The Mass Spectrometric Ortho Effect for Distinguishing the Coeluting Isomers of Polychlorinated Biphenyls and the Coeluting Isomers of Polybrominated Biphenyls: Qualitative and Quantitative Aspects.

Polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs) are persistent organic pollutants still widespread in the environment and in the food chain. Both groups of these synthetic xenobiotics consist of 209 possible congeners depending on the number and position of halogens. PCBs with the same number of chlorine atoms and PBBs with the same number of bromine atoms are isomers: ten different degrees of halogenation are allowed, which results in a lot of existing isomers for both groups. The isomers have perfect correspondence in the number and type of atoms with differences only in positioning, so their mass spectra are expected to be identical with a consequent significant analytical problem in the event of coelution of the chromatographic peaks. This is not always the case, since the mass spectrometric ortho effect is capable of effectively discriminating many coeluting PCB or PBB isomers, although not all possible ones. The present paper investigates, for the first time, the reliability of qualitative and quantitative analysis by using the ortho effect: this was conducted through targeted experimental measurements on real samples of food by using different detectors. In this context, it is shown how to recognize the presence of a PCB that does not have the ortho effect when coeluting with an isomer that has. This is an important aspect that has never been studied until now. The ortho effect is extremely simple to operate once the ordinary GC-MS runs have been performed: the analyst only needs to recheck the mass spectrum for measuring the intensity of the first dehalogenation ion. The topic is of practical relevance since two different isomers can have different health hazards, and the presence of a very toxic isomer could be masked by a less toxic one. The same mass spectrometric ortho effect also deals with PXBs (i.e., mixed poly-brominated/chlorinated biphenyls), which are emerging contaminants.

Human developmental toxicity mechanism of polybrominated biphenyl exposure and health risk regulation strategy for special populations.

Polybrominated biphenyls (PBBs) can bioaccumulate in nature and are toxic to humans. Long-time exposure to PBBs in pregnant women can lead to the birth of an infant with abnormal conditions. Hence, in this study, we used molecular docking, molecular dynamics, Taguchi experimental design, and fractional factorial experimental design to identify the developmental toxicity characteristics of 10 typical developmental toxic pollutants such as PBBs to which humans are frequently exposed. Furthermore, the correlation and sensitivity analyses of molecular developmental toxicity and structural parameters were performed. The molecular key structural parameters of the pollutants affecting human development were screened. Moreover, the supplementary food factors that could alleviate the developmental toxicity of pollutants were screened to develop supplementary food schemes to prevent or alleviate human developmental toxicity in the special population (e.g., pregnant women, infants) exposed to the pollutants. The results showed that the developmental toxicity was controlled by the main effects of the 10 pollutants. Among the 10 pollutants with developmental toxicity, the most significant pollutant with the main effects was PBB-153 (37.06%). In addition, the correlation and sensitivity analyses of the molecular developmental toxicity of the pollutants and structural parameters showed that the total energy value and infrared C-H vibration frequency of the pollutants were significantly correlated with human developmental toxicity. Accordingly, 15 supplementary food cofactors were selected for the Taguchi experiment design, among which the top seven cofactors were designed by fractional factorial analysis. The most significant cofactor that alleviated the developmental toxicity of PBB-153 exposure was the combination of carotene and docosahexaenoic acid (DHA), with an improvement of 17.28%. The combination of carotene and DHA significantly alleviated the effects of toxicity caused by most of the other pollutants, indicating that the selected supplementary food has certain universality. In this study, we developed a method to identify the characteristics of the developmental toxicity of pollutant exposure and developmental toxicity alleviation. Our study provided theoretical support for the regulation strategy of developmental toxicity caused by pollutants such as PBBs.

Plasma concentration of brominated flame retardants and postmenopausal breast cancer risk: a nested case-control study in the French E3N cohort.

