Congener-specific C10C13 and C14C17 chlorinated paraffins in Chinese agricultural soils: Spatio-vertical distribution, homologue pattern and environmental behavior

Tissue-Specific Accumulation of Orally Administered Short- and Medium-Chain Chlorinated Paraffins in Honeybees (Apis mellifera L.)

The prevalence and distribution of chlorinated paraffins (CPs) have been extensively studied in various matrices and organisms; however, there is a lack of information about insects, particularly in honeybees. To address this gap, we studied young honeybee workers exposed to short- and medium-chain CPs (SCCPs and MCCPs) at an environmentally relevant concentration of 10 mg/L for 7 days, followed by a 7-day elimination period. Results indicated that CPs could transfer into the head after oral consumption and SCCPs and MCCPs exhibited clear bioaccumulation trends: midgut > hindgut > head. An evaluation of congener group distribution patterns demonstrated that the dominant congener groups in all target tissues were C11-13Cl7-8 and C14Cl7-8 for SCCPs and MCCPs, respectively, consistent with the treated CP standards. In honeybees, a significant negative relationship was observed for the log concentration of MCCP congener groups and their log KOW, but not with their log KOA. Conversely, no such correlation was found for SCCPs. These findings suggest that honeybees have a high potential to bioaccumulate MCCPs, particularly those with a low log KOW, and exhibit weak selectivity for SCCPs.

Cattle hair as a bioindicator for short- and medium-chain chlorinated paraffin monitoring on cattle farms

Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) are hazardous industrial chemicals that tend to bioaccumulate in animal-derived foodstuffs through the food supply chain. However, the lack of reliable noninvasive bioindicators hinders the monitoring of farm animal exposure to CPs. In this study, 169 cattle hair samples were collected from beef cattle farms in six Chinese provinces, with further beef, feed, and soil samples being collected in Hebei province. Geographical differences in CP concentrations were observed in the hair samples, and CP concentrations in samples collected from Hebei province decreased in the following order: hair > feed > beef > soil. C10-11Cl6-7 and C14Cl7-8 were the predominant SCCPs and MCCPs, respectively, in all the hair, beef, feed, and soil samples. CP concentrations in hair samples significantly correlated with those in beef, feed, and soil samples, indicating that hair can be used as a bioindicator of cattle exposure to CPs. The possible health risks associated with exposure to CPs through beef consumption, especially for children and high-volume beef consumers, should be further investigated.

Bee colonies map the short- and medium-chain chlorinated paraffin contamination from the apiary environment

Chlorinated paraffins (CPs) are industrial chemicals that have potential adverse effects in the environment and on human health. This study investigated CPs in apiary environment, honeybees, and bee products from two rural areas of Beijing, China. The median concentrations of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) were 22 and 1.6 ng/m3 in the ambient air, 1350 and 708 ng/g dry mass (dw) in bees, 1050 and 427 ng/g dw in flowers, 37 and 54 ng/g in honey, 78 and 53 ng/g dw in bee pollen, 36 and 30 ng/g dw in soil, and 293 and 319 ng/g dw in bee wax. C10Cl6-7 and C14Cl7-8 dominated SCCPs and MCCPs in these samples, respectively. The concentrations and distributions of CPs in samples from apiaries located in the two regions varied. Long-range transportation of air masses was identified as an important source of CPs in apiaries. A close relationship between CPs in bees and the apiary environment indicated that bees could act as bioindicators for CP contamination in the environment. A human health risk assessment found that there were low risks for adults and children exposed to CPs through consumption of honey and pollen from the studied regions.

Uptake, accumulation and toxicity of short chain chlorinated paraffins to wheat (Triticum aestivum L.)

Short chain chlorinated paraffins (SCCPs) are ubiquitous persistent organic pollutants. They have been widely detected in plant-based foods and might cause adverse impacts on humans. Nevertheless, uptake and accumulation mechanisms of SCCPs in plants remain unclear. In this study, the soil culture data indicated that SCCPs were strongly absorbed by roots (root concentration factor, RCF>1) yet limited translocated to shoots (translocation factor<1). The uptake mechanism was explored by hydroponic exposure, showing that hydrophobicity and molecular size influenced the root uptake and translocation of SCCPs. RCFs were significantly correlated with logKow values and molecular weights in a parabolic curve relationship. Besides, it was extremely difficult for SCCPs to translocate from shoots back to roots via phloem. An active energy-dependent process was proposed to be involved in the root uptake of SCCPs, which was supported by the uptake inhibition by the low temperature and metabolic inhibitor. Though SCCPs at environmentally relevant concentrations had no negative impacts on root morphology and chlorophyll contents, it caused obvious changes in cellular ultrastructure of root tip cells and induced a significant increase in superoxide dismutase activity. This information may be beneficial to moderate crop contamination by SCCPs, and to remedy soils polluted by SCCPs with plants.

