Congener Groups Research Articles

Altitude-dependent accumulation of short chain chlorinated paraffins in fish from alpine lakes and Lhasa river on the Tibetan Plateau

High mountain cold-trapping effects can play important roles in the global long-range transport of persistent organic pollutants (POPs). Short chain chlorinated paraffins (SCCPs) have recently been included into the Stockholm Convention as a new class of POPs. However, the long-range transport behavior and environmental fate of SCCPs still remain largely unknown in high-altitude mountain areas. In this study, a total of 51 fish samples were collected from five high-altitude mountain lakes and Lasha river across the Tibetan Plateau. SCCPs were positively detected in all fish samples, and the concentrations ranged from 3.9 to 107 ng g−1 dry weight (dw) with an average of 26.6 ng g−1 dw. Compared to aquatic organisms from the Artic and Antarctica, the SCCP levels found in alpine fish from the Tibetan Plateau were lower. A significant increasing trend in accumulation levels of SCCPs in alpine fish with the increasing altitude was found on the Tibetan Plateau (r = 0.98, p < 0.001). Shorter chain congener group C10 showed a significant increase in percentage contribution to total SCCPs with increasing altitude, but a contrary tendency was found for longer chain congener group C13. The widespread occurrence of SCCPs in Tibetan fish was mainly sourced from the long-range atmospheric transport, and the altitude-dependent distribution of SCCPs was due to the mountain cold-trapping effects and potential susceptibility to bioaccumulation. To our knowledge, this is the first report regarding the altitude-dependent accumulation of SCCPs in biota in the polar environment.

Tissue-Specific Accumulation, Sexual Difference, and Maternal Transfer of Chlorinated Paraffins in Black-Spotted Frogs.

The restriction on usage of short-chain chlorinated paraffins (SCCPs) under Stockholm Convention may promote the production and application of medium chain chlorinated paraffins (MCCPs) and long chain chlorinated paraffins (LCCPs) as substitutes. This study focused on the tissue-specific exposure to SCCPs, MCCPs, and LCCPs in black-spotted frog, a prevalent amphibian species in the Yangtze River Delta, China. The total CP concentrations in frog liver, muscle, and egg samples ranged of 35-1200, 6.3-97, and 6.8-300 ng/g wet weight (ww), respectively. Livers and eggs contained primary SCCPs (on average 78%) while MCCPs (43%) together with SCCPs (41%) were dominant in muscles. A significantly negative correlation was observed between hepatosomatic index and CPs concentration in liver ( p < 0.01), indicating that CP exposure may lower survival rates of frogs by suppressing the energy storage in liver. Additionally, maternal transfer, an important uptake pathway for CPs, was evaluated for the first time by calculating the ratios of CP levels in eggs to those in their paired liver tissues. The ratio of egg to liver for CP congener groups raised with the increasing of log Kow values, indicating mother to egg transport of CPs was related to the lipophilicity of the chemicals.

Characterization of short- and medium-chain chlorinated paraffins in cereals and legumes from 19 Chinese provinces

Short-chain chlorinated paraffins (SCCPs) were added to the Stockholm Convention Annex A in May 2017. China is the largest producer of chlorinated paraffins (CPs). CPs in the environment can be transferred to foodstuffs directly and through bioaccumulation and then ingested by humans. Cereals and legumes are important components of Chinese diets, so the risks posed by CPs in cereals and legumes should be of concern. 1710 cereal samples and 1710 legume samples from 19 Chinese provinces were pooled by type and province (giving 19 pooled cereal and 19 pooled legume samples). The SCCP and medium-chain chlorinated paraffin (MCCP) concentrations in the samples were determined by comprehensive two-dimensional gas chromatography tandem time-of-flight mass spectrometry (GC × GC-TOFMS). The mean SCCP concentrations in the cereal and legume samples were 343 and 328 ng g−1 wet weight (ww), respectively, and the mean MCCP concentrations were 213 and 184 ng g−1 ww, respectively. The dominant SCCP congener groups were C10Cl6–7 in cereals and C10Cl5–6 in legumes. The MCCP congener groups C14Cl6–7 were dominant in both cereals and legumes. The CP concentrations were higher in samples from eastern China than in samples from other regions. Risk assessments indicated that SCCPs and MCCPs in cereals and legumes do not pose strong risks to Chinese residents.

