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

First comprehensive assessment of dietary chlorinated paraffins intake and exposure risk for the rural population of the Tibetan Plateau, China

Knowledge regarding the occurrence of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) in foodstuffs and their dietary exposure risks for rural Tibetan residents remains largely unknown. Herein, we collected main foodstuffs (including highland barley, vegetables, Tibetan butter, mutton, and yak beef) across the rural Tibetan Plateau and characterized the CP profiles and concentrations. The highest SCCPs concentrations were detected in Tibetan butter (geometric mean (GM): 240.6 ng/g wet weight (ww)), followed by vegetables (59.4 ng/g ww), mutton (51.4 ng/g ww), highland barley (46.3 ng/g ww), and yak beef (31.7 ng/g ww). For MCCPs, the highest concentrations were also detected in Tibetan butter (319.5 ng/g ww), followed by mutton (181.9 ng/g ww), vegetables (127.0 ng/g ww), yak beef (71.2 ng/g ww), and highland barley (30.3 ng/g ww). The predominant congener profiles of SCCPs were C13Cl7-8 in mutton and yak beef, C10Cl7-8 in Tibetan butter, and C10-11Cl6-7 in highland barley and vegetables. The predominant congener profiles of MCCPs were C14Cl7-9 in all sample types. Combined with our previous results of free-range chicken eggs, the median estimated daily intakes (EDIs) of SCCPs and MCCPs via diet for Tibetan rural adults and children was estimated to be 728.8 and 1853.9 ng/kg bw/day and 2565.6 and 5952.8 ng/kg bw/day, respectively. In the worst scenario, MCCPs might induce potential health risks for rural Tibetan population. To our knowledge, this is the first systematic dietary exposure research of SCCPs and MCCPs in the remote rural areas.

Novel and legacy brominated flame retardants in snakes and frogs: Tissue distribution, biomagnification, and maternal transfer

Although many studies have examined polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) in biota, information on the bioaccumulation characteristics of NBFRs from field works is limited. This study investigated the tissue-specific exposure to PBDEs and NBFRs in two reptilian (short-tailed mamushi and red-backed rat snake) and one amphibian species (black-spotted frog) prevalent in the Yangtze River Delta, China. The levels of ΣPBDEs and ΣNBFRs ranged from 4.4-250 and 2.9-22 ng/g lipid weight for snakes respectively and 2.9-120 and 7.1-97 ng/g lipid weight for frogs respectively. BDE-209, BDE-154, and BDE-47 were three major PBDE congeners while decabromodiphenylethane (DBDPE) dominated in NBFRs. Tissue burdens indicated that snake adipose was the major storage site of PBDEs and NBFRs. The biomagnification factors (BMFs) estimated from black-spotted frog to red-backed rat snake indicated the biomagnification of penta- to nona-BDE congeners (BMFs 1.1-4.0) but the lack of biomagnification of other BDE and all NBFR congeners (BMFs 0.16-0.78). Mother to egg transfer of PBDEs and NBFRs evaluated in frogs showed that maternal transfer efficiency was positively related to chemical lipophilicity. This is the first field study on the tissue distribution of NBFRs in reptiles and amphibians and the maternal transfer behavior of 5 major NBFRs. The results underline the bioaccumulation potential of alternative NBFRs.

Toxic effects and toxicological mechanisms of chlorinated paraffins: A review for insight into species sensitivity and toxicity difference

Chlorinated paraffins (CPs), a group of chlorinated alkane mixtures, are frequently detected in various environmental matrices and human bodies. Recently, CPs have garnered considerable attention owing to their potential to induce health hazards in wildlife and human. Several reviews have discussed short-chain CPs (SCCPs) induced ecological risk; however, a comprehensive understanding of the underlying toxic mechanisms and a comparison among SCCPs, medium-, and long-chain CPs (MCCPs and LCCPs, respectively) are yet to be established. This review summarizes the latest research progress on the toxic effects and the underlying molecular mechanisms of CPs. The main toxicity mechanisms of CPs include activation of several receptors, oxidative stress, disturbance of energy metabolism, and inhibition of gap junction-mediated communication. The sensitivity of different species to CP-mediated toxicities varies markedly, with aquatic organisms exhibiting the highest sensitivity to CP-induced toxicity. The toxicity comparison analysis indicated that MCCPs may be unsafe as potential substitutes for SCCPs.