Short- and medium-chain chlorinated paraffins in agricultural and industrial soils from Shanghai, China: surface and vertical distribution, penetration behavior, and health risk assessment

The widespread contamination of chlorinated paraffins (CPs) of the soil environment has raised global concern due to their highly persistent and toxic properties. However, little information is available regarding these industrial toxicants' spatial-vertical distribution and penetration potentials. In this study, short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively) were analyzed in pooled surface and core soils (0-45 cm) samples collected from agricultural and industrial areas in Shanghai. ∑SCCP concentrations in agricultural and industrial surface soils ranged from 52.6 to 237.6 and 98.3 to 977.1 ng/g dry weight (dw), respectively. ∑MCCP levels were comparatively higher and ranged from 417.2 to 1690.8 and 370.9 to 10,712.7 ng/g dw in agricultural and industrial soils, respectively. C10Cl5-10 SCCPs and C14-15Cl5-7 MCCPs were the predominant homologues in all samples. Analysis of the soil vertical profiles revealed that MCCP concentrations decreased significantly with depth (P < 0.01). SCCPs more efficiently penetrated into the soils than MCCPs because of their higher water solubility and less octanol-water partition coefficient (Kow) values. A preliminary risk assessment suggested no potential health risks caused by non-dietary exposure. The daily exposure doses of CPs via ingestion were significantly (P < 0.01) higher for children (5.41 ± 2.11 × 10-3 and 1.68 ± 1.03 × 10-2 μg kg-1 day-1) and adults (2.56 ± 0.99 × 10-4 and 7.94 ± 4.87 × 10-4 μg kg-1 day-1) than dermal permeation exposure. Furthermore, CPs at current levels posed low ecological risks (0.1 ≤ RQ < 1) according to the risk quotient model. This study enhanced our understanding of the fates and behaviors of CPs in the terrestrial environment.

Integrating compound-specific stable isotope and enantiomer-specific analysis to characterize the isomeric and enantiomeric signatures of hexachlorocyclohexanes (HCHs) in paddy soils

Organic pollutants in paddy fields may undergo different processes from those in dryland due to the anaerobic environment. The integrated use of compound-specific stable isotope analysis (CSIA) and enantiomer-specific analysis is a promising technique for understanding the behavior and fate of organic pollutants in soils. In this study, soil samples were collected from paddy fields in three major rice cultivation regions of China, spanning a transect of 4000 km. The mean concentrations of ƩHCHs in paddy soils from the Taihu Plain were the highest (1.44 ng/g). The ratios of α-HCH/β-HCH (all below 11.8) and α-HCH/γ-HCH (92% below 4.64), as well as the enantiomeric fractions (EFs) of chiral α-HCH (mean of 0.81), reflected that the distribution of HCHs was affected by the use of both technical HCHs and lindane. The preferential depletion of (-)-α-HCH and pronounced carbon isotope fractionation of α-HCH (δ13C of -28.22 ± 0.92‰ -23.63 ± 1.89‰) demonstrated its effective transformation. Factors such as altitude, soil temperature, soil pH, soil conductivity and soil organic matter significantly influenced the fate and transformation of HCHs. The current study highlights the integrated application of CSIA and enantiomer-specific analysis to provide multiple lines of evidence for the transformation of HCHs in soils.

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.

Occurrence, Distribution and Health Risk of Short-Chain Chlorinated Paraffins (SCCPs) in China: A Critical Review

With being listed in the Stockholm Convention, the ban on short-chain chlorinated paraffins (SCCPs) has been put on the agenda in China. Based on the literature over the past decade, this study comprehensively analyzed the occurrence, distribution of and human exposure to SCCPs in China, aiming to provide a reference for the changes in SCCPs after the ban. SCCPs were ubiquitous in environmental matrices, and the levels were considerably higher than those in other countries. SCCPs from the emission region were 2–4 orders of magnitude higher than those in the background area. Environmental processes may play an important role in the SCCP profiles in the environment, and C10 and Cl6 were identified as potential factors distinguishing their spatial distribution. River input was the dominant source in the sea areas, and atmospheric transport was the main source in the remote inland areas. Ingestion and dermal absorption and food intake may pose potential risk to residents, especially for children and infants. More studies are needed on their temporal trend, source emission and environmental degradation. The enactment of the restriction order will have a great impact on China’s CP industry; nevertheless, it will play a positive role in the remediation of SCCP pollution in the environment.

