Biological monitoring of indoor-exposure to dioxin-like and non-dioxin-like polychlorinated biphenyls (PCB) in a public building

Metabolic activation of WHO-congeners PCB28, 52, and 101 by human CYP2A6: evidence from in vitro and in vivo experiments

Despite extensive research on the metabolism of polychlorinated biphenyls (PCBs), knowledge gaps persist regarding their isoform-specific biotransformation pathways. This study aimed to elucidate the role of different cytochrome P450 enzymes in PCB metabolism, focusing on WHO-congeners 2,4,4'-trichlorobiphenyl (PCB28), 2,2',5,5'-tetrachlorobiphenyl (PCB52), and 2,2',4,5,5'-pentachlorobiphenyl (PCB101). Utilizing engineered HEK293 cell lines, we investigated the in vitro metabolism of these PCBs by CYP1A2, CYP2C8, CYP2C9, CYP3A4, CYP2A6, and CYP2E1, revealing robust production of hydroxylated metabolites. Our results show that CYP2A6 plays a major role in the metabolism of these congeners responsible for predominant formation of para-position hydroxylated metabolites, with concentrations reaching up to 1.61 µg/L (5,89 nM) for PCB28, 316.98 µg/L (1,03 µM) for PCB52, and 151.1 µg/L (441 nM) for PCB101 from a 20 µM parent PCB concentration. Moreover, concentration-dependent cytotoxic and cytostatic effects induced by reactive intermediates of the PCB hydroxylation pathway were observed in HEK293CYP2A6 cells, for all three congeners tested. CYP2A6 was specifically capable of activating PCBs 28 and 101 to genotoxic metabolites which produced genetic defects which were propagated to subsequent generations, potentially contributing to carcinogenesis. In a clinical study examining CYP2A6 enzyme activity in formerly exposed individuals with elevated internal PCB levels, a participant with increased enzyme activity showed a direct association between the phenotypic activity of CYP2A6 and the metabolism of PCB28, confirming the role of CYP2A6 in the in vivo metabolism of PCB28 also in humans. These results altogether reinforce the concept that CYP2A6 plays a pivotal role in PCB congener metabolism and suggest its significance in human health, particularly in the metabolism of lower chlorinated, volatile PCB congeners.

Release of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) from cigarette butts into the aquatic environment: Levels and ecotoxicity

Discarded cigarette waste may leach toxic elements and can contaminate different environments. In this study, the levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in cigarette butts (CBs) leachates were determined, and the release rate of these pollutants from three CBs types such as smoked CBs with and without tobacco (SCBs and SFs) and unsmoked filters (USFs) were examined. The mean concentration levels of PCBs compounds were Collapse

Key Words

• Cigarette butts
• Leachates
• Organochlorine pesticides
• Polychlorinated biphenyls
• Water bodies

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Affiliation(s)

Hossein Arfaeinia Department of Environmental Health Engineering, Faculty of Health, Bushehr University of Medical Sciences, Bushehr, Iran
Mohammad Reza Masjedi Tobacco Control Research Center (TCRC), Iranian Anti-Tobacco Association, Tehran, Iran
Rasoul Asgariyan Department of Environmental, Esfahan Steel Company, Esfahan, 8477153111, Iran
Farshid Soleimani Tobacco and Health Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Vali Alipour Tobacco and Health Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Sara Dadipoor Tobacco and Health Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Reza Saeedi Department of Health, Safety and Environment (HSE), School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Anis Jahantigh Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran
Ammar Maryamabadi R &D Department, Shakheh Zeytoon Lian Co., Bushehr, Iran

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The catalytic hydro-dechlorination of 2, 4, 4' trichlorobiphenyl at mild temperatures and atmospheric pressure

Polychlorinated biphenyls (PCBs), including all 209 congeners, are designated as persistent organic pollutants (POPs) due to their high toxicity and bioaccumulation in human bodies and the ecosystem. The need for PCB remediation still remains long after their production ban. In this study, a catalytic hydro-dechlorination (HDC) method was employed to dechlorinate 2,4,4'-trichlorobiphenyl (PCB 28), a congener found ubiquitously in multiple environmental media. The HDC of PCB 28 was experimentally studied at mild temperatures viz. ~20, 50, and ~77°C and atmospheric pressure. Et3N (triethylamine) was added as a co-catalyst. The dechlorination rates increased with temperature as well as Et3N dosage, and the HDC pathway was hypothesized based on the product and intermediates observed. The less chlorinated intermediates suggested that the position of the chlorine strongly impacted HDC rates, and the preference of HDC at para positions can be orders of magnitudes higher than the ortho. The activation energy was estimated in the range of 12.4-13.9 kJ/mole, indicating a diffusion-controlled HDC system.Implications: The remediation need for polychlorinated biphenyls (PCBs) still remains long after their production ban around the world. The development of low-cost methods is highly desirable, especially for developing countries, in response to the Stockholm Convention. In this study, the dechorination of a ubiquitously present PCB congener was studied using a catalytic hydro-dechlorination (HDC) method in low temperatures up to ~77°C and was able to achieve near 100% dechlorination in 6 hr. Results indicated that the HDC process can be performed under mild temperatures and atmospheric conditions and can be a potential solution to real world PCB contamination issues.

Polychlorinated biphenyl (PCB) half-lives in humans: A systematic review

This manuscript presents a systematic review of PCB half-lives reported in the scientific literature. The review was completed in accordance with PRISMA guidelines and included a review of almost 1000 peer-reviewed publications. In total, 26 articles were found to report half-lives in humans, with the majority of data coming from studies performed in North America on individuals suspected to have been exposed to PCBs. Terminology for reporting PCB half-lives was inconsistent, so we have attempted to consolidate this and recommend using either "apparent half-life" or "intrinsic half-life" in future studies. Within the literature, values for reported half-lives varied considerably for different PCBs. Less chlorinated PCBs generally have shorter half-lives than more chlorinated PCBs. It was interesting to note the large variability of half-lives reported for the same PCB. For example, the reported half-life for PCB 180 varied by nearly 3 orders of magnitude (0.34 years-300 years). Our review identified that the half-lives estimated were largely dependent on the studied cohort. We discuss the importance of PCB body burden, degree of chlorination and PCB structure, gender, age, breastfeeding, BMI, and smoking status on half-life estimations. We also identified significantly shorter half-lives for some PCBs in occupationally exposed individuals compared to results reported from the general population. PCB half-lives are not the same for every PCB or every individual. Therefore, careful consideration is needed when these values are used in human exposure studies.

