Partitioning of Chlorinated Paraffins (CPs) to Daphnia magna Overlaps between Restricted and in-Use Categories

Spatial distribution and ecological risk assessment of short and medium chain chlorinated paraffins in water and sediments of river Ravi, Pakistan

Short (SCCPs) and medium (MCCPs) chain chlorinated paraffins being the emerging organic pollutants have raised serious concerns due to their widespread use and related human health risks. However, their occurrence in aquatic bodies like rivers and associated damage to ecological integrity is yet unknown in some regions of the world. The current study is the first ever assessment of SCCPs and MCCPs in sediment and water of river Ravi, Pakistan. Spatial occurrence and associated ecological risks were investigated from sediments (n = 16) and composite water samples (n = 8) collected at eight locations along the stretch of river Ravi. The concentrations of SCCPs and MCCPs varied from below limit of detection ( Collapse

Key Words

• Aquatic body
• Partitioning coefficient
• Risk assessment
• Source identification
• Total organic carbon

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MESH Headings

• Humans
• Animals
• Chlorine
• Hydrocarbons, Chlorinated/analysis
• Paraffin/analysis
• Rivers
• Pakistan
• Environmental Monitoring
• Risk Assessment
• Carbon
• China

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Grants Collapse

Affiliation(s)

Areej Tahir College of Earth and Environmental Sciences, University of the Punjab, Lahore 54590, Pakistan
Naeem Akhtar Abbasi College of Earth and Environmental Sciences, University of the Punjab, Lahore 54590, Pakistan.
Chang He Queensland Alliance for Environmental Health Science, The University of Queensland, Brisbane 4102, Australia; Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, PR China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
Sajid Rashid Ahmad College of Earth and Environmental Sciences, University of the Punjab, Lahore 54590, Pakistan
Mujtaba Baqar Sustainable Development Study Centre, Government College University, Lahore 54000, Pakistan
Abdul Qadir College of Earth and Environmental Sciences, University of the Punjab, Lahore 54590, Pakistan

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Polychlorinated alkanes in paired blood serum and breast milk in a Swedish cohort study: Matrix dependent partitioning differences compared to legacy POPs

BACKGROUND

Polychlorinated alkanes (PCAs) constitute a large group of individual congeners originating from commercial chlorinated paraffin (CP) products with carbon chain lengths of PCAs-C10-13, PCAs-C14-17, and PCAs-C18-32, occasionally containing PCAs-C6-9 impurities. The extensive use of CPs has led to global environmental pollution of PCAs. This study aimed to quantify PCAs in paired serum and breast milk of lactating Swedish mothers, exploring their concentration relationship.

METHODS

Twenty-five paired samples of mothers' blood serum and breast milk were analysed and concentrations were determined for PCAs C6-32 and compared to 4,4'-DDE, the PCB congener 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153), and hexachlorobenzene (HCB).

RESULTS

The median concentrations of PCAs-C6-9, PCAs-C10-13, PCAs-C14-17, PCAs-C18-32 and ΣPCAs in serum were 14, 790, 520, 16 and 1350 ng/g lipid weight (lw), respectively, and in breast milk 0.84, 36, 63, 6.0 and 107 ng/g lw. Levels of 4,4'-DDE, CB-153 and HCB were comparable in the two matrices, serum and breast milk at 17, 12 and 4.9 ng/g lw. The results show significant differences of PCAs-C10-13 and PCAs-C14-17 in breast milk with 22- and 6.2-times lower lw-based concentrations than those measured in serum. On wet weight the differences serum/breast milk ratios of PCAs-C6-9, PCAs-C10-13, PCAs-C14-17, PCAs-C18-32 and ΣPCAs were 1.7, 3.2, 1.0, 0.4 and 1.6, respectively, while the ratio for 4,4'-DDE, CB-153 and HCB were each close to 0.1.

CONCLUSION

Swedish lactating mothers had high serum concentrations of PCAs-C10-13 and PCAs-C14-17, with the ΣPCAs median serum concentration of 1350 ng/g lw. The breast milk concentration, although considerably lower at 107 ng/g lw, still surpassed those of 4,4'-DDE, CB-153 and HCB, suggesting an exposure risk of infants to PCAs. The variation in blood and breast milk accumulation between PCAs and studied legacy POPs, is rarely discussed but warrants further studies on partitioning properties as well as associated toxicological implications.