Migration of chlorinated paraffins from plastic food packaging into food simulants: Concentrations and differences in congener profiles

Human exposure to chlorinated paraffins (CPs) is of increasing concern for human health. Previous studies have focused on human CP exposure through food intake; however, the migration behaviors of CPs from food packaging into food are yet to be assessed. Herein, we used four food simulants (water, 3% acetic acid, 15% ethanol, and hexane) to investigate the migration of CPs from food packaging into food. The average migration efficiencies of short-chain chlorinated paraffins (SCCPs) (12.15%) were significantly higher than medium-chain chlorinated paraffins (MCCPs) (1.51%) except in hexane food simulants (ANOVA, p < 0.05). Differences in congener profiles of CPs were found in food simulants, compared with in food packaging. In food simulants, C10-congener groups were predominant in SCCP carbon homologues and Cl6-and Cl7-congener groups were predominant in chlorine homologues. The shorter chain and lower chlorinated congener groups of CPs had higher migration efficiencies. Moreover, the average estimated dietary intakes of SCCPs and MCCPs due to migration were 12.8 and 10.3 ng/kg·bw/day, respectively. These results revealed that migration of CPs from food packaging into food does not pose immediate risks to human health.

Bioaccessibility of short chain chlorinated paraffins in meat and seafood

Bioaccessibility of short chain chlorinated paraffins (SCCPs), which is important for estimation of dietary exposure, has not been evaluated in previous studies. In the present study, we determined the bioaccessibility of SCCPs in meat (pork, beef and chicken) and seafood (fish, clams, and prawns) using the colon-extended physiologically based extraction test as an in vitro model. The bioaccessibility percentages (BAs) ranged from 33% to 84% in the fed state and from 41% to 63% in the unfed state. The BAs observed in the fed state were lower than in the unfed state in most samples, except for pork sample, which had the highest lipid content. This could be attributed to the effects caused by dietary components added in the fed state. The effects of lipid and protein in samples on bioaccessibility were investigated. In food with a high lipid content, like pork in this study, lipid was the main factor controlling SCCP bioaccessibility. In the other five foods, which had low–medium lipid contents, BA in the unfed state was positively correlated with lipid content (p < 0.05) and negatively correlated with the protein-to-lipid content ratio (p < 0.05). No significant relationships between lipid and protein content and BA were found in the fed state. As to SCCP congener groups, a positive relationship between the BAs of SCCP congener groups and their octanol-water partition coefficients (log Kow) was found in pork sample in the fed state (p < 0.05). The BAs obtained in samples from fish, prawn, clam, and pork in the unfed state and that obtained in clam sample in the fed state were negatively correlated with log Kow (p < 0.05). We calculated more accurate estimated dietary intakes of SCCPs using our SCCP bioaccessibility data. These results will contribute to more reliable dietary risk assessments of SCCPs.

Distribution, Toxic Potential, and Influence of Land Use on Conventional and Emerging Contaminants in Urban Stormwater Pond Sediments.