Air-soil exchange of and risks posed by short- and medium-chain chlorinated paraffins: Case study in a contaminated area in China

Short-chain (SC) and medium-chain (MC) chlorinated paraffins (CPs) are found widely in the environment. Little research into air-soil exchange of SCCPs and MCCPs has been performed. In this study, CP concentrations, congener group profiles, and air-soil exchange in a typical contaminated area were investigated. A total of 10 soil samples and 10 air samples were collected from Zhoushan, an island in China. The samples were analyzed by two-dimensional gas chromatography electron capture negative ionization mass spectrometry. The SCCP and MCCP concentrations in the soil samples were 72-3842 and 117-8819 ng/g, respectively, and the SCCP and MCCP concentrations in the air samples were 57-208 and 1.8-25 ng/m³, respectively. The highest CP concentrations in both soil and air were found in samples from near shipyards, possibly because of CPs being emitted from metal cutting fluids and marine paints used at the shipyards. C₁₄-₁₅Cl_7-9 were the dominant CP congener groups in the soil samples. C₁₀Cl_6-7 were the dominant CP congener groups in the air samples. Chlorinated decane and undecane and penta-, hexa-, and hepta-chlorinated CPs were enriched in the air relative to the soil. These congeners may have been released from the commercial CP-42 and CP-52. The fugacity fractions (ffs) of 48 homologs decreased as Koa increased. The ffs indicated that SCCPs and MCCPs dominated deposition. The net air-soil exchange fluxes of CPs were 201-769 ng/(m²·h). A preliminary risk assessment indicated that CPs pose low ecological risk except at sampling site S7 and do not pose significant health risks.

Short- and medium-chain chlorinated paraffins in soil from an urban area of northern China: Levels, distribution, and homolog patterns

Short-chain chlorinated paraffins (SCCPs) are persistent organic pollutants that are present in relatively high concentrations in various environmental media in China. Many studies have focused on chlorinated paraffins in soil from agricultural land and contaminated areas. There are limited data on the levels of chlorinated paraffins in soil from urban areas. In this study, to investigate the levels, distribution, and homolog patterns of chlorinated paraffins (CPs) in soil from a typical urban area, 130 soil samples were collected and combined to form 26 pooled samples. The samples were analyzed for 50 CP congener groups (C_9-17Cl_5-10). The concentration ranges for SCCPs, medium-chain CPs (MCCP), and chlorinated nonane paraffin (C₉-CP) were 19-1456 ng/g (average: 234 ng/g), <10-385 ng/g (average: 54 ng/g), and 1-39 ng/g (average: 11 ng/g), respectively. The CP concentrations were not significantly correlated with the total organic carbon content (P > 0.05). Compared with other areas worldwide, the SCCP and C₉-CP concentrations in soil in this area were at the medium level, and the concentrations of MCCPs were at a low level. The CP concentrations were higher in soil samples collected near factories and domestic garbage disposal sites. C₁₀Cl_6-7 were the main SCCP homologs and C₁₄Cl_7-8 were the main MCCP homologs. Principal component analysis showed that the sources of C₉-CPs, SCCPs, and MCCPs in the soils were similar. Risk assessment showed that the concentrations of SCCPs and MCCPs in soil in this area did not pose a significant risk to soil organisms or human health.

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.