Chlorinated paraffins and dechloranes in free-range chicken eggs and soil around waste disposal sites in Tanzania

Electronic waste is a source of both legacy and emerging flame retardants to the environment, especially in regions where sufficient waste handling systems are lacking. In the present study, we quantified the occurrence of short- and medium chain chlorinated paraffins (SCCPs and MCCPs) and dechloranes in household chicken (Gallus domesticus) eggs and soil collected near waste disposal sites on Zanzibar and the Tanzanian mainland. Sampling locations included an e-waste facility and the active dumpsite of Dar es Salaam, a historical dumpsite in Dar es Salaam, and an informal dumpsite on Zanzibar. We compared concentrations and contaminant profiles between soil and eggs, as free-range chickens ingest a considerable amount of soil during foraging, with potential for maternal transfer to the eggs. We found no correlation between soil and egg concentrations or patterns of dechloranes or CPs. CPs with shorter chain lengths and higher chlorination degree were associated with soil, while longer chain lengths and lower chlorination degree were associated with eggs. MCCPs dominated the CP profile in eggs, with median concentrations ranging from 500 to 900 ng/g lipid weight (lw) among locations. SCCP concentrations in eggs ranged from below the detection limit (LOD) to 370 ng/g lw. Dechlorane Plus was the dominating dechlorane compound in all egg samples, with median concentrations ranging from 0.5 to 2.8 ng/g lw. SCCPs dominated in the soil samples (400-21300 ng/g soil organic matter, SOM), except at the official dumpsite where MCCPs were highest (65000 ng/g SOM). Concentrations of dechloranes in soil ranged from below LOD to 240 ng/g SOM, and the dominating compounds were Dechlorane Plus and Dechlorane 603. Risk assessment of CP levels gave margins of exposure (MOE) close to or below 1000 for SCCPs at one location.

Widespread presence of chlorinated paraffins in consumer products

Short-chain chlorinated paraffins (SCCPs) were listed for elimination under the Stockholm Convention in 2017 due to their persistence and toxicity. Although Canada and other Stockholm signatories have prohibited the manufacture, usage and import of SCCPs since 2013, they can still be detected at high concentrations in indoor dust. To identify the sources of the SCCPs in the Canadian indoor environment, short-, medium- and long-chain chlorinated paraffins (SCCPs, MCCPs, LCCPs, respectively) were measured using a sensitive LC-ESI-orbitrap method. SCCPs were detected in 84 of the 96 products purchased in Canada after 2013 (87.5%) including electronic devices, clothing, plastics (toys), and paintings. Concentrations of SCCPs were up to 0.93% (9.34 mg g^-1). SCCPs were also detected in newly purchased toys at 0.005-2.02 mg g^-1, indicating the potential for children's exposure. Profiles of chlorinated paraffins differed among categories of products. For example, C₁₃-SCCPs were most common in toys, while electronic devices like headphones showed comparable concentrations of SCCPs and MCCPs. Additionally, four new carboxylate derivatives of CPs were detected in an electronic device sample. These are the first data to show the ubiquitous occurrences of SCCPs in a wide range of products currently marketed in Canada, suggesting continuing indoor exposure to SCCPs despite their prohibition.