This study examined the distribution and toxic potential of conventional and emerging contaminants in composite sediment samples from 15 stormwater ponds in the Minneapolis-St. Paul, MN metropolitan area. Previously, coal tar-based sealants were shown to be a major source of polycyclic aromatic hydrocarbons to these ponds, and concentrations of carcinogenic benzo[a]pyrene (B[a]P) equivalents were influencing management options about pond maintenance. For the second component of this study, a complex mixture of 13 metal(loid)s, 4-nonylphenols, 8 brominated diphenyl ethers (BDEs), and total polybrominated diphenyl ethers (PBDEs) were detected in all surficial samples. Contaminants with detection frequencies ≥ 20% included: silver (46.7%), beryllium (20.0%), chloride (60.0%), bis(2-ethylhexyl)phthalate (60.0%), 10 per- and polyfluoroalkyl substances (PFASs; 26.7-80.0%), 4-nonylphenol monoethoxylate (66.7%), 4-nonylphenol diethoxylate (40.0%), bifenthrin (20.0%), total permethrins (33.3%), and 24 other BDE congener groups (20.0-93.3%). Five stormwater ponds had contaminants exceeding benchmarks likely to be associated with harmful effects to benthic organisms. Ponds with watersheds dominated by either commercial and/or industrial land uses had significantly higher (p < 0.05) concentrations of zinc, 4-nonylphenol, six BDEs (28 + 33, 47, 99, 100, 154, and 209), and total PBDEs than those dominated by residential land uses. Multivariate statistical analyses verified that updated B[a]P equivalents were an effective chemical proxy for making management decisions about excavated pond sediment. Jurisdictions that do not test their stormwater pond sediments prior to maintenance dredging should consider the environmental ramifications of applying this potentially contaminated material to land.

Occurrence and Human Exposure Assessment of Short- and Medium-Chain Chlorinated Paraffins in Dusts from Plastic Sports Courts and Synthetic Turf in Beijing, China.

This study presents the first investigation of concentrations and congener group patterns of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) in 159 dust samples from plastic sports courts and synthetic turf in Beijing, China. The geometric mean concentration of SCCPs and MCCPs in dusts from plastic tracks (5429 and 15157 μg g-1) and basketball courts (5139 and 11878 μg g-1) were significantly higher than those from plastic tennis courts, badminton courts, and synthetic turf; meanwhile, they were 1-3 orders of magnitude higher than in dusts from other indoor environments. The friction between sneaker soles and plastic track materials may lead to the wear and decomposition of rubber, which may be an important source of chlorinated paraffins (CPs) in the dust from plastic tracks. The mean estimated daily intakes of CPs from plastic tracks and basketball courts are generally higher than those estimated from dietary, breast milk, or other indoor dust sources. The margin of exposure for adults and children was greater than 1000 both at mean and high-exposure scenarios, indicating that no significant health risks were posed by CPs in the dust from plastic sports courts and synthetic turf.

Congener-specific C10[sbnd]C13 and C14[sbnd]C17 chlorinated paraffins in Chinese agricultural soils: Spatio-vertical distribution, homologue pattern and environmental behavior

A comprehensive spatio-vertical survey of short-chain (SCCPs, C10-13) and medium-chain (MCCPs, C14-17) chlorinated paraffins (CPs) was performed in surface and core soils from Chinese nation-wide agricultural lands in 2016, and a total of 48 congener groups were measured. The shorter carbon chain C10-11 in SCCP and C14-15 in MCCP homologue groups, and the lower chlorinated congeners (Cl5-7) for both CP groups were predominant. The ∑SCCP and ∑MCCP concentrations in surface soils ranged from 39 to 1609 ng/g and 127–1969 ng/g, dry weight (dw), respectively. The spatial distribution trend showed that SCCP congener groups with relatively low octanol-water partition coefficient (KOW) and octanol-air partition coefficient (KOA) are uniformly distributed across surface soils compared to MCCP congener groups. Significant relationships were observed between the spatial variation of SCCP concentrations and the driving factors responsible for dispersion and deposition. The distribution behavior of SCCPs and MCCPs in highland and plain surface soils showed an increasing trend of MCCP concentrations with elevation, indicating the “mountain cold-trapping effect”. Vertical distribution profile revealed similar homologue group composition patterns of SCCP and MCCP congener groups as those of surface soils. Furthermore, the penetration potential ratios (r) of chlorine and carbon atoms of CPs demonstrated that the lower chlorinated (Cl5-7) and the shorter carbon chain (C10-13) congener groups are more prone to vertical movement into deeper soil layers compared to the longer carbon chain (C14-17) and highly chlorinated (Cl8-10) congener groups.