The effect of anthropogenic activities on the environmental fate of chlorinated paraffins in surface soil in an urbanized zone of northern China

Chlorinated paraffins (CPs) have been widely used as halogenated flame retardants and plasticizers since the mid-20th century. The prevalence of CPs in soil has been widely reported, but the distribution pattern of CPs in urbanized zones and their association with multiple socioeconomic variables have not been adequately explored. Herein, short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) were investigated in surface soil samples from Tianjin, China, a typical urbanized area. The concentration distributions of SCCPs and MCCPs showed similar trends in different administrative divisions and land use types: urban areas > suburbs > outer suburbs (p < 0.001) and residential areas > greenbelts > agricultural areas (p < 0.001). The CP congeners in residential surface soils mainly included those with longer carbon chains and high degree of chlorination, while the CP congeners in agricultural surface soils mainly consisted of those with shorter carbon chains and fewer chlorine substituents. Multiple statistical approaches were used to explore the association between socioeconomic factors and CP distribution. CP concentration was significantly correlated to population density and gross domestic product (GDP) (p < 0.001), and structural equation models incorporating administrative regional planning showed an indirect impact on the distribution of MCCP concentration due to the influence of regional planning on population density. These results highlight the association between CP contamination and the degree of urbanization, and this paper provides useful information toward mitigating the exposure risk of CPs for urban inhabitants.

A simplified method for determination of short-, medium-, and long-chain chlorinated paraffins using tetramethyl ammonium chloride as mobile phase modifier

The formation of halide adducts ion is an important pathway to improve the sensitivity of analytes in liquid chromatography (LC) combined with negative electrospray ionization (ESI) mass spectrometry (MS). Although adding modifier in mobile phase is generally the simplest way to form anions adducts, the formation of halide adducts ion requires a complex post-column addition strategy since traditional halide ionization enhancement reagents are incompatible with LC systems. To solve this problem, the volatile organochlorine salt tetramethyl ammonium chloride (TMAC) was therefore investigated as a potentially non-corrosive mobile phase modifier that was confirmed to be compatible with both LC and MS systems in this study. When short-chain, medium-chain, and long-chain chlorinated paraffins (CPs) were determinated simultaneously by ultra-high performance LC combined with ESI high resolution MS (UPLC-ESI-HRMS), all of them tended to ionize by forming [M+Cl]^- ions and exhibited excellent sensitivity with the instrumental detection limits of 1-4 pg/μL. Meanwhile, their sensitivities towards CPs were less dependent on their Cl content with the total relative response factors of 0.8-3.5. The method's utility was demonstrated through determination of CPs in surface soil and chicken muscle samples. This was an effective and practical method to enhance the selectivity for [M + Cl]^- ions and improve sensitivity towards CPs with various carbon lengths. Importantly, post-column addition was not required, and thus the analytical procedure was simplified. The method has also improved sensitivity towards some other organohalides and may be generally useful in the determination of challenging organic analytes.

Accumulation of short-, medium-, and long- chain chlorinated paraffins in tissues of laying hens after dietary exposure

Reliable human health risk assessment associated with chlorinated paraffins (CPs) exposure is limited by the lack of data on the fate of this complex family of contaminants. To gain knowledge on the accumulation and distribution of CPs in biota after ingestion, laying hens were dietary exposed to technical mixtures of short- (SCCPs), medium- (MCCPs), or long-chain (LCCPs) CPs of various chlorine contents during 91 days, at 200 ng/g of feed, each. Adipose tissue, liver, muscle and serum were collected at the steady-state, along with excreta. All C₁₀-C₃₆ CPs were detected in liver. However, differences were observed in CP distribution: LCCPs high %Cl were retained in the liver; LCCPs low %Cl circulated through the serum and were distributed in the different compartments, but were mostly excreted through the eggs; SCCPs and MCCPs were found in all tissues at similar levels. Finally, a mass balance indicated a potential for biotransformation.

Short-chain chlorinated paraffins in soils indicate landfills as local sources in the Tibetan Plateau

Background contamination levels of contemporary persistent organic pollutants (POPs) may be elevated due to local discharges, and hence it is of high importance to assess and monitor them in alpine and Polar Regions. This study investigated the role of waste disposal in the Tibetan plateau as the local source of short-chain chlorinated paraffins (SCCPs). SCCPs were determined in soils from the urban landfill and rural dumpsites, with a concentration range of 56.8-1348 ng/g dw. The gradient descent of SCCP levels from Lhasa landfill to the surrounding soils with increasing distances suggested a significant SCCP release from waste disposal. The transport pattern was well fitted by the Boltzmann equation after normalization in terms of soil organic carbon contents. Compared to the landfill cells closed in early years, the recently closed cells contained higher concentrations but lower proportions of the short-chain congener groups, likely reflecting the SCCP use history in Tibet. In open-burning dumpsites, higher SCCP levels and dominance of lighter congener groups indicates that such crude waste treatment process might cause an extra release of volatile SCCPs. This study elucidates local SCCP inputs to the background environment, and demonstrates that both urbanization and badly-managed landfill have been contributing to the presence of contemporary POPs in the Tibetan Plateau.