Transplacental transfer of plasticizers and flame retardants in fin whales (Balaenoptera physalus) from the North Atlantic Ocean

Marine mammals are one of the groups of animals most affected by marine pollution including that by organic compounds which, besides bearing recognised harmful effects to adults, they may also affect foetuses through placental transfer. In this study we analysed samples of fin whale (Balaenoptera physalus) females and their foetuses collected in the western Iceland summer feeding grounds in 2018. Three different families of organic pollutants: organophosphate esters (OPEs); halogenated flame retardants (HFRs); and short chain chlorinated paraffins (SCCPs), were analysed and their placental transfer investigated. HFRs were detected in 87.5% of females and 100% of foetus samples with concentrations that ranged between nd-15.4 and 6.37-101 ng/g lipid weight (lw), respectively. OPEs were detected in all samples, both from females (85.8-567 ng/g lw) and foetuses (nq-1130 ng/g lw). SCCPs were detected in 87.5% of female samples and 100% of foetal samples with concentrations that ranged between nd-30.9 and nq-574 ng/g lw, respectively. For OPE compounds, a significant negative correlation was observed between the logarithm maternal transfer ratio and their log K_ow, indicating that a high lipophilicity reduced placental transfer rate. Interestingly, the decabromodiphenyl ethane (DBDPE) was the compound with the highest log K_ow but also the one that was transferred the most from mothers to foetuses, calling for in-depth research on this pollutant. These results constitute the first evidence of mother-calf transfer of plasticizers and flame retardants in fin whales. Further investigations are needed to determine their potential effects on this species and other groups of animals.

Distribution, behavior, and risk assessment of chlorinated paraffins in paddy plants throughout whole growth cycle

Paddy plants provide staple food for 3 billion people worldwide. This study explores the environmental fate and behavior of a high-volume production emerging contaminants chlorinated paraffins (CPs) in the paddy ecosystem. Very-short-, short-, medium-, and long-chain CPs (vSCCPs, SCCPs, MCCPs, and LCCPs, respectively) were analyzed in specific tissue of paddy plants at four main growth stages and soils from the Yangtze River Delta, China throughout a full rice growing season. The total CP concentrations in the paddy roots, stalks, leaves, panicles, hulls, rice, and soils ranged from 181 to 1.74 × 10³, 21.7-383, 19.6-585, 108-332, 245-470, 59.6-130, and 99.6-400 ng/g dry weight, respectively. The distribution profile indicated the translocation of SCCPs and MCCPs from soils to paddy tissue, highlighting their elevated bioaccumulative potential. The evolution of CP level/mass/pattern during the whole growth cycle suggested atmospheric CPs deposition on leaves and hulls, as well as stalk-rice transfer. CSOIL plant uptake model well predicted the level, distribution pattern, and bioconcentration factors (BCFs) of SCCPs and MCCPs in paddy shoot and recognized the soil-air-shoot pathway as the major contributor. Moreover, risk evaluation indicated that MCCPs intake and subsequent risks dominated the total exposure to CPs via rice ingestion. This is the first report on the occurrence, fate and risk assessment of all CPs classes in paddy ecosystems, and the results underline the potential health effects caused by the in-use MCCPs via rice ingestion.

Occurrence and Distribution of Persistent Organic Pollutants (POPs) in Amphibian Species: Implications from Biomagnification Factors Based on Quantitative Fatty Acid Signature Analysis

Contaminants pose a great threat to amphibian populations, but the bioaccumulation and distribution of contaminants in amphibians are still unclear. Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) had median concentrations of 468-3560 ng/g lipid weight (lw) and 206-2720 ng/g lw in the muscle of amphibians, respectively. BDE 209 was the predominant PBDE congener, while CBs 118, 138, 153, and 180 were the main PCB congeners. The diet compositions of amphibians were estimated by quantitative fatty acid signature analysis (QFASA). Dragonfly contributed the most to the diet of amphibians. Biomagnification factors (BMFs) based on quantitative amphibian/insect relationships showed more credible results than BMFs based on amphibian/each insect or amphibian/combined prey relationships. BMFs derived from QFASA declined with log K_OW from 5 to 6.5 and then showed a parabolic relationship with log K_OW greater than 6.5. BMFs of PCBs were significantly influenced by the elimination capacity of PCBs in amphibians. Less-hydrophobic PCBs preferentially accumulated in the skin than in muscle, which was probably due to the dermal exposure of less-hydrophobic PCBs for amphibians. The biomagnification and distribution of contaminants may be affected by multiple exposure pathways and the toxicokinetics of contaminants in various life stages of amphibians.

