Concentrations and sources of short- and medium-chain chlorinated paraffins in farmed Chinese mitten crabs in China

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.

Chlorinated paraffins in takeout food and its packaging in Beijing, China and dietary exposure risk

Chlorinated paraffins (CPs) are hazardous to humans, and dietary intake acts as the primary pathway for human exposure to CPs. Takeout food is popular worldwide, but the presence of CPs in takeout food and its packaging is unclear. In this study, the concentrations and distributions of short- and median-chain CPs (SCCPs and MCCPs, respectively) were measured in 97 samples of four categories of takeout food and 33 samples of three types of takeout packaging. The SCCP and MCCP median concentrations for the takeout food samples were 248 and 339, 77.2 and 98.2, 118 and 258, 42.9 and 64.4 ng/g wet weight in meat, starch, half meat/half starch, and vegetables, respectively. Takeout food contained higher concentrations of SCCPs than MCCPs. The dominant SCCP and MCCP congener groups in takeout food were C10Cl6-7 and C14Cl7-8, respectively. The CP concentrations in takeout food were lower than those in packaging. The SCCP and MCCP median concentrations, respectively, in packaging were 9750 and 245 ng/g in polypropylene, 2830 and 135 ng/g in paper, and 2060 and 119 ng/g in aluminum foil. The concentrations of SCCPs and MCCPs were comparable in aluminum foil, whereas the concentrations of SCCPs were higher than those of MCCPs in polypropylene and paper. Correlations between CP concentrations in the takeout food and packaging indicated that CPs in packaging were potentially an important source of CPs in the takeout food. A dietary exposure risk assessment showed the takeout food posed a low risk for human exposure to CPs; however, high-frequency consumption may pose a health risk. This study clarified the current contamination situation in takeout food in Beijing, China. The resulting data could be used to prevent human exposure to CPs through dietary intake and to facilitate the market's control over the quality of takeout food.

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.

A preliminary study on short- and medium-chain chlorinated paraffins in duck farms: Concentrations, distribution, and dietary exposure risks

Chlorinated paraffins (CPs) in poultry feed and the farm environment might bioaccumulate in poultry eggs. Unlike chickens, which are mostly raised in cages, ducks are commonly raised free range. This would expose ducks to CPs in the environment. However, information on the presence of CPs on duck farms is scarce. In the present study, samples of duck eggs, duck feathers, poultry feed, and soil were collected from 25 duck farms in South China. Forty-eight congener groups of short- and medium-chain CPs (SCCPs and MCCPs) were detected in the samples. Interestingly, relatively high concentrations of SCCPs and MCCPs were found in the duck feathers. The median concentrations of SCCPs and MCCPs in the duck eggs, feathers, feed and soil were: 46 and 18 ng/g wet weight, 2460 and 992 ng/g, 103 and 47 ng/g, and 24 and 10 ng/g dry weight, respectively. The dominant groups of SCCPs and MCCPs were C10Cl6-7 and C14Cl7-8, respectively. The close relationship between duck feathers and poultry feed indicated that the duck feathers might act as a bioindicator for the exposure of ducks to CPs. The margin of exposure approach was used to assess the health risk, with the results showing that the consumption of duck eggs posed a low risk to different age groups from exposure to SCCPs and MCCPs.

Biomonitoring, exposure routes and risk assessment of chlorinated paraffins in humans: a mini-review

