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

Short-Chain Chlorinated Paraffins May Induce Ovarian Damage in Mice via AIM2- and NLRP12-PANoptosome

Humans may intake 0.02 mg/kg/day of short-chain chlorinated paraffins (SCCPs), and no study is available on mammalian ovarian damage caused by low-level SCCPs. In this study, four groups of 5-week-old female Institute of Cancer Research (ICR) mice were orally administered 0, 0.01, 0.1, and 1.0 mg/kg/day SCCPs for 21 consecutive days, and serum and ovaries were collected 20 h after the last SCCPs-administration. SCCPs at ≥0.1 mg/kg/day were found to reduce follicle counts at each stage, induce dose-dependent oxidative stress in mice, and lower serum E2 and ovarian anti-Müllerian hormone levels. The data indicated that cellular PANoptosis increased in the ovaries of all SCCP-treated mice. Furthermore, AIM2- and NLRP12-PANoptosome gene and protein levels were considerably elevated. Female germline stem cells (FGSCs) in the cortical portion of the ovary exhibited substantial damage in all SCCP groups, additionally, the expression of FGSC marker genes and major marker proteins was diminished in the ovaries. Oral administration of SCCPs with 0.01, 0.1, and 1.0 mg/kg/day to mice resulted in PANoptosis of the ovaries. Therefore, it was suggested that the oral administration of ≥0.1 mg/kg/day of SCCPs suppressed ovarian function, which may be attributed to the fact that SCCPs induced the generation of AIM2- and NLRP12-PANoptosome in ovary cells.

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.

Short-chain chlorinated paraffin (SCCP) exposure and type 2 diabetes risk: A population-based case-control study in East China

Exposure to persistent organic pollutants may be associated to type 2 diabetes, but the studies on associations between short-chain chlorinated paraffin (SCCP) exposure and type 2 diabetes risk in humans are still scarce. Here, we conducted a case-control study involving 344 participants in Shandong Province, East China, to explore the effects of SCCPs on type 2 diabetes risk and their correlations with glycemic biomarker and serum lipid parameters. SCCPs were detected in all serum samples with a median concentration of 24 ng mL-1 in cases and 19 ng mL-1 in controls. Exposure to C10-CPs, C11-CPs, and ΣSCCPs were positively associated with the risk of type 2 diabetes after adjusting for confounders. The associations remained consistent in stratified analyses but stronger in male participants and obese individuals. In the control group, there were significant and positive correlations between SCCP exposure and levels of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), total lipid, and non-high-density lipoprotein-cholesterol. Significant joint effects on SCCP exposure and lipid parameters were observed in females when analyzed by the quantile-based g-computation model, and C10-CPs showed the highest contribution. Mediation analysis showed that LDL-C had significant mediation effects on the associations between C10-CPs, C11-CPs, and ΣSCCPs exposure and risk of type 2 diabetes. Moreover, TC and high-density lipoprotein-cholesterol were mediators in the relationship between C11-CPs and type 2 diabetes. Taken together, our study revealed that human exposure to SCCPs may increase the risk of type 2 diabetes and disrupt lipid metabolism.

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.

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.

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.

Characterization of short-, medium- and long-chain chlorinated paraffins in ambient PM2.5 from the Pearl River Delta, China

Research on the environmental occurrence of long-chain chlorinated paraffins (LCCPs) in ambient fine particulate matter (PM_2.5) is still scarce. In the present study, short-chain chlorinated paraffins (SCCPs), medium-chain chlorinated paraffins (MCCPs) and LCCPs were simultaneously quantified and profiled in PM_2.5 samples collected from 96 primary or secondary schools in the Pearl River Delta of South China. SCCPs, MCCPs and LCCPs were detected in higher than 90% samples with concentrations in the range of 0.832-109, 1.02-110, and 0.173-17.4 ng/m³, respectively. The dominant congener groups of SCCPs, MCCPs and LCCPs were C₁₃Cl_6-8, C₁₄Cl_7-8, and C₁₈Cl_7-9, respectively. The concentrations of SCCPs and MCCPs were higher in summer than in winter, while an opposite seasonal trend was observed for LCCPs. Principal components analysis showed there were seasonal variations in the congener group patterns with C₁₃Cl_6-7 and C₁₄Cl₇ more abundant in summer than in winter_. Concentrations of CPs also exhibited slight spatial variations. Exposure risk assessment based on different age groups suggested exposure to PM_2.5-associated CPs would not pose significant health risk. The present study expands the existing knowledge of CPs contamination in atmospheric environment.

Distribution and exposure risk assessment of chlorinated paraffins and novel brominated flame retardants in toys

Chlorinated paraffins (CPs) and novel brominated flame retardants (NBFRs) were examined in children's toys collected from 13 families in China. The concentrations of short-chain CPs (SCCPs), medium-chain CPs (MCCPs) and NBFRs in toys were 32.8-1,220,954 ng/g, not detected-2,688,656 ng/g and 0.08-103,461 ng/g, respectively. Median concentrations of SCCPs and MCCPs in toys were 1355 and 1984 ng/g, respectively, while except for pentabromobenzene (median:0.04 ng/g), the median concentrations of the other 8 NBFRs were below method detection limits. Rubber and foam toys contained higher amounts of CPs and NBFRs. Among the SCCPs and MCCPs monitored, Cl_6-8-SCCPs/MCCPs and C₁₄-MCCPs were the most abundant congener groups. On the other hand, decabromodiphenyl ethane was the predominant NBFR in toys. Moreover, to understand the role of toys in children's daily exposure to CPs and NBFRs, hand-to-mouth contact, mouthing, and dermal exposure were assessed for children aged 3 months to 6 years. Hand-to-mouth contact is the primary exposure route for children's exposure to CPs (25.4-536 ng/kg/day) and NBFRs (1.24-26.2 ng/kg/day) through toys. A low deleterious risk associated with children's toys concerning CPs and NBFRs was investigated based on the margin of exposure and hazard quotient values.