Inventory approach for short-chain chlorinated paraffins for the Stockholm Convention implementation in Brazil

Chlorinated paraffins (CPs) are chemicals with multipurpose applications. Their global production has increased despite their adverse impacts on the environment and human health. In 2017, short-chain chlorinated paraffins (SCCPs) were listed as persistent organic pollutants (POPs) in the Stockholm Convention. Yet, specific exemptions were granted for their applications despite the recycling prohibition for products containing SCCPs. Therefore, we aimed to produce the first Brazilian inventory of SCCPs following its respective guidance to evaluate the applicability of the SCCP inventory guidance and to provide technical insights regarding SCCPs in the update of the Brazilian National Implementation Plan (NIP). Moreover, we performed a review of SCCP occurrence in Brazil to fulfil data gaps in the inventory development. We identified and consulted nationwide stakeholders and assessed foreign trade data of CPs and products that might contain CPs in relevant amounts. The Brazilian production of CPs was discontinued in 1994. However, CPs are still imported and used in the country. CPs have been mostly applied as plasticizers, flame retardants and lubricants in Brazil. The import of products containing CPs also pose a significant route of CP entrance into Brazil. Thus, the current end-of-life management of CP-containing products is a bottleneck towards the Convention implementation. The guidance application was feasible and useful despite the low engagement of stakeholders. To assess foreign trade of CPs and CP-containing products, we recommend the use of more specific tracking codes. Besides, the review of SCCP occurrence is not a demanded part for an inventory but was a useful complementation.

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.

Maternal transfer and occurrence of siloxanes, chlorinated paraffins, metals, PFAS and legacy POPs in herring gulls (Larus argentatus) of different urban influence

Urban herring gulls (Larus argentatus) are exposed to contaminants from aquatic, terrestrial and anthropogenic sources. We aim to assess if differences in urbanisation affect ecological niche and contaminant concentrations in female herring gulls. Furthermore, we investigated maternal transfer from mothers to eggs for all the target compounds, including chlorinated paraffins (CPs) and cyclic volatile methyl siloxane (cVMSs), which to our knowledge have not been assessed in herring gulls previously. We compare concentrations of legacy and emerging contaminants and metals in blood and eggs between two herring gull colonies located 51 km apart, in the urban influenced Norwegian Oslofjord. While both colonies are within an urbanised area, the inner fjord is more so, as it is surrounded by Oslo, the capital and largest city in Norway Stable isotopes of carbon and nitrogen indicated a more marine ecological niche in the outer than the inner fjord colony, although with overlap. Persistent organic pollutant (POP) concentrations were similar in the inner and outer fjord colonies, while the short-chained chlorinated paraffins (SCCP), which are recently added to the Stockholm convention and contaminants of emerging concern (CECs) varied, with higher concentrations of SCCP and the cVMS decamethylcyclopentasiloxane (D5) in females and eggs of the inner fjord colony. Per- and polyfluorinated substances (PFAS) concentrations were higher in the outer fjord colony, likely linked to releases from a point-source (airport and waste management facility with open access to food waste). In blood, chlorinated paraffins contributed most the total lipophilic contaminants (inner: 78%, outer: 56%), while polychlorinated biphenyls (PCBs) were the most abundant lipophilic contaminants in eggs (inner: 62%, outer: 46%). Dechloranes and brominated flame retardants (BFRs) were detected in few samples. Maternal transfer, assessed by egg to blood ratios, of cVMSs were similar to the POPs with mean log ratio 0.39 (D5), while it was lower for SCCPs, with log ratios-0.77. Our results indicate comparable POP exposure of the herring gulls in the inner and outer Oslofjord, likely due to overlap in ecological niches between the colonies and wide distribution of POPs. The differences between the colonies in concentrations of PFAS, cVMS and CPs shows that point source exposures and urban influence may be more important than ecological niche for these compounds.