Chlorinated paraffins (CPs), which were conventionally classified into short- (SCCPs), medium- (MCCPs) and long- (LCCPs) chain CPs, have received growing attention due to their wide usage and extensive detection in environmental samples and biota. The number of studies regarding the biomonitoring of CPs in human beings increased rapidly and their health risk gained great concern. This review summarized their occurrence and homologue patterns in human matrices including blood/serum, placenta, cord serum and breast milk. As the production and usage of SCCPs was progressively banned after being listed in Annex A of the Stockholm Convention, the production of MCCPs and LCCPs was stimulated. Accordingly, the ratio of MCCPs/SCCPs in human samples has increased rapidly in the last 5 years. The current understanding of exposure routes and risk assessments of CPs was also reviewed. Oral dietary intake is the most predominant source of daily CP intake, but dust ingestion, inhalation and dermal exposure is also nonnegligible, especially for MCCPs and LCCPs. Furthermore, the reported upper bound of the estimated daily intakes (EDIs) in various risk assessment studies was close to or exceeded the tolerable daily intakes (TDIs). Considering the bioaccumulation and long-lasting exposure of CPs, their health impacts on humans and the ecosystem required continuous monitoring and evaluation.

Determination of 25 polybrominated diphenyl ethers in Chinese mitten crab ecosystems by gas chromatography-mass spectrometry

A sensitive and reliable method for determining 25 polybrominated diphenyl ethers (PBDEs) in Chinese mitten crabs and their ecosystems ranging from the growing environment to edible feed by gas chromatography coupled to triple quadrupole mass spectrometry with advanced electron ionization (GC-AEI-MS/MS) was developed and validated. Accelerated solvent extraction (ASE) and liquid-liquid extraction were used to extract solid and water samples, respectively. On the basis of a traditional acid-base silica column, deactivated silica was added and n-hexane elution was used to increase the effect of separation and purification. Two oven temperature programs were applied to achieve good separation of low brominated congeners and increase the sensitivity of high brominated congeners. The method provided good linearity (>0.9996). The recoveries of four matrices were in the range of 82-115% and the method quantification limits (MQLs) in crabs, feed, sediment and water ranged from 0.36-6 pg per g wet weight, 0.69-22.29 pg per g dry weight, 1.02-25.26 pg per g dry weight, and 2.43-40.14 pg L-1, respectively. The proposed method was used for ten samples from two aquatic sites and PBDEs were detected in Chinese mitten crabs, commercial feed and sediment, with the highest in crabs. This analytical technique can be used to monitor the content and the accumulation behavior of PBDEs in Chinese mitten crab ecosystems or other aquaculture systems.

Source toxicity characteristics of short- and medium-chain chlorinated paraffin in multi-environmental media: Product source toxicity, molecular source toxicity and food chain migration control through silica methods

Short and medium-chain chlorinated paraffin (SCCP/MCCP) have been widely studied because of their extensive environmental hazards. In this study, product source toxicity, molecular source toxicity and food chain migration of SCCP and MCCP in multi-environmental media were comprehensively considered. The additive combination of SCCP and MCCP in the air, water and soil environment was adjusted, and PVC, PU and rubber products with the lowest source toxicity were screened. The source toxicity of SCCP and MCCP in the water environment was inhibited by design of the feed additive addition scheme (highest inhibition was 16.29 %), and the source toxicity of SCCP and MCCP in the soil environment was affected by different field management measures (highest inhibition was 38.22 %). A forage fertilizer addition plan, a cattle feed addition plan and a special population healthy complementary food regulation plan were developed to prevent the migration step by step and absorption of SCCP and MCCP in the terrestrial food chain. In addition, by means of density functional theory and analysis of key amino acid residues, the mechanism of toxicity difference between SCCP and MCCP was analyzed from the level of chemical interaction, and rationality of the inhibition scheme designed in this study was verified.

