Positive association between chlorinated paraffins and the risk of allergic diseases in children and adolescents

Contaminants may induce immune response polarization, leading to immune diseases, such as allergic diseases. Evidence concerning the effects of chlorinated paraffins (CPs), an emerging persistent organic pollutant, on immune system is scarce, particularly for epidemiological evidence. This study explores the association between CPs exposure and allergic diseases (allergic rhinitis, atopic eczema, and allergic conjunctivitis) in children and adolescents in the Pearl River Delta (PRD) in China. Herein, 131,304 children and adolescents from primary and secondary schools in the PRD were included and completed the questionnaire survey. The particulate matter (PM) samples were collected in the PRD and the PM2.5-bound CP concentrations were analyzed. In the multivarious adjustment mixed effect model (MEM), an IQR increase in ∑CPs was significantly associated with allergic diseases (rhinitis, eczema, and conjunctivitis) with the estimated odds ratios (ORs) for 1.11 (95% CI: 1.10, 1.13), 1.17 (95% CI: 1.15, 1.19), and 1.82 (95% CI: 1.76, 1.88), respectively. Interaction analysis indicated that overweight and obese individuals might have greater risk. Similar effect estimates were observed in several sensitivity analyses. This study provided epidemiological evidence on the immunotoxicity of CPs. More studies to confirm our findings and investigate mechanisms are needed.

Metabolic disturbance of short- and medium-chain chlorinated paraffins to zebrafish larva

Chlorinated paraffins (CPs) are widely produced chemicals. Short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) were listed as Persistent Organic Pollutants (POPs) and candidate POPs under the Stockholm Convention, respectively. The present study explored the developmental toxicity and metabolic disruption caused by SCCPs and MCCPs in zebrafish (Danio rerio) larvae. CPs exposure at environmentally relevant levels caused no obvious phenotypic changes with zebrafish larvae except that the body length shortening was observed after exposure to CPs at 1-200 μg/L for 7 day post fertilization. A further metabolomic approach was conducted to explore the early biological responses of developmental toxicity induced by CPs at low dose (1, 5, and 10 μg/L). The results of metabolic disorder, pathway analysis and chronic values indicated that, compared with SCCPs, MCCPs exhibited more risks to zebrafish larvae at low doses. Lipid metabolism was markedly affected in SCCPs exposure group, whereas MCCPs primarily disturbed lipid metabolism, amino acid, and nucleotide metabolisms. Compare with SCCPs, the relatively higher lipid solubility, protein affinity and metabolic rate of MCCPs can probably explain why MCCP-mediated metabolic disruption was significantly higher than that of SCCP. Notably, SCCPs and MCCPs have the same potential to cause cancer, but no evidence indicates the mutagenicity. In summary, our study provides insight into the potential adverse outcome for SCCP and MCCP at low doses.

Developmental toxicity of short-chain chlorinated paraffins on early-stage chicken embryos in a shell-less (ex-ovo) incubation system

Short-chain chlorinated paraffins (SCCPs) are listed as a category of globally controlled persistent organic pollutants (POPs) by the Stockholm Convention in 2017. However, SCCP toxicity, particularly their developmental toxicity in avian embryos, has not been well studied. In this study, we observed the early development of chicken embryos (Gallus gallus domesticus) by applying a shell-less (ex-ovo) incubation system developed in our previous studies. After exposing embryos at Hamburger Hamilton stage (HHS) 1 to SCCPs (control, 0.1% DMSO; SCCPs-L, 200 ng/g; SCCPs-M, 2000 ng/g; SCCPs-H, 20,000 ng/g), we observed the development of embryos from the 3rd to 9th incubation day. Exposure to SCCPs-M and -H induced a significant reduction in survival, with an LD50 of 3100 ng/g on the 9th incubation day. Significant dose-dependent decreases in body length were observed from days 4-9. We also found that SCCPs-H decreased the blood vessel length and branch number on the 4th incubation day. Additionally, SCCPs-H significantly reduced the heart rate on the 4th and 5th incubation days. These findings suggest that SCCPs may have potential of developmental and cardiovascular toxicity during the early stages of chicken embryos. Quantitative PCR of the mRNA of genes related to embryonic development showed that SLC16A10 (a triiodothyronine transporter) level decreased in the SCCPs-H group, showing a significant positive correlation with the body length of embryos. THRA level, a thyroid hormone receptor, was significantly decreased in the SCCPs-H group, whereas that of DIO3 level, a deiodinase was significantly increased. These results suggest that SCCPs exposure induces developmental delays via the thyroxine signaling pathway. Analysis of thyroid hormones (THs) in blood plasma also indicated a significant reduction in thyroxine (T4) levels in the SCCPs-H group on the 9th incubation day of embryos. In conclusion, SCCPs induce developmental toxicity by disrupting thyroid functions at the early-life stage of chicken embryos.

