Search Results (28)

Chlorinated paraffins (CPs) are widely used, structurally complex mixtures of chlorinated alkanes whose ecological risks in aquatic ecosystems have raised increasing concern. However, the toxic effects and molecular mechanisms of CPs on primary aquatic producers remain poorly understood. In this study, we used the eukaryotic green algae Chlorella sp. and the prokaryotic cyanobacterium Microcystis aeruginosa (M. aeruginosa) as test organisms to systematically investigate the effects of CPs with different carbon chain lengths, namely short-chain CPs (SCCPs), medium-chain CPs (MCCPs), and long-chain CPs (LCCPs), on algal growth, photosynthetic pigment content, antioxidant systems, cellular ultrastructure, and the underlying molecular responses. Our results showed that CPs toxicity to algae is significantly dependent on both CPs carbon-chain length and algal species. Exposure to 1.0 mg/L SCCPs for 96 h produced a growth inhibition of Chlorella sp. of 14.45%. CPs’ exposure significantly altered algal Chl-a content and elicited antioxidant defense responses, and affected the synthesis and extracellular release of MC-RR and MC-LR in M. aeruginosa. Ultrastructural observations revealed cell surface wrinkling and deformation in both Chlorella sp. and M. aeruginosa. Chlorella sp. additionally exhibited thylakoid disintegration and plasmolysis. Transcriptomic analysis indicated that CPs with different chain lengths significantly downregulated genes in Chlorella sp. associated with DNA replication and mismatch repair, suggesting impairment of replication initiation and elongation and compromised genome stability. Concurrently, genes encoding photosynthetic antenna proteins and carbon fixation were upregulated. In M. aeruginosa, CPs exposure markedly disturbed energy metabolism pathways, including glycolysis/gluconeogenesis and oxidative phosphorylation, which were generally downregulated. This study provides a comparative assessment of CPs’ toxicity between the eukaryotic algae Chlorella sp. and the prokaryotic algae M. aeruginosa, revealing that toxicity is co-determined by carbon chain length and algal species. Additionally, it provides critical toxicological data and establishes a theoretical foundation for the scientific assessment of the aquatic ecological risks posed by CPs with different carbon chain lengths. Full article

The environmental concerns associated with the excessive use and improper disposal of plastic waste have led to increased interest in chemical recycling methods such as pyrolysis. In this study, waste plastic pyrolysis oil (WPPO) was evaluated as a potential feedstock to produce high-quality feedstock for lubricant base oils through hydroprocessing. WPPO was obtained via the thermal degradation of waste plastic at 400 °C under a nitrogen atmosphere using a 2 t/day pyrolysis reactor. The physicochemical properties of WPPO were analyzed, including the sulfur, chlorine, and metal contents. A series of Pt-supported catalysts based on different acidic supports (SAPO-11, SAPO-34, and Zeolite Y100) was prepared using an incipient wetness impregnation method and characterized by BET, XRD, and TPD techniques. The hydroprocessing reactions were conducted under varying temperature and pressure conditions to evaluate conversion and optimize product selectivity. The catalysts exhibited different surface areas, pore structures, and acidity profiles, which directly impacted their hydroprocessing performance. The results demonstrate that Pt/Y-100 exhibited the best upgrading performance among the tested catalysts, achieving an olefin-to-paraffin conversion of over 88.65% with a dominant paraffinic hydrocarbon distribution in the C15–C25 range under optimal conditions (300 °C and 40 bar). The results demonstrate that the conversion of olefins to paraffins in WPPO can be effectively controlled by tuning the reaction conditions and catalyst. Full article

Chlorinated paraffins (CPs) are persistent, bioaccumulative, and toxic. In marine environments, most studies have focused on short-chain CPs (SCCPs) in animals, while medium-and long-chain CPs (MCCPs and LCCPs) in plants have been neglected. In this study, samples collected from kelp mariculture zones in different seasons were analyzed for the CPs’ contamination characteristics and spatiotemporal distributions in seawater and contamination profiles, bioaccumulation behavior, and dietary exposure risks in kelp. In seawater, the total concentration ranges of SCCPs, MCCPs, and LCCPs were 25.44–245.75, 8.24–27.19, and not detected at 3.26 ng/L, respectively. Spatially, the CP concentrations were influenced by industrial discharge, riverine inputs, and dilution effects, and were significantly higher in nearshore water than in offshore areas (p < 0.05). The concentrations were significantly higher in February than in May, which was attributed to emissions from winter heating and reduced vessel activity during a fishing moratorium. In kelp, the total concentration ranges of SCCPs, MCCPs, and LCCPs were 5.4–210.9, 0.007–0.87, and 0.0–4.45 ng/g wet weight, respectively. Kelp exhibited significant growth-stage-dependent bioaccumulation of CPs, with higher CP concentrations and bioaccumulation factors in its tender stage (February) than during its mature stage (May). Congener analysis revealed similar composition patterns between seawater and kelp. According to a dietary risk assessment (hazard quotient < 0.01), the potential health risks associated with kelp consumption are low. Full article