Ten years after: findings from the medical surveillance program on Health Effects in High-Level Exposure to PCB (HELPcB)

After the detection of high environmental and occupational exposure to polychlorinated biphenyls (PCBs) in a German recycling company for transformers and capacitors in 2010, the multidisciplinary medical surveillance program "HELPcB" (Health Effects in High-Level Exposure to PCB) was established for former PCB-exposed workers of the company, their family members, employees of surrounding companies, and area residents to investigate potential adverse health effects by PCB exposure in a longitudinal study approach with up to seven examination time points between 2010 and 2019. More than 300 individuals were enrolled into the program. Assessments particularly included plasma and urine concentrations of PCB congeners and their metabolites, clinical laboratory parameters, Comet assay, analysis of telomere length, neuropsychological examinations, psychological screening, abdominal and thyroid ultrasound examination. This review summarizes the main results of the studies conducted in the HELPcB program yielding relevant new data on potential adverse effects of PCB exposure in humans and potential mechanisms that underlie these effects. Even larger studies in PCB-exposed individuals are warranted to confirm the results of this program and to further establish causality between PCB exposure and clinical effects in humans.

A comparative monitoring of maternal and cord serum polychlorinated biphenyls levels from Iranian pregnant women between industrial and urban areas

The aim of this study was to compare maternal and fetal exposure to PCBs in pregnant women from a petrochemical and gas area (PGA) and an urban area (UA), by the analyses of serum samples from mother (MS) and cord (CS). After liquid-liquid extracting, samples were analyzed for 12 PCBs congeners by gas chromatography mass spectrometer. Adjusted multiple linear regression models showed the mean levels (μg/L) of total PCBs in the MS and CS samples from the PGA (1.70 ± 0.81 and 1.19 ± 0.43) were significantly higher than those from UA (1.64 ± 0.75 and 1.07 ± 0.38). PCB 44 was predominant in both MS and CS serum samples, and in both PGA (0.80 ± 0.70 and 0.76 ± 0.67) and UA (0.79 ± 0.39 and 0.67 ± 0.34). A negative correlation was found for PCB 52 as one-unit increase in the cord serum levels was associated with 0.024 g decrease in newborn weight. Similarly, one-unit increase in the maternal serum PCB 18 concentrations were associated with 0.09 and 0.086 cm decrease in newborn height and head circumference. The serum levels of PCB 18 and 52 in the mothers who consumed meat and milk at least 1 meal/week were higher than these who consumed meat and milk never or less than 1 meal/month. The findings in this study indicated that higher maternal exposure to PCBs, as result of living in an industrialized area, leads to higher PCBs accumulation in cord blood, which consequently passes to the developing fetus. These events may cause harmful effects on both them in-utero and afterbirth growth and development.

Inhalation and dermal absorption as dominant pathways of PCB exposure for residents of contaminated apartment buildings

Applications of polychlorinated biphenyls (PCBs) in buildings and their persistence in indoor environments have led to cases of current and highly elevated exposure in humans, despite the global cease of production decades ago. Personal exposure to PCBs was assessed among residents in a social housing estate in Denmark containing both contaminated (n = 67) and non-contaminated (n = 23) apartments. Samples and estimated daily intakes (EDIs) were assessed for 15 PCB congeners, and body burden, which was limited by the dietary data availability, was compared across 7 indicator PCBs, with its sum (PCB_sum7) often applied in European regulation of PCBs. Median PCB_sum7 EDI across measured pathways for exposed residents was 101 ng· (kg bodyweight)^-1· day^-1, with the majority of exposure (60%) coming from inhalation of contaminated indoor air. Calculated from both PCBs measured in indoor air and on hand wipes, dermal absorption estimates showed comparable results and served as a secondary exposure pathway, accounting for 35% of personal exposure and considering selected assumptions and sources of physical-chemical parameters. Estimates revealed that diet was the primary PCB source among the reference group, accounting for over 75% of the PCB_sum7 EDI across exposure routes. When evaluating overall EDIs across the two study groups and including dietary estimates, PCB exposure among exposed residents was around 10 times higher than the reference group. Solely within the exposed population, pathway-specific body burdens were calculated to account for exposure across years of residence in contaminated apartments, where lower chlorinated PCBs were dominant in indoor air. Among these dominant congeners, estimated body burdens of PCB-28 and -52 were significantly correlated with measured serum (r_s = 0.49, 0.45; p < 0.001). This study demonstrates that inhalation and dermal absorption serve as dominant exposure pathways for residents of apartments contaminated with predominantly lower chlorinated PCBs and suggest that predictions of body burden from indoor environment measurements may be comparable to measured serum PCBs.

A Review of Polychlorinated Biphenyls (PCBs) Pollution in the Air: Where and How Much Are We Exposed to?

Polychlorinated biphenyls (PCBs) were widely used in industrial and commercial applications, until they were banned in the late 1970s as a result of their significant environmental pollution. PCBs in the environment gained scientific interest because of their persistence and the potential threats they pose to humans. Traditionally, human exposure to PCBs was linked to dietary ingestion. Inhalational exposure to these contaminants is often overlooked. This review discusses the occurrence and distribution of PCBs in environmental matrices and their associated health impacts. Severe PCB contamination levels have been reported in e-waste recycling areas. The occurrence of high PCB levels, notably in urban and industrial areas, might result from extensive PCB use and intensive human activity. Furthermore, PCB contamination in the indoor environment is ten-fold higher than outdoors, which may present expose risk for humans through the inhalation of contaminated air or through the ingestion of dust. In such settings, the inhalation route may contribute significantly to PCB exposure. The data on human health effects due to PCB inhalation are scarce. More epidemiological studies should be performed to investigate the inhalation dose and response mechanism and to evaluate the health risks. Further studies should also evaluate the health impact of prolonged low-concentration PCB exposure.