Trophic Magnification of Short- and Medium-Chain Chlorinated Paraffins in Terrestrial Food Webs and Their Bioamplification in Insects and Amphibians during Metamorphosis

Studies on the biomagnification of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) in terrestrial ecosystems and their bioamplification during metamorphosis in insects and amphibians are scarce. Therefore, this study sought to characterize the occurrence and trophic dynamics of SCCPs and MCCPs in an insect-dominated terrestrial food web in an e-waste recycling site in South China. Median ∑SCCPs and ∑MCCPs concentrations in the organisms ranged from 2200 to 34 000 ng/g lipid weight and from 990 to 19 000 ng/g lipid weight, respectively. The homologue profiles of CPs in the predators were distinct from those in insects, presenting more short chain-high chlorinated congeners (C_10-12Cl_8-10). The trophic magnification factors (TMFs) of ∑SCCPs and ∑MCCPs were 2.08 and 2.45, respectively, indicating biomagnification in the terrestrial food web. A significant positive relationship between the TMFs and octanol-air partition coefficients was observed. TMFs were also positively correlated with chlorination degree but did not correlate with carbon chain length. Nonlinear correlations between metamorphosis-associated bioamplification and the octanol-water partition coefficients of SCCPs and MCCPs were observed for insects, whereas negative linear correlations were observed for amphibians, which suggested species-specific alterations to the chemicals during metamorphosis.

Prenatal and postnatal exposure risk assessment of chlorinated paraffins in mothers and neonates: Occurrence, congener profile, and transfer behavior

Gestation and lactation are very sensitive and vulnerable stages for human growth and development. During these two periods, short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) can be transported to neonates via transplacental and breastfeeding transfers, and eventually posing potential adverse effects to neonates. Up to date, no simultaneous investigation of prenatal and postnatal exposure of CPs is reported. To bridge this knowledge gap, we have analyzed SCCPs and MCCPs in 20 complete sets of maternal serum, umbilical cord serum, placenta, and breast milk. The levels of both ∑SCCP and ∑MCCP followed the order of maternal serum > breast milk > cord serum > placenta. The breastfeeding transfer ratios (R_BM, ≈ 1.0) of CPs were greater than the corresponding transplacental transfer ratios (R_CM, < 1.0), demonstrating the higher transport of CPs during the lactation period. The placental retention/or accumulation ratios (R_PM) showed that CPs were effectively retained by the placental barrier. Furthermore, the total exposure amount of SCCPs and MCCPs during the lactation period was> 100 times higher than the gestation exposure amounts. This study helps to better understand the prenatal and postnatal exposure of CPs and provides a solid basis for accurate human health risk assessment of CPs.

In vitro oxidative stress, mitochondrial impairment and G1 phase cell cycle arrest induced by alkyl-phosphorus-containing flame retardants

Phosphorus-containing flame retardants (PFRs) have been frequently detected in various environmental samples at relatively high concentrations and are considered emerging environmental pollutants. However, their biological effects and the underlying mechanism remain unclear, especially alkyl-PFRs. In this study, a battery of in vitro bioassays was conducted to analyze the cytotoxicity, oxidative stress, mitochondrial impairment, DNA damage and the involved molecular mechanisms of several selected alkyl-PFRs. Results showed that alkyl-PFRs induced structural related toxicity, where alkyl-PFRs with higher logKow values induced higher cytotoxicity. Long-chain alkyl-PFRs caused mitochondrial and DNA damage, resulting from intracellular reactive oxygen species (ROS) and mitochondrial superoxide overproduction; while short-chain alkyl-PFRs displayed adverse outcomes by significantly impairing mitochondria without obvious ROS generation. In addition, alkyl-PFRs caused DNA damage-induced cell cycle arrest, as determined by flow cytometry, and transcriptionally upregulated key transcription factors in p53/p21-mediated cell cycle pathways. Moreover, compared to the control condition, triisobutyl phosphate and trimethyl phosphate exposure increased the sub-G1 apoptotic peak and upregulated the p53/bax apoptosis pathway, indicating potential cell apoptosis at the cellular and molecular levels. These results provide insight into PFR toxicity and the involved mode of action and indicate the mitochondria is an important target for some alkyl-PFRs.