Determination of short-chain chlorinated paraffins using comprehensive two-dimensional gas chromatography coupled with low resolution mass spectrometry

Short-chain chlorinated paraffins (SCCPs), recently listed as Persistent Organic Pollutants (POPs) under the Stockholm Convention, are contained in commercial chlorinated paraffin (CP) products, which are used in industries such as metalworking fluids, sealants, and textiles. A novel method to determine SCCPs by comprehensive two-dimensional gas chromatography coupled with low resolution mass spectrometry was developed. Calibration curves of response factor versus chlorine content in two chlorine content ranges (R2 were 0.9544 and 0.9736, respectively) were used for quantification of SCCP total concentration. Moreover, relative concentrations of 24 congener groups were also theoretically calculated. Results showed that this method was able to detect SCCP concentration in commercial CP products and urban air samples. SCCP contribution varied largely among different CP products, which is highly determined by carbon chain distribution in paraffins. SCCP concentration in urban air ranged between 12.8–49.1 ng m−3 during nine-month sampling period. The highest SCCP concentration appeared in summer, and the lowest concentration occurred in winter. Gas phase was dominantly occupied by lighter congeners such as C10 group and Cl6 group, while heavier congeners such as C13 group and Cl7 and Cl8 groups contributed more in particle phase.

The atmospheric transport and pattern of Medium chain chlorinated paraffins at Shergyla Mountain on the Tibetan Plateau of China

Large amounts of short chain and medium chain chlorinated paraffins (SCCPs and MCCPs) are released into the environment during production and usage. However, compared to SCCPs, there is a significant lack of attention for MCCPs. In this work, 83 air samples, collected between 2012 and 2015 from the Tibetan Plateau, were analyzed to investigate the airborne levels and distributions of MCCPs, further to evaluate their potential long-range transport behavior on the alpine area. The total air MCCP concentrations at Shergyla Mountain and Lhasa were between 50 and 690 pg/m3 and 800–6700 pg/m3, respectively. At Shergyla Mountain, MCCP concentrations in the air appeared an increasing trend with altitude, which indicated that MCCPs could potentially possess the ability of “mountain cold trapping”. C14 and C15 congener groups were the dominant homologue groups. The mountain contamination potential (MCP) of different congener groups is closely related to their equilibrium partitioning coefficients between octanol and air (KOA), and water and air (KWA). Increasing MCCPs levels might be a potential threat to the environment and human exposure.

Headspace Solid-Phase Microextraction Coupled to Comprehensive Two-Dimensional Gas Chromatography Time-of-Flight Mass Spectrometry for the Determination of Short-Chain Chlorinated Paraffins in Water Samples.

Short-chain chlorinated paraffins (SCCPs) are a new type of persistent organic pollutants. In this work, a simple and effective method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF-MS) was developed and optimized for the determination of trace SCCPs in water samples. The key parameters related to extraction and separation efficiency were systematically optimized. The SCCP congener groups were best resolved using an Rxi-5Sil MS (30 m × 0.25 mm × 0.25 µm) column followed by an Rxi-17Sil MS (1.0 m × 0.15 mm × 0.15 µm) column; the optimum extraction conditions were achieved with a 100 µm polydimethylsiloxane SPME fiber, when a 10 mL water sample added with 3.6 g sodium chloride was incubated for 15 min at 90°C and then extracted during 60 min at 90°C and desorption at 260°C for 2 min. The proposed method showed good linearity in the concentration range of 0.2–20.0 µg/L with the determination coefficient greater than 0.995. The detection and quantification limits ranged from 0.06 to 0.13 µg/L and 0.18 to 0.40 µg/L, respectively, which are sufficient to meet the regulatory detection limits as set by most environmental regulations. The accuracy and precision of the method was also good, where the recoveries ranged from 82.5 to 95.4%, and intra- and interday precision was within 7.2% and 14.5%, respectively. The optimized method has been applied to the determination of SCCPs in ten freshwater samples of three different types.