Short- and medium-chain chlorinated paraffins in fish from an anthropized south-western Atlantic estuary, Bahía Blanca, Argentina

Chlorinated paraffins (CPs) are synthetic organic compounds of growing environmental and social concern. Short-chain chlorinated paraffins (SCCPs) were listed under the Stockholm Convention on Persistent Organic Pollutants (POPs) in 2017. Further, in 2021, medium-chain chlorinated paraffins (MCCPs) were proposed to be listed as POPs. We investigated SCCP and MCCP amounts and homolog profiles in four wild fish species from Bahía Blanca Estuary, a South Atlantic Ocean coastal habitat in Argentina. SCCPs and MCCPs were detected in 41% and 36% of the samples, respectively. SCCP amounts ranged from <12 to 29 ng g^-1 wet weight and <750-5887 ng g^-1 lipid weight, whereas MCCP amounts ranged from <7 to 19 ng g^-1 wet weight and <440-2848 ng g^-1 lipid weight. Amounts were equivalent to those found in fish from the Arctic and Antarctic Oceans and from some North American and Tibetan Plateau lakes. We performed a human health risk assessment and found no direct risks to human health for SCCP or MCCP ingestion, according to present knowledge. Regarding their environmental behavior, no significant differences were observed among SCCP amounts, sampling locations, species, sizes, lipid content, and age of the specimens. However, there were significant differences in MCCP amounts across species, which could be attributed to fish size and feeding habits. Homolog profiles in all fish were dominated by the medium-chlorinated (Cl₆ and Cl₇) CPs and shorter chain length CPs were the most abundant, with C₁₀Cl₆ (12.8%) and C₁₁Cl₆ (10.1%) being the predominant SCCPs and C₁₄Cl₆ (19.2%) and C₁₄Cl₇ (12.4%) the predominant MCCPs. To the best of our knowledge, this is the first study on the presence of CPs in the environment in Argentina and the South Atlantic Ocean. CP occurrence in the environment, particularly in the food chain, promotes the need for further research on their occurrence and behavior, and the impact of CPs in marine ecosystems in Argentina.

Short- and medium-chain chlorinated paraffins in urban road dust of Shanghai, China: concentrations, source apportionment and human exposure assessment

Chlorinated paraffins (CPs) are ubiquitous anthropogenic contaminants that have been found in various environmental media. The objective of this study was to determine concentrations, spatial distribution, possible sources and potential health risk of SCCPs and MCCPs in urban road dust collected from Shanghai, China. The concentrations ranged from 9.74 to 11,400 ng g^-1 for ΣSCCPs, 44.1 to 49,900 ng g^-1 for ΣMCCPs and 53.9 to 61,400 ng g^-1 for total CPs, respectively. MCCPs were the dominant component in all road dust, averagely accounting for 82.8% of total CPs. The concentrations of CPs in dust collected from traffic and commercial areas were significantly higher than those from campus, industrial, park and residential areas (p < 0.01), which could be attributed to tire wear in heavy traffic. All dust samples were divided into two groups by hierarchical cluster analysis for both SCCPs and MCCPs, and the most abundant homologue groups in most samples were C₁₀Cl_7-10 and C₁₃Cl_7-9 for SCCPs, and C₁₄Cl_7-9 and C₁₅Cl_8-9 for MCCPs. Correlation analysis showed that all carbon homologues in road dusts were highly correlated each other, suggesting SCCPs and MCCPs in dust maybe came from similar sources. Three sources for CPs in dust samples were apportioned by the PMF model; their relative contributions to the total CPs burden in dust were 25.6% for factor 1 (commercial CP mixture), 13.7% for factor 2 (long-distance transport) and 60.7% for factor 3 (commercial CP mixture). The median estimated daily intakes of total CPs via road dust were 1.78 × 10^-5 for children and 3.0 × 10^-6 mg kg^-1 day^-1 for adults, respectively. Quantitative risk assessment using non-cancer hazard index and total margin of exposure of total CPs indicated that total CPs at the present level in road dust pose no significant risk for both children and adults in Shanghai.

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 (PM_2.5) 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 PM_2.5 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 C₁₃Cl_6-8, C₁₄Cl_7-8, and C₁₈Cl_7-9, 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 C₁₃Cl_6-7 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 PM_2.5-associated CPs would not pose significant health risk. The present study expands the existing knowledge of CPs contamination in atmospheric environment.

Occurrence, spatial distribution, and risk assessment of short- and medium-chain chlorinated paraffins in sediment from black-odorous rivers across China