Spatial distributions and homolog profiles of chlorinated nonane paraffins, and short and medium chain chlorinated paraffins in soils from Yunnan, China

To preliminarily investigate the occurrence, spatial distributions, homolog compositions, and ecological risks of chlorinated paraffins (CPs) in Yunnan, China, 110 soil samples were collected from an area part of Yunnan, representative of the whole Yunnan area, where had similar characteristics to most parts of Yunnan and 22 pooled soil samples were analyzed for 50 CP congener groups (C₉-₁₇Cl_5-10). The chlorinated nonane paraffin (C₉-CP), short chain (SCCP), and medium chain chlorinated paraffin (MCCP) concentrations in soil samples were 8-109 ng/g (average 39 ng/g), 79-948 ng/g (average 348 ng/g), and 20-1206 ng/g (average 229 ng/g), respectively. The C₉-CP homologs contributed 5%-16% of the C_9-13-CP concentrations in soils. No significant correlation was found between CP concentrations and the total organic carbon content (P > 0.05). The CP levels in soils from Yunnan were at a medium level compared with those in other areas worldwide. Human activity and atmosphere deposition would influence the levels and spatial distributions of CPs in this area. The concentrations of CPs in east area were higher than those in west area. C₁₀Cl_6-7 were the major SCCP congeners and C₁₄Cl_6-7 were the major MCCP congeners. Principal component analysis indicated that SCCPs and MCCPs came from different sources. A preliminary risk assessment indicated that these concentrations of CPs in soil from Yunnan do not pose a significant ecological risk for soil organisms.

Advances in Studies on Toxic Effects of Short-Chain Chlorinated Paraffins (SCCPs) and Characterization of Environmental Pollution in China

Short-chain chlorinated paraffins (SCCPs) were included in the Stockholm Convention in 2017. SCCPs have persistence, bioaccumulation, long-range environmental mobility and biological toxicity, significant toxicity to aquatic organisms, and potential carcinogenicity. Little study was on the progress research on the current environmental pollution in China. We reviewed the pollution conditions of SCCPs in air, soil, and water and their accumulation in food and organisms in China, especially for the contaminations of aquatic ecosystem. Meanwhile, we summarize the recent studies on the toxic effects and toxicological mechanisms of SCCPs on aquatic organisms and mammals. Finally, the further direction and trends for SCCP research were proposed. More efforts are necessary to conduct a comprehensive risk assessment and evaluate the relative importance of the various exposure routes.

Exploratory analysis and ranking of analytical procedures for short-chain chlorinated paraffins determination in environmental solid samples

Short-chain chlorinated paraffins are ones of the most recent chemical compounds that have been classified as persistent organic pollutants. They have various applications and are emitted to the environment. Despite the fact, that the content levels of these compounds in the environmental compartments should be monitored, there is still a lack of well-defined and validated analytical procedures, proposed or suggested by the national or international environmental protection agencies. Finding an appropriate analytical procedure (sensitive and green at the same time) from many available ones is very often a difficult task. Therefore it can be supported with multicriteria decision analysis. The dataset consisting of 22 procedures was described by 7 criteria, mainly referring to procedures greenness. The data treatment with cluster analysis and principal component analysis revealed the internal structure of the dataset. Moreover, both statistical tools allowed for reduction of dataset criteria to three. This was used for applying ternary plot to show the multicriteria decision analysis results within all possible weights. With the aid of chemometric and multicriteria decision analysis tools it was easy to assess the set of analytical procedure. Depending on the applied weights to assessment criteria different analytical procedures are the most appropriate (winners).

Concentrations of and risks posed by short-chain and medium-chain chlorinated paraffins in soil at a chemical industrial park on the southeast coast of China

The concentrations, spatial distributions, and sources of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in soil at a chemical industrial park were determined. The samples were analyzed by two-dimensional gas chromatography coupled with electron capture-negative ion mass spectrometry. The risks posed by SCCPs and MCCPs to soil biota were assessed. The SCCP and MCCP concentrations were 37.5-995.7 and 15.1-739.6 ng/g dry weight, respectively, and the chlorine contents were 60.5%-63.0% and 56.7%-58.3%, respectively. The CP concentrations in soil were at medium levels relative to concentrations at other areas. The median CP concentration in soil from the sewage treatment plant was higher than the median concentration in road soil, and this was attributed to wastewater being treated centrally. No significant correlations were found between the total organic carbon content and CP concentrations (p > 0.05), so the total organic carbon content did not strongly affect the CP concentrations in the study area. Hierarchical cluster analysis divided the soil samples into three groups. C₁₀Cl_6-7, C₁₁Cl_7-8, and C₁₄Cl_7-9 were the main congeners in most soil samples. Principal component analysis and correlation analysis indicated that the relative abundances of MCCP and SCCP were correlated and that the SCCPs may have been derived from the CP-42 and CP-52 commercial products. A preliminary risk assessment indicated that CPs in soil at the industrial park do not pose clear risks to the environmental organisms.