This study systematically assessed the dietary exposure risks of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) through chicken consumption in China, where these persistent organic pollutants are widely produced and used. As an important component of the Chinese diet, chicken was selected as the research matrix due to its high lipid content and potential for chlorinated paraffin bio-accumulation, while available data on these contaminants in market-sold chicken remains limited. We collected 126 representative commercial chicken samples from eight major provinces and municipalities across China and conducted precise analysis using two-dimensional gas chromatography with electron capture negative ionization mass spectrometry (GC×GC-ECNI/MS). The probabilistic exposure assessment was performed through Monte Carlo simulation, and health risks were characterized using the margin of exposure (MOE) approach. The results revealed mean concentrations of 95.8 ng/g wet weight (range: 9.5–1542.4 ng/g ww) for SCCPs and 156.6 ng/g ww (range: 20.0–1517.9 ng/g ww) for MCCPs in chicken samples, with Jiangsu Province exhibiting significantly higher contamination levels compared to other regions (p < 0.001). The estimated mean dietary exposures through chicken consumption were 32.8 ng/kg bw/d for SCCPs and 52.6 ng/kg bw/d for MCCPs in the general Chinese population. Notably, children aged 3–6 years and the Consumer only showed the highest exposure levels. All calculated MOE values substantially exceeded the risk threshold of 1000, indicating no significant health concerns from current exposure to SCCPs and MCCPs through chicken consumption in China. Full article

Chlorinated paraffins (CPs) are a class of persistent organic pollutants that pose potential human health risks through dietary exposure. In this study, we analyzed CPs in 55 chicken egg samples collected from five regions across China. Short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) were detected using a two-dimensional gas chromatograph coupled with an electron-capture negative-ionization mass spectrometer. Dietary exposure risks were assessed using the margin of exposure (MOE) approach based on the food consumption data of Chinese residents from 2018 to 2020. The average concentrations of SCCPs and MCCPs in all samples were 28.4 ng/g wet weight (ww) and 176.5 ng/g ww, respectively. The congener profiles of SCCPs and MCCPs were similar across different regions, with C_10–11 Cl_6–7 as the dominant homologs. For MCCPs, the average contributions of C₁₄-CP, C₁₅-CP, C₁₆-CP, and C₁₇-CP were 25%, 21%, 27%, and 27%, respectively. The estimated daily intake (EDI) for the entire population was 18.3 ng/kg body weight (bw)/d for SCCPs and 118.3 ng/kg bw/d for MCCPs. In the consumer-only group, the average exposure levels of SCCPs and MCCPs were 27.8 ng/kg bw/d and 174.1 ng/kg bw/d, respectively. This preliminary risk assessment indicates that there is no health risk to the Chinese population from exposure to CP through consumption of chicken eggs. Full article

Dietary intake is the major route of human exposure to fat-soluble and persistent chlorinated paraffins (CPs), which tend to accumulate in lipid-rich foods such as edible vegetable oils. This study investigated the levels of short-chain (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in commercially available vegetable oils and assessed their potential health risks. The concentrations of SCCPs and MCCPs in 29 commercial edible vegetable oils were analyzed using comprehensive two-dimensional gas chromatography coupled with electron capture negative ionization mass spectrometry (GC × GC-ECNI-MS). Dietary exposure levels were estimated through probabilistic assessment integrating analytical results with dietary consumption data from the Chinese Total Diet Study (2017–2020). The margin of exposure (MOE) approach was employed for risk characterization. The average concentrations of SCCPs and MCCPs were 112 ng/g and 139 ng/g, respectively. The highest SCCP and MCCP concentration were found in sesame oil and peanut oil, respectively. Overall, MCCPs levels were generally higher than SCCPs. The estimated daily intakes (EDIs) of SCCPs and MCCPs were 56.06 and 73.63 ng/kg bw/d on average, with high consumers (P95) exposed to 180.91 and 230.49 ng/kg bw/d, respectively. Corresponding MOE at P95 were 1.27 × 10⁴ for SCCPs and 1.56 × 10⁵ for MCCPs. The current SCCPs and MCCPs dietary intake originated from edible vegetable oils did not pose a significant health risk. This study provides the first probabilistic exposure assessment of CPs in Chinese edible vegetable oils, offering current contamination profiles. Full article