BACKGROUND: Brominated flame retardants (BFRs) are lipophilic substances with endocrine-disrupting properties. To date, only few investigations, mainly retrospective case-control studies, have explored the link between internal levels of BFRs and the risk of breast cancer, leading to conflicting results. We investigated the associations between plasma concentrations of two main groups of BFRs, PBDEs (pentabromodiphenyl ethers) and PBBs (polybrominated biphenyls), and the risk of breast cancer in a nested case-control study. METHODS: A total of 197 incident breast cancer cases and 197 controls with a blood sample collected in 1994-1999 were included. Plasma levels of PBDE congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE153, BDE-154) and of PBB-153 were measured by gas chromatography coupled to high-resolution mass spectrometry. Conditional logistic regression models, adjusted for potential confounders, were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Women were aged 56 years on average at blood draw. All cases, except for one, were diagnosed after menopause, with an average age at diagnosis of 68 years. Overall, we found no evidence of an association between plasma levels of PBDEs and PBB-153 and postmenopausal breast cancer risk (log-concentrations of BFRs yielding non-statistically significant ORs of 0.87 to 1.07). The analysis showed a non-linear inverse association for BDE-100 and BDE-153 and postmenopausal breast cancer risk; nevertheless, these findings were statistically significant only when the exposure was modeled as ng/L plasma (third vs. first quintile: OR = 0.42, 95%CI = 0.19-0.93 and OR = 0.42, 95%CI = 0.18-0.98, respectively) and not when modeled as ng/gr of lipids (OR = 0.58, 95%CI = 0.27-1.25 and OR = 0.53, 95%CI = 0.25-1.17). These results were unchanged in stratified analyses by tumor hormone receptor expression or body mass index. CONCLUSIONS: Our results suggest no clear association between internal levels of PBDEs and PBB-153 and the risk of breast cancer in postmenopausal women. However, these findings need to be carefully interpreted, taking into account limitations due to the limited number of women included in the study, the lack of information concerning genetic susceptibility of cases, and the unavailability of exposure assessment during critical windows of susceptibility for breast cancer. More studies are warranted to further investigate the relationships between PBDE and PBB exposure and breast cancer risk.

The Relationship Between Polychlorinated and Polybrominated Biphenyls and Glycated Hemoglobin among Electronics Workers.

Background: Polychlorinated biphenyls (PCBs) are persistent organic pollutants classified as endocrine disruptors related to prediabetes and diabetes. Polybrominated biphenyls are similar in structure to PCBs and are used as flame retardants. Due to the increased worldwide prevalence of diabetes, there is increased interest in understanding the role of environmental and occupational pollutants in its development. The study aims to assess the relation between PCBs and PBBs in the serum of electronic workers and glycated hemoglobin level as an early indicator of prediabetes and type 2 diabetes mellitus among occupationally exposed workers. Methods: Blood samples were collected from 152 workers to assess PCBs (by GCMS), random blood sugar (RBS), and glycated hemoglobin (HbA1c). Participants were classified into two groups according to the presence or absence of PCBs in their serum and were compared for RBS and HbA1c levels. Results: Only two participants had detectable PCB derivate in their serum by GCMS, PCB 1 with methyl and benzole side chains. Regarding PBBs, 18 participants (12%) had detectable PBBs in their serum by GCMS. All participants had RBS and HbA1c levels within the normal range. No statistically significant difference was found between mean levels of RBS and HbA1c between participants with detected biphenyls and those without. Conclusion: The banning of PCB use in industry and modern automated techniques have prevented exposure to PCBs among electronics workers. However, exposure to PBBs continues in electronic industries, but it has no association with diabetes or prediabetes.

Utility of an alternative method (to USEPA Method 1613) for analysis of priority persistent organic pollutants in soil from mixed industrial-suburban areas of Durban, South Africa.