Exposure to several polychlorinated biphenyls (PCBs) is associated with chronic kidney disease among general adults: Korean National Environmental Health Survey (KoNEHS) 2015-2017

We investigated the association between major persistent organic pollutants (POPs) exposure and chronic kidney disease (CKD) among general adult population of Korea. For this purpose, a subset of the adult population (n = 1276) participated in Korean National Environmental Health Survey (KoNEHS) Cycle 3 (2015-2017) were analyzed for twenty-four POPs in serum, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), and were derived for estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (uACR). Multivariable linear regression was conducted to assess the association between POPs exposure and CKD-related parameters including eGFR and uACR. As sensitivity analyses, principal component analysis was conducted. Moreover, the U.S. National Health and Nutrition Examination Survey (NHANES) 1999-2004 data were chosen to compare with the observations of the Korean adults. Approximately 7.7% of the Korean adult population possessed CKD based on either eGFR (<60 ml/min/1.73 m²) or uACR (≥30 mg/g) criteria. Among the POPs that were detected in ≥70% of the subjects, PCB153 (β = -1.61, 95% CI: -2.55, -0.67, P = 0.001) and PCB180 (β = -1.47, 95% CI: -2.53, -0.40, P = 0.007) exhibited significant associations with decreased eGFR, especially in females. In male participants, hexachlorobenzene (HCB) was associated with eGFR (β = -0.79, 95% CI: -1.53, -0.04, P = 0.040). Sex-dependent associations with eGFR were also shown in the PCA model. Moreover, the sex-dependent associations of PCBs were similarly observed in the adult populations of the US NHANES. However, POPs exposure was not associated with uACR, regardless of association model or population. The observed associations of PCBs are supported by several experimental studies reported elsewhere. To our knowledge, it is the first report that suggests significant associations of PCBs and HCB with eGFR among general population, and further validations in other populations are warranted.

Application of a pharmacokinetic model in characterizing sources of polychlorinated biphenyl exposure and determining threshold daily intakes for adverse health effects in infants and toddlers

Characterization of PCB exposure sources for vulnerable population groups is essential to minimize the health effects of PCB exposure. At the same time, it is important to consolidate the knowledge on threshold intakes of PCBs for infants and toddlers to prevent health effects. We estimated total PCB concentrations from birth to 2 years of age in children from Slovak and Czech populations, which continue to have high PCB concentrations in breast milk. Using a pharmacokinetic (PK) model, we characterized dominant PCB exposure sources and estimated new threshold estimated daily intakes (TEDI) (above which adverse effects cannot be excluded) for postnatal PCB exposure in infants and toddlers. In the PK model, concentrations of seven indicator PCBs in breast milk and cord blood samples from 291 mother-child pairs from the Slovak birth cohort, and 396 breast milk samples from Czech mothers we used, together with their physiological characteristics and PCB concentrations from other exposure sources (food, dust, air). The estimated total PCB concentrations in children's blood at different ages were compared with threshold PCB concentrations of 500, 700 and 1000 ng·g_lipid^-1 in serum proposed by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) and the German Environment Agency (UBA), above which possible adverse health effects may be expected. We estimated that up to 20.6% of Slovak children and up to 45.7% of Czech children at two years of age exceeded the threshold value of 700 ng·g_lipid^-1 in blood. Mean TEDIs leading to values of 500 ng·g_lipid^-1 in blood for children up to two years ranged between 110 and 220 ng·kg^-1·bw·day^-1, varying according to breastfeeding duration. Breast milk and prenatal exposure contributed to 71%-85% of PCBs exposure at two years of age. In contrast, the contributions of PCBs from dust and indoor air were negligible.

Decomposition Products of the Initiator Bis(2,4-dichlorobenzoyl)peroxide in the Silicone Industry: Human Biomonitoring in Plasma and Urine of Workers

Bis(2,4-dichlorobenzoyl)peroxide (2,4-DCBP) is used as an initiator for silicone rubber production. During hot curing, 2,4-DCBP decomposes into 2,4-dichlorobenzoic acid, 1,3-dichlorobenzene, and the polychlorinated biphenyl (PCB) congeners PCB-47, PCB-51, and PCB-68. The extent of occupational exposure to these decomposition products has not been investigated yet. We determined for the first time the corresponding internal exposure of employees (n = 104) of a German silicone rubber facility by human biomonitoring in plasma and urine. Collected samples were investigated by gas chromatography/mass spectrometry for levels of PCBs in plasma and by liquid chromatography/tandem mass spectrometry for urinary post-shift levels of 2,4-dichlorobenzoic acid (2,4-DCBA) and the metabolites 3,5-dichlorocatechol (3,5-DCK), 2,4-dichlorophenol (2,4-DCP), and 3,5-dichlorophenol (3,5-DCP). PCB-47 and PCB-68 levels correlated significantly and were found in >97% of all samples with maximum values of 4.43 and 0.77 μg/L, respectively. 2,4-DCBA, 3,5-DCK, 2,4-DCP, and 3,5-DCP were quantified in >80% of all urine samples with maximum levels of 1.46; 26.92; 7.68; and 0.39 mg/L, respectively. There is a considerable uptake of decomposition products of 2,4-DCBP in workers of a silicone rubber facility, affecting employees in all work areas. Individual levels depended on the work task. Considering the carcinogenic potential of PCBs, the workers' additional exposure to PCB-47 and PCB-68 might be of concern.

Modelling past human internal exposure to lower chlorinated indicator PCBs using proxies - A calculation based on multiple longitudinal PCB analyses

Polychlorinated biphenyls (PCBs) are persistent organic pollutants with former applications in electric transformers, capacitors, hydraulic fluids or joint sealants. While current internal exposure to PCBs can be readily assessed by human biomonitoring, the evaluation of longgone past exposures, in particular the estimation of past exposure to lower chlorinated non-dioxin-like PCB 28, 52 or 101 is limited due to the relatively short biological half-life of these PCB-congeners. This study was aimed to find a proxy that would allow an estimation of the former plasma level for these congeners even several years after exposure cessation. We used biomonitoring data of the German HELPcB cohort with six consecutive follow-up investigations and identified the congeners PCB 66, 74 and 99 as suitable proxies for the congeners of interest. The biological half-lives of the proxies as well as their individual correlation with the plasma levels of PCB 28, 52 and 101 was considered in the calculation models. The correlation coefficients and the inter correlation coefficient 3 (ICC3) between measured and calculated initial values were applied for validation. For external validation purposes we used longitudinal biomonitoring data from two different cohorts with indoor exposure to lower chlorinated PCBs. The backward estimation from current PCB 74 levels to former PCB 28 levels led to an ICC3 of 0.682 and a correlation of rho = 0.724 within the HELPcB cohort. The external validation revealed an ICC3 of 0.723 and a correlation of rho = 0.654. The external validation for PCB 101 was feasible, but measures were not comparably good (ICC3 = 0.460; Rho = 0.516). External validation for PCB 52 was not successful, maybe due to the lower level of burden. Our model shows that a rough estimation of former plasma levels of lower chlorinated PCBs is possible even years after exposure cessation using current measurements of PCB74.