Short- and medium-chain chlorinated paraffins in sediments from the Laizhou Bay area, North China: Implications for transportation from rivers to marine environment

The concentrations of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) were measured for riverine and marine sediments from the Laizhou Bay area in order to investigate their spatial distributions, possible sources and transport behaviors. Concentrations of SCCPs and MCCPs in riverine sediments varied from 8.4 to 2000 ng g−1 dw and from 1.8 to 3200 ng g−1 dw, respectively. Higher concentrations were found exclusively at industrial sites. Emissions from local factories were the main source of CPs in river sediments of this region. It was 5–22 ng g-1 dw and 6–63 ng g−1 dw with an average value of 11 ng g−1 dw and 9 ng g−1 dw for SCCPs and MCCPs in marine sediments of Laizhou Bay, respectively. In addition to riverine input, ship related emissions are suggested to be another important source of CPs in the Laizhou Bay. MCCPs/SCCPs values and compositional profiles of SCCPs were found to vary along with CP concentrations. A distinct shift to congener groups with shorter carbon chains and lower chlorination from emission sources to remote areas was noticed. The role of log octanol-water partition coefficient (LogKow) values indicated decisive in their transportation from emission sources to remote areas in the Laizhou Bay area.

Mass Fractions, Congener Group Patterns, and Placental Transfer of Short- and Medium-Chain Chlorinated Paraffins in Paired Maternal and Cord Serum.

Multiple studies have demonstrated the occurrences of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in environmental matrixes, but human internal exposure to them has been studied rarely. Mass fractions and congener group patterns of SCCPs and MCCPs in paired maternal and cord serum were studied for the first time to investigate the placental transport mechanism and prenatal exposure risks of CPs. Samples were collected in Beijing, China, and analyzed using two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. SCCP and MCCP mass fractions in maternal serum were 21.7-373 and 3.76-31.8 ng/g ww, respectively. They were 8.51-107 and 1.33-12.9 ng/g ww, respectively, in cord serum. Significant positive correlation between SCCP and MCCP levels in maternal serum was found ( p < 0.01), suggesting SCCPs and MCCPs may undergo similar accumulation, transfer, and transformation pathways. The predominant congener groups for SCCP and MCCP in maternal serum were C10-11Cl6-7 and C14Cl7-8. The homologue profiles of CPs in cord serum were similar but with varied contribution percentage compared with those in maternal serum. By calculating and comparing cord-maternal serum ratios for each individual congener group, passive diffusion was recognized to be the possible placental transport form. The relationships between CP and thyroid hormone concentrations (THs) indicated that exposure to CPs might affect circulating TSHs. C9-CPs were also detected, improving our understanding of CPs in human serum.

Concentrations and congener group profiles of short- and medium-chain chlorinated paraffins in animal feed materials

Chlorinated paraffins (CPs) are ubiquitous environmental pollutants that are lipophilic and can accumulate in the food chain. Animal-derived products are predominant contributors to human CP exposure. CPs in animal feed might accumulate in domestic animals through dietary exposure, leading to potential contamination of animal-derived food products and human health risks. However, information on the presence of CPs in animal feed materials is scarce. In this study, 16 animal feed material samples were collected in China in 2016. Thirteen of the samples were of animal origin and three were of plant origin. The concentrations and carbon and chlorine congener group profiles of shortchain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in these animal feed materials were investigated. The concentrations of SCCPs were higher than those of MCCPs in all of the samples. The SCCP concentration range was 120 to 1700 ng/g (mean 640 ng/g), and the MCCP concentration range was 6.4 to 260 ng/g (mean 78 ng/g). Fish meal had the highest SCCP and MCCP concentrations. The lowest SCCP and MCCP concentrations were detected in peanut meal and whey powder, respectively. The concentrations of SCCPs and MCCPs varied among the types of animal feed materials. SCCP and MCCP concentrations also varied among samples of the same type of animal feed material. Relatively high concentrations of SCCPs and MCCPs were detected in feed materials of animal origin. The predominant congener groups in the animal feed materials were C10-11Cl6-7 for SCCPs and C14Cl7 for MCCPs. The carbon and chlorine congener group profiles of SCCPs indicated that SCCP contamination in the animal feed materials might arise from commercial CP mixtures.