In this study, we investigated the tribological properties of various additives (lubricity, friction modifiers, anti-wear and extreme pressure) in a highly volatile paraffinic base oil formulated for stamping applications, using a newly developed methodology for tribological testing. The investigation focused on the short-term (10 cycles) and long-term (10,000 cycles) effects of the different additive mixtures on friction and wear behaviour. It was found that the performance of the additive mixtures evolves with sliding time, which is due to changes in contact conditions: the transfer of the Fe film from the steel sheet to the WC-Co surface increases the contact area, which in turn leads to a significant reduction in contact pressure and changes the activation of tribofilm formation. The presence of tribofilms influences the amount and size of the contact area and reduces the adhesion between the contact surfaces. Among the conventional additives, sulphurised additive mixtures show stable performance under both short and long-term conditions, while more aggressive chlorinated additive mixtures perform well in the short term, but their performance decreases with prolonged sliding. Importantly, the additives with a decreasing environmental impact outperformed the conventional additives under long-term conditions: the less harmful phosphorus-based mixture outperformed the sulphurised mixtures in terms of wear properties, while the performance of environmentally acceptable polyol ester was particularly encouraging, exhibiting the lowest friction coefficient (~0.11, compared with ~0.12 for S-oil and 0.14 for S-ester) and the second lowest wear coefficient (~1.1 × 10⁻¹ mm³/Nm compared with ~1.5 × 10⁻¹ mm³/Nm for S-ester). Overall, the polyol ester reduced the coefficient of friction by approximately 8 to 21% compared to sulphurised additive mixtures, and its wear coefficient was also about 27% lower. Full article

Background: Only a few studies have reported on chlorinated paraffin (CP) levels, especially long-chain chlorinated paraffins (LCCPs), in submicron particulate matter (PM₁) in the outdoor air around primary and secondary schools. Methods: This study examined concentrations of short-chain CPs (SCCPs), medium-chain CPs (MCCPs), and LCCPs in PM₁ samples from 96 schools across six cities in China’s Pearl River Delta region during the winter (October to December 2018). Results: The median total CP concentration was 34 ng/m³, with median values for SCCP, MCCP, and LCCP of 17.3, 15, and 0.7 ng/m³, respectively. The primary congeners were C₁₃Cl_6–8 for SCCPs, C₁₄Cl_6–9 for MCCPs, and C₁₈Cl_7–10 for LCCPs. The SCCPs and MCCPs largely originated from fugitive dust, whereas the LCCPs were mainly sourced from organic chemical industries. Air masses from the South China Sea contributed most to SCCP and MCCP levels, while those from the east coast accounted for the highest LCCP levels. The concentrations of CP in PM₁ were significantly positively correlated with PM₁ levels. Conclusions: The exposure risk assessments by age indicated a very low current health risk from PM₁-related CP inhalation, although prolonged pollution could raise these risks as CP concentrations in ambient PM may continue to increase. Full article

In the present study, liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was employed to analyze chlorinated paraffin (CP) homolog distributions and concentrations in household dust from South China and the Midwestern United States. The median levels of short-, medium-, and long-chain CPs (∑SCCPs, ∑MCCPs, ∑LCCPs) in South China were quantified as 23.1, 36.2, and 32.8 μg/g, respectively. Comparatively, the corresponding values in the Midwestern U.S. samples were 9.4, 39.5, and 15.4 μg/g, respectively. Notably, ∑LCCP concentrations in South China significantly exceeded those in the U.S. (p < 0.05), while no difference was found for ∑SCCPs and ∑MCCPs. Additionally, very short-chain CPs (C_≤9) were detected in 13% of samples across both regions. The distribution of CP homologues in the dust samples from the two regions was similar, with C₁₃, C₁₄, and C₁₈ groups as the predominant carbon homologue and Cl_7-8, Cl_7-9, and Cl_9-10 as the predominant chlorine homologue of SCCPs, MCCPs, and LCCPs, respectively. Risk assessment indicated dust ingestion-derived CP intakes for adults and toddlers were 2–5 orders of magnitude below reference doses. However, given other exposure pathways and the combined effects of CP monomers, the potential health risks from exposure via dust should not be underestimated. Full article