This study evaluates the adequacy of a USEPA Method 1613 alternative analytical method for analysis of persistent organic pollutants (POPs) in soil from the immediate vicinity of industrialized areas in the eThekwini municipal area in South Africa. The objective of this study is in line with the Stockholm Convention Article 11 on research, development, and monitoring. Furthermore, it became imperative to find an alternative analytical procedure to USEPA Method 1613 that could cater to studies conducted in Africa where recent reviews have indicated that most African countries lack the technical and instrumental capacity for performing analysis of dioxin-like compounds according to USEPA Method 1613, which entails the use of high-resolution chromatography and high-resolution mass spectrometry instrumentation. The study aimed to ascertain the utility of an alternative two-dimensional gas chromatography-time of flight mass spectrometry method for analysis of trace-level priority POPs in soil, along with a fast single quadrupole gas chromatography-mass spectrometry method. The analytical methods were applied to the analysis of POPs on soil samples from industrial areas with oil refineries and a pulp and paper manufacturing company, while other samples were collected near the electricity substations and a landfill site. Analytical results showed BDE 209 as the dominant contaminating polybrominated diphenyl ether (concentration ranges from 0.006 to 5.71 ng g-1 ). Polybrominated biphenyls (PBBs) 9, 10, and 49 were the dominant PBBs detected in 78% of the sites tested, although their concentrations were below the limit of quantification (LOQ). Polychlorinated dibenzo-p-dioxins and furans and dioxin-like polychlorinated biphenyls detected could not be quantified above their respective LOQs, indicating that the Durban area has low priority pollutant contamination levels compared to other regions around the world. The methods developed are a starting point that will inform considerations for routine evaluation and management of soil contamination, which plays a vital role in environmental management. Integr Environ Assess Manag 2023;19:749-762. © 2022 SETAC.

Serum concentrations of polybrominated biphenyls (PBBs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the Michigan PBB Registry 40 years after the PBB contamination incident.

Widespread polybrominated biphenyls (PBBs) contamination occurred in Michigan from 1973 to 1974, when PBBs were accidentally substituted for a nutritional supplement in livestock feed. People who lived in the state were exposed to PBBs via several routes including ingestion, inhalation and skin absorption. PBBs sequestered in lipid-rich matrices such as adipose tissue, are slowly eliminated after entering the human body, and can also be transferred from a mother to her offspring through the placenta and breastfeeding. Due to the long biological half-lives of PBBs, as well as concerns from the exposed community, biomonitoring measurements were conducted from 2012 to 2015. Because of their similar structures, serum PBBs, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were all measured 40 years after the PBB contamination incident (N = 862). The serum PBB-153 levels among the original highly-exposed groups (i.e., chemical workers, the family of chemical workers, and individuals who lived on or received food from the contaminated farms) remains significantly higher than other Michigan residents. Several predictors such as sampling age, sex, and smoking status were significantly associated with the serum levels of some persistent organic pollutants (POPs). Higher average values and also wider ranges of serum POP levels were found in this study compared to the National Health and Nutrition Examination Survey (NHANES), with the most substantial difference in serum PBB-153. This was true for all groups of Michigan residents including those who were not part of the above-described highly-exposed groups. Moreover, the people born after the contamination incident began also have higher serum PBB-153 levels when compared with more recent NHANES data (2010-2014), which suggests potential intergenerational exposure and/or continued environmental exposure following the contamination period.

Formation of polybrominated dibenzofurans from polybrominated biphenyls.

Decades after phasing out their production and use, especially in the formulations of brominated flame retardants (BFRs), polybrominated biphenyls (PBBs) still pose serious environmental and health problems. The oxidation of PBB has been hypothesised as a pathway for the formation of the notorious polybrominated dibenzofurans (PBDFs) and their dispersion in the environment. However, the exact reaction corridor remains misunderstood, with the existing mechanisms predicting the reaction to proceed via a high energy process that involves the breakage of C-C linkage (∼118.0 kcal mol(-1)) and the subsequent formation of bromophenols molecules, where the latter are supposed to act as precursors for the formation of PBDFs (∼40.0-60.0 kcal mol(-1)). Herein, we show that PBBs produce PBDFs in a facile mechanism through a series of highly exothermic reactions (i.e., overall barriers reside 8.2-10.0 kcal mol(-1) below the entrance channel). Whilst the fate of the ROO-type intermediates in oxidation of all aromatics is to emit CO or CO2, PBDFs constitute the dominant products from the oxidation of PBBs. Initially formed R-OO adduct evolves in a very exoergic mechanism to yield PBDFs. In view of the facile oxidative transformation of PBBs into PBDFs, we conclude that, it is unsafe to dispose BFRs in oxidation processes, as this practice generates high yields of toxic PBDFs.