Concentrations and homologue patterns of SCCPs and MCCPs in the serum of the general population of adults in Hangzhou, China

Due to their ubiquitous presence in the environment and humans, chlorinated paraffins (CPs) are a major environmental and public health concern. CPs are known to persist, bioaccumulate and potentially threaten human health, but reports on their internal exposure in the adult general population are still scarce. In this study, serum samples collected from adults living in Hangzhou, China, were quantified for SCCPs and MCCPs using GC-NCI-MS methods. A total of 150 samples were collected and subjected to analysis. ∑SCCPs were detected in 98% of the samples with a median concentration of 721 ng/g lw. MCCPs were found in all serum samples with a median concentration of 2210 ng/g lw, indicating that MCCPs were the dominant homologous group. For SCCPs and MCCPs, ∑C₁₀ and ∑C₁₄ were found to be the dominant carbon chain length homologues. Our results showed that age, BMI and lifestyle were not found to be significantly associated with internal exposure to CPs for the samples in this study. Based on PCA analysis, an age-specific distribution of CP homologues was observed. This suggests that internal exposure to CPs in the general population is related to exposure scenarios and history. The results of this study may contribute to a better understanding of the internal exposure to CPs in the general population and may provide a direction for the investigation of the source of exposure to CPs in the environment and daily life.

The potential health risks of short-chain chlorinated paraffin: A mini-review from a toxicological perspective

Short-chain chlorinated paraffins (SCCPs) are ubiquitously distributed in various environmental matrics due to their wide production and consumption globally in the past and ongoing production and use in some developing countries. SCCPs have been detected in various human samples including serum, milk, placenta, nail, and hair, and internal SCCP levels were found to be positively correlated with biomarkers of some diseases. While the environmental occurrence has been reported in a lot of studies, the toxicity and underlying molecular mechanisms of SCCPs remain largely unknown. The current tolerable daily intakes (TDIs) recommended by the world health organization/international programme on chemical safety (WHO/IPCS, 100 μg/kg bw/d) and the UK Committee on Toxicity (COT, 30 μg/kg bw/d) were obtained based on a no observed adverse effect level (NOAEL) of SCCP from the repeated-dose study (90 d exposure) in rodents performed nearly 40 years ago. Importantly, the health risks assessment of SCCPs in a variety of studies has shown that the estimated daily intakes (EDIs) may approach and even over the established TDI by UK COT. Furthermore, recent studies revealed that lower doses of SCCPs could also result in damage to multiple organs including the liver, kidney, and thyroid. Long-term effects of SCCPs at environmental-related doses are warranted.

The impact of three related emission industries on regional atmospheric chlorinated paraffins pollution

Identifying the contributions of various chlorinated paraffins (CPs) sources in the environment plays an important practical role in the prevention and control of the CPs contamination. However, little is known about how main CP-related emission industries affect the regional atmospheric characteristics of CPs, including CP products industry, metal working industry, and polyvinyl chloride (PVC) industry. In this study, 60 passive air samples were collected from five typical cities in Henan Province, China, which had serious CP pollution and different structures of CP-related emission industry. Short chain CPs (SCCPs) and medium chain CPs (MCCPs) were detected in all samples in concentrations ranging of 2.6-7.7 × 10² and 2.1-4.3 × 10² ng m^-3, respectively, which were higher than those in most reports. Moreover, Luoyang (LY) is different from other cities, showing a relatively severe MCCP contaminations. The CP pollution characteristics between different cities are obviously affected by the proportion of local CP-related industries. According to the results of cluster heatmaps, the local CP-related emission industrial structure had a greater impact on MCCPs pollution than SCCPs. Additionally, the contribution of metal working industry was beyond that of PVC production industry and CP products industry.

Bioaccumulation and Biotransformation of Chlorinated Paraffins

Chlorinated paraffins (CPs), a class of persistent, toxic, and bioaccumulated compounds, have received increasing attention for their environmental occurrence and ecological and human health risks worldwide in the past decades. Understanding the environmental behavior and fate of CPs faces a huge challenge owing to the extremely complex CP congeners. Consequently, the aims of the present study are to summarize and integrate the bioaccumulation and biotransformation of CPs, including the occurrence of CPs in biota, tissue distribution, biomagnification, and trophic transfer, and biotransformation of CPs in plants, invertebrates, and vertebrates in detail. Biota samples collected in China showed higher CP concentrations than other regions, which is consistent with their huge production and usage. The lipid content is the major factor that determines the physical burden of CPs in tissues or organs. Regarding the bioaccumulation of CPs and their influence factors, inconsistent results were obtained. Biotransformation is an important reason for this variable. Some CP congeners are readily biodegradable in plants, animals, and microorganisms. Hydroxylation, dechlorination, chlorine rearrangement, and carbon chain decomposition are potential biotransformation pathways for the CP congeners. Knowledge of the influence of chain length, chlorination degree, constitution, and stereochemistry on the tissue distribution, bioaccumulation, and biotransformation is still scarce.