Chlorinated paraffins (CPs) were massively produced for varied industrial purposes, of which improper handling and consequent environmental release resulted in worldwide contamination. The present study investigated the occurrence and spatial distribution of short- and medium-chain chlorinated paraffins (SCCP/MCCPs) in 171 sediment samples from black-odorous urban rivers across China. Total SCCP and MCCP concentrations ranged from 8.3 to 9.4 × 10⁴ (median: 1.1 × 10³) ng/g dw, and from not-detected-value to 1.0 × 10⁶ (median: 1.3 × 10⁴) ng/g dw, respectively. No clear spatial distribution of SCCPs and MCCPs was observed since black-odorous urban rivers were polluted by point-sources of the SCCP/MCCPs. Significant positive correlations were identified between SCCP/MCCPs and total organic carbon, and between SCCP/MCCPs and other persistent organic matter, including polybrominated diethyl ethers, polychlorinated biphenyls, antibiotics, and plasticizers. The average ratios of MCCPs to SCCPs in most samples were divided into 11 and 16, implying the manufacturing and use of at least two types of CP technical mixtures in China. The composition of SCCP/MCCPs were similar to that in their commercial products. Ecological risk assessments by two approaches, including the Federal Environmental Quality Guidelines and Risk Quotient, both revealed that SCCP/MCCP in surface sediments confer an ecological risk. ENVIRONMENTAL IMPLICATION: SCCPs and MCCPs can be considered "hazardous materials" because of their massive production and their potential persistence, long-distance transfer, bioaccumulation potential, and toxicity. This research conducted a comprehensive study on SCCP/MCCP in black-odorous urban river sediments across China and revealed their environmental risk, which may improve understanding of SCCP/MCCP contamination characteristics.

Passive sampling of chlorinated paraffins by silicone: Focus on diffusion and silicone-water partition coefficients

Short-chain chlorinated paraffins (SCCPs) are under regulation through the European Water Framework Directive and were recently classified as POPs. Consecutively, the increasing use of middle-chain chlorinated paraffins (MCCPs) becomes of growing concern. Knowledge on the occurrence of chlorinated paraffins (CPs) is still scarce particularly in water phase. To achieve sufficient method sensitivity, the passive sampling approach, acting as a relevant alternative to usual grab sampling, has been considered only very recently for the monitoring of CPs in water. The present work aimed at determining the diffusion coefficients in silicone (D_s) and the silicone-water partition coefficients (K_sw) of various CP groups, having different chlorine contents and carbon chain lengths, in four commercial CP mixtures. Log D_s (-10.78 to -10.21) was found to vary little and to be high for the groups of CPs studied. Thus, their uptake in silicone is controlled by the water boundary layer, which allows to consider the release of performance and reference compounds for in-field estimation of the sampling rate. Moreover, CPs partitioned strongly towards silicone rubbers. Both the chlorination degree and the carbon chain length of CPs cause large uncertainties in the partitioning between silicone and water (log K_sw between 4.85 and 6.30), indicating that instead of an average value, differentiated K_sw should be used to estimate aqueous CPs more accurately. Even so, the probable influence of chlorine atoms position on polarity and partitioning may be an argument for favoring sampling in the kinetic stage.

Overlooked long-chain chlorinated paraffin (LCCP) contamination in foodstuff from China

Data on long-chain chlorinated paraffins (LCCPs) is extremely sparse, despite their use and emission are increasing with the phasing out of short-chain chlorinated paraffins (SCCPs). In this study, we analyzed chlorinated paraffins (CPs) in foodstuff samples (551 pooled samples, 93 items) divided into eight categories collected from Jinan, Shandong Province of China, by atmospheric-pressure chemical ionization quadrupole time-of-flight mass spectrometry (APCI-qToF-MS), to investigate the occurrence, contamination patterns and homologue patterns of LCCPs in foodstuff commonly consumed in traditional Chinese diet. LCCP intake through diet was estimated as well. LCCPs were detected in all pooled samples with geometric mean (GM) concentrations ranging from 1.8 to 21.9 ng/g wet weight (ng/g ww), contributing to 9-28% of the total CP mass in the studied foodstuff categories. The contamination patterns of LCCPs differed from SCCPs and medium-chain chlorinated paraffins (MCCPs), as reflected by the patterns of mass distribution, and by the lack of correlations between LCCP and S/MCCP concentrations in various foodstuff categories. The homologue profiles of LCCPs were extremely complex and diverse, with frequent detection of C_30-36Cl_2-15 very-long-chain chlorinated paraffin (vLCCP) congeners. The homologue profiles of eggs stood out for their high abundance of C_18-22Cl_9-13 LCCP congeners. LCCPs contributed 6.0-25.2% (8.9% for median estimation) to the estimated dietary intake (EDI) for total CPs through diet based on estimations using different percentiles of CP concentrations. The median estimate of dietary LCCP intake for adults in Jinan was 287.9 ng/kg_bw/day, reaching ~10- to 100-fold of that in Sweden and Canada. Considering the continuing production, use and emission of LCCPs, as well as the similar toxicity effects induced by LCCPs as SCCPs and MCCPs, attention should be paid to the health risk posed by LCCPs, or all CPs as a class of contaminants.

Male renal functions are associated with serum short- and medium-chain chlorinated paraffins in residents from Jinan, China

BACKGROUND

Chlorinated paraffins (CPs) are contaminants ubiquitously detected in environmental samples, and reports addressing CPs in human samples are expanding. While CP exposure was suggested to impair kidney function by in vivo/in vitro experiments, epidemiological evidence is lacking.

OBJECTIVE

To examine the associations between serum total short-chain CP and medium-chain CP concentrations (∑SCCPs and ∑MCCPs) with human kidney function.

