Short-chain Chlorinated Paraffins Concentrations Research Articles

Physicochemical properties dominating the behaviors of short/medium chain chlorinated paraffins in the atmosphere

Chlorinated paraffins (CPs) are chlorinated alkane mixtures widely used as flame retardants and plasticizers in multiple industrial products. Systematic research on how homolog-specific properties affect their atmospheric behaviors is limited. Herein, we investigated the levels of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) in long-timescale, seasonal, and size-fractioned particles in the urban area of Dalian, a coastal city in northern China. The average SCCP and MCCP concentrations in particles with diameters ≤ 10 µm were 3.36 and 4.89 ng/m3, respectively, and a general increase in the SCCP concentration was observed from 2.59 ng/m3 in 2018 – 2019 to 7.84 ng/m3 in 2021 – 2023. CP levels and patterns showed significant seasonal variation, with a higher abundance of C11–13Cl7–9 in winter and C10–12Cl5 in summer. Elevated particle levels in winter and high temperatures in summer contributed to the seasonal variations. SCCPs and MCCPs were concentrated on particles with diameters of < 1 µm and their geometric mean diameter increased with the increasing carbon and chlorine numbers. Total Daily intake of SCCP and MCCP was calculated to be 0.15 and 0.22 ng/kg bw/day for adults. 53.1 %, 8.5 %, and 38.4 % of inhaled SCCPs, and 60.6 %, 7.6 %, and 31.8 % of inhaled MCCPs deposited into the head airway, tracheobronchial region, and alveolar region, respectively. This study reports on how homolog-specific physicochemical properties alter the temporal variations, size distributions, and inhaled fractions of CPs.

Tracking and optimizing toxic chemical exposure pathways through food trade: A case study in SCCPs contaminated seafood in China

Abstract Food safety is related to human health and sustainable development. International food trade poses food safety risks through the collateral transport of toxic chemicals that are detrimental to human health. Domestic interprovincial trade has similar effects within countries but has not been comprehensively investigated previously. Here we assessed the effects of interprovincial trade on food safety and human dietary exposure to short-chain chlorinated paraffins (SCCPs), a group of emerging persistent toxic chemicals, in seafood across China by synthesizing data from field observation and various models. Our findings indicate that there is a higher level of SCCPs exposure risk in coastal provinces compared to inland provinces. Approximately 70.3% of human exposure to SCCPs through seafood consumption in China was embodied in the interprovincial seafood trade in 2021. Specifically, the domestic trade led to a remarkable increase in SCCPs exposure in the coastal provinces in South China, attributable to low SCCPs pollution in these provinces and imported seafood from those provinces with high SCCPs pollution. In contrast, human exposure to SCCPs decreased in those coastal provinces in East China due to importing seafood from those provinces with low SCCPs concentrations. The interprovincial seafood trade routes were optimized by linear programming to minimize human exposure to SCCPs considering both shipping cost and health risk constraints. The optimized trade routes reduced the national per capita SCCPs exposure through seafood consumption by over 12%. This study highlights the importance of interprovincial food trade in the risk assessment of toxic chemicals.

Short- and medium-chain chlorinated paraffins in breast milk in Shanghai, China: Occurrence, characteristics, and risk assessment

As novel contaminants, short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) have been of great concern in the past several years. Shanghai was one of the provinces with the largest chlorinated paraffins (CPs) emission in China; nevertheless, there is currently little information on the human exposure to SCCPs and MCCPs, particularly MCCPs. In this study, 25 breast milk samples were collected in Shanghai from 2016 to 2017. The concentrations of SCCPs and MCCPs were determined using two-dimensional gas chromatography coupled with orbitrap high-resolution mass spectrometry (GC × GC-orbitrap-HRMS) to investigate their characteristics and assess the associated health risks for breast-fed infants. Compared with the previous studies in other areas, the current study presented the higher CPs concentrations, with median concentrations of SCCPs and MCCPs up to 771 and 125 ng/g lipid weight (lw), respectively. The exposure profiles of the CPs were characterized by C10 and Cl6-7 as the predominant congeners of SCCPs, while C14 and Cl7–9 were identified as the dominant groups of MCCPs. CP-42 and CP-52 were identified as potential sources of CPs found in breast milk samples collected in Shanghai. The concentrations of MCCPs exhibited a positive correlation (p value < 0.05) with the dietary consumption of meat and poultry. No significant positive correlations were observed for SCCPs and MCCPs with polychlorinated dibenzodioxins/furans (PCDD/Fs) congeners. A preliminary exposure assessment showed that SCCPs in breast milk potentially posed high risks to the breast-fed infants in Shanghai.