Initial dietary risk assessment of chlorinated paraffins in edible fungi in Chinese markets

Dietary intake is one of the main pathways for residents to become exposed to chlorinated paraffins (CPs). In China, due to the popularization of nutritional and medicinal edible fungi, consumption has increased on a yearly basis. Edible fungi have a variety of active substances and are consumed daily by residents. However, there is limited information on the concentration and source of chlorinated paraffins in edible fungi. In this study, the concentrations of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in 105 edible fungi samples and 36 culture material samples were detected. The concentration range of SCCPs was 79.8 ng/g dw to 3879.3 ng/g dw, and the MCCPs was ND to 572.3 ng/g dw. Spearman correlation analysis indicated that the sources of SCCPs and MCCPs in edible fungi were similar (r = 0.57, p < 0.01). The preponderant SCCPs and MCCPs congener group profiles were C₁₀ Cl_7-8 and C₁₄ Cl_6-8 . CPs were detected in culture materials, the concentration range of SCCPs was 320.2 ng/g dw to 4326 ng/g dw, and the MCCPs was 333.4 ng/g dw to 4517.4 ng/g dw. And the preponderant SCCPs and MCCPs homologues in culture materials were C_11-12 Cl₆ and C₁₄ Cl₆ . The linear discriminant analysis results indicated different contamination models of CPs between edible fungi and culture materials. The mean estimated daily intake values of SCCPs and MCCPs were 308.1 ng/kg bw/d and 94.4 ng/kg bw/d, respectively, indicating no potential health risk posed by CP exposure in edible fungi.

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 C₁₀-₁₁Cl_6-7 and C₁₄Cl_6-7, 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.

New insights into the transfer and accumulation of dioxins and dioxin-like PCBs in the food web of farmed Chinese mitten crabs: A typical case from the Yangtze River area

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) transfer and accumulation behavior remains poorly understood in the farmed Chinese mitten crab (Eriocheir sinensis). In this study, dioxins and DL-PCBs concentration in 48 farming crabs in lower reaches of the Yangtze River was monitored and controlled field design was conducted in a typical farm to dissect the dioxins and DL-PCBs contamination in crab food web (crab, feeds, and environment). Results showed that dioxins and DL-PCBs were ubiquitous in farmed crabs with concentrations ranging from 0.390 to 37.2 pg toxic equivalents (TEQ) g^-1 ww and do not present a health risk to general consumers. Of the total dioxins TEQ found in crab in treated farms, 45.6% was attributed to direct transfer from the aquaculture environment and 46.5% to the consumption of snails. Consumption of feed material accounted for nearly all of the total DL-PCBs TEQ, divided as 58.2% from feed and 41.8% from snails. These results demonstrated that dominant routes of dioxins accumulation in crabs were transferred for the sediment-snail-crab and sediment-crab chains, whereas DL-PCBs is mainly transferred through consumption of feeds and snails. To our knowledge, this work is the first report of snails serving as a biomagnification medium that promotes accumulation of dioxins in mitten crabs. This observation provided crucial insight to prevent and reduce contamination of crab by dioxins and DL-PCBs.