Medium-chain chlorinated paraffins (MCCPs) induce renal cell aging and ferroptosis

PURPOSE

Medium-chained chlorinated paraffins (MCCPs) are a class of chlorinated derivatives of straight-chain n-alkanes with complex compositions, which are widely used in industry. The chlorinated paraffins (CPs) are divided into short chain chlorinated paraffins (SCCPs), medium chain chlorinated paraffins (MCCPs) and long chain chlorinated paraffins (LCCPs). SCCPs have been banned due to their severe bioaccumulation and biotoxicity. Therefore, MCCPs are used as a substitute for SCCPs. However, the toxicological data of MCCPs are still very limited. For this, we systematically investigated the toxicological impact of MCCPs on a renal cell model in the current study. Our work provides basic research data for analyzing the toxicological effects of MCCPs, suggesting that MCCPs should be restricted in their usage.

METHOD

A series of biochemical experiments was performed, including Western blot, indirect immunofluorescence assay, and ELISA was performed to analyze the toxicological effects of MCCPs.

RESULTS

Two renal cell lines were used as a model for assessing the toxicological effects of MCCPs. Cell proliferation assays showed that MCCPs could inhibit the proliferation of kidney cells in a dose-dependent manner. Further studies showed that MCCPs induced ferroptosis in kidney cells by evaluating a series of ferroptosis marker molecules. Additionally, MCCPs induced inflammatory response and premature senescence in HEK293 and NRK-52E cells. Molecular mechanism experiments showed that ferroptosis induced by MCCPs emerged as a significant contributor to premature aging of kidney cells.

CONCLUSION

The current study provides basic research data to analyze the toxicological effects of MCCPs and their toxicity mechanisms. It also provides a theoretical basis for the assessment of the potential ecological risk of MCCPs, as well as basic experimental data for the rational and standardized use of MCCPs.

In vitro assessment of potential endocrine disrupting activities of chlorinated paraffins of various chain lengths

The production of chlorinated paraffins (CPs) has risen in the past two decades due to their versatile industrial applications. Consequently, CPs are now widely detected in human food sources, the environment, and in human matrices such as serum, the placenta and breast milk. This raises concern about prenatal and postnatal exposure. While some studies suggest that certain short-chained CPs (SCCPs) may have endocrine disrupting properties, knowledge about potential endocrine disrupting potential of medium- (MCCP) and long-chained CPs (LCCPs) remains relativity sparse. Here, we used a panel of in vitro assays to investigate seven pure CPs and two technical mixtures of CPs. These varied in chain length and, chlorination degree. The in vitro panel covered androgen, estrogen, and retinoic acid receptor activities, transthyretin displacement, and steroidogenesis. One of the SCCPs inhibited androgen receptor (AR) activity. All SCCPs induced estrogen receptor (ER) activity. Some SCCPs and MCCPs increased 17β-estradiol levels in the steroidogenesis assay, though not consistently across all substances in these groups. SCCPs exhibited the most pronounced effects in multiple in vitro assays, while the tested LCCPs showed no effects. Based on our results, some CPs can have endocrine disrupting potential in vitro. These findings warrant further examinations to ensure that CPs do not cause issues in intact organisms, including humans.