Short-chain chlorinated paraffins (SCCPs) are ubiquitous environmental pollutants that have been detected in various human tissues and organs. Based on the results of numerous studies indicating that exposure to environmentally relevant doses could induce harm to humans and animals, they have been listed in Annex A (Elimination) of the Stockholm Convention on Persistent Organic Pollutants. They are also listed as hazardous materials likely to lead to significant adverse effects on human health or the environment by the International Convention for the Safe and Environmentally Sound Recycling of Ships (Hong Kong Convention) and the EU Ship Recycling Regulation (EU SRR). This paper analyzes recent literature on the environmental and human health impacts of SCCPs and the actual practice of shipbreaking to demonstrate that the current treatment of SCCPs under these two regulations does not provide sufficient protection for human health and the environment. Based on the presented data, it is proposed that SCCPs should be reclassified as materials whose installation or use is prohibited in shipyards, ship repair yards, and ships by the EU SRR and the Hong Kong Convention. Full article

Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) are environmental contaminants known for their persistence and bioaccumulation in fatty tissues. SCCPs are considered potential carcinogens and endocrine disruptors, with similar effects expected for MCCPs. This study investigated the body burden of SCCPs and MCCPs in residents of two regions of the Czech Republic with different levels of industrial pollution. Blood serum samples from 62 individuals in Ceske Budejovice (control area) and Ostrava (industrial area) were analysed. The results showed higher concentrations of SCCPs (<120–650 ng/g lipid weight (lw)) and MCCPs (<240–1530 ng/g lw) in Ostrava compared to Ceske Budejovice (SCCPs: <120–210 ng/g lw, MCCPs: <240–340 ng/g lw). The statistical analysis revealed no significant correlations between chemical concentrations and demographic variables such as age, BMI, or gender. The findings are consistent with European and Australian studies but significantly lower than levels reported in China. This is the first comprehensive survey of SCCPs and MCCPs in human blood serum in the Czech Republic and the second study in Europe. The data collected in this study are essential for assessing SCCPs and MCCPs. They will contribute to a better understanding the potential health risks associated with exposure to these chemicals. Full article

Short-chain chlorinated paraffins (SCCPs) are a persistent organic pollutant, and limited information is available on their bioaccumulation and trophic transfer, which would be affected by carbon chain length, chlorine content, and hydrophobicity. In this study, relevant data on SCCPs in water, sediments, and organisms collected from Laizhou Bay were analyzed to investigate the specific distribution of SCCPs and their bioaccumulation and trophic transfer. In water and sediments, the average SCCP concentrations (ΣSCCPs) were 362.23 ± 81.03 ng/L and 609.68 ± 90.28 ng/g d.w., respectively. In 28 species of organisms, the ΣSCCPs varied from 70.05 to 47,244.13 ng/g l.w. (average = 648 ± 7360) and the predominant homologs were C₁₃ (average = 34.91%) and Cl_5–7 (average = 93.13%), differing from those in water (average = C₁₁ 32.75% and average = Cl_5–7 88%) and sediments (average = C₁₃ 31.60% and average = Cl_6–8 87.16%). The logarithm bioaccumulation factors (BAFs) of ΣSCCPs were 1.18–2.74 and were positively correlated with the log K_ow. A significant negative linear relationship was observed between biota-sediment accumulation factors (BSAFs) and log K_ow. It is suggested that the hydrophobicity may affect the bioaccumulation of SCCPs. SCCPs demonstrated a trophic magnification factor (TMF) ranging from 2.19 to 3.00 (average = 2.51) and exhibited a significant linear correlation with carbon chain length (p < 0.05) and log K_ow values (p < 0.05), suggesting that SCCPs have biomagnification potential in Laizhou Bay that is affected by hydrophobicity and carbon chain length. Full article

