Desert oases sediments

This preliminary investigation aimed to detect concentrations of chlorinated pesticides and PCBs in 40 sediment samples from three desert oases located in Kharga, Dakhla and Farafra in western Egypt. The residues of 18 PCBs and 16 chlorinated pesticides were measured by GC–MS/MS (SRM) method. The results showed that PCBs and pesticides were present in all studied samples. The concentrations of individual PCBs ranged from undetected to 3.99 ng/g dw in all these sediment samples. The total residue of pesticides (ng/g, dry weight) in sediment samples also varied from 5.18 to 25.92, 5.41 to 29.49, and 5.93 to 24.19 ng/g dw for the Kharga, Dakhla and Farafra Oases, respectively. The concentrations of PCBs and chlorinated pesticides detected in these oasis sediments were lower than that reported for other worldwide locations. According to the recorded concentrations in this baseline study of PCBs and total DDTs, the results revealed the minimal risks to organisms and people in the studied area according to the Effects Range-Low (ERL) and Effects Range-Median (ERM) guideline values.

Impacts of shipyard oil leakage on the PAHs and PCBs occurrence in Xiangshan Bay, China

Here, we studied the shipyard impacts on the distribution of PAHs and PCBs in the semi-enclosed Xiangshan Bay, an important mariculture zone in China. The results showed that the shipyard caused a pollution plume for PAHs but not for PCBs. As characteristic pollutants of oil leakage, the PAHs had concentrations of up to 55.82 ng L−1 in the water, 2235.04 ng g−1 in suspended particulate matter (SPM), and 1489.60 ng g−1 in sediment. The PAHs in water and SPM were dominated by phenanthrene and pyrene that were mostly derived from lubricant and diesel, while those in sediments were dominated by the high-molecular-weight PAHs, such as indeno[1,2,3-c,d]pyrene. In contrast, the PCBs concentrations reached up to 10.17 ng L−1, 79.72 ng g−1, and 124.33 ng g−1 in the seawater, SPM, and sediment samples, respectively, and they did not show spatial patterns affected by the shipyard. Moreover, the health risk assessment indicated that the shipyard discharge caused a substantial PAHs ecological risk to the adjacent and downstream water environment. Therefore, point source discharge in semi-enclosed bays should be paid close attention to due to the strong pollutant transport effect.

Dietary exposure and risk assessment of polychlorinated biphenyls to artisanal fishermen and fish vendors: A case study of Dar es Salaam

AbstractBackgroundFish is one of the main sources of food and income in Tanzania, with 25% of the population depending on fishing activities as a source of food, income, and employment. But fish consumers are vulnerable to exposure to toxic pollutants including PCBs due to the lipophilic nature of the pollutants which accumulate in fish.ResultsThe estimated mean NDL PCBs concentration level was 0.84 ng/g w/w and the mean fish consumption rate among fishermen was 0.4 kg/day. Mean exposure of the fishermen and fish vendors to total PCBs ranged between 9.62 and 36.12 ng/kg bw/day depending on the estimation scenario (lower bound/upper bound) for both normal and higher fish consumers. The general population exposure to total PCBs was 0.4 and 0.8 ng/kg bw/day in lower‐bound and upper‐bound estimation scenarios respectively. The estimated lifetime carcinogenic and non‐carcinogenic hazard indices from intake of estimated total PCBs by fishermen and fish vendors exceeded the recommended tolerable daily intake, TDI, raising serious concerns for adverse health effects to fishermen and fish vendors. However, for the general population, there was no concern for any potential health effects as the estimated hazard indices were far below the recommended levels for intake of total PCBs.ConclusionThe exposure levels of fishermen and fish vendors to PCBs via consumption of Rastrelliger kanagutra (Indian mackerel) in Dar es Salaam are high enough to course serious health concerns, especially for high fish consumers and efforts should be taken to encourage diversification of fish species intake.

Decontamination of recycled LDPE using different washing methods

Post-consumer low density polyethylene samples were analysed for PAHs, PCDD/Fs and dioxin-like PCBs content. Subsequently, various treatments were applied to determine a process capable of decontaminating the plastic samples: extraction with polyethylene glycol at different temperatures with and without agitation; extraction using subcritical and hot water at different temperatures in a basic medium; compound degradation by ultraviolet radiation; and compound degradation by advanced oxidation processes using H2O2. The most effective treatment was extraction with polyethylene glycol (agitated) at 120 °C, reducing contamination by 89%, 85% and 95% of PAHs, PCDD/Fs, and dioxin-like PCBs, respectively. The least effective treatments (subcritical and hot water), maximum reductions of 47% and 19% of PAHs were obtained for the temperatures of 160 °C and 90 °C. UV oxidation increased the toxic equivalency of the samples (calculated using the toxicity equivalency factors) by up to 1400%, through the co-formation of the most toxic congeners, e.g., the non-ortho PCBs