Chemical synthesis and characterization of single-chain C18-chloroparaffin materials with defined degrees of chlorination

Cumulative exposure assessment to polychlorinated alkanes (C8-36) to indoor dust from Iranian kindergartens: Occurrence and health risk

The environmental and public health concerns associated with chlorinated paraffins (CPs) are significant, given their widespread use, long-lasting persistence, and potential adverse health effects. The objective of this study was to assess the contamination of polychlorinated alkanes (PCAs-C8-36), the major contaminants in the CP technical mixtures, in kindergartens in Tehran, Iran, and to evaluate the cumulative exposure risks through various routes, including ingestion, dermal contact, and inhalation of dust. The results revealed a pervasive contamination with PCAs. The sum of PCAs-C10-20 across all samples was found to be 1370 ng/g dw, with median values of 500 ng/g dw for ∑PCAs-C10-13, 620 ng/g dw for ∑PCAs-C14-17, and 280 ng/g dw for ∑PCAs-C18-20. These levels did not correlate with outdoor environmental factors or indoor characteristics. Dermal contact constituted 64-84 % of total exposure, with toddlers showing higher intake than caretakers. A cumulative exposure assessment was conducted to calculate the hazard quotient (HQ). The highest HQ value was observed for girls in the case of ∑PCAs-C10-13 (6.2 × 10-5), and the HQ for all groups remained well below the risk threshold. Despite the low level of immediate risks, chronic exposure in vulnerable population groups justifies proactive measures. Further investigation of exposure sources and implementation of interventions to reduce potential health risks are recommended, given the ubiquity of CPs in indoor environments. ENVIRONMENTAL IMPLICATIONS: This study highlights significant environmental implications of pervasive polychlorinated alkanes (PCAs-C8-36) contamination in Tehran's kindergartens, highlighting their persistence and potential long-term ecological impacts. Despite cumulative exposure risks (HQs <1) via dust ingestion, dermal contact, and inhalation, the ubiquity of PCAs (∑PCAs-C10-20: 1370 ng/g dw) raises concerns about chronic low-dose exposure in vulnerable toddlers. The lack of correlation between contamination levels and environmental/indoor factors suggests complex, unidentified emission sources. These findings emphasize the need for proactive regulatory measures to mitigate CP releases and prioritize indoor environmental quality, particularly in child-centric settings. Further research is critical to identify exposure pathways and inform policies safeguarding public health against persistent organic pollutants.

The metabolome of Sphingobium chinhatense IP26 exposed to chlorinated paraffins - Efficient data analysis with RASER

The universe of possible chloro-paraffin (CP) structures is a complex one. Even the world of short-chain CPs (SCCPs) is large, containing thousands of constitutional isomers and stereoisomers. We investigated a technical SCCP mixture (Hordalub 80, Vantage Leuna, mCl = 56%) and found 33 CP-homologues in this material with carbon- (nC) and chlorine-numbers (nCl) varying from 10 to 13 and 4-12, respectively. In addition, 27 chloro-olefins (COs) and 18 chloro-diolefins (CdiOs) could be detected with high-resolution mass spectrometry (HRMS, R > 100'000). Respective mass spectra were processed with the R-based automated spectra evaluation routine (RASER). The SCCP mixture was then exposed to Sphingobium chinhatense IP26, which have been isolated and cultivated from a strain found in a chemical dumpsite in Chinhat, Lucknow, India. After exposure for 6 days, additional signals corresponding to hydroxylated and olefinic metabolites were observed in respective mass spectra. RASER was adapted to identify and read-out these metabolite signals too. S. chinhatense expressed the enzymes LinA and LinB. LinA, a dehydrohalogenase (17.3 kDa), is catalyzing the elimination of HCl, converting paraffinic to olefinic material (C(H)-C(X) to CC). LinB, a dehalohydroxylase (32 kDa), transforms halides to alcohols (C-X to C-OH). Both enzymes were active and we identified 9 different metabolite classes. We found mono- (CP-ols), di- (CP-diols), tri- (CP-triols) and some tetra-hydroxylated CPs (CP-tetraols). In addition to the chloro-olefins and chloro-diolefins, we also observed mono- (CO-ols) and di-hydroxylated olefins (CO-diols) and hydroxylated diolefins (CdiO-ols). In other words, the exposure of 33 SCCP homologues to S. chinhatense resulted in a metabolome with 176 metabolites including 27 COs, 18 CdiOs, 72 mono-to tetra-hydroxylated CPs, 23 CO-ols and 19 CO-diols and 17 CdiO-ols. The qualitative characterization based on HR-MS and chromatographic retention times confirmed the formation of these phase-I metabolites, which can now be searched for in other materials and environmental samples.

Temporal trends and spatial variations of chlorinated paraffins and olefins in sewage sludge from eight Swiss wastewater treatment plants from 1993 to 2020

High production rates of chlorinated paraffins (CPs) and their widespread use resulted in a global contamination. Since 2017, short-chain CPs (SCCPs, C10-C13) are listed as persistent organic pollutants (POPs) in the Stockholm Convention. Technical CP mixtures contain hundreds of homologues and side products such as chlorinated olefins (COs), diolefins (CdiOs) and triolefins (CtriOs). Sewage sludge from wastewater treatment plants (WWTPs) is a suitable indicator to assess anthropogenic emissions of POPs. We studied 40 sewage sludge samples from eight WWTPs taken in 1993, 2002, 2007, 2012 and 2020. These samples represent effluents of households of ∼344000 inhabitants corresponding to 4% of the Swiss population. Extracts were studied by liquid chromatography high-resolution mass spectrometry (LC-MS, R > 100000). Respective mass spectra contained more than 20000 m/z values which were evaluated with the R-based automated spectra evaluation routine (RASER). We assigned ∼4300 ions to 226 CP, 94 CO, 32 CdiO and 26 CtriO homologues. Proportions of olefinic material were on average 8%, 1% and <1%, respectively. Homologue distributions from 1993 sludge were rich in SCCPs (26%) and SCCOs (36%). Average SCCP levels dropped by 85% from 15600 ± 14300 (1993) to 2370 ± 840 ng/g dry matter (2020). Thus, SCCP emissions from Swiss households and industry were reduced successfully from 1993 to 2020. Levels of medium- (MCCPs, C14-C17), long- (LCCPs, C18-C21) and very long-chain CPs (vLCCPs, C ≥ 22) decreased by 67%, 11% and 11%. 2020 samples contained some (<1%) very short-chain CPs (vSCCPs, C ≤ 9). Spatial variations for different WWTPs are minor, except for one, which received high MCCP loads from 2002 to 2012. We assume that wastewater from a point source has reached this plant in those years. According to the levels of sludge from WWTPs, we conclude that the use of SCCPs in Swiss households and thus the exposure of people was reduced in the last three decades.

Evaluation of atmospheric-plasma-source absorption mode Fourier transform Orbitrap mass spectrometry for chlorinated paraffin mixtures

Chlorinated paraffins (CP) are complex molecular mixtures occurring in a wide range of isomers and homologs of environmental hazards, whose analytical complexity demand advanced mass spectrometry (MS) methods for their characterization. The reported formation of chlorinated olefins (COs) and other transformation products during CP biotransformation and degradation can alter the MS analysis, increasing the high resolution required to distinguish CPs from their degradation products. An advanced setup hyphenating a plasma ionization source and an external high-performance data acquisition and processing system to the legacy hybrid LTQ Orbitrap XL mass spectrometer is reported. First, the study demonstrated the versatility of a liquid sampling atmospheric pressure glow discharge, as a soft ionization technique, for CP analysis. Second, enhanced resolution and sensitivity provided by the absorption mode Fourier transform spectral representation on this legacy mass spectrometer are shown. The developed Orbitrap-based platform allowed the detection of new isotopic clusters and CPs and COs to be distinguished at medium resolution (setting 30,000 at m/z 400, ~ 400 ms transients), and even chlorinated di-olefins (CdiOs) at higher resolution (setting 100,000 at m/z 400, ~ 1500 ms transients). Overall, such proof-of-principle instrumental improvements are promising for environmental and analytical research in the field of CP analysis.

Identification of Sulfur-Containing Chlorinated Paraffin Structural Analogues in Human Serum: Origination from Biotransformation or Bioaccumulation?

Chlorinated paraffins (CPs) are manufactured and used in high quantities and have diverse structural analogues. It is generally recognized that sulfur-containing structural analogues of CPs are mainly derived from sulfate-conjugated phase II metabolism. In this study, we non-targeted identified three classes of sulfur-containing CP structural analogues (CPs-S) in human serum, including 44 CP sulfates (CPs-SO4H/CPs-SO4H-OH), 14 chlorinated benzene sulfates (CBs-SO4H), and 19 CP sulfite esters (CPs-SO3/CPs-S2O6), which were generated during the production of commercial mixtures of CPs and, thus, bioaccumulated via environmental exposures. We first wrote a program to screen CPs-S, which were baseline-separated from CPs according to their polar functional groups. Then, mass spectral analyses of alkalization-acidification liquid-liquid extracts of serum samples and Orbitrap mass spectrometry analyses in the presence and absence of tetraphenylphosphonium chloride (Ph4PCl), respectively, were performed to determine the ionization forms ([M + Cl]- or [M - H]-) of CPs-S. The presence of fragment ions (SO4H-, SO3-, SO2Cl-, and HSO3-) revealed the structures of CPs-S, which were validated by their detections in commercial mixtures of CPs. The estimated total concentrations of CPs-S in the human serum samples were higher than the concentrations of medium- and long-chain CPs. The profiles of CPs-S in human serum were similar to those detected in CP commercial mixtures and rats exposed to the commercial mixtures, but CPs-S were not detected in human liver S9 fractions or rat tissues after exposure to CP standards. These results, together with the knowledge of the processes used to chemically synthesize CPs, demonstrate that CPs-S in humans originates from environmental bioaccumulation.

Evolution of chlorinated paraffin and olefin fingerprints in sewage sludge from 1993 to 2020 of a Swiss municipal wastewater treatment plant

Exposure of humans to chlorinated paraffins (CPs) and chlorinated olefins (COs) can occur via contact with CP-containing plastic materials. Such plastic materials can contain short-chain CPs (SCCPs), which are regulated as persistent organic pollutants (POPs) under the Stockholm Convention since 2017. Municipal wastewater treatment plants (WWTP) collect effluents of thousands of households and their sludge is a marker for CP exposure. We investigated digested sewage sludge collected in the years 1993, 2002, 2007, 2012, and 2020 from a Swiss WWTP serving between 20000 and 23000 inhabitants. A liquid chromatography mass spectrometry (R > 100000) method, in combination with an atmospheric pressure chemical ionization source (LC-APCI-MS), was used to detect mass spectra of CPs and olefinic side products. A R-based automated spectra evaluation routine (RASER) was applied to search for ∼23000 ions whereof ∼6000 ions could be assigned to CPs, chlorinated mono- (COs), di- (CdiOs) and tri-olefins (CtriOs). Up to 230 CP-, 120 CO-, 50 CdiO- and 20 CtriO-homologues could be identified in sludge. Characteristic fingerprints were deduced describing C- and Cl-homologue distributions, chlorine- (nCl) and carbon- (nC) numbers of CPs and COs. In addition, proportions of saturated and unsaturated material were determined together with proportions of different chain length classes including short- (SC), medium- (MC), long- (LC) and very long-chain (vLC) material. A substantial reduction of SCCPs of 84% was observed from 1993 to 2020. Respective levels of MCCPs, LCCPs and vLCCPs decreased by 61, 69 and 58%. These trends confirm that banned SCCPs and non-regulated CPs are present in WWTP sludge and higher-chlorinated SCCPs were replaced by lower chlorinated MCCPs. Combining high-resolution mass spectrometry with a selective and fast data evaluation method can produce characteristic fingerprints of sewage sludge describing the long-term trends in a WWTP catchment area.

Fingerprinting of chlorinated paraffins and their transformation products in plastic consumer products

Chlorinated paraffins (CPs) can be classified according to their length as short-chain (SC, C10-C13), medium-chain (MC, C14-C17) and long-chain (LC, C ≥ 18) CPs. Technical CP-mixtures can contain a wide range of carbon- (C-, nC = 10-30) and chlorine- (Cl-, nCl = 3-19) homologues. CPs are high-production volume chemicals (>106 t/y). They are used as flame-retardants, plasticizers and coolant fluids. Due to the persistence, bioaccumulation, long-range environmental transport potential and adverse effects, SCCPs are regulated as persistent organic pollutants (POPs) by the Stockholm Convention. Transformation of CPs can lead to the formation of unsaturated compounds such as chlorinated mono- (CO), di- (CdiO) and tri-olefins (CtriO). Such transformation reactions can occur at different stages of CP manipulation providing characteristic C-/Cl-homologue distributions. All this results in unique patterns that collectively create a fingerprint, which can be distinguished from CP-containing samples. Therefore, CP-fingerprinting can develop into a promising tool for future source apportionment studies and with it, the reduction of environmental burden of CPs and hazards to humans. Herein, CP-containing plastics were studied to establish fingerprints and develop this method. We analyzed four household items by reverse-phase liquid-chromatography coupled with a mass spectrometer with an atmospheric pressure chemical ionization source and an Orbitrap mass analyzer (RP-LC-APCI-Orbitrap-MS) operated at a resolution of 120000 (FWHM at m/z 200). MS-data of different CP-, CO-, CdiO- and CtriO-homologues were efficiently processed with an R-based automatic mass spectra evaluation routine (RASER). From the 16720 ions searched for, up to 4300 ions per sample were assigned to 340 C-/Cl-homologues of CPs and their transformation products. Specific fingerprints were deduced from the C-/Cl-homologues distributions, the carbon- (nC) and chlorine- (nCl) numbers and saturation degree. These fingerprints were compared with the ones obtained by a GC-ECNI-Orbitrap-MS method.

Selective and Fast Analysis of Chlorinated Paraffins in the Presence of Chlorinated Mono-, Di-, and Tri-Olefins with the R-Based Automated Spectra Evaluation Routine (RASER)

Chlorinated paraffins (CPs) are complex mixtures consisting of various C homologues (n_C ≈ 10-30) and Cl homologues (n_Cl ≈ 2-20). Technical CP mixtures are produced on a large scale (>10⁶ t/y) and are widely used such as plasticizers in plastic and coolants in metalwork. Since 2017, short-chain CPs (C₁₀-C₁₃) are classified as persistent organic pollutants (POPs) by the Stockholm Convention but longer-chain CPs are not regulated. Analysis of technical CP mixtures is challenging because they consist of hundreds of homologues and millions of constitutional isomers and stereoisomers. Furthermore, such mixtures can also contain byproducts and transformation products such as chlorinated olefins (COs). We applied a liquid-chromatography method coupled to an atmospheric pressure chemical ionization technique with a high-resolution mass detector (LC-APCI-Orbitrap-MS) to study CP and CO homologues in two plastic materials. Respective mass spectra can contain up to 23,000 signals from 1320 different C-Cl homologue classes. The R-based automated spectra evaluation routine (RASER) was developed to efficiently search for characteristic ions in these complex mass spectra. With it, the time needed to evaluate such spectra was reduced from weeks to hours, compared to manual data evaluation. Unique sets of homologue distributions could be obtained from the two plastic materials. CPs were found together with their transformation products, the chlorinated mono-olefins (COs), di-olefins (CdiOs), and tri-olefins (CtriOs) in both plastic materials. Based on these examples, it can be shown that RASER is an efficient and selective tool for evaluating high-resolution mass spectra of CP mixtures containing hundreds of homologues.