Tissue-Specific Distribution of Legacy and Emerging Organophosphorus Flame Retardants and Plasticizers in Frogs

Five types of tissues, including the liver, kidney, intestine, lung, and heart, were collected from black-spotted frogs and bullfrogs to study the tissue-specific accumulation of organophosphorus flame retardants (PFRs) and plasticizers. Thirteen PFRs and nine plasticizers were detected, with average total concentrations of 1.4–13 ng/g ww and 858–5503 ng/g ww in black-spotted frogs, 3.6–46 ng/g ww and 355–3504 ng/g ww in bullfrogs. Significant differences in pollutant concentrations among different tissues in the two frog species were found, indicating the specific selectivity distribution of PFRs and plasticizers. Overall, liver tissues exhibited significantly higher pollutant concentrations. The pollutant concentration ratios of other tissue to the sum of liver tissue and other tissues (OLR, C_other/(C_other + C_liver)) corresponding to male frogs were significantly greater than those of females, suggesting that male frogs could have higher metabolic potentials for PFRs and plasticizers. No obvious correlations between OLR and log K_OW were found, indicating that the other factors (e.g., bioaccumulation pathway and metabolism) besides lipophicity could influence the deposition of PFRs and plasticizers in frog livers. Different parental transfer patterns for PFRs and plasticizers were observed in frogs when using different tissues as parental tissues. Moreover, the liver tissues had similar parental transfer mechanism with muscle tissues.

Short- and medium-chain chlorinated paraffin exposure in South Germany: A total diet, meal and market basket study

Short- and medium-chain chlorinated paraffins (SCCPs, MCCPs) are high-production volume industrial chemicals that have been previously reported to occur in food, packaging material and the environment. This study presents an assessment of dietary exposure for consumers in Southern Germany based on three different sampling approaches: (i) a classical market basket study (n = 154), (ii) the analysis of ready-made meals from restaurants (n = 10), and (iii) a total diet approach (n = 21). In 35% of the samples, CPs were below the method limit of quantification. Highest amounts of SCCPs and MCCPs were found especially in extra virgin olive oils (EVOOs) and fish. Homologue patterns indicated the partial removal of CPs during the refining of (other) edible oils. Ready-made meals contained only low amounts of CPs equal to estimations based on market basket samples. Total diet samples from the same hospital were generally comparable with each other regardless of diet, although vegetarian meal plans with high amounts of cheese and other dairy products contained up to an order of magnitude more CPs than other diets. Taking all approaches into account, calculated daily exposures for adults ranged 35-420 ng/kg bw/day for ΣSCCPs and 22-840 ng/kg bw/day for ΣMCCPs, which is between one and two orders of magnitude higher than the current dietary intake of polychlorinated biphenyls (indicator PCBs) in Europe.

Human Exposure to Chlorinated Paraffins via Inhalation and Dust Ingestion in a Norwegian Cohort

Very-short- (vSCCPs, C_6-9), short- (SCCPs, C_10-13), medium- (MCCPs, C_14-17), and long-chain chlorinated paraffins (LCCPs, C_>17) were analyzed in indoor air and dust collected from the living rooms and personal 24 h air of 61 adults from a Norwegian cohort. Relatively volatile CPs, i.e., vSCCPs and SCCPs, showed a greater tendency to partition from settled indoor dust to paired stationary indoor air from the same living rooms than MCCPs and LCCPs, with median logarithmic dust-air partition ratios of 1.3, 2.9, 4.1, and 5.4, respectively. Using the stationary indoor air and settled indoor dust concentrations, the combined median daily exposures to vSCCPs, SCCPs, MCCPs, and LCCPs were estimated to be 0.074, 2.7, 0.93, and 0.095 ng/kg bw/d, respectively. Inhalation was the predominant exposure pathway for vSCCPs (median 99%) and SCCPs (59%), while dust ingestion was the predominant exposure pathway for MCCPs (75%) and LCCPs (95%). The estimated inhalation exposure to total CPs was ∼ 5 times higher when the personal 24 h air results were used rather than the corresponding stationary indoor air results in 13 paired samples, indicating that exposure situations other than living rooms contributed significantly to the overall personal exposure. The 95^th percentile exposure for CPs did not exceed the reference dose.