METHODS

The study samples were obtained from 387 participants living in Jinan, North China. We quantified ∑SCCPs and ∑MCCPs in serum samples and evaluated the kidney function of included subjects by estimated glomerular filtration rate (eGFR). The associations between serum ∑SCCPs, ∑MCCPs and eGFR were estimated using multivariable linear regression and logistic regression. The possible gender-dependent effects were studied by stratified analysis.

RESULTS

After adjusting for age, education, smoking status, drinking status, body mass index (BMI), family history of chronic kidney disease (CKD), fasting serum glucose, systolic blood pressure and diastolic blood pressure, higher concentrations of serum ∑SCCPs and ∑MCCPs were associated with higher male eGFR (β = 3.13 mL/min/1.73 m² per one ln-unit increase of serum ∑SCCPs, 95%CI: 1.72, 4.54, p = 0.016; β = 3.52 mL/min/1.73 m² per one ln-unit increase of serum ∑MCCPs, 95%CI: 1.89, 5.17, p = 0.011). Associations between serum ∑SCCPs, ∑MCCPs and female eGFR were null. Comparing higher (above the median serum CP levels) vs. lower exposure groups, serum ∑SCCPs and ∑MCCPs were associated with an elevated risk of glomerular hyperfiltration (GH, eGFR ≥ 135 mL/min/1.73 m²), which was associated with glomerular damage and represented as an early stage of chronic kidney disease (OR = 2.98; 95% CI: 1.24, 4.71 for SCCPs; OR = 3.25; 95% CI: 1.20, 5.29 for MCCPs).

CONCLUSIONS

Our study suggests that male serum ∑SCCPs and ∑MCCPs are associated with an increased risk of GH, indicating early-stage kidney impairment.

Passive Dosing of Petroleum and Essential Oil UVCBs-Whole Mixture Toxicity Testing at Controlled Exposure

Petroleum products and essential oils are produced and used in large amounts and are categorized as "Substances of Unknown or Variable composition, Complex reaction products or Biological materials (UVCBs)." These UVCBs are notorious difficult-to-test substances, since they are complex mixtures of hydrophobic and volatile compounds. This study introduces two passive dosing (PD) approaches for whole UVCB toxicity testing: (1) headspace PD applies the UVCB and purified lipid oil as a donor to control exposure via the headspace and (2) silicone rod PD applies UVCB-loaded silicone rods to control exposure via an aqueous test medium and headspace. Headspace gas chromatography-mass spectrometry measurements were used to cross-validate the approaches at the saturation level and to confirm exposure and maintain mixture composition at varying donor concentration levels. Both approaches were applied to whole-mixture toxicity tests of petroleum and essential oil UVCBs with daphnia and algae. Finally, the observed toxicity was linked to concentrations in the donor and in lipid membranes at equilibrium with the donors. Dose-response curves were similar across the dosing approaches and tested species for petroleum products but differed by an order of magnitude between essential oils and PD systems. All observed toxic effects were consistent with baseline toxicity, and no excess mixture toxicity was observed.

Evaluating oral and inhalation bioaccessibility of indoor dust-borne short- and median-chain chlorinated paraffins using in vitro Tenax-assisted physiologically based method

Though ingestion and inhalation of dust have been suggested as important exposure routes contributing chlorinated paraffins (CPs) build-up in humans, the bioaccessibility of dust-borne CPs in the organ environment has not been well-studied, which may hinder an accurate estimation of exposure risks. In this study, the ingestion and inhalation bioaccessibility of dust-borne short- and median-chain CPs (SCCPs and MCCPs) was assessed using (colon-extended) physiologically based extraction test with the addition of Tenax. The ingestion bioaccessibility of SCCPs 51.5 %Cl, SCCPs 63 %Cl, MCCPs 42 %Cl, and MCCPs 57 %Cl was in ranges of 21.1-44.0 %, 11.7-45.8 %, 21.9-36.6 %, and 7.9-32.9 %, respectively. Multiple linear regression analysis demonstrated statistically significant associations of ingestion bioaccessibility with carbon chain length and chlorine substitution. The ingestion bioaccessibility of CPs also increased with co-existence of carbohydrate/protein. The inhalation bioaccessibility of SCCPs (16.7-38.7 % in artificial lysosomal fluid and 15.5-34.1 % in modified Gamble solution) was significantly higher than MCCPs (<5 %), and varied with dust particle size/total organic carbon content. Our study indicates that modest bioaccessible fractions of CPs in dust should be taken into account to refine the estimation of human exposure, and their bioaccessibility may be affected by CP molecular size, nutritional content and dust property.

The association of liver function biomarkers with internal exposure of short- and medium-chain chlorinated paraffins in residents from Jinan, China

Chlorinated paraffins (CPs) are pervasive environmental pollutants which have been reported to be hepatotoxic by laboratory cell and animal studies. However, the related epidemiological reports on their hepatotoxic effects to humans are sparse. In this study, we evaluated the associations between six liver enzymes and serum short-chain CP (SCCP) or medium-chain CP (MCCP) concentrations of 197 residents in Jinan, China. Serum S/MCCPs were detected by quadrupole time-of-flight high-resolution mass spectrometry coupled with atmospheric pressure chemical ionization source (APCI-QTOF-HRMS), and quantified by pattern deconvolution method. The associations between total serum S/MCCP concentrations (ΣS/MCCPs) and continuous liver enzyme levels were assessed by linear regression. Odds ratios (ORs) for the effects of serum ΣS/MCCPs concentrations on liver function biomarkers dichotomized by clinical reference intervals were predicted by logistic regression, either treating ΣS/MCCPs as continuous or categorical dependents. After multivariable adjustment, linear regression results illustrated that 1-ln unit increase in serum ΣSCCPs was negatively associated with male PA levels [-6.08, 95% confidence interval (CI): -11.90, -3.25, p < 0.05], positively associated with male TB levels (1.80, 95% CI: 0.28, 3.31, p < 0.05), and positively associated with female AST levels (1.39, 95% CI: 0.07, 2.70, p < 0.05). One-ln unit increase in serum ΣMCCPs was negatively associated male PA levels (-7.56, 95% CI: -17.15, -4.03, p < 0.05). Logistic regression results suggested that male serum ΣSCCPs were associated with increased prevalence of abnormal PA (OR = 1.47 per 1 ln-unit increase, CI = 1.18, 1.82) and TB (OR = 1.75, 95% CI = 1.12, 2.76) levels, and male serum ΣMCCPs were significantly associated with increased prevalence of abnormal PA (OR = 1.43, 95% CI = 1.03, 1.97) levels. In addition, male participants with concentrations above the median ΣS/MCCPs were associated with increased risk for abnormal PA levels [SCCPs, 2.11-fold (95% CI = 1.15, 3.87); MCCPs, 1.94-fold (95% CI = 1.24, 3.03)]. Male participants with concentrations above the median ΣSCCPs were also associated with increased risk for abnormal TB levels (OR = 1.75, 95% CI = 1.12, 2.76). Conclusively, our results revealed that CP internal exposure was associated with disturbed liver biomarker levels, suggesting the hepatotoxicity of both SCCPs and MCCPs to humans.

First study of passive sampling to monitor short-chain chlorinated paraffins in water: Comparing capabilities of Chemcatcher® and silicone rubber samplers

Short-chain chlorinated paraffins (SCCPs) are high-volume chemicals raising concerns because of their classification as priority hazardous substances by the European Water Framework Directive (WFD) and their recent inclusion in the persistent organic pollutants' (POPs) list by the Stockholm convention. As this group cover up to 5000 isomers, their measurement is still challenging. Hence the SCCPs occurrence in the environment is poorly documented in comparison with other POPs, especially in matrices where they are present at ultratrace levels such as waters. In the two-past decades, passive sampling has been increasingly used as it overcomes some major drawbacks associated to the conventional grab sampling. This study constitutes the first work aiming to examine the passive sampling's applicability for the monitoring of such complex analytes' mixtures in waters. Optimization and calibration of two proven passive samplers, namely silicone rubbers and Chemcatcher®, were performed through batch and laboratory pilot experiments. Despite the thousands of molecules present in the SCCPs mixture, the resulting global kinetic uptakes fitted well with the theorical model, for both samplers. Sampling rates of 8.0 L d^-1 for silicone rubbers and 0.53 L d^-1 for Chemcatcher® were found, and logK_sw determined for silicone rubbers equaled 4.24 to 4.95. These values are in complete agreement with published data for other HOCs. A field trial carried out in marine coastal environments provided further evidence to demonstrate the applicability of the passive samplers to measure CPs amounts in water bodies. All these results unveil that passive sampling using silicone rubbers or Chemcatcher® can be a relevant approach to track traces of such complex mixtures in water.

Occurrence of short- and medium-chain chlorinated paraffins in soils and sediments from Dongguan City, South China

As a group of emerging organic pollutants, chlorinated paraffins (CPs) have attracted rising global attention due to their persistence and toxicity. In this study, we have investigated the concentration levels and profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in soils and sediments from Dongguan City, an industrial area in South China, and have also screened very short-chain chlorinated paraffins (vSCCPs) by means of ultra-high resolution liquid chromatograph coupled with an Orbitrap Fusion Tribrid mass spectrometer. The results indicated that total SCCP concentrations ranged from 6.75 to 993 ng/g (mean 172 ng/g) in soils and from 4.00 to 613 ng/g (mean 153 ng/g) in sediments, respectively. Higher MCCP levels were observed with a range of 23.9-2427 ng/g (mean 369 ng/g) in soils and 14.0-1581 ng/g (mean 493 ng/g) in sediments, respectively. The results indicated that MCCPs dominated over SCCPs in the studied region. The dominant homologues in soils and sediments were C₁₃Cl_6-7 and C₁₄Cl_7-8, C₁₃Cl₇, and C₁₄Cl_7-8, respectively. Furthermore, six vSCCP homologues (C₈Cl_7-8 and C₉Cl_5-8) in soils and four vSCCPs (C₉Cl_5-8) in sediments have been identified. Because of their higher detection frequencies, further studies should focus on the transformation mechanisms and toxicities of these vSCCPs in environmental media and biota.

Blood partitioning and whole-blood-based maternal transfer assessment of chlorinated paraffins in mother-infant pairs from South China

As a new group of persistent organic pollutants of concern, chlorinated paraffins (CPs) have been widely detected in the environment and biota, but their occurrence, partitioning, and transfer in humans have been not well documented. In this study, 32 pairs of maternal blood, cord blood, and placenta samples were collected from pregnant women in South China, and the blood was further separated into plasma and red blood cells (RBCs) for blood partitioning study. Short- and medium-chain CPs (SCCPs and MCCPs, respectively) were detected in all the five human biological matrices, suggesting prevalent exposure and maternal transfer of CPs in the pregnant women. Discrepant congener group profiles of CPs were observed in different human biological matrices. Significant differences in the plasma-RBC partitioning of CPs in the maternal and cord bloods were identified (p < 0.001). CP partitioning to plasma was stronger than that to RBCs in maternal blood, but the converse was true for cord blood. Mass fractions in plasma (F_p) for SCCPs (mean, 0.78) and MCCPs (0.74) in maternal blood were significantly higher than the values in cord blood. Transplacental transfer efficiencies (TTEs) were evaluated based on the whole blood concentrations of CPs in the maternal and cord bloods, and the TTEs ranged from 0.50 to 0.69 (first to third quartiles) for SCCPs and MCCPs, indicating that the placenta can partially restrict maternal transfer. The extent of CP retention in the placenta was assessed by the concentration ratio (R_PM) of matched placenta and maternal blood, and interestingly, a U-shaped trend for placental retention (R_PM) with increasing chain length was observed for individual congener groups. Significant relationships of the CP concentrations among the maternal blood, cord blood, and placenta were observed (p < 0.001). To our knowledge, this is the first study to report the plasma-RBC partitioning of CPs in human maternal and cord bloods, as well as the first study to evaluate TTEs based on whole blood concentrations. Our study confirmed that whole blood is the preferred matrix for accurately assessing human internal exposure and transplacental transfer of CPs.

Short and medium-chain chlorinated paraffins in serum from residents aged from 50 to 84 in Jinan, China: Occurrence, composition and association with hematologic parameters

Human exposure to chlorinated paraffins (CPs) has been expected and assessed by external pathways considering their pervasive environmental occurrence. However, the deficiency of external exposure assessment in characterizing human burden is unavoidable. In addition, the associations between health outcomes and CP contents in human biospecimen are rarely assessed. In this study, we reported the occurrence and homologue profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in serum samples from 145 residents aged from 50 to 84 in Jinan, Shandong Province of China using quadrupole time-of-flight high-resolution mass spectrometry coupled with atmospheric pressure chemical ionization source operated in negative ion mode (APCI-qTOF-HRMS). The associations between serum CP concentrations and hematologic parameters were further analyzed by linear regression. We identified high level of ∑SCCPs (median = 107 ng/g wet weight, ww; 13,800 ng/g lipid, lw), ∑MCCPs (median = 134 ng/g ww; 15,200 ng/g lw) and elevated ∑MCCPs/∑SCCPs (median = 1.12) in serum of the studied population. C₁₃-CPs and C₁₄-CPs were the most abundant SCCP and MCCP groups, respectively. While the predominant chlorine homologues among SCCPs and MCCPs were Cl_7-8-CPs. ∑SCCPs, ∑MCCPs, ∑MCCPs/∑SCCPs and the homologue patterns presented no significant variance among age, sex and BMI groups. Further explorations suggested that perturbation of hematologic homeostasis could be induced by CP exposure in a sex-specific way, reflected by significant negative associations of serum SCCP and MCCP concentrations in lipid weight basis with sex-specific hematologic parameters. This study suffered from some limitations and should be interpreted with caution. However, the CP burdens of residents in China and the subsequent health risks must be underscored.

