Development a simple and rapid HPLC-ESI-Q-TOF/MS method for determination of short- and medium- chain chlorinated paraffins in human serum

The ototoxicity of chlorinated paraffins via inducing apoptosis, oxidative stress and endoplasmic reticulum stress in cochlea hair cells

Hearing loss is a common chronic sensory deficit that affects millions of people worldwide and has emerged as a significant public health concern. The association between environmental exposure to chemicals and the prevalence of hearing impairment has recently attracted increased attention. Chlorinated paraffins (CPs) are a type of chemical compound that has been widely used and commonly detected in samples of both environmental and human origin. The knowledge of the toxicological effects of CPs, particularly its ototoxicity, remains limited at present. In this study, six commercial CPs were selected and evaluated using cochlea hair HEI-OC1 cells for their cytotoxicity, apoptosis, DNA damage, reactive oxygen species (ROS) accumulation and oxidative response. The cytotoxicity was observed after CPs exposure at high concentrations except for C-40 and was positively related to the chlorine content (Cl-content) in both CCK-8 and trypan blue assays. All 6 CPs induced cells apoptosis through caspase-dependent apoptotic pathway. CPs exposure induced DNA damage and stimulated ROS overproduction. Antioxidant N-acetyl-L-cysteine (NAC) could reverse the cytotoxicity and ROS accumulation caused by CPs exposure. The overexpression of ATF4 and CHOP indicated that endoplasmic reticulum (ER) stress was involved in the CPs induced cytotoxicity. Thus, CPs induced cytotoxicity and apoptosis via ROS accumulation, ER stress and DNA damage and positively related to the Cl-content and our findings indicate that CPs may pose a risk of ototoxicity at environmental relevant exposure levels.

A Quasi Real-Time Evaluation of High-Resolution Mass Spectra of Complex Chlorinated Paraffin Mixtures and Their Transformation Products

Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes with multiple carbon- (C-, nC = 9-30) and chlorine homologues (Cl-, nCl = 3-18). The mass spectrometric analysis of CPs is time-consuming and challenging, especially when interferences between CPs, their transformation products, or from the matrix are numerous. These analytical challenges and the lack of appropriate and accessible data evaluation tools are obstacles to their analysis. CP-Hunter is a web-based, open-access data processing platform for the automatic analysis of mass spectra of CPs and their transformation products. Extracts of two consumer plastic materials and sewage sludge were evaluated with CP-Hunter. C- and Cl-homologue distributions were obtained in quasi-real-time and the posterior calculated fingerprints were in agreement with the ones obtained by traditional methods. However, the data extraction and evaluation time were now reduced from several minutes to seconds. The implemented signal deconvolution method, i.e., to resolve mass spectrometric interferences, provides robust results, even when severe matrix effects are present. CP-Hunter facilitates the untargeted analysis of unknown products and the detection and elimination of false positive signals. Finally, data evaluation with CP-Hunter is performed locally without the transfer of data to external servers. The tool is safe, public, and accessible at https://cphunter.cheminfo.org/.

Exposure to Short- and Medium-Chain Chlorinated Paraffins and the Risk of Gestational Diabetes Mellitus: A Nested Case-Control Study in Eastern China

Toxicological studies have indicated that exposure to chlorinated paraffins (CPs) may disrupt intracellular glucose and energy metabolism. However, limited information exists regarding the impact of human CP exposure on glucose homeostasis and its potential association with an increased risk of developing gestational diabetes mellitus (GDM). Here, we conducted a prospective study with a nested case-control design to evaluate the link between short- and medium-chain CP (SCCPs and MCCPs) exposures during pregnancy and the risk of GDM. Serum samples from 102 GDM-diagnosed pregnant women and 204 healthy controls were collected in Hangzhou, Eastern China. The median (interquartile range, IQR) concentration of SCCPs was 161 (127, 236) ng/mL in the GDM group compared to 127 (96.9, 176) ng/mL in the non-GDM group (p < 0.01). For MCCPs, the GDM group had a median concentration of 144 (117, 174) ng/mL, while the control group was 114 (78.1, 162) ng/mL (p < 0.01). Compared to the lowest quartile as the reference, the adjusted odds ratios (ORs) of GDM were 7.07 (95% CI: 2.87, 17.40) and 3.34 (95% CI: 1.48, 7.53) in the highest quartile of ∑SCCP and ∑MCCP levels, respectively, with MCCPs demonstrating an inverted U-shaped association with GDM. Weighted quantile sum regression evaluated the joint effects of all CPs on GDM and glucose homeostasis. Among all CP congeners, C13H23Cl5 and C10H16Cl6 were the crucial variables driving the positive association with the GDM risk. Our results demonstrated a significant positive association between CP concentration in maternal serum and GDM risk, and exposure to SCCPs and MCCPs may disturb maternal glucose homeostasis. These findings contribute to a better understanding of the health risks of CP exposure and the role of environmental contaminants in the pathogenesis of GDM.