Short-chain chlorinated paraffin (SCCP) pollution from a CP production plant in China: Dispersion, congener patterns and health risk assessment

China is the largest chlorinated paraffin (CP) producer in the world. Given that CP production is a major source of short-chain CP (SCCP) pollution in China, the effects of CP production on the environment inside and outside of CP production plants are worth revealing. The concentrations and specific congener group patterns of SCCPs in various environmental matrices, such as air, soil and dust, inside and outside of a chosen CP production plant surrounded by farmlands and villages were analyzed to explore SCCP pollution and transportation behaviors. SCCP concentrations in air (129–1442 ng/m3) and soil (28–554 μg/g) samples inside the CP production plant were dramatically higher than those in air (91–333 ng/m3) and soil (102–441 ng/g) samples outside the CP production plant. Based on the congener abundance patterns among these samples, lighter groups (C10-11 and Cl5-6) were dominant in atmospheric environment, with greater long-range transport potential, whereas heavier groups (C12-13 and Cl7-10) were inclined toward deposition. It was clear that substantial amounts of SCCPs were released from the CP production plant, which contaminated the environment inside and outside of the plant. The daily occupational SCCP exposure of employees in the production hall (21.8 μg/day-kg) exceeded the tolerable daily intake (TDI, 10 μg/day-kg) given by Canadian Environmental Protection Act, suggesting that production employees were confronted with high health risk from SCCP exposure; while daily SCCP exposure of employees in office areas (0.57 μg/day-kg) and residents near the CP plant (1.22–25.5 × 10−2 μg/day-kg) were significantly lower, representing low health risk.

Исследование сорбционно-газохроматографического определения полихлорированных бифенилов в маслах

Проведено исследование использования многослойных сорбционных колонок, в состав которых включены сорбенты различной природы (силикагель, полихром-1, полисорб-1, флорисил или оксид алюминия), для извлечения смеси полихлорированных бифенилов (ПХБ), содержащей ди-, три-, тетра-, пента-, гекса- и гептахлорбифенилы, из трансформаторного и растительного масел. Показано, что наиболее подходящим является использование колонок с полихромом-1, в этом случае требуется меньший расход элюента, степень извлечения одинаковая для всех групп конгенеров ПХБ и составляет 80%. Минимальное определяемое содержание смеси ПХБ при анализе в условиях ГХ-ЭЗД составило 0.002%.

Two new species of the millipede family Cambalopsidae from Myanmar (Diplopoda, Spirostreptida).

Two new species of cave-dwelling millipedes are described from Myanmar, one each in the genera Plusioglyphiulus Silvestri, 1923 and Trachyjulus Peters, 1864. Plusioglyphiulus digitiformis sp. n. joins the small peculiar group of congeners from Thailand which is characterized by such plesiomorphies as the tergal crests on the collum and following metaterga being transversely divided into two, not three parts, as in species of the genus Glyphiulus Gervais, 1847. However, this new species differs by the 3-segmented telopodites of ♂ legs 1, the anterior gonopodal coxosternum showing higher and nearly straight apicomesal processes and very evident apicolateral teeth, as well as the higher and acuminate paramedian coxal processes of the posterior gonopods, the latter’s telopodites demonstrating an apical fovea bearing a group of microsetae at the bottom. Trachyjulus bifidus sp. n. is primarily distinguished by the telopodites of their anterior gonopods being strikingly and deeply bifid. A key to the five species of Cambalopsidae currently known to occur in Myanmar is presented, and a map showing their distributions given.