PCB plasma level in different occupational groups in Iran

Despite the ban of polychlorinated biphenyls (PCBs) some decades ago, concerns regarding their adverse health effects are continuing, because the workers employed for installation and repair of electrical equipment may be still exposed to PCBs. This study aimed to assess serum PCBs levels in workers in different industries. To do this, we determined the serum concentrations of 9 non-dioxin-like PCBs and 12 dioxin-like PCBs in 147 workers from seven occupational groups and 35 housewives. An electrical distribution company, paint manufacturer, and pesticide manufacturer were categorized as high probability exposure jobs, whereas turning and casting operations, polymer plastic manufacturing, professional driving, and office work were categorized as low probability exposure jobs. In addition, the average of PCB 138, 153, and 180 and PCB sums were observed to be significantly higher in paint manufacture workers compared to the another groups. In addition, the average PCB 118 level was higher in electrical distribution workers and housewives. Following the adjustment for age, blood lipid, residency place, and seafood in the regression model, the association of PCB 118 in electrical distribution workers and PCB 153 in paint manufacture workers remained significant. The results of this study served as further support for the hypothesis for an occupational basis for bioaccumulation of some PCB types. However, the plasma levels of almost all PCB congeners in Iran were found to be lower than many other countries.

Contamination of polychlorinated biphenyls in honey from the Brazilian state of Rio Grande do Sul

Persistent organic pollutants are characterised by their chemical structure, environmental persistence and toxicity to human and wildlife populations. The production of these chemicals is regulated and restricted. However, they continue to be detected in the environment. In this study, the occurrence of 11 congeners of polychlorinated biphenyls (PCBs 28, 52, 77, 81, 101, 118, 126, 138, 153, 169, and 180) was investigated in 90 honey samples produced in the Brazilian state of Rio Grande do Sul. The samples were from different municipalities, production systems and floral origins. Extraction was performed using the modified QuEChERS method (Quick, Easy, Cheap, Effective, Rugged and Safe) followed by gas chromatography with micro-electron capture detector. The results showed the presence of four congeners (PCBs 28, 77, 81, 101) in 15 honey samples confirming the environmental contamination in Southern Brazil. Among the contaminated samples, no significant differences were identified regarding the production system and floral origin.

Estimating plasma half-lives of dioxin like and non-dioxin like polychlorinated biphenyls after occupational exposure in the German HELPcB cohort

Polychlorinated biphenyls (PCBs) are carcinogenic persistent organic pollutants that have been used as mixtures in transformers, electrical capacitors or hydraulic oils in underground mining until their ban in the late 1980s in Germany. The widespread use of PCBs has led to an age-dependent body burden in the general population. In order to determine the human half-lives of different PCB-congeners, we have used data collected between 2010 and 2017 from the prospective investigation of the German HELPcB-cohort with high initial occupational exposure to PCBs from a transformer recycling company. PCBs were quantified in plasma of the study participants in six cross-sectional investigations using gas-chromatography coupled to mass-spectrometry. Applying logistic regression on the individual plasma levels after statistical elimination of outliers, the elimination half-lives of 18 PCB-congeners were determined. Further stratifications were performed using adjustment for blood lipids, calculation of the total amount of PCB in the body and by using a statistical model taking into account the individual age-dependent background burden. The calculated plasma half-lives ranged from 0.8 years for PCB 52 until a maximum of 28.9 years for PCB 189, depending on the model applied. E.g. the total body amount related half-live for PCB 28 is 2.41 years, for PCB 74 it is 12.81 years, for PCB 118 it is 6.65 years and for PCB 153 = 10.75 years. The model with adjustment for age dependent background burden led to shorter half-lives. The analysis revealed structure-related differences in the kinetics for the PCB-congeners examined. Congeners with a chlorine substitution in 2,4,(5)- and 4'-position showed longer half-lives than other isomers with one (or two) free 4-positions. Due to the high number of included cases and repeated measurements, our results provide valid half-live data for a large number of PCB congeners. Using these data, a rough estimation of former occupational exposures from current PCB-levels seems feasible.

Informal e-waste recycling and plasma levels of non-dioxin-like polychlorinated biphenyls (NDL-PCBs) - A cross-sectional study at Agbogbloshie, Ghana

Informal e-waste recycling leads to a contamination of the workers with several hazardous substances, in particular heavy metals and persistent organic pollutants (POPs). Polychlorinated biphenyls (PCBs) belong to the group of POPs and are suspected to be associated with adverse health effects. In particular lower chlorinated PCBs, such as the congeners PCB 28 and PCB 52 are a marker of occupational exposure. The aim of our study was to assess the occupational PCB exposure in e-waste workers in relation to their specific recycling task (e.g. dismantling, burning). Altogether, n = 88 e-waste workers and n = 196 control subjects have been included in this study. All plasma participant's samples were evaluated for the PCB congeners PCB 28, 52, 101, 138, 153, 180 and sum of NDL-indicator congeners by human biomonitoring. A significant difference could be detected for the lower chlorinated PCB congeners (PCB 28, 52, and 101) for e-waste workers in comparison to the control group. Analyzing specific recycling tasks, workers who dismantle and those who burn e-waste showed the highest plasma levels of PCB 28 and 52. In conclusion, e-waste workers showed occupational related elevated PCB levels. Although those levels did not exceed the BAT value, workers were contaminated with PCBs during their task. Occupational health and safety measure are therefore necessary to protect the worker's health.

Association of plasma levels of lipid and polychlorinated biphenyls in Iranian adult

Background

Exposure to Polychlorinated biphenyls (PCBs) continues over the world through seafood consumption and indoor exposure to building materials containing PCB. This study aimed to assess the relationship between plasma level of PCB congeners and lipid profile and Body Mass Index (BMI) as well.

Methods

The study population consisted of 181 Iranian adults. Data on BMI, plasma concentration of PCB congeners and serum level of lipid profile including Triglyceride, low-density lipoproteins and high-density lipoproteins, recruited from database of a project entitled “Occupational and environmental exposure to PCBs in Iran”. Multiple linear regression analysis of associations between different quartiles of PCB congeners and various lipid fractions and BMI have been conducted.

Results

A linear increase in average serum Triglyceride and low-density lipoproteins (LDL) levels of participants in first, second, third and fourth quartiles of some PCB congeners was obtained. Following adjustment for age, gender, diet and other variables, only the association between different quartiles of PCB 138, PCB 153, PCB 118 and PCB sum and TG remained statistically significant.

Conclusion

The study showed a significant positive relation between plasma PCBs concentrations and serum level of TG in the study population with normal PCBs levels.