Liposome-mediated delivery of challenging chemicals to aid environmental assessment of Bioaccumulative (B) and Toxic (T) properties

Standard aquatic toxicity tests of chemicals are often limited by the chemicals’ water solubility. Liposomes have been widely used in the pharmaceutical industry to overcome poor pharmacokinetics and biodistribution. In this work, liposomes were synthesized and used in an ecotoxicological context, as a tool to assure stable dosing of technically challenging chemicals to zooplankton. Three chemicals with distinctly different characteristics were successfully incorporated into the liposomes: Tetrabromobisphenol A (TBBPA, log K_ow 5.9, pK_a1 7.5, pK_a2 8.5), chlorinated paraffin CP-52 (log K_ow 8–12) and perfluorooctanoic acid (PFOA, pK_a 2.8). The size, production yield and stability over time was similar for all blank and chemical-loaded liposomes, except for when the liposomes were loaded with 10 or 100 mg g⁻¹ PFOA. PFOA increased the size and decreased the production yield and stability of the liposomes. Daphnia magna were exposed to blank and chemical-loaded liposomes in 48 hour incubation experiments. A dose-dependent increase in body burden in D. magna and increased immobilization (LD₅₀ = 7.6 ng CPs per individual) was observed. This confirms not only the ingestion of the liposomes but also the successful internalization of chemicals. This study shows that liposomes can be a reliable alternative to aid the study of aquatic toxicity of challenging chemicals.

Complex Mixtures of Chlorinated Paraffins Found in Hand Wipes of a Norwegian Cohort

Up to 18000 ng of total chlorinated paraffins (CPs) was found in hand wipes of individual adult participants in a Norwegian cohort study (n = 60), with a geometric mean (SD) value of 870 (2700) ng. The CPs covered a wide range of alkane chain lengths from C₇ to C₄₈ with variable chlorine substitution. Complex mixtures of very-short-chain (vSCCPs, C_<10), short-chain (SCCPs, C_10-13), medium-chain (MCCPs, C_14-17), and long-chain (LCCPs, C_>17) CPs were found, contributing on average 0.3%, 20%, 58%, and 22%, respectively, of the total CPs. Significant positive correlations were found between CP levels and factors related to the indoor environment and product use, including living in a house/apartment built before the ban of SCCPs, having a sofa, the number of TVs in the home, and owning a car, which mirrors CP usage as flame retardants and/or plasticizers in consumer products. Compared to previous studies of other organic contaminants in hand wipe samples from the same cohort, CPs were the most abundant flame retardants. This is the first report of CPs in hand wipes, and dermal exposure based on these data suggested that hand contact could be an important human exposure pathway for LCCPs.

Occurrence and mass balance of medium- and long-chain chlorinated paraffins in a municipal sewage treatment plant: Comparison to short-chain compounds

Short-, medium-, and long-chain chlorinated paraffins (SCCPs, MCCPs, and LCCPs) are persistent in sediment and bioaccumulative in organisms in the coastal regions, and sewage treatment plants (STPs) play a crucial role in the control of emissions and risks of CPs in the aquatic environment. In this study, the occurrences of the three CP groups were simultaneously studied in a typical STP with anoxic/anaerobic/aerobic bioreactors as the core treatment units. MCCPs were the predominant CPs in wastewater samples tested, and SCCPs and LCCPs were in the similar concentrations. Proportions of LCCPs in solid samples increased steadily from 26% in influent to 53% in effluent, those of MCCPs decreased from 55% to 39%, while no obvious variations in the proportions (5.5-24%) of SCCPs were observed compared to the aqueous phase. The overall removal efficiencies were 93-97% for SCCPs, 75-89% for MCCPs, and 84-97% for LCCPs. A total of 50-67%, 25-64% and 55-92% of the initial mass loadings of SCCPs, MCCPs and LCCPs, respectively, were found in the dehydrated sludge, and 2.8-26% of the three CP groups were found in effluent. The removal pathway of three groups of CPs is dominated by sorption in the STP, especially for the longer chained and highly chlorinated CPs. Effluent discharge of STP is also an important source of CPs in the aqueous environment.

Chlorinated paraffins in indoor dust from Australia: Levels, congener patterns and preliminary assessment of human exposure

Chlorinated paraffins (CPs) are a group of polychlorinated n-alkanes with high production volumes. Until now, there are only limited data on the levels of CPs in the environment, especially in the indoor environment. In this study, dust samples were collected from 44 indoor environments, including 27 private houses, 10 offices, and 7 vehicles. Short-, medium-, and long-chain CPs were detected in all dust samples. The median concentration of ∑CPs (C₁₀-C₂₁) was 57, 160 and 290 μg/g, in houses, offices, and vehicles, respectively. Medium-chain CPs were the dominant group, on average accounting for 86% of ∑CPs. Cl₆ and Cl₈ groups had the highest contributions to ∑CPs across all the different microenvironments, while C₁₃ and C₁₄ were the predominant groups of SCCPs and MCCPs. Median exposure to ∑CPs via indoor dust were estimated at 80 ng/kg/day and 620 μg/kg/day for Australian adults and toddlers respectively. The daily intake of CPs via dust, in the worse scenario, was still 2-3 orders of magnitudes lower than the reference doses based on neoplastic effects.