The environmental distribution and toxicity of short-chain chlorinated paraffins and underlying mechanisms: Implications for further toxicological investigation

Short-chain chlorinated paraffin (SCCP) pollution has become a global threat. Much attention has been paid to their environmental occurrence and toxicity. In this review, we summarized the wide distribution of SCCPs in various environmental matrices and biota, including human beings. Toxicokinetics and the toxicities of SCCPs, including lethality, hepatotoxicity, developmental toxicity, carcinogenicity, endocrine- and metabolism-disrupting effects, and immunomodulatory effects have been considered. The mechanisms of SCCP toxicity are mainly related to oxidative stress, metabolic disturbance, endocrine disruption and binding to biomacromolecules. In the future, further studies of SCCPs should focus on searching for their novel toxicity targets, and uncovering their toxic effects using transcriptomics, proteomics, metabolomics, and mutigenerational toxicity.

Congener-Specific Mother-Fetus Distribution, Placental Retention, and Transport of C10-13 and C14-17 Chlorinated Paraffins in Pregnant Women

Short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) are high-production-volume persistent and toxic industrial chemicals found ubiquitously in various environmental matrices. However, information is scarce regarding human internal exposure. The congener-specific SCCP and MCCP levels in matched maternal serum (n = 31), umbilical cord serum (n = 31), and placenta (n = 31) were studied to investigate the maternal-placenta-fetus distribution and the placental transport mechanisms of SCCPs and MCCPs. The results indicated that lower chlorinated and shorter carbon chain CPs were efficiently transported across placenta compared to highly chlorinated and longer carbon chain CPs. Meanwhile, ∑MCCP concentration followed the order of maternal sera > placentas > cord sera. The cord/maternal concentration fraction ratios (R_CM) of CPs exhibited similar values from C₁₀ to C₁₄, and then from C₁₅, a decreasing trend was observed with increasing carbon chain length. The log-normalized maternal SCCP concentrations were positively correlated (P < 0.01) with that in the cord, suggesting fetus exposure to SCCPs during pregnancy. Furthermore, the placenta/maternal concentration fraction ratio (R_PM) values for MCCPs were relatively higher than those for SCCPs, demonstrating that MCCPs were not efficiently transported and effectively retained in placenta tissues. These findings provide a better understanding of the maternal-fetal transmission and neonatal exposure to CPs.

The chlorine contents and chain lengths influence the neurobehavioral effects of commercial chlorinated paraffins on zebrafish larvae

Increasing concern has arisen regarding ubiquitous environmental distribution and potential ecological and health risks of chlorinated paraffins (CPs), especially short chain congeners. Four commercial CP products with different carbon chain lengths and chlorine contents were employed to investigate and compare the possible neurotoxic effects on zebrafish larvae at 5 days post fertilization using behavioral tests, including locomotion, path angle, and two-fish social interaction. The high-chlorinated short-chain CP-70 product resulted in the strongest effects in all three tests, while the low-chlorinated long-chain CP-42 product was on the other end of the spectrum. The consequences of the chain length of two CP-52 products could be clearly distinguished by the tests. Although exposure to the two products both caused inhibition in the locomotion test, they resulted in different kinds of effects in the path angle and interaction tests. Our results suggested, as evidenced by the sensitivity and resolution of the behavioral tests, that the influence of the chain length and chlorine content of CPs could be well characterized and that chlorine content consistently showed a more significant impact than chain length. The health threats of long-chain CPs could also not be overlooked when they contained relatively high chlorine contents.

Analytical procedures for short chain chlorinated paraffins determination - How to make them greener?