[Metabolomic interference induced by short-chain chlorinated paraffins in human normal hepatic cells]

Short-chain chlorinated paraffins (SCCPs) are an emerging class of persistent organic pollutants (POPs) that are widely detected in environmental matrices and human samples. Because of their environmental persistence, long-range transport potential, bioaccumulation potential, and biotoxicity, SCCPs pose a significant threat to human health. In this study, metabolomics technology was applied to reveal the metabolomic interference in human normal hepatic (L02) cells after exposure to low (1 μg/L), moderate (10 μg/L), and high (100 μg/L) doses of SCCPs. Principal component analysis (PCA) and metabolic effect level index (MELI) values showed that all three SCCP doses caused notable metabolic perturbations in L02 cells. A total of 72 metabolites that were annotated by MS/MS and matched with the experimental spectra in the Human Metabolome Database (HMDB) or validated by commercially available standards were selected as differential metabolites (DMs) across all groups. The low-dose exposure group shared 33 and 36 DMs with the moderate- and high-dose exposure groups, respectively. The moderate-dose exposure group shared 46 DMs with the high-dose exposure group. In addition, 33 DMs were shared among the three exposure groups. Among the 72 DMs, 9, 9, and 45 metabolites participated in the amino acid, nucleotide, and lipid metabolism pathways, respectively. The results of pathway enrichment analysis showed that the most relevant metabolic pathways affected by SCCPs were the lipid metabolism, fatty acid β-oxidation, and nucleotide metabolism pathways, and that compared with low-dose exposure, moderate- and high-dose SCCP exposures caused more notable perturbations of these metabolic pathways in L02 cells. Exposure to SCCPs perturbed glycerophospholipid and sphingolipid metabolism. Significant alterations in the levels of phosphatidylcholines, phosphatidylethanolamines, and sphingomyelins indicated SCCP-induced biomembrane damage. SCCPs inhibited fatty acid β-oxidation by decreasing the levels of short- and medium-chain acylcarnitines in L02 cells, indicating that the energy supplied by fatty acid oxidation was reduced in these cells. Furthermore, compared with low- and moderate-dose SCCPs, high-dose SCCPs produced a significantly stronger inhibition of fatty acid β-oxidation. In addition, SCCPs perturbed nucleotide metabolism. The higher hypoxanthine levels observed in L02 cells after SCCP exposures indicate that SCCPs may induce several adverse effects, including hypoxia, reactive oxygen species production, and mutagenesis in L02 cells.

Stress Response in the Honeybee (Apis mellifera L.) Gut Induced by Chlorinated Paraffins at Residue Levels Found in Bee Products

Chlorinated paraffins (CPs) have become global pollutants and are of considerable concern as a result of their persistence and long-distance transmission in the environment and toxicity to mammals. However, their risks to pollinating insects are unknown. Honeybees are classical pollinators and sensitive indicators of environmental pollution. Herein, the effects of CPs on the gut microenvironment and underlying mechanisms were evaluated and explored using Apis mellifera L. Both short- and medium-chain CPs had significant sublethal effects on honeybees at a residue dose of 10 mg/L detected in bee products but did not significantly alter the composition or diversity of the gut microbiota. However, this concentration did induce significant immune, detoxification, and antioxidation responses and metabolic imbalances in the midgut. The mechanisms of CP toxicity in bees are complicated by the complex composition of these chemicals, but this study indicated that CPs could substantially affect intestinal physiology and metabolic homeostasis. Therefore, CPs in the environment could have long-lasting impacts on bee health. Future studies are encouraged to identify novel bioindicators of CP exposure to detect early contamination and uncover the detailed mechanisms underlying the adverse effects of CPs on living organisms, especially pollinating insects.