Shorter than short-chain: Very short-chain chlorinated paraffins (vSCCPs) found in wildlife from the Yangtze River Delta

Very short-chain chlorinated paraffins (vSCCPs, C_6-9) occurred in 94% of wildlife samples from the Yangtze River Delta (YRD), China, with C_nCl_m comparable to that of a local CP product, CP-52. Therefore, we determined the content of vSCCPs in CP-52 using a mathematical deconvolution technique. Then with CP-52 and several other reference standards, vSCCPs together with short-, medium-, and long-chain CPs were quantified in 21 wildlife species from an artificial wetland ecosystem and a freshwater ecosystem in the YRD. Concentrations of vSCCPs ranged from 2.6 to 8400 ng/g lipid. These concentrations were 1.2-380 fold lower than SCCPs, but were significantly correlated with those of SCCPs. vSCCP concentrations were comparable to or higher than reported for brominated flame retardants in the same samples. Bioaccumulation tendency of vSCCPs was identified in two benthic species, indicating congener-specific accumulation of vSCCPs in the environment.

Bioaccumulation Potential of CPs in Aquatic Organisms: Uptake and Depuration in Daphnia magna

Chlorinated paraffins (CPs) are industrial chemicals, subdivided into three categories: short chain (SCCPs), medium chain (MCCPs), and long chain (LCCPs) chlorinated paraffins. SCCPs are currently restricted in Europe and North America. MC and LCCPs are being used as substitution products, but there is a knowledge gap concerning their bioaccumulation potential in aquatic organisms. In this work, we performed laboratory bioconcentration (passive uptake) and bioaccumulation (including dietary uptake) experiments with Daphnia magna using five different CP technical substances. All tested CP technical substances were bioaccumulative in D. magna, with log BCF and log BAF values ranging between 6.7-7.0 and 6.5-7.0 (L kg lipid^-1), respectively. An increase in carbon chain length and an increase in chlorine content (% w/w) of the CP technical substances had significant positive effects on the log BCF and log BAF values. For the different CP technical substances, 50% depuration was achieved after 2 to 10 h when D. magna were transferred to clean media. Our results show that SC, MC, and LCCPs are (very)bioaccumulative in aquatic organisms. We believe these data can aid the ongoing policy discussion concerning the environmental risk posed by CPs.

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 K_ow values, indicating mother to egg transport of CPs was related to the lipophilicity of the chemicals.

Accumulation of Short-, Medium-, and Long-Chain Chlorinated Paraffins in Marine and Terrestrial Animals from Scandinavia

Short-, medium-, and long-chain chlorinated paraffins (SCCPs, MCCPs, and LCCPs) have a wide range of physical-chemical properties, indicating their varying bioaccumulation tendencies in marine and terrestrial ecosystems. However, there are few empirical data to reveal such bioaccumulation tendencies. In this study, we analyzed SCCPs, MCCPs, and LCCPs in samples from 18 species at both low and high trophic levels of marine and terrestrial ecosystems from the Scandinavian region collected during the past decade. These included fish, seabirds, marine mammals, and terrestrial birds and mammals. SCCPs, MCCPs, and LCCPs were present in all the species, with concentrations ranging from 26-1500, 30-1600, 6.0-1200 ng/g lipid, respectively. Although MCCPs and SCCPs predominated in most species, many terrestrial species had generally higher concentrations of LCCPs than marine species. Terrestrial raptors in particular accumulated higher concentrations of LCCPs, including C_24/25-which are predominant among very-long-chain components. LCCP concentrations were highest and predominated (55% of total CPs) in peregrine falcons in this study, which is the first report where concentrations of LCCPs surpass those of SCCPs and MCCPs in wildlife. The results also indicate biomagnification of SCCPs, MCCPs, and LCCPs in both marine and terrestrial food chains, but in-depth studies of specific food webs are needed.

Methods for trace analysis of short-, medium-, and long-chain chlorinated paraffins: Critical review and recommendations

Many methods for quantifying chlorinated paraffins (CPs) yield only a total concentration of the mixture as a single value. With appropriate analytical instrumentation and quantification methods, more reliable and detailed analysis can be performed by quantifying total concentrations of short-, medium-, and long-chain CPs (SCCPs, MCCPs, and LCCPs), and in the current optimal situation by quantifying individual carbon-chlorine congener groups (C_nCl_m). Sample extraction and clean-up methods for other persistent organochlorines that have been adapted for recovery of CPs must be applied prior to quantification with appropriate quality assurance and quality control to ensure applicability of the methods for SCCPs, MCCPs, and LCCPs. Part critical review, part tutorial, and part perspective, this paper provides practical guidance to analytical chemists who are interested in establishing a method for analysis of CPs in their lab facilities using commercial reference standards, or for expanding existing analysis of total CPs or SCCPs to analysis of SCCPs, MCCPs, and LCCPs, or to analysis of C_nCl_m congener groups.