Background: Humans cannot avoid plastic exposure due to its ubiquitous presence in the natural environment. The waste generated is poorly biodegradable and exists in the form of MPs, which can enter the human body primarily through the digestive tract, respiratory tract, or damaged skin and accumulate in various tissues by crossing biological membrane barriers. There is an increasing amount of research on the health effects of MPs. Most literature reports focus on the impact of plastics on the respiratory, digestive, reproductive, hormonal, nervous, and immune systems, as well as the metabolic effects of MPs accumulation leading to epidemics of obesity, diabetes, hypertension, and non-alcoholic fatty liver disease. MPs, as xenobiotics, undergo ADMET processes in the body, i.e., absorption, distribution, metabolism, and excretion, which are not fully understood. Of particular concern are the carcinogenic chemicals added to plastics during manufacturing or adsorbed from the environment, such as chlorinated paraffins, phthalates, phenols, and bisphenols, which can be released when absorbed by the body. The continuous increase in NMP exposure has accelerated during the SARS-CoV-2 pandemic when there was a need to use single-use plastic products in daily life. Therefore, there is an urgent need to diagnose problems related to the health effects of MP exposure and detection. Methods: We collected eligible publications mainly from PubMed published between 2017 and 2024. Results: In this review, we summarize the current knowledge on potential sources and routes of exposure, translocation pathways, identification methods, and carcinogenic potential confirmed by in vitro and in vivo studies. Additionally, we discuss the limitations of studies such as contamination during sample preparation and instrumental limitations constraints affecting imaging quality and MPs detection sensitivity. Conclusions: The assessment of MP content in samples should be performed according to the appropriate procedure and analytical technique to ensure Quality and Control (QA/QC). It was confirmed that MPs can be absorbed and accumulated in distant tissues, leading to an inflammatory response and initiation of signaling pathways responsible for malignant transformation. Full article

This study focuses on an innovative green propellant based on paraffin, stearic acid, and coal, used in hybrid rocket engines. Additionally, lab-scale firing tests were conducted using a hybrid rocket motor with gaseous oxygen as the oxidizer, utilizing paraffin-based fuels containing stearic acid and coal. The mechanical performance results revealed that the addition of stearic acid and coal improved the mechanical properties of paraffin-based fuel, including tensile, compression, and flexural strength, under both ambient and sub-zero temperatures (−21 °C). Macrostructural and microstructural examinations, conducted through optical and scanning electron microscopy (SEM), highlighted its resilience, despite minimal imperfections such as impurities and micro-voids. These characteristics could be attributed to factors such as raw material composition and the manufacturing process. Following the mechanical tests, the second stage involved conducting a firing test on a hybrid rocket motor using the new propellant and gaseous oxygen. A numerical simulation was carried out using ProPEP software to identify the optimal oxidant-to-fuel ratio for the maximum specific impulse. Following simulations, it was observed that the specific impulse for the paraffin and for the new propellant differs very little at each oxidant-to-fuel (O/F) ratio. It is noticeable that the maximum specific impulse is achieved for both propellants around the O/F value of 2.2. It was observed that no hazardous substances were present, unlike in traditional solid propellants based on ammonium perchlorate or aluminum. Consequently, there are no traces of chlorine, ammonia, or aluminum-based compounds after combustion. The resulting components for the simulated motor include H₂, H₂O, O₂, CO₂, CO, and other combinations in insignificant percentages. It is worth noting that the CO concentration decreases with an increase in the O/F ratio for both propellants, and the differences between concentrations are negligible. Additionally, the CO₂ concentration peaks at an O/F ratio of around 4.7. The test proceeded under normal conditions, without compromising the integrity of the test stand and the motor. These findings position the developed propellant as a promising candidate for applications in low-temperature hybrid rocket technology and pave the way for future advancements. Full article

Chlorinated paraffins (CPs), a class of complex mixtures synthesized from polychlorinated n-alkanes, are widely used as flame retardants, plasticizers, lubricant additives, coolants, metalworking cutting fluids, and sealants. This study investigated the spatial distribution, the potential pollution sources, and ecological risk of 24 short-chain CPs (SCCPs) and 24 medium-chain CPs (MCCPs) from 29 surface marine sediment samples from the East China Sea and Yellow Sea in September 2019. All of the 48 CPs were detected. The concentrations of SCCPs and MCCPs ranged from 0.703 to 13.4 ng/g dw and 0.0936 to 4.19 ng/g dw, respectively. C₁₀ congeners showed the highest abundancy. The median concentrations of the SCCPs and MCCPs declined gradually with carbon atoms and chlorine atoms, except for Cl₅ congeners. Spatial variations showed that all CP congeners in the East China Sea were larger than in the Yellow Sea and displayed a point-source-type distribution, which is consistent with the industrial park distribution. Although the potential ecological risk was at a relatively low level, bioaccumulation and trophic magnification could amplify the risk to marine organisms. Our results provide data support and theoretical assistance for SCCP and MCCP pollution control and sewage outlets in the East China Sea and Yellow Sea. Full article