Dynamics of PCB exposure in the past 50 years and recent high concentrations in human breast milk: Analysis of influencing factors using a physiologically based pharmacokinetic model

In this study we reconstruct the long-term exposure of Czech mothers to polychlorinated biphenyls (PCBs) and determine the causes of high contamination of breast milk by indicator PCBs (iPCBs). A data set containing information from more than 1000 primiparous women from the Czech Republic was used, including iPCB concentrations in breast milk, individual physiology and living characteristics. The time series of PCB intakes for the whole period from the beginning of PCB production in 1958 until 2011 were reconstructed. We estimated the individual lifetime exposure of mothers for all iPCBs, i.e. congeners 28, 52, 101, 118, 138, 153 and 180, using a physiologically based pharmacokinetic (PBPK) model. Various model scenarios were investigated to determine the influence of physiology, age at delivery, past dietary exposure, and food composition on concentrations in breast milk for all iPCBs. The highest contributions to the presence of iPCBs in breast milk were observed for food composition. The main factor determining the concentration of higher-chlorinated PCBs (138, 153 and 180) was past exposure. The most important parameter for identification of children's postnatal exposure through breast milk was the time-span from the maximum of the exposure peak to the birth of the child. The current concentrations of iPCBs in breast milk in the Czech population are still high because the maximum of the exposure peak occurred more than 10 years later than in other European countries and was very broad, e.g. covered more than 10 years.

Functional and structural liver abnormalities in former PCB exposed workers - analyses from the HELPcB cohort

The effects of polychlorinated biphenyls (PCB) on liver function and structure are still under debate. Although higher transaminase activity and tumor promoting potential of PCB reported for animal and human studies was suggested, these studies were not able to provide definitive evidence on the ability of these chemicals to affect liver function and contribution to tumor development. The aim of this study was to determine the influence of PCB on liver function and morphology in a cohort of former PCB exposed workers. Over 5 years, a longitudinal analysis of the association between PCB concentration and hepatic transaminases such as alanine transaminase (ALT) aspartate amino transaminase (AST) and gamma glutamyltransferase (γGT), as well as liver size and structure was undertaken. Data demonstrated a significant inverse association between PCB concentration and γGT activity levels but there was no marked relationship with AST and ALT activities. Regarding sonographic examination, a significant association was found between liver size and PCB concentration. This association remained, even after adjusting for alcohol consumption, liver affecting drugs, timespan of internal exposure, or age. No marked correlation was noted between PCB concentration and liver structure changes. In summary, an association was observed between PCB concentration and γGT activity levels as well as liver size in humans. The long-term health consequences attributed to PCB on liver and in particular in tumorigenesis are not foreseeable in our cohort thus far, but remain a focus in further ongoing surveillance.

Telomerase gene expression bioassays indicate metabolic activation of genotoxic lower chlorinated polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are ubiquitously occurring pollutants with different chemical and toxicological properties. In this study we evaluated blood plasma samples of two PCB-exposed cohorts for their ability to alter telomerase (hTERT) gene expression. Blood plasma from PCB-exposed individuals inhibited hTERT expression depending solely on the concentration of lower chlorinated PCBs, with the lowest observed adverse effect level (LOAEL) at a plasma concentration between 0.5 and 2 µg/L of LC PCBs. Individual OH-metabolites derived from the WHO indicator congeners PCB 28 and PCB 101 mimicked these effects on hTERT expression in vitro with high toxicity, including DNA damage. However, by the combination of different OH-metabolites, the bio effective PCB concentration was reduced and the respective effects on hTERT expression could be increased. At a concentration which showed no toxic activity in MTT assay, hTERT inhibition reflected the interference of OH-PCBs with the mitochondrial respiratory chain, which could lead to the production of reactive oxygen species (ROS). As individual OH-metabolites already showed a much stronger inhibition of hTERT gene expression at a lower concentration than their parental compounds, the hTERT gene expression bioassay described in this study seems to indicate metabolic activation of LC PCBs rather than the mere effect of LC PCBs on their own. In summary, this study provides dose-response linkages between effects of lower chlorinated PCBs and their concentrations in human plasma.

Revisiting the Contributions of Far- and Near-Field Routes to Aggregate Human Exposure to Polychlorinated Biphenyls (PCBs)

The general population is exposed to polychlorinated biphenyls (PCBs) by consuming food from far-field contaminated agricultural and aquatic environments, and inhalation and nondietary ingestion in near-field indoor or residential environments. Here, we seek to evaluate the relative importance of far- and near-field routes by simulating the time-variant aggregate exposure of Swedish females to PCB congeners from 1930 to 2030. We rely on a mechanistic model, which integrates a food-chain bioaccumulation module and a human toxicokinetic module with dynamic substance flow analysis and nested indoor-urban-rural environmental fate modeling. Confidence in the model is established by successfully reproducing the observed PCB concentrations in Swedish human milk between 1972 and 2016. In general, far-field routes contribute most to total PCB uptake. However, near-field exposure is notable for (i) children and teenagers, who have frequent hand-to-mouth contact, (ii) cohorts born in earlier years, e.g., in 1956, when indoor environments were severely contaminated, and (iii) lighter chlorinated congeners. The relative importance of far- and near-field exposure in a cross-section of individuals of different age sampled at the same time is shown to depend on the time of sampling. The transition from the dominance of near- to far-field exposure that has happened for PCBs may also occur for other chemicals used indoors.

Mono-, di-, and trichlorinated biphenyls (PCB 1-PCB 39) in the indoor air of office rooms and their relevance on human blood burden

Exposure to polychlorinated biphenyls (PCBs) from indoor air can lead to a significant increase in lower chlorinated congeners in human blood. Lower chlorinated congeners with short biological half-lives can exhibit an indirect genotoxic potential via their highly reactive metabolites. However, little is known about their occurrence in indoor air and, therefore, about the effects of possible exposure to these congeners. We analyzed all mono-, di-, and trichlorinated biphenyls in the indoor air of 35 contaminated offices, as well as in the blood of the 35 individuals worked in these offices for a minimum of 2 years. The median concentration of total PCB in the indoor air was 479 ng/m³ . The most prevalent PCBs in the indoor air samples were the trichlorinated congeners PCB 31, PCB 18, and PCB 28, with median levels of 39, 31, and 26 ng/m³ , respectively. PCB 8 was the most prevalent dichlorinated congener (median: 9.1 ng/m³ ). Monochlorinated biphenyls were not detected in relevant concentrations. In the blood samples, the most abundant congener was PCB 28; nearly 90% of all mono-, di-, and trichlorinated congeners were attributed to this congener (median: 12 ng/g blood lipid).