Characterization of persistent organic contaminants in the atmosphere of Gadani's ship breaking yards and its surrounding: Implications for sustainable ship recycling practices

Gadani is internationally renowned for its extensive ship-breaking operations, positioning it as one of the globe's primary ship-breaking hubs. A comprehensive study was conducted to evaluate the presence of organic contaminants in the air within Gadani, encompassing the areas surrounding ship-breaking facilities, proximate residential settlements, and adjacent roadways. Passive air samplers were employed to collect a total of 30 air samples. The analytical results unveiled a notably elevated concentration of specific organic compounds, with a pronounced prevalence of polycyclic aromatic hydrocarbons (PAHs), short-chain chlorinated paraffins (SCCPs), and polychlorinated biphenyls (PCBs) at the ship-breaking yard. Notably, dichlorodiphenyltrichloroethanes (DDTs) and DDE were detected at substantially lower levels. In particular, sites in close proximity to ship-breaking activities exhibited elevated concentrations of PCBs (Σ7PCB 0.065429 to 7.345714 ng/sample), PAHs (Σ8PAH 2.44 to 134.23 ng/sample), and SCCPs (0.18 to 25.6 ng/sample). Conversely, DDTs and DDE demonstrated higher concentrations near residential settlements. The evaluation of Molecular Diagnostic Ratios for PAHs revealed anthracene/anthracene + phenanthrene ratios of 0.88, 0.69, and 0.5 for ship-breaking areas, roadside locations, and community surroundings, respectively. Furthermore, the benz[a]anthracene/benz-[a]anthracene + chrysene molecular ratios were measured at 0.77 (ship-breaking sites), 0.82 (roadside), and 0.83 (community), respectively. The molecular ratio of fluoranthene/fluoranthene + pyrene at ship-breaking sites was 0.23, while roadside and community ratios were 0.36 and 0.89, respectively. These findings underscore the significant contribution of ship-recycling activities to the atmospheric release of SCCPs, PCBs, and PAHs, emphasizing the global imperative for responsible ship recycling practices.

Short- and medium-chain chlorinated paraffins in sediment from the Haihe River Basin: Sources, distributions, and ecological risk assessment

Chlorinated paraffins (CPs) can accumulate in sediment and pose risks to ecological systems and human health. The Haihe River Basin is one of the seven main river basins in China and is mainly in the Beijing–Tianjin–Hebei region, which is densely populated and very urbanized. There is therefore a high probability of CP pollution in the Haihe River Basin. However, CP pollution and the environmental risks posed by CPs in the Haihe River are not well understood. In this study, the concentrations of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) in sediment from six rivers in the Haihe River Basin system were determined using two-dimensional gas chromatography electron-capture negative ionization mass spectrometry. The total SCCP and MCCP concentrations in the sediment samples ranged from 131.83 to 1767.71 and from 89.72 to 1442.82 ng/g dry weight, respectively. The total organic carbon content did not significantly correlate with the CP concentrations. The dominant SCCP congener groups were C10Cl6–7 and the dominant MCCP congener groups were C14Cl7–8. Significant relationships (R = 0.700, p < 0.05) were found between the SCCP and MCCP concentrations, indicating that SCCPs and MCCPs may have similar sources. Hierarchical cluster analysis and principal component analysis indicated that sediment in the study area was contaminated with CPs through the use of the CP-42 and CP-52 commercial products in industrial processes and human activities. The ecological risks posed by CPs were assessed and SCCPs were found to pose high risks in the Yongding New River but moderate risks in the other rivers. MCCPs were found to pose minimal risks to the aquatic environment at most of the sampling points.