Determination of Chlorinated Paraffins by Bromide-Anion Attachment Atmospheric-Pressure Chemical Ionization Mass Spectrometry

A novel method for the quantitative determination of chlorinated paraffins (CPs) was developed using bromide-anion attachment atmospheric-pressure chemical ionization mass spectrometry (APCI-MS). Bromoform was used to enhance ionization of CPs. Near exclusive formation of stable bromide adduct ions ([M + Br]−) enabled accurate detection of individual CP congener groups (CnClm) with only a moderate-resolution quadrupole time-of-flight mass spectrometer. Furthermore, the method was free from interference commonly observed with chloride-anion attachment methods (e.g., decomposition ions [M + Cl – HCl]−) that require deconvolution. Together with a CnClm-response-factor algorithm for quantifying short-chain CPs and a CnClm-pattern-reconstruction algorithm for quantifying medium- and long-chain CPs, method applicability was demonstrated on biota and sediment samples. These data were generated significantly faster and with improved selectivity and sensitivity versus those of conventional measurements by chloride...

Validation of a HRGC–ECNI/LRMS method to monitor short-chain chlorinated paraffins in human plasma

Short-chain chlorinated paraffins (SCCPs) are produced in high volume and have the high potential to pose a threat to human health. However, little information is available for SCCP contamination in human blood/plasma/serum, mainly due to the difficulty of sample preparation and quantitative analysis. A method using high resolution gas chromatography coupled with electron capture negative ionization low resolution mass spectrometry (HRGC–ECNI/LRMS) was developed and validated to measure SCCPs in human plasma. The pretreatment process included protein denaturation and lipid elimination, liquid–liquid extraction with a mixture of n-hexane/dichloromethane (1:1, V/V), and cleanup on a multi-layer silica column. The blank controls, including procedural blank, vacuum blood collection tube blank, and instrumental blank, were the most pivotal points for the reliable analysis of SCCPs. The average value of procedural blanks was 9.0ng/g; and the method detection limit (MDL), calculated as the sum of the average procedural blank value and 3 times of the standard deviation of the procedural blanks, was 12.6ng/g plasma. The validated method was applied to measure the concentrations of the total SCCPs (∑SCCPs) in 50 plasma samples from a general population. The measured plasma concentrations of ∑SCCPs ranged from <MDL to 203ng/g wet weight (ww), with an average value of 32.0ng/g ww. The relative abundance profiles of SCCPs in plasma samples were dominated by C10- and C11-CP congener groups centered on Cl6–7. The developed method can be used for the comprehensive and large-scale investigation of SCCP levels in human plasma.

Concentrations and congener profiles of chlorinated paraffins in domestic polymeric products in China

Chlorinated paraffins (CPs) are widely used in domestic polymeric products as plasticizers and fire retardants. In this study, concentrations and congener profiles of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) were investigated in domestic polymeric products, including plastics, rubber and food packaging in China. The average concentrations of SCCPs in polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE) and food packaging were 234, 3968, 150 and 188 ng/g, respectively and the corresponding average concentrations of MCCPs in these samples were 37.4, 2537, 208 and 644 ng/g, respectively. The concentrations of CPs in rubber and polyvinylchloride (PVC) were significantly higher than in other matrices. The highest concentrations of SCCPs and MCCPs were found in a PVC cable sheath with 191 mg/g and 145 mg/g, respectively. Congener group profiles analysis indicated C11- and C13-congener groups were predominant in carbon homologues of SCCPs, and C14-congener groups were predominant in MCCPs. High levels of SCCPs and MCCPs in domestic polymeric products implied that they might be a significant source to the environment and human exposure.