Long-term time trends in human intake of POPs in the Czech Republic indicate a need for continuous monitoring

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) from the group of persistent organic pollutants are detected in human tissues years or even decades after their ban. Exposure to PCBs and OCPs can pose risks to human health. In the present study, we calculated the daily intakes of PCBs and OCPs in the Czech population and investigated the long-term trends of human exposure to POPs. Data on POP concentrations from a 16-year period of breast-milk monitoring were used. A toxicokinetic model with consideration of compound-specific elimination half-lives was used to calculate the mothers' daily intake of PCBs and OCPs representing the intake of POPs by all exposure routes. The calculated intakes were compared with dietary intakes calculated by the Czech National Institute of Public Health. The comparison shows good agreement of both intake estimates with decreasing intake trends of POPs in the Czech population in the time period studied. However, several fluctuations with peaks of higher levels were observed in both datasets which are not typical for the period after the ban of use and production of POPs. The available evidence suggests that the increases in chemical concentrations might be caused by food contamination. The calculated intakes of compounds with longer elimination half-lives, such as higher-chlorinated PCBs, were higher in older mothers. This "memory effect" was already observed in other studies and indicates higher exposure in earlier life periods of the mother. Our results suggest that exposure to POPs is still relevant for the Czech population in the period after the ban of the use and production of POPs (post-ban period), especially via food ingestion, though the intake trends are decreasing. Possible food contamination by POPs in the post-ban period requires further assessment.

Use of plasma exchange or double filtration plasmapheresis to reduce body burden of polychlorinated biphenyls: A pilot trial

The aim of the study was to examine whether plasma exchange (PE) or selective double filtration plasmapheresis (DFPP) is able to reduce the internal Polychlorinated biphenyl (PCB) burden of highly exposed participants of the health effects in high-level exposure to PCB (HELPcB) cohort. HELPcB is a surveillance program for former PCB-exposed workers of a German capacitor recycling company. After comparative evaluation of PE and DFPP in a phase I, DFPP was chosen as method for further treatment. In phase II, five participants underwent DFPP at weekly intervals for the duration of 12 weeks. Six PCB species were selected as indicators and were analyzed in the plasma before and after each treatment and 4 weeks after the last treatment. The PCB levels before and after each DFPP treatment showed a significant reduction in PCB blood levels; however, there was no significant change in PCB levels within the samples collected before each treatment as compared with the samples collected in the following week before treatment. Even the difference between PCB levels at the onset of the study and 4 weeks after the last treatment was not significant. The results of this pilot trial do not encourage further investigations in using therapeutic apheresis to reduce the PCB body burden.

Developmental neurotoxicants in human milk: Comparison of levels and intakes in three European countries

Developmental neurotoxicants (DNTs), such as methylmercury (MeHg), polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs), have gained increasing interest recently due to their possible relation to developmental disorders in children, which are increasing worldwide. We analyzed levels of 14 developmental neurotoxicants in human milk samples from Slovakia (n=37), the Netherlands (n=120) and Norway (n=388). Positive identification for most target analytes was >95% in all samples. In all three countries MeHg was measured for the first time in mother milk. The highest MeHg levels were observed in Norway (39pgg^-1 ww) with the highest fish consumption. Levels of indicator PCBs (iPCBs, sum of PCB 28, 52, 101, 138, 153 and 180), HCB and DDE+DDT were 2-4 times higher in Slovakia compared to the Netherlands or Norway. The levels of MeHg and organochlorine compounds were used for calculations of weekly or daily intakes (top-down approach) by means of pharmacokinetic modeling. The intakes ranged from 0.014 to 0.142μgkg_bw^-1week^-1 for MeHg and from 0.043 to 17.4ngkg_bw^-1day^-1 for organochlorine compounds in all three countries. Intakes of iPCBs exceeded a tolerable daily intake of 10ngkg_bw^-1day^-1 in 16% of the Slovak participants. The top-down estimates were compared with bottom-up intakes based on national dietary estimates and the results showed good consistency between both approaches, with the bottom-up intakes exceeding the top-down by a factor of maximum 3.8 for iPCBs in the Netherlands and 3.9 for HCB in Slovakia. This confirms that food consumption in all three countries represents the dominant pathway of exposure to these developmental neurotoxicants.

Determination of hydroxylated polychlorinated biphenyls (OH-PCBs) in human urine in a highly occupationally exposed German cohort: New prospects for urinary biomarkers of PCB exposure

The present study evaluates for the first time the determination of 20 hydroxylated polychlorinated biphenyl (OH-PCB) congeners and their glucuronide and sulfate conjugates in urine as a biomarker of exposure to PCBs in humans. Thereby, a fast, sensitive and selective online solid phase extraction (SPE) method coupled to LC-MS/MS was validated for the determination of OH-PCBs in human urine, being previously successfully developed and applied for the separation and quantitation of OH-PCBs in human plasma. The lowest limit of quantification (LLOQ) ranged from 0.01 to 0.19ngmL^-1 and average extraction recoveries from 79 to 125% for all hydroxylated congeners. Within-run precision and between-run precision were between 2 and 17%. Extraction recovery tests were also performed in urine with different creatinine contents (0.52-3.92gL^-1) for an estimation of matrix influences and ranged between 69 and 125%. In order to evaluate the applicability of the method, the study was conducted in three different groups, which were distinctly separated as non-exposed to known sources of PCBs (N=21), low-to-moderate PCB-exposed individuals (N=25) and highly occupationally PCB-exposed individuals (N=25), which included workers of a transformer recycling plant, their relatives and workers of surrounding companies from a German cohort. As part of the biomonitoring program HELPcB (Health Effects in High-Level Exposure to polychlorinated biphenyls), urine and blood samples were collected annually from 2010 to 2014. In this way, OH-PCB elimination profile in urine over time, correlations between OH-PCB levels in human plasma and urine, and associations with their parent compounds in plasma of the studied PCB cohort could be also assessed. Tri-chlorinated OH-PCBs were the predominant congeners in urine with concentrations up to 174ngmL^-1. High chlorinated OH-PCBs (penta- through hepta-chlorinated OH-PCBs) were also frequently detected in urine samples from non-exposed and occupationally exposed individuals, although levels were in general very low or lower than LLOQ.

Exposure to polychlorinated biphenyls and the thyroid gland - examining and discussing possible longitudinal health effects in humans

BACKGROUND

Many previous studies have dealt with the effect of polychlorinated biphenyls (PCBs) on the thyroid gland, but their findings are inconsistent. One problem of these studies has been their use of cross-sectional designs.

OBJECTIVES

The aim of the current study is to investigate longitudinal effects of PCBs on the thyroid gland, focusing on: morphological changes in thyroid tissue (i.e. thyroid volume), changes in thyroid hormones and in thyroid antibodies.

METHODS

A total of 122 individuals (Mage=44.7) were examined over a period of four years (t(1) until t(4)). Medical history was collected via interviews, an ultrasound examination was performed and blood samples were taken to determine plasma PCB levels, thyroid stimulating hormone (TSH), free triiodthyronine (fT3), free thyroxine (fT4), thyroid peroxidase antibodies (TPOab), thyreoglobulin antibodies (TGab) and thyroid-stimulating hormone receptor antibodies (TSHRab). Rank correlation coefficients and mixed effect models were performed controlling for age and total lipids.

RESULTS

There were negative correlations between higher chlorinated biphenyls and fT3, cross-sectionally as well as longitudinally. We also found an interaction effect of higher-chlorinated PCBs over time for fT4 as well as TSHRab. In case of high exposure, a decrease in fT4 and an increase in TSHRab level were found over time. In regards to the other variables, our findings yielded no clear results in the examined time period.

CONCLUSION

This is the first study to shows a PCB-related effect on fT3, fT4 and TSHRab over a four year period. The data also suggest that morphological and antibody findings remain inconsistent and do not allow for unambiguous interpretation.

Health Effects of PCBs in Residences and Schools (HESPERUS): PCB - health Cohort Profile

Polychlorinated-biphenyls (PCBs) were introduced in the late 1920s and used until the 1970s when they were banned in most countries due to evidence of environmental build-up and possible adverse health effects. However they still persist in the environment, indoors and in humans. Indoor air in contaminated buildings may confer airborne exposure markedly above background regional PCB levels. To date, no epidemiological studies have assessed the health effects from exposure to semi-volatile PCBs in the indoor environment. Indoor air PCBs are generally less chlorinated than PCBs that are absorbed via the diet, or via past occupational exposure; therefore their health effects require separate risk assessment. Two separate cohorts of individuals who have either attended schools (n = 66,769; 26% exposed) or lived in apartment buildings (n = 37,185; 19% exposed), where indoor air PCB concentrations have been measured were created. An individual estimate of long-term airborne PCB exposure was assigned based on measurements. The cohorts will be linked to eight different national data sources on mortality, school records, residential history, socioeconomic status, and chronic disease and reproductive outcomes. The linking of indoor air exposures with health outcomes provides a dataset unprecedented worldwide. We describe a project, called HESPERUS (Health Effects of PCBs in Residences and Schools), which will be the first study of the long term health effects of the lower-chlorinated, semi-volatile PCBs in the indoor environment.

Associations between plasma concentrations of PCB 28 and possible indoor exposure sources in Danish school children and mothers

BACKGROUND

Polychlorinated biphenyls (PCBs) are ubiquitously present in the environment and are suspected of carcinogenic, neurotoxic and immunotoxic effects. Significantly higher plasma concentrations of the congener PCB 28 occur in children compared to adults. Exposure in schools may contribute to this difference.

OBJECTIVE

To determine whether increased blood plasma concentrations of PCB 28 in Danish school children and mothers are associated with living in homes or attending schools constructed in the PCB period (1959-1977).

METHODS

PCB 28 was analyzed in plasma samples from 116 children aged 6-11years and 143 mothers living in an urban and a rural area in Denmark and participating in the European pilot project DEMOCOPHES (Demonstration of a study to COordinate and Perform Human Biomonitoring on a European Scale). In Denmark, PCBs were used in construction in the period 1950-1977, and year of construction or renovation of the homes and schools was used as a proxy for indoor PCB exposure. Linear regression models were used to assess the association between potential PCB exposure from building materials and lipid adjusted concentrations of PCB 28 in plasma, with and without adjustment for potential confounders.

RESULTS

Among the 116 children and 143 mothers, we were able to specify home construction period in all but 4 children and 5 mothers leaving 111 children and 138 mothers for our analyses. The median lipid adjusted plasma PCB 28 concentration was 3 (range: 1-28) ng/g lipid in the children and 2 (range: 1-8) ng/g lipid in the mothers. Children living in homes built in the PCB period had significantly higher lipid adjusted plasma PCB 28 concentrations compared to children living in homes built before or after the PCB period. Following adjustment for covariates, PCB 28 concentrations in children were 40 (95% CI: 13; 68) percent higher than concentrations of children living in homes constructed at other times. Furthermore, children attending schools built or substantially refurbished in the PCB period also had significantly higher (46%, 95% CI: 22; 70) PCB 28 concentrations compared to children attending schools constructed before or after the PCB period, while their mothers had similar concentrations. Adjustment for the most prevalent congener, PCB 153, did not change this effect of home or school construction. When both home and school construction year were included in the models, the increase in lipid adjusted plasma PCB 28 for children living in or attending schools from the PCB period was no longer statistically significant. The individual effect of home and school construction periods could not be evaluated further with the available data.

CONCLUSION

Our results suggest that PCB exposure in the indoor environment in schools and homes constructed during the PCB period may contribute significantly to children's plasma PCB 28 concentration. Efforts to minimize PCB exposure in indoor environments should be considered.

Exposure to 27 polychlorinated biphenyls in the indoor environment of a workplace: a controlled bio-monitoring study

PURPOSE

To assess the exposure to a broad-spectrum of polychlorinated biphenyl congeners (PCBs) from the indoor environment through bio-monitoring of people working in a building with PCB-containing materials and elevated PCB levels in the indoor air.

METHODS

A cross-sectional study comparing the plasma concentration of 27 PCB congeners in 15 people working in a PCB-contaminated building and 30 matched controls.

RESULTS

Median concentration of eight low-chlorinated PCB congeners was significantly higher in the exposed than in the control group. The sum of median concentrations of tri + tetra-chlorinated PCB was almost ten times higher in the exposed group than in the unexposed, and sums of dioxin-like and non-dioxin-like PCB were both relatively increased by 60 % in the exposed group.

CONCLUSIONS

The occupational indoor environment may significantly add to PCB exposure, especially to the lower-chlorinated congeners. Health effect from this little-acknowledged exposure has not yet been documented, but data supporting lack of effect are sparse and research generating information on effect of exposure to specific congeners including at levels relevant for the indoor environment should be encouraged.

Evaluating health risks from inhaled polychlorinated biphenyls: research needs for addressing uncertainty

BACKGROUND

Indoor air concentrations of polychlorinated biphenyls (PCBs) in some buildings are one or more orders of magnitude higher than background levels. In response to this, efforts have been made to assess the potential health risk posed by inhaled PCBs. These efforts are hindered by uncertainties related to the characterization and assessment of source, exposure, and exposure-response.