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.

Effect of short-chain chlorinated paraffins (SCCPs) on lipid membranes: Combination of molecular dynamics and membrane damage experiments

In recent years, more attention has been paid to the biological effects of short-chain chlorinated paraffin (SCCP). Studies have shown that SCCPs exposure could cause metabolic damage and lipid metabolic damage. In the present work, based on E. coli membrane damage experiments and molecular dynamics (MD) simulation, the effects of SCCPs on the membrane structure and membrane properties were studied to explore the possible toxic damage effects of SCCPs on cell membrane. Experiments results showed that SCCPs had a significant inhibitory effect on E. coli. The E. coli cell membrane of the bacteria was broken and the macromolecules of the cell flowed out when exposed to SCCPs. SCCPs would lead to the decrease and depolarization of cell membrane potential, and then affect the integrity and permeability of cell membrane. The further molecular dynamic simulation revealed that SCCP molecules can easily enter the lipid DPPC membranes from the aqueous phase and tended to aggregate inside bilayer stably. The bound of SCCPs could lead to significant variations in DPPC bilayer with a less dense, more disorder and rougher layer, which thus made the damage of cell membrane. In a word, although the overall toxicity of SCCPs to cell was relatively weak, the damage to the cell membrane may be one of the mechanisms of its toxicity. MAIN FINDING OF THE WORK: The exposure of SCCPs could cause structural change of cell membrane in E. coli, which verified the damage to the cell membrane may be one of the mechanisms of its toxicity.

Metabolomic mechanisms of short chain chlorinated paraffins toxicity in rats

Short chain chlorinated paraffins (SCCPs) have received increased interest worldwide since they were added to the list of controlled POPs in Annex A of the Stockholm Convention in 2017. Although many toxicological studies have already shown that SCCPs are hepatotoxic, nephrotoxic, and thyrotoxic to rodents, there have been few studies to date that have characterized changes in the metabolic pathways targeted by SCCPs. In this study, a UPLC-Q-TOF-MS based plasma metabolomics approach was used to investigate the toxicity of SCCPs in rats. Liver and kidney injury occurred rapidly after high-dose SCCP exposure, and the most relevant pathways affected were energy metabolism, amino acid metabolism, glycerophospholipid metabolism, nucleotide metabolism, and vitamin B metabolism. Exposure to SCCPs inhibited the tricarboxylic acid cycle and accelerated degradation. Fluctuating levels of phospholipids and nucleotides may have contributed to the neurotoxicity of SCCPs. In addition, the down regulation of folic acid induced by SCCPs may have led to malformations during the early development of laboratory animals. These results suggested that high exposure levels of SCCPs may have serious health risks and more research is needed to assess the health status of relevant occupational groups.

Increased adverse effects during metabolic transformation of short-chain chlorinated paraffins by cytochrome P450: A theoretical insight into 1-chlorodecane

Short-chain chlorinated paraffins (SCCPs), frequently detected in human tissues or organs, can result in threat to human health by disturbing normal metabolism. However, their metabolism mechanisms and fates are largely unclear. Therefore, to better understand the impacts of SCCPs and their metabolites on the human health, the metabolic mechanism and kinetics of SCCPs by cytochrome P450 enzymes (CYPs) were explored using density functional theory employed 1-chlorodecane as a model SCCPs. The results show that 1-chlorodecane could be readily metabolized by CYPs, and the rate constant reaches up 42.3 s^-1 in human body. Dechlorination of 1-chlorodecane is unlikely to occur and hydroxylation is dominated via H-abstraction pathways, especially from the intermediate C atom of 1-chlorodecane. The toxicity assessments suggest that the two metabolites, 10-chloro-decan-5-ol and 1-chlorodecanol could exhibit higher bioaccumulation, carcinogenicity and more serious damage on cardiovascular system after the metabolism of 1-chlorodecane. To our knowledge, this is the first study from the viewpoint of theoretical analysis to explore the metabolism of typical SCCPs in human body. It may provide deep insight into the metabolic transformation mechanism of SCCPs and cause the concerns about the adverse effects of their metabolites in human body.