Chlorinated paraffins (CPs) in vegetable oils from the Dutch market and the effects of the refining process on their levels

Chlorinated paraffins (CPs) are of growing public health concern because of their ubiquitous presence in food samples. To get more insight into levels of CPs in vegetable oils from the Dutch market and human exposure via these oils, two series of samples were analysed in this study for the presence of CPs by UHPLC coupled with Q-Exactive Orbitrap mass spectrometry: 1) 39 vegetable oils from local supermarkets; 2) 13 paired crude and refined vegetable oils obtained from a contract refining company. Short chain CPs (SCCPs) and medium chain CPs (MCCPs) were detected in vegetable oils from supermarkets with an overall range from <LOQ to 78 ng/g lipid weight (lw) and <LOQ to 391 ng/g lw, respectively. The tridecane and tetradecane groups dominated in SCCPs and MCCPs, respectively. As regards to paired crude and refined oils from a refining company, a marked decrease in concentrations of both SCCPs and MCCPs were detected by the refining process (average reduction: 82% and 69% for SCCPs and MCCPs, respectively). Based on the data obtained, it can be concluded that CPs with a relatively short carbon chain length and low chlorination degree are more likely to be removed in the refining process. The estimated margins of exposure (MoEs) due to oil consumption alone were all higher than 1000, indicating no health concern from CPs for the Dutch population.

Short- and Medium-Chain Chlorinated Paraffins in the Sediment of the East China Sea and Yellow Sea: Distribution, Composition, and Ecological Risks.

Chlorinated paraffins (CPs), a class of complex mixtures synthesized from polychlorinated n-alkanes, are widely used as flame retardants, plasticizers, lubricant additives, coolants, metalworking cutting fluids, and sealants. This study investigated the spatial distribution, the potential pollution sources, and ecological risk of 24 short-chain CPs (SCCPs) and 24 medium-chain CPs (MCCPs) from 29 surface marine sediment samples from the East China Sea and Yellow Sea in September 2019. All of the 48 CPs were detected. The concentrations of SCCPs and MCCPs ranged from 0.703 to 13.4 ng/g dw and 0.0936 to 4.19 ng/g dw, respectively. C10 congeners showed the highest abundancy. The median concentrations of the SCCPs and MCCPs declined gradually with carbon atoms and chlorine atoms, except for Cl5 congeners. Spatial variations showed that all CP congeners in the East China Sea were larger than in the Yellow Sea and displayed a point-source-type distribution, which is consistent with the industrial park distribution. Although the potential ecological risk was at a relatively low level, bioaccumulation and trophic magnification could amplify the risk to marine organisms. Our results provide data support and theoretical assistance for SCCP and MCCP pollution control and sewage outlets in the East China Sea and Yellow Sea.

Characterization of short-, medium- and long-chain chlorinated paraffins in ambient PM2.5 from the Pearl River Delta, China

Research on the environmental occurrence of long-chain chlorinated paraffins (LCCPs) in ambient fine particulate matter (PM2.5) is still scarce. In the present study, short-chain chlorinated paraffins (SCCPs), medium-chain chlorinated paraffins (MCCPs) and LCCPs were simultaneously quantified and profiled in PM2.5 samples collected from 96 primary or secondary schools in the Pearl River Delta of South China. SCCPs, MCCPs and LCCPs were detected in higher than 90% samples with concentrations in the range of 0.832–109, 1.02–110, and 0.173–17.4 ng/m3, respectively. The dominant congener groups of SCCPs, MCCPs and LCCPs were C13Cl6-8, C14Cl7-8, and C18Cl7-9, respectively. The concentrations of SCCPs and MCCPs were higher in summer than in winter, while an opposite seasonal trend was observed for LCCPs. Principal components analysis showed there were seasonal variations in the congener group patterns with C13Cl6-7 and C14Cl7 more abundant in summer than in winter. Concentrations of CPs also exhibited slight spatial variations. Exposure risk assessment based on different age groups suggested exposure to PM2.5-associated CPs would not pose significant health risk. The present study expands the existing knowledge of CPs contamination in atmospheric environment.

Physical and chemical processes driving remote seasonal atmospheric exposure to cyclic volatile methysiloxanes and short-chain chlorinated paraffins

Cyclic volatile methylsiloxanes (cVMS) and short-chain chlorinated paraffins (SCCPs) use has been restricted in recent years due to environmental health concerns. Both of these classes of emerging contaminants possess long range transport potential (LRTP), highlighting the need for continuous monitoring to assess effectiveness of implemented regulations. However, emission source elucidation and understanding processes affecting atmospheric transport remain challenging. Atmospheric levels of cVMSs and SCCPs were simultaneously monitored at a background monitoring site in Norway from January–July 2020. Concentrations obtained from active air samplers ranged from 49.9 to 845 (mean: 208) pg/m3 for ƩSCCPs and from 0.4 to 3.5 (mean: 1.5), 1.1–15 (mean: 5.6) and 0.1–0.9 (mean: 0.4) ng/m3 for octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6), respectively. As SCCPs pose several challenges to analysts, different quantification methodologies and blank handling procedures were investigated to ensure reliable environmental measurements. Simulations using a Lagrangian atmospheric transport model (FLEXPART) revealed air masses impacting sampling measurements were of Oceanic origin, but periodic emission events from Europe and Russia were also observed. Seasonal pattern in cVMS concentrations was mainly driven by atmospheric degradation via hydroxyl radical reaction, whereas SCCP concentrations were more influenced by periodic anthropogenic inputs from local and continental Europe. No clear correlation could be observed with SCCP atmospheric concentrations and temperature over the entire sampling campaign. However, increased volatilization at elevated temperatures may be important with emissions originating from local sources. Higher chlorinated homologue groups dominated during the winter season and declined towards spring and summer, whereas reverse was found for the lower and more volatile chlorinated homologue groups.

Understanding inter-individual variability in short-chain chlorinated paraffin concentrations in human blood.

Chlorinated paraffins (CPs), particularly short-chain CPs (SCCPs), have been reported in human blood with high detection frequency and often high variation among individuals. However, factors associated with and their contributions to inter-individual variability in SCCP concentrations in human blood have not been assessed. In this study, we first measured SCCP concentrations in 57 human blood samples collected from individuals living in the same vicinity in China. We then used the PROduction-To-Exposure model to investigate the impacts of variations in sociodemographic data, biotransformation rates, dietary patterns, and indoor contamination on inter-individual variability in SCCP concentrations in human blood. Measured ∑SCCP concentrations varied by a factor of 10 among individuals with values ranging from 122 to 1230ng/g, wet weight. Model results show that age, sex, body weight, and dietary composition played a minor role in causing variability in ∑SCCP concentrations in human blood given that modeled ∑SCCP concentrations ranged over a factor of 2 - 3 correlated to the variations of these factors. In contrast, variations in the modeled ΣSCCP concentrations increased to factors of 6 and 8 when variability in biotransformation rates and indoor contamination were considered, respectively, indicating these two factors could be the most influential on inter-individual variability in SCCP concentrations in human blood.

Distribution and exposure risk assessment of chlorinated paraffins and novel brominated flame retardants in toys

Chlorinated paraffins (CPs) and novel brominated flame retardants (NBFRs) were examined in children’s toys collected from 13 families in China. The concentrations of short-chain CPs (SCCPs), medium-chain CPs (MCCPs) and NBFRs in toys were 32.8−1,220,954 ng/g, not detected−2,688,656 ng/g and 0.08−103,461 ng/g, respectively. Median concentrations of SCCPs and MCCPs in toys were 1355 and 1984 ng/g, respectively, while except for pentabromobenzene (median:0.04 ng/g), the median concentrations of the other 8 NBFRs were below method detection limits. Rubber and foam toys contained higher amounts of CPs and NBFRs. Among the SCCPs and MCCPs monitored, Cl6−8-SCCPs/MCCPs and C14-MCCPs were the most abundant congener groups. On the other hand, decabromodiphenyl ethane was the predominant NBFR in toys. Moreover, to understand the role of toys in children’s daily exposure to CPs and NBFRs, hand-to-mouth contact, mouthing, and dermal exposure were assessed for children aged 3 months to 6 years. Hand-to-mouth contact is the primary exposure route for children’s exposure to CPs (25.4−536 ng/kg/day) and NBFRs (1.24−26.2 ng/kg/day) through toys. A low deleterious risk associated with children’s toys concerning CPs and NBFRs was investigated based on the margin of exposure and hazard quotient values.

Homologue-based Estimations of Short-Chain Chlorinated Paraffin Emissions and Concentrations in Japan

Short-chain chlorinated paraffins (SCCPs) are persistent organic pollutants. In Japan, SCCPs are widely detected in the environment although the production and use of SCCPs have been banned. It is essential to estimate the amount and sources of SCCPs to implement countermeasures for SCCP emission. In this study, we estimated the emission and environmental concentrations of SCCP homologues in Japan from 1950 to 2050. Initially, the material flow of total SCCPs was estimated considering the material recycling process. The emission from each process during the entire life cycle of products containing SCCPs was estimated for each homologue. Volatilization factors of long-term-use products were specifically estimated from release factors and surface area, weight, and SCCP concentration of products containing SCCPs. The environmental concentrations were then estimated using the environmental fate model. In the material flow and emission estimation, parameter uncertainties, such as emission factors and SCCP application distribution, were considered, assuming each parameter follows a uniform distribution. The results of emission estimation suggested a decreasing trend of SCCP emission in recent years and continuation of this trend in the future. However, some emissions from long-term-use products may persist. In the future, products that have a long lifetime with closed-loop recycling, such as polyvinyl chloride wire-coating materials, are expected to significantly contribute to atmospheric emission. Moreover, recycled products may contain SCCPs. Based on the estimated concentration, the estimated water and sediment concentrations were within the range of the observed concentrations. Conversely, we could reduce the gap between the estimated and observed atmospheric SCCP concentrations compared with those in previous studies that did not consider the volatilization factor for each SCCP-containing product and material recycling process. However, a difference between the estimated and observed concentrations suggests that some unconsidered emission sources may exist that emit SCCPs into the atmosphere, such as SCCPs as impurities in medium-chain chlorinated paraffins, imported products containing SCCPs, and atmospheric advection from other countries. Hence, it is essential to calculate emissions from sources other than products that intentionally contain SCCPs produced in the past.

Distinct biomagnification of chlorinated persistent organic pollutants in adjacent aquatic and terrestrial food webs

Biomagnification of persistent organic pollutants (POPs) in food webs has been studied for many years. However, the different processes and influencing factors in biomagnification of POPs in aquatic and terrestrial food webs still need clarification. Polychlorinated biphenyls (PCBs) and short-chain chlorinated paraffins (SCCPs) were measured in organisms from adjacent terrestrial and aquatic environment in this study. The median levels of PCBs in terrestrial and aquatic organisms were 21.7–138 ng/g lw and 37.1–149 ng/g lw, respectively. SCCP concentrations were 18.6–87.3 μg/g lw and 21.4–93.9 μg/g lw in terrestrial and aquatic organisms, respectively. Biomagnification factors (BMFs) of PCBs increased with higher log KOW in all food chains. BMFs of SCCPs were negatively correlated with log KOW in aquatic food chains, but positively correlated with log KOW in terrestrial food chains. The terrestrial food web had similar trophic magnification factors (TMFs) of PCBs, and higher TMFs of SCCPs than the aquatic food web. Biomagnification of PCBs was consistent in aquatic and terrestrial food webs, while SCCPs had higher biomagnification potential in terrestrial than aquatic organisms. The distinct biomagnification of SCCPs was affected by the respiratory elimination for terrestrial organisms, the different metabolism rates in various species, and more homotherms in terrestrial food webs. Fugacity model can well predict levels of less hydrophobic chemicals, and warrants more precise toxicokinetic data of SCCPs.

Dietary Intake Contributed the Most to Chlorinated Paraffin Body Burden in a Norwegian Cohort.

Determining the major human exposure pathways is a prerequisite for the development of effective management strategies for environmental pollutants such as chlorinated paraffins (CPs). As a first step, the internal and external exposure to CPs were quantified for a well-defined human cohort. CPs in participants' plasma and diet samples were analyzed in the present study, and previous results on paired air, dust, and hand wipe samples were used for the total exposure assessment. Both one compartment pharmacokinetic modeling and forensic fingerprinting indicate that dietary intake contributed the most to body burden of CPs in this cohort, contributing a median of 60-88% of the total daily intakes. The contribution from dust ingestion and dermal exposure was greater for the intake of long-chain CPs (LCCPs) than short-chain CPs (SCCPs), while the contribution from inhalation was greater for the intake of SCCPs than medium-chain CPs (MCCPs) and LCCPs. Significantly higher concentrations of SCCPs and MCCPs were observed in diets containing butter and eggs, respectively (p < 0.05). Additionally, other exposure sources were correlated to plasma levels of CPs, including residence construction parameters such as the construction year (p < 0.05). This human exposure to CPs is not a local case. From a global perspective, there are major knowledge gaps in biomonitoring and exposure data for CPs from regions other than China and European countries.

Short- and medium-chain chlorinated paraffins in honey from China: Distribution, source analysis, and risk assessment

Chlorinated paraffins (CPs) are industrial chemicals produced in large quantities. Short-chain CPs (SCCPs) were classified as persistent organic pollutants under the Stockholm Convention in 2017. Medium-chain CPs (MCCPs) became candidate persistent organic pollutants in 2021. CPs are now ubiquitously found in the environment. Honey bees can be exposed to CPs during foraging, and this exposure subsequently results in the contamination of honey and other bee products along with colony food production and storage. Here, SCCP and MCCP concentrations in honey collected from Chinese apiaries in 2015 and 2021 were determined. Total CP concentrations in honey from 2021 to 2015 were comparable, but the ratio of MCCPs/SCCPs was higher in 2021 than in 2015. SCCP and MCCP congener group profiles in all honey samples were similar and dominated by C10–11Cl6–7 and C14Cl6–7, respectively. MCCP concentrations were also higher than SCCP concentrations in bees, pollen, and wax but not in bee bread, which were all collected in 2021. The order of average CP concentrations was determined as wax > bee > pollen > bee bread > honey. Poor relationships were found between SCCP concentrations in honey and other samples, but a relationship between MCCP concentrations in honey and other samples was observed. Migration tests of CPs in plastic bottles showed essentially no migration into honey during storage. The risks to humans from CPs in honey are low.

Dietary exposure and risk assessment of chlorinated paraffins in roots and rhizomes of traditional Chinese medicine herbs.

Traditional Chinese medicine (TCM) provides therapeutic and health care effects through dietary intake. Owing to the susceptibility of plants to contaminations, a risk assessment system is urgently needed to ensure the safe use of TCMs. In this study, the contamination levels and risks associated with the dietary intake of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) were investigated in six kinds of frequently-used TCM herbs. The concentrations varied from 144.4 to 1527.8ng·g-1 dw for SCCPs and non-detect to 1214.1ng·g-1 dw for MCCPs, with mean values of 551.5 and 259.8ng·g-1 dw, respectively. A geographic distribution analysis indicated that the concentrations of CPs in TCMs were mainly associated with their levels of contamination in the ambient environment. Carbon atom-chlorine congener profiles of CPs were dominated by C10Cl7-8 and C14Cl7-8 congeners, accounting for 20.1% and 32.4% of the total SCCP and MCCP concentrations, respectively. Principal component analysis indicated that the TCM species might be the main factor influencing the accumulation of SCCPs congeners. Finally, a risk assessment reveals that the estimated daily intake and margin of exposure were far below levels that might pose a health risk, indicating an acceptable dietary intake of SCCPs and MCCPs in the studied TCMs. This is the first report of CPs in the TCM herbs and the obtained results are expected to aid in future evaluation of the quality of TCMs and ensuring diet and drug safety.

Occurrence, congener patterns, and potential ecological risk of chlorinated paraffins in sediments of Yangtze River Estuary and adjacent East China Sea.

Chlorinated paraffins (CPs) are high production volume chemicals with immense scientific research interest due to their wide distribution, persistence, toxicity, and bioaccumulation potential. In this study, 87 surface sediments were collected from the Yangtze River Estuary (YRE) and the adjacent East China Sea (ECS). We investigated the concentrations, spatial distribution, and composition profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) using ultra-high-performance liquid chromatography coupled with Orbitrap Fusion Tribrid mass spectrometry. The sedimentary concentrations of SCCPs and MCCPs ranged from 2.85 to 94.7 ng·g-1 (median 13.7 ng·g-1) and 3.33 to 77.8 ng·g-1 (median 13.3 ng·g-1), respectively. Higher CP concentrations were found in YRE sediments. The values decreased away from the location, implying a direct influence of the Yangtze River. The SCCP concentrations were higher than those of MCCPs in most sediment samples. Overall, the predominant homologs were C13Cl5-7 and C14Cl6-8 for MCCPs and SCCPs, respectively. Overall, the sediment-dwelling organisms in the region are susceptible to low ecological risks.

Spatial distribution, partitioning, and ecological risk of short chain chlorinated paraffins in seawater and sediment from East China Sea

Short chain chlorinated paraffins (SCCPs) have attracted increasing attention due to their potential risks to the ecosystem and human health. However, there is still a lack of systematic research on their environmental fate in the coastal marine environment. In this study, we collected paired seawater (n = 40) and surface sediment samples (n = 40) from East China Sea, and investigated their spatial distribution, partitioning behaviors and ecological risks. The total SCCP concentrations (∑SCCPs) in seawater and sediment samples were in the range of 12.2–430 ng/L and 89.6–351 ng/g (dry weight), respectively. C10–11 SCCPs and Cl5–7 SCCPs were the predominant homologues in all of the samples. This study first calculated the field-based logKOC values for ∑SCCPs in the marine environment, which ranged from 5.0 to 6.5 (mean 5.5). The logKOC values of SCCP homologues (range 3.6–8.0, mean 5.6) showed a weak correlation with their logKOW (R = 0.214, p < 0.05). A preliminary risk assessment indicated that SCCPs at current levels posed no significant ecological risk. Overall, this study contributes to the further understanding of environmental behaviors of SCCPs in the marine environment.

Comparison of short-chain chlorinated paraffin concentrations and homolog profiles by interlaboratory trial using a candidate reference material

Chlorinated paraffins (CPs) are industrial chemicals that have been primarily used in applications involving metalworking fluids. Among CPs, short-chain chlorinated paraffins (SCCPs) are a well-known environmental pollutant and are listed under Annex A of the Stockholm Convention on Persistent Organic Pollutants. CPs are alkanes substituted with chlorine atoms, and SCCPs are comprised of 10–13 carbon atoms. Reliable quantification of SCCPs is a critical issue because of the large number of SCCP isomers that are in use across multiple industries. Some interlaboratory comparisons of SCCP analyses have been conducted, and the reliability of these results was overwhelmingly determined as inferior to that of comparable PCB and dioxin analyses because of variations in the quality of commercial reagents that were employed as quantification standards. In order to address such inconsistencies, this study endeavored to prepare and evaluate a novel SCCP formulation as a candidate reference material for use as a reliable quantification standard. A subject trial study was hence performed to evaluate methods such as gas- and liquid-chromatography mass spectrometry (GC/MS and LC/MS) on sample matrices (without a clean-up process), and to subsequently elucidate the interpreted specifications for their candidacy as a reliable quantification standard. Results ultimately showed that the SCCP concentrations obtained from GC and LC were comparable. When the homologs reported by a subset of 14 separate laboratories were unified (excluding all results for Cl4 homologs), the carbon chain length profiles obtained from GC and LC were found to be similar; however, the overall chlorine homolog profiles did exhibit slight differences. Moreover, the results from high-resolution MS showed less variation than those from low-resolution MS. Thus, it was overarchingly determined that the deployment of this candidate reference material would serve as an effective mechanism for estimating the comparability of SCCP quantifications/evaluations of standard materials.

Concentrations, homolog profiles, and risk assessment of short- and medium-chain chlorinated paraffins in soil around factories in a non-ferrous metal recycling park

Chlorinated paraffins (CPs) are used as additives in metal processing in the metal smelting industry. Data on CPs in the environment near metal smelting plants are limited. The objectives of this study were to investigate the concentrations and congener profiles of CPs in soil around factories in a non-ferrous metal recycling park located in Hebei, China, and to investigate human exposure to CPs in the soil. The concentrations of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) were determined by two-dimensional gas chromatography with electron capture negative ionization mass spectrometry. The SCCP and MCCP concentrations in the soil samples were 121–5159 ng/g and 47–6079 ng/g, respectively. Generally, the CP concentrations in soils around the factories were relatively high compared with those near other contaminated sites and in rural and urban areas. There were significant correlations between the MCCP concentrations, some SCCP carbon homologs, and the total organic carbon content (p < 0.05). The major SCCP and MCCP congener groups were C10Cl6–7 and C15–16Cl5, respectively. Hierarchical cluster analysis and principal component analysis indicated that SCCPs and MCCPs in the soil might originate from extreme pressure additives containing CP-42 and CP-52 and CP-containing waste material from the factories. The concentrations in two samples collected near a metal recycling factory posed a moderate risk according to a risk assessment conducted using risk quotients. Further risk assessment showed that the CPs concentrations in soil did not pose significant health risks to either children or adults.