Polychlorinated naphthalenes in farmed Chinese mitten crabs in China: Concentration, distribution and source analysis

Polychlorinated naphthalenes (PCNs) are both highly toxic and bioaccumulative environmental contaminates. Dietary intake is the primary pathway for human exposure to PCNs, and PCN concentrations in aquatic foodstuffs are relatively high. Chinese mitten crab (Eriocheir sinensis) is one kind of popular aquatic foodstuffs in Asian countries. Farmed crabs could exposure to PCNs both through feed and environment. However, information on the occurrence of PCNs in farmed crabs is scarce. The present study investigated 75 PCN congeners in farmed Chinese mitten crabs, crab compound feed and sediments collected from Anhui Province and Shanghai in China. The total PCN concentrations in farmed Chinese mitten crabs from Anhui Province and Shanghai were 11.2-42.2 and 5.46-43.8 pg/g wet weight (ww), respectively. The PCN homologue profiles in crabs from both areas were similar, and both were dominated by di-CNs and penta-CNs. In contrast, lower chlorinated PCNs (di-CNs, tri-CNs and tetra-CNs) were the most common homologues in specimens of crab compound feed and sediment samples, indicating that selective bioaccumulation and metabolism of PCNs might occur in farmed crabs. No regional differences were found in the PCN congener profiles of farmed crabs, feed and sediment samples taken from Anhui Province and Shanghai. An assessment found no significant health risk associated with Chinese exposure to PCNs through farmed Chinese mitten crab consumption.

Short- and medium-chain chlorinated paraffins in green tea from 11 Chinese provinces and their migration from packaging

Chlorinated paraffins (CPs) have been found to occur ubiquitously in foodstuff of both animal and plant origin. However, limited information is available on the content of CPs in green tea, one of the most commonly consumed beverages worldwide. Herein, 107 commercial green tea samples originating from 11 provinces of China, were collected to study the occurrence of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively). The concentration of SCCPs in all green tea samples ranged from 4.99 to 717 ng/g (mean: 55.7 ng/g), while MCCPs ranged from 2.55 to 543 ng/g (mean: 33.5 ng/g). CP profiles in green tea samples from different provinces exhibited no regional differences. To identify the potential sources of CPs in green tea, 19 tea packaging samples were collected and analyzed, showing that SCCPs and MCCPs existed at much higher concentrations in the tea packaging material than in the teas. Migration tests indicated that CPs could migrate from packaging into teas during storage, with the migration velocity and efficiency of SCCPs being higher than MCCPs.

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.

Concentrations and distribution of chlorinated paraffins in Belgian foods

This study reports on concentrations of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively) in a wide range of food samples (n = 211) purchased in Belgium during 2020. Samples were analysed by gas chromatography-mass spectrometry (GC-MS) and quantified using chlorine content calibration. ∑SCCPs were present above LOQ in 25% of samples with an overall range of <LOQ to 58 ng/g wet weight (ww), while ∑MCCPs were identified in 66% of samples ranging from <LOQ to 250 ng/g ww. ∑MCCP concentrations were greater than those of ∑SCCPs in all 48 samples in which both groups were detected with an average ∑MCCP/∑SCCP ratio of 5.8 (ranging from 1.3 to 81). In general, the greatest CP concentrations were observed in foods classified as animal and vegetable fats and oils and sugar and confectionary for both SCCPs and MCCPs. Significant correlations between lipid content in food samples and CP levels illustrated the role of lipids in accumulating CPs within foodstuffs, while industrial processing, food packaging and environmental conditions are each likely to contribute to overall CP loads. Selected samples (n = 20) were further analysed by liquid chromatography-high resolution MS (LC-HRMS) to investigate homologue profiles and the occurrence of long-chain CPs (LCCPs). LCCPs were detected in 35% of the 20 subset samples while the HRMS results for SCCPs and MCCPs matched closely with those obtained by GC-MS. This study reveals the widespread occurrence of SCCPs and MCCPs in Belgian food and indicates that LCCPs may represent a substantial contribution to overall CP levels in foodstuffs.