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.

In Vivo Profiling and Quantification of Chlorinated Paraffin Homologues in Living Fish

Herein, we demonstrate the ability of a dual-purpose periodic mesoporous organosilica (PMO) probe to track the complex chlorinated paraffin (CP) composition in living animals by assembling it as an adsorbent-assisted atmospheric pressure chemical ionization Fourier-transform ion cyclotron resonance mass spectrometry (APCI-FT-ICR-MS) platform and synchronously performing it as the in vivo sampling device. First, synchronous solvent-free ionization and in-source thermal desorption of CP homologues were achieved by the introduction of the PMO adsorbent-assisted APCI module, generating exclusive adduct ions ([M - H]^-) of individual CP homologues (C_nCl_m) with enhanced ionization efficiency. Improved detection limits of short- and medium-chain CPs (0.10-24 and 0.48-5.0 pg/μL) were achieved versus those of the chloride-anion attachment APCI-MS methods. Second, the dual-purpose PMO probe was applied to extract the complex CP compositions in living animals, following APCI-FT-ICR-MS analysis. A modified pattern-deconvolution algorithm coupled with the sampling-rate calibration method was used for the quantification of CPs in living fish. In vivo quantification of a tilapia exposed to technical CPs for 7 days was successfully achieved, with ∑SCCPs and ∑MCCPs of the sampled fish calculated to be 1108 ± 289 and 831 ± 266 μg/kg, respectively. Meanwhile, 58 potential CP metabolites were identified in living fish for the first time during in vivo sampling of CPs, a capacity that could provide an important tool for future study regarding its expected risks to humans and its environmental fate.

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.

Status of short-chain chlorinated paraffins in matrices and research gap priorities in Africa: a review

Chlorinated paraffins (CPs) have been applied as additives in a wide range of consumer products, including polyvinyl chloride (PVC) products, mining conveyor belts, paints, sealants, adhesives and as flame retardants. Consequently, CPs have been found in many matrices. Of all the CP groups, short-chain chlorinated paraffins (SCCPs) have raised an alarming concern globally due to their toxicity, persistence and long-range transportation in the environment. As a result, SCCPs were listed in the Stockholm Convention on Persistent Organic Pollutants (POPs) in May 2017. Additionally, a limit for the presence of SCCPs in other CP mixtures was set at 1% by weight. CPs can be released into the environment throughout their life cycle; therefore, it becomes crucial to assess their effects in different matrices. Although about 199 studies on SCCP concentration in different matrices have been published in other continents; however, there are scarce/or limited studies on SCCP concentration in Africa, particularly on consumer products, landfill leachates and sediment samples. So far, published studies on SCCP concentration in the continent include SCCPs in egg samples, e-waste recycling area and indoor dust in Ghana and South Africa, despite absence of any production of SCCPs in Africa. However, there still remains a huge research gap in the continent of Africa on SCCPs. Consequently, there is a need to develop robust SCCP inventories in Africa since the Stockholm Convention has already developed guidance document in this respect. This review, therefore, examines the state of knowledge pertaining to the levels and trends of these contaminants in Africa and further provides research gaps that need to be considered in order to better understand the global scale of the contaminant.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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.

Evaluating age and temporal trends of chlorinated paraffins in pooled serum collected from males in Australia between 2004 and 2015

Chlorinated paraffins (CPs) are high production volume chemicals of which some show resistance to environmental degradation, long-rang transport, bioaccumulation and toxicity potential. Information regarding their presence in humans is limited, including their human bioaccumulation potential. The present study aimed to evaluate CP levels in human serum from Australia in order to better understand their exposure and current pollution status as well as trends associated with age and time between 2004 and 2015. For this, we selected a male sub-group of the Australian population under 60 years old (n = 16 pools, total 1600 serum samples). While long-chain CP (C_18-20) and most short-chain CP (C_10-13, SCCPs) levels were below method detection limits (MDL), medium-chain CPs (C_14-17, MCCPs) were found in most serum samples (detection frequency 94%) as well as CPs with a carbon chain length of nine (detection frequency 76%). The levels of ΣSCCPs and ΣMCCPs ranged from <MDL-140 and <MDL-520 ng/g lipid weight (lw), respectively, with a median value of 97 ng/g lw for SCCPs and 190 ng/g lw for MCCPs. Analysis by age stratification did not identify any trends but an increase of a factor of 2 in MCCPs levels was observed over time (p < 0.05). Plotting the MCCP/SCCP ratio of all available data in humans over time showed also an increasing trend, including for China. The reported levels are relatively low considering the levels reported in environmental media from Australia such which raises the question to what extent CPs accumulate in humans. Future studies on this aspect are required.