The aim of the following paper was to gather current scientific information about the analytical protocols dedicated to measuring the content level of short-chain chlorinated paraffins (SCCPs) in various types of environmental samples. Moreover, the data about the basic validation parameters of applied procedures for SCCPs determination are listed. The main issue which is highlighted in the paper is the possibility of the application of green analytical chemistry (GAC) principals in the SCCPs measuring process to reduce the environmental impact of the applied methodology. Analytical methods dedicated to SCCPs determination contain a significant number of steps and require advanced analytical equipment during the quantitative and qualitative analysis. In addition, there is a substantial issue associated with the reliability of the obtained results, especially in the case of the quantification of individual SCCPs in the studied samples. Due to this fact, the paper attempts to discuss the various stages of the analytical procedure, in which appropriate changes in the formula or equipment solutions might be introduced to ensure a better quality of the analytical results, as well as to meet the requirements of the philosophy of green analytical chemistry. The most important case which concerns this subject is finding an optimal consensus between the economic and logistic aspects and the quality and "greenness" of the analytical procedure employed in SCCPs determination process.

1H NMR-based metabolomic analysis of nine organophosphate flame retardants metabolic disturbance in Hep G2 cell line

Organophosphate flame retardants (OPFRs) are frequently found in the environment and could be adversely affecting organisms. In fact, nine OPFRs have been shown to cause endocrine disruptions, but information on the metabolism-perturbing properties of these OPFRs remains unclear. In this study, the ¹H-nuclear magnetic resonance (NMR) based metabolomic method was applied to evaluate the metabolic disturbances caused by these nine OPFRs. From the analysis of the metabolic phenotypes, we found that TDBPP, TMPP and TPHP could be clustered into one group; TBOEP, TCIPP, TCEP and TEHP could be clustered into another group; and the residual OPFRs could be clustered into another. The classification results agree with the antagonistic activities of glucocorticoid and mineralocorticoid receptors. Then, we found that when HepG2 cells were exposed to TMPP, TPHP and TDBPP, the main metabolic sub-network disturbances focused on metabolism linked with oxidative stress, osmotic pressure equilibrium, and glucocorticoid and mineralocorticoid receptor antagonist activities; this was also true for TNBP and TDCIPP. Meanwhile, the other OPFRs mainly affected oxidative stress and amino acid metabolism. With multivariate statistical analysis, we found many differential metabolites in each group. Notably, Trimethylamine‑N‑oxide (TMAO) was the differential metabolite in six of the tested OPFRs, excluding TMPP, TPHP and TDBPP, and was one of the potential cardiovascular biomarkers. The data provided here could be helpful in gaining a more in-depth understanding of the metabolic disturbances of these nine OPFRs and may offer a new perspective for understanding potential pollutants with endocrine-disrupting effects on host metabolism.

Organophosphorus Flame Retardants Impair Intracellular Lipid Metabolic Function in Human Hepatocellular Cells

Organophosphorus flame retardants (OPFRs), a replacement for brominated flame retardants, have gradually been accepted as endocrine disrupting chemicals (EDCs). Recently, evidence has shown that these EDCs could cause chronic health problems, such as obesity, and referred to as metabolic disruptors. However, the disturbance to lipid metabolism caused by OPFRs remains poorly understood, especially at biological molecular levels. Herein, we used the human hepatocellular cells (HepG2) to study the lipid metabolism disruption caused by nine OPFRs (halogenated-, aryl-, and alkyl-containing). All the tested OPFRs, excluding the long carbon chain alkyl-OPFRs, could cause intracellular triglyceride (TG) and/or total cholesterol (TC) accumulation. In detail, aryl-OPFRs (TPhP and TCP) induced both TC and TG deposition. Halogenated-OPFRs (TCEP, TBPP, TDCPP, and TCPP) induced intracellular TG accumulation, and only TDCPP also induced TC accumulation. Furthermore, TPhP induced lipid accumulation through regulation genes encoding proteins involved in fatty acid β-oxidation, lipid, and fatty acid synthesis. All the halogenated-OPFRs cause TG accumulation only, enacted through β-oxidation rather than lipid synthesis. TPhP and TDCPP induced TC accumulation through both PPARγ and srebp2 signaling. Mitochondrial dysfunction including decreased oxygen consumption rate and ATP content may also contribute to lipid metabolic disruption by the tested OPFRs. Our data indicated that halogenated- and aryl-OPFRs may not be safe candidates, and further information should be made available as potential for, as well as the mechanism of, metabolic disruption. And long carbon chain alkyl-OPFRs may be safer than the other two groups.