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.

Legacy and emerging organophosphorus flame retardants and plasticizers in frogs: Sex difference and parental transfer

Black-spotted frogs and bullfrogs from an e-waste polluted area were collected and examined for legacy and emerging organophosphorus flame retardants (PFRs) and plasticizers. Total concentrations of PFRs and plasticizers were 0.62-15 ng/g wet weight (ww) and 316-4904 ng/g ww in muscles, 2.2-59 ng/g ww and 127-5757 ng/g ww in eggs and gonads, and 1.2-15 ng/g ww and 51-1510 ng/g ww in oviducts, respectively. For muscle tissues, concentrations of ∑PFRs, triethyl phosphate, tris-(2-chloroethyl) phosphate, and tris-(chloro-2-propyl) phosphate were significantly higher in the males than females (p < 0.05). However, for reproductive tissues, eggs exhibited higher levels of those contaminants than gonads (p < 0.05). No significant sex difference in levels of plasticizers was observed in muscles. In contrast, levels for (2-ethylhexyl) phthalate, di-n-butyl phthalate, and di-iso-butyl phthalate in gonads were significantly higher than those in eggs (p < 0.05). Significantly negative linear correlations between maternal transfer ratios and log K_OW were found in female frogs. Paternal transfer potentials were first significantly and positively correlated to log K_OW (<6) and then decreased afterward in the males. These results indicated that parental transfer was answer for the sex-specific accumulation of PFRs and plasticizers in frogs.

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.

Addressing Main Challenges Regarding Short- and Medium-Chain Chlorinated Paraffin Analysis Using GC/ECNI-MS and LC/ESI-MS Methods

The risk assessment of chlorinated paraffins (CPs), chemicals of widespread industrial use, is struggling without standardized analytical methods to obtain reliable occurrence data. Indeed, scientists face analytical challenges that hinder the comparability of analytical methods, among them uncontrolled ionization efficiency and lack of quantification standards. In this study, our goal was to investigate potential issues faced when comparing data from different mass spectrometry platforms and quantification methods. First, the injection of the same set of single-chain length standards in three different instrumental mass spectrometry set-ups (liquid chromatography-electrospray-Orbitrap (LC/ESI-HRMS), liquid chromatography-electrospray-time-of-flight (LC/ESI-MS), and gas chromatography-electron capture negative ion-Orbitrap (GC/ECNI-HRMS)) revealed a shift of homologue response patterns even in-between LC/ESI-based set-ups, which was more pronounced for CPs of low chlorination degree. This finding emphasizes the need for a comprehensive description of instrument parameters when publishing occurrence data. Second, the quantification of a data set of samples with four quantification methods showed that quantification at the sum SCCP and MCCP levels presented good comparability, while quantification at the homologue level remained unsatisfactory. In light of those results, we suggest that (i) response pattern comparison should only be performed between similar instrumental set-ups, (ii) experimental chlorination degrees should be used when quantifying according to the %Cl (instead of those provided by the suppliers), and (iii) concentration results should be expressed as the sum of SCCPs and MCCPs primarily, with an indication on the match between samples and quantification standards (for example their chlorine content).

Uptake, Accumulation, and Biomarkers of PM2.5-Associated Organophosphate Flame Retardants in C57BL/6 Mice after Chronic Exposure at Real Environmental Concentrations

Although the bioaccumulation of organophosphate flame retardants (OPFRs) in aquatic organisms has been investigated, little information is available about their bioaccumulation in mammals following chronic inhalation exposure. To address this knowledge gap, C57BL/6 mice were exposed to 7 PM_2.5-associated OPFRs via the trachea to study their bioaccumulation, tissue distribution, and urinary metabolites. Low (corresponding to the real PM_2.5 concentrations occurring during winter in Guangzhou), medium, and high dosages were examined. After 72 days' exposure, ∑OPFR concentrations in tissues from mice in the medium dosage group decreased in the order of intestine > heart > stomach > testis > kidney > spleen > brain > liver > lung > muscle. Of the OPFRs detected in all three exposure groups, chlorinated alkyl OPFRs were most heavily accumulated in mice. We found a significant positive correlation between the bioaccumulation ratio and octanol-air partition coefficient (K_OA) in mice tissues for low log K_OW OPFR congeners (log K_OW ≤ 4, p < 0.05). Three urinary metabolites (di-p-cresyl phosphate: DCrP, diphenyl phosphate: DPhP, dibutyl phosphate: DnBP) were detected from the high dosage group. These results provide important insights into the bioaccumulation potential of OPFRs in mammals and emphasize the health risk of chlorinated alkyl OPFRs.

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.

Short- and medium-chain chlorinated paraffins in aquatic organisms from an e-waste site: Biomagnification and maternal transfer

Chlorinated paraffins (CPs) are globally pervasive contaminants that are toxic to humans and wildlife. Inconsistent biomagnification behaviors in different food chains have been reported, and very few studies have been conducted to investigate the maternal transfer of CPs in ovoviviparous species. This study investigated the biomagnification of short- and medium-chain chlorinated paraffins (S/MCCPs) in two aquatic food chains, as well as maternal transfer of S/MCCPs in watersnakes collected from an e-waste polluted pond in southern China. The concentrations of SCCPs and MCCPs varied from 1.2 to 250 μg/g lipid weight (lw) and from 2.3 to 200 μg/g lw in the collected organisms. The SCCP homologue profiles in prey (fish and prawn) differed from those in predators (watersnake and waterbird egg), while MCCP homologue group patterns were homogeneous. All maternal transfer concentration ratios (egg to muscle) of S/MCCPs in the watersnakes were lower than 1 and negatively correlated with the octanol-water partition coefficients (log K_OW), different from the maternal transfer of halogenated aromatic pollutants in the watersnake. Biomagnification factors (BMFs) of S/MCCPs for fish-watersnake muscle food chain were larger than 1, while BMFs for the fish-waterbird egg food chain were less than 1. However, when watersnake egg was used to calculate BMF, no biomagnification was found. BMFs in the two food chains showed significant positive linear correlations with chlorine atoms, but no significant correlation with carbon atom numbers, which suggested that a congener-group-specific elimination and excretion process for S/MCCPs exist.

Chlorinated Paraffins in Two Snake Species from the Yangtze River Delta: Tissue Distribution and Biomagnification

Very-short, short-, medium-, and long-chain chlorinated paraffins (vSCCPs, SCCPs, MCCPs, and LCCPs, respectively) were analyzed in different tissues of the terrestrial short-tailed mamushi (Gloydius brevicaudus) and the semi-aquatic red-backed rat snake (Elaphe rufodorsata) from the Yangtze River Delta, China. The total CP concentrations in liver, muscle, and adipose tissues in the two snake species were in the range of 2500-24 000, 4900-48 000, and 12-630 ng/g lw, respectively. Tissue burdens indicated that vSCCPs (C_6-9) and SCCPs (C_10-13) preferentially distributed to snake liver, while adipose was an important storage site and sink of MCCPs (C_14-17) and LCCPs (C_>18). On a lipid weight basis, vSCCPs and SCCPs were found in highest concentrations in red-backed rat snake liver and MCCPs and LCCPs in muscle, whereas for short-tailed mamushi, all CP groups were predominant in muscle, probably reflecting ecosystem/food web differences. Moreover, vSCCPs, SCCPs, MCCPs, and LCCPs were found to be biomagnified from black-spotted frogs to red-backed rat snakes with mean (maximum) biomagnification factors of 2.2 (3.4), 1.9 (3.7), 1.8 (2.8), and 1.7 (4.5), respectively. This is the first field study of biomagnification potential involving vSCCPs and LCCPs and highlights the need to include all CPs in studies.

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.