OBJECTIVES

We briefly describe some common sources of PCBs in indoor air and estimate the contribution of inhalation exposure to total PCB exposure for select age groups. Next, we identify critical areas of research needed to improve assessment of exposure and exposure response for inhaled PCBs.

DISCUSSION

Although the manufacture of PCBs was banned in the United States in 1979, many buildings constructed before then still contain potential sources of indoor air PCB contamination. In some indoor settings and for some age groups, inhalation may contribute more to total PCB exposure than any other route of exposure. PCB exposure has been associated with human health effects, but data specific to the inhalation route are scarce. To support exposure-response assessment, it is critical that future investigations of the health impacts of PCB inhalation carefully consider certain aspects of study design, including characterization of the PCB mixture present.

CONCLUSIONS

In certain contexts, inhalation exposure to PCBs may contribute more to total PCB exposure than previously assumed. New epidemiological and toxicological studies addressing the potential health impacts of inhaled PCBs may be useful for quantifying exposure-response relationships and evaluating risks.

Inhalation and dietary exposure to PCBs in urban and rural cohorts via congener-specific measurements

Polychlorinated biphenyls (PCBs) are a group of 209 persistent organic pollutants, whose documented carcinogenic, neurological, and respiratory toxicities are expansive and growing. However, PCB inhalation exposure assessments have been lacking for North American ambient conditions and lower-chlorinated congeners. We assessed congener-specific inhalation and dietary exposure for 78 adolescent children and their mothers (n = 68) in the Airborne Exposure to Semi-volatile Organic Pollutants (AESOP) Study. Congener-specific PCB inhalation exposure was modeled using 293 measurements of indoor and outdoor airborne PCB concentrations at homes and schools, analyzed via tandem quadrupole GS-MS/MS, combined with questionnaire data from the AESOP Study. Dietary exposure was modeled using Canadian Total Diet Survey PCB concentrations and National Health and Nutrition Examination Survey (NHANES) food ingestion rates. For ∑PCB, dietary exposure dominates. For individual lower-chlorinated congeners (e.g., PCBs 40+41+71, 52), inhalation exposure was as high as one-third of the total (dietary+inhalation) exposure. ∑PCB inhalation (geometric mean (SE)) was greater for urban mothers (7.1 (1.2) μg yr(–1)) and children (12.0 (1.2) μg yr(–1)) than for rural mothers (2.4 (0.4) μg yr(–1)) and children (8.9 (0.3) μg yr(–1)). Schools attended by AESOP Study children had higher indoor PCB concentrations than did homes, and account for the majority of children’s inhalation exposure.

Occurrence and distribution of PCB metabolites in blood and their potential health effects in humans: a review

In recent years, attention has been directed to chemicals with possible endocrine-disrupting properties. Polychlorinated biphenyls (PCBs) and their metabolites belong to one group of environmental contaminants that have been shown to interact with the endocrine system in mammals, including humans. Although recent developments have been made in terms of determination of PCB metabolites in blood samples, still limited number of studies have been able to elucidate their profiles and toxicological and health effects in humans. This review aims to evaluate and compare the levels of hydroxylated PCBs (OH-PCBs) and methyl sulfone PCBs (MeSO2-PCBs) in blood and their relationship to parent compounds and also address the potential risks and adverse health effects in humans. Levels of OH-PCBs varied between 0.0002 and 1.6 ng g(-1) w/w in human serum/plasma from the selected literature, correlating well with ∑PCBs. In contrast, ∑OH-PCB/∑PCB ratio in animals did not show a significant correlation, which might suggest that the bioaccumulation plays an even more important role in the concentration of OH-PCBs compared to PCB metabolism. Highest levels of MeSO2-PCBs were reported in marine mammals with high selectivity retention in the liver. Health effects of PCB metabolites included carcinogenicity, reproductive impairment, and developmental neurotoxicity, being more efficiently transferred to the brain and across the placenta from mother to fetus in comparison to the parent PCBs. Based on the lack of knowledge on the occurrence and distribution of lower chlorinated OH-PCBs in humans, further studies to identify and assess the risks associated to human exposure are essential.

Levels of PCDD/Fs, PCBs and PBDEs in breast milk of women living in the vicinity of a hazardous waste incinerator: assessment of the temporal trend

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined in breast milk from women living in the vicinity of a hazardous waste incinerator (HWI) in Catalonia, Spain. The results were compared with the levels obtained in previous surveys carried out in the same area in 1998 (baseline study), 2002 and 2007. The current total concentrations of 2,3,7,8-chlorinated PCDD/Fs in breast milk ranged from 18 to 126 pg g(-1)fat (1.1-12. 3 pg WHO2005-TEQPCDD/F), while the total levels of PCBs ranged from 27 to 405 pg g(-1)fat(0.7-5.3 pg WHO2005-TEQPCB). In turn, PBDE concentrations (sum of 15 congeners) ranged 0.3-5.1 g g(-1)fat, with a mean value of 1.3 ng g(-1)fat. A general decrease in the concentrations for PCDD/Fs, both planar and total PCBs, and PBDEs in breast milk was observed. The levels of PCDD/Fs, PCBs, and PBDEs in milk of women living in urban zones were higher than those corresponding to industrial zones (41%, 26%, and 8%, respectively). For PCDD/Fs and PCBs, the current decreases are in accordance with the reduction in the dietary intake of these pollutants that we have also observed in recent studies carried out in the same area of study.

Alteration of serotonin system by polychlorinated biphenyls exposure

Although commercial production of polychlorinated biphenyls (PCBs) was banned in 1979, PCBs continue to be an environmental and health concern due to their high bioaccumulation and slow degradation rates. In fact, PCBs are still present in our food supply (fish, meat, and dairy products). In laboratory animals, exposure to single PCB congener or to mixtures of different congeners induces a variety of physiological alterations. PCBs cross the placenta and even exposure at low level is harmful for the foetus by leading to neurodevelopment alterations. Serotonin system which regulates many physiological functions from platelet activation to high cerebral processes and neurodevelopment is one of the targets of PCBs toxicity. The effects of PCBs exposure on serotonin system have been investigated although to a lesser extent compared to its effect in other neurotransmitter systems. This review provides a summary of the results concerning the impact of PCBs exposure (in vitro and in vivo) on serotonin system. Further research is needed to correlate specific deficits with PCB-induced changes in the serotonin system.