Effect of short-chain chlorinated paraffins on metabolic profiling of male SD rats

The toxic effect of high-dose of short-chain chlorinated paraffins (SCCPs) has been extensively studied, however the possible health risks induced by SCCPs at low-dose remain largely unknown. In this study, a comprehensive toxicology analysis of SCCPs was conducted with the exposure levels from the environmental dose to the Lowest Observed Adverse Effect Level (LOAEL) of 100 mg/kg/day. General toxicology analysis revealed inconspicuous toxicity of the environmental dose of SCCPs, high dose SCCP exposure inhibited the growth rate and increased the liver weight of rat. Metabolomics analysis indicated that SCCP-induced toxicity was triggered at environmentally relevant doses. First, inhibition of energy metabolism was observed with the decrease in blood glucose and the dysfunction of TCA cycle, which may have contributed to lower body weight gain in rats exposed to a high dose of SCCPs. Second, the increase of free fatty acids indicated the acceleration of lipid metabolism to compensate for the energy deficiency caused by hypoglycemia. Lipid oxidative metabolism inevitably leads to oxidative stress and stimulates the up-regulation of antioxidant metabolites such as GSH and GSSH. The up-regulation of polyunsaturated fatty acids (PUFAs) and phospholipids composed of arachidonic acid indicates the occurrence of inflammation. Dysfunction of lipid metabolism can be an indicator of SCCP-induced liver injury.

Advances in Studies on Toxic Effects of Short-Chain Chlorinated Paraffins (SCCPs) and Characterization of Environmental Pollution in China

Short-chain chlorinated paraffins (SCCPs) were included in the Stockholm Convention in 2017. SCCPs have persistence, bioaccumulation, long-range environmental mobility and biological toxicity, significant toxicity to aquatic organisms, and potential carcinogenicity. Little study was on the progress research on the current environmental pollution in China. We reviewed the pollution conditions of SCCPs in air, soil, and water and their accumulation in food and organisms in China, especially for the contaminations of aquatic ecosystem. Meanwhile, we summarize the recent studies on the toxic effects and toxicological mechanisms of SCCPs on aquatic organisms and mammals. Finally, the further direction and trends for SCCP research were proposed. More efforts are necessary to conduct a comprehensive risk assessment and evaluate the relative importance of the various exposure routes.

Integration of metabolomics and transcriptomics reveals short-chain chlorinated paraffin-induced hepatotoxicity in male Sprague-Dawley rat

BACKGROUND

Short-chain chlorinated paraffins (SCCPs) used in various industrial applications have been listed as new POPs. Previous studies based on high-dose exposures indicate their hepatotoxicity. However, their mechanisms of toxicity or adverse outcome pathways and health risks remain largely unknown.

OBJECTIVES

This study aimed to evaluate metabolic consequences of chronic dietary exposure to SCCPs at low doses and reveal the molecular mechanisms underlying hepatotoxicity of SCCPs.

METHODS

A combination of transcriptomics and metabolomics, together with general pathophysiological tests were performed to assess the hepatic response of male rats exposed to SCCPs.

RESULTS

Our results highlight two major modes of action: Inhibition of energy metabolism and activation of the peroxisome proliferator-activated receptor α (PPARα). Exposure to SCCPs suppressed oxidative phosphorylation, glycolysis, gluconeogenesis and turnover of ATP-ADP-AMP and thus results in deficiencies of amino acids and nucleotides in liver of the rat. Exposure to SCCPs affected expression levels of 13 genes downstream of PPARα that encode proteins associated with metabolism of fatty acids. As a result, peroxisomal and mitochondrial fatty acid β-oxidation, microsomal fatty acid ω-oxidation, and lipogenesis were accelerated.

CONCLUSIONS

Results of this work strongly support the conclusion that low-dose exposure to SCCPs can result in adverse outcomes in the rat model. Significant SCCP-induced inhibition of energy metabolism occurs at environmentally relevant dosages, which suggests that SCCPs exhibit metabolic toxicity. Interactions of SCCPs with PPARα signaling pathway can explain the disruption of lipids and amino acids metabolism.

Short-chain chlorinated paraffins (SCCPs) disrupt hepatic fatty acid metabolism in liver of male rat via interacting with peroxisome proliferator-activated receptor α (PPARα)

Short-chain chlorinated paraffins (SCCPs) are frequently detected in environmental matrices and human tissues. It was hypothesized that SCCPs might interact with the peroxisome proliferator-activated receptor α (PPARα). In the present study, an in vitro, dual-luciferase reporter gene assay and in silico molecular docking analysis were employed together to study the interactions between SCCPs congeners and PPARα. Expressions of genes downstream in pathways activated by PPARα in liver of rats exposed to 1, 10, or 100 mg/kg bm/d of C_10-13-CPs (56.5% Cl) for 28 days were examined to confirm activation potencies of SCCPs toward PPARα signaling. Effects of exposure to C_10-13-CPs (56.5% Cl) on fatty acid metabolism in rat liver were also explored via a pseudo-targeted metabolomics strategy. Our results showed that C_10-13-CPs (56.5% Cl) caused a dose-dependent greater expression of luciferase activity of rat PPARα. Molecular docking modeling revealed that SCCPs had a strong capacity to bind with PPARα only through hydrophobic interactions and the binding affinity was dependent on the degree of chlorination in SCCPs congeners. In livers of male rats, exposure to 100 mg/kg bm/d of C_10-13-CPs (56.5% Cl) resulted in up-regulated expressions of 11 genes that are downstream in the PPARα-activated pathway and regulate catabolism of fatty acid. Consistently, accelerated fatty acid oxidation was observed mainly characterized by lesser concentrations of ∑fatty acids in livers of rats. Overall, these results demonstrated, for the first time, that SCCPs could activate rat PPARα signaling and thereby disrupt metabolism of fatty acid in livers of male rats.

Comparing the disrupting effects of short-, medium- and long-chain chlorinated Paraffins on cell viability and metabolism

With the phasing out of short-chain chlorinated paraffins (SCCPs), the production and emissions of medium- and long-chain chlorinated paraffins (MCCPs and LCCPs) are expected to increase. In this study, cell viability assay and pseudotargeted metabolomics approach were adopted to define and compare the toxic effects induced by SCCPs, MCCPs and LCCPs. The dose response curves indicated that three CP mixtures with comparable chlorine contents produced similar inhibitory effects on cell viability. At exposure concentration of 100 μg/L, three CP mixtures all induced significant increases in levels of reactive oxygen species (ROS) and malondialdehyde (MDA) and a significant reduction in level of adenosine triphosphate production (ATP), and produced similar impact intensities on overall metabolism. A stronger perturbation in phospholipid and fatty acid metabolism was observed in all CP exposure groups. In comparison with SCCPs and MCCPs, LCCPs produced a stronger suppressive effect on amino acid transport across cell membrane and induced an opposite effect on purine metabolism. Furthermore, the toxicity mechanism and possible health risks of the three types of CPs were discussed. MCCPs shared the most similar cytotoxicity and metabolic perturbation with SCCPs, suggesting that there should be concern about using MCCPs as alternatives to SCCPs.

C9-13 chlorinated paraffins cause immunomodulatory effects in adult C57BL/6 mice

Short-chain chlorinated paraffins (SCCPs, C_10-13) were listed as persistent organic pollutants (POPs) by the Stockholm Convention in 2017 and pose extensive exposure risks to humans. To our knowledge, there have been no studies reporting the immmunomodulatory effects of SCCPs until now. C₉-CPs have also been shown to be present in the environment. In this study, adult male C57BL/6 mice were exposed to 1, 10, or 100 mg/kg/d C_9-13-CPs by gavage for 28 d. The results showed that compared to those of the controls, exposure to C_9-13-CPs led to increased spleen weight, delimited germinal centers, enhanced energy metabolism, and elevated glutathione content, but no variation in the malonaldehyde level in the spleen was observed. Exposure to C_9-13-CPs also increased the populations of splenic lymphocytes, T lymphocytes, NK cells, and the ratio of the CD3⁺/CD19⁺ subsets and CD4⁺/CD8⁺ subsets compared to those of the controls. RNA-seq revealed 424 differentially expressed genes (DEGs) (fold change ≥ 1.5, FDR < 0.05) in the spleen between the control group and the 100 mg/kg/d C_9-13-CPs-treated group. KEGG analysis demonstrated that folate biosynthesis, pathways in cancer and thyroid hormone signaling were the three most significantly enriched pathways, and despite not reaching statistical significance, some immune-related pathways were also enriched in the KEGG functional enrichment analysis, including the chemokine signaling pathway (FDR < 0.0584), the NF-κB signaling pathway (FDR < 0.0663), Th17 cell differentiation (FDR < 0.0839), and the Jak-STAT signaling pathway. Moreover, compared to those of the controls, exposure to C_9-13-CPs enhanced the Concanavalin A (Con A)-stimulated cultured splenocyte proliferation, while the exposure showed no effect on the splenocyte proliferation that was stimulated by lipopolysaccharides (LPS). Taken together, these results demonstrated that subacute exposure to C_9-13-CPs could have immunomodulatory effects in mice. The present study helps to provide an understanding of the comprehensive health risks posed by C_9-13-CPs.

Short-chain chlorinated paraffins (SCCPs) induced thyroid disruption by enhancement of hepatic thyroid hormone influx and degradation in male Sprague Dawley rats

Short-chain chlorinated paraffins (SCCPs) are known to disturb thyroid hormone (TH) homeostasis in rodents. However, the mechanism remains to be fully characterized. In this study, male Sprague Dawley rats received SCCPs (0, 1, 10, or 100mg/kg/day) via gavage once a day for consecutive 28days. Plasma and hepatic TH concentrations, thyrocyte structure, as well as thyroid and hepatic mRNA and protein levels of genes associated with TH homeostasis were examined. Moreover, we performed molecular docking to predict interactions between constitutive androstane receptor (CAR), a key regulator in xenobiotic-induced TH metabolism, with different SCCP molecules. Exposure to SCCPs significantly decreased the circulating free thyroxine (T₄) and triiodothyronine (T₃) levels, but increased thyroid-stimulating hormone (TSH) levels by a feedback mechanism. Decreased hepatic T₄ and increased hepatic T₃ levels were also seen after 100mg/kg/day SCCPs exposure. SCCPs didn't show any significant effects on the expression of thyroid TH synthesis genes or thyrocyte structure. However, stimulation effects were observed for mRNA and protein levels of hepatic uridine diphosphoglucuronosyl transferase (UGT) 1A1 and organic anion transporter 2, suggesting an accelerated TH metabolism in rat liver. The increased cytochrome P450 2B1 but not 1A1 mRNA and protein levels indicated that the CAR signaling was activated by SCCPs exposure. According to docking analysis, SCCPs form hydrophobic interactions with CAR and the binding affinity shows dependency on chlorine content. Overall, our data showed that CAR implicated enhancement of hepatic TH influx and degradation could be the main cause for SCCPs induced TH deficiency in male rats.

Developmental and metabolic responses of zebrafish (Danio rerio) embryos and larvae to short-chain chlorinated paraffins (SCCPs) exposure

Short-chain chlorinated paraffins (SCCPs) are highly toxic to aquatic organisms, but their toxicity is yet not well characterized. In this study, the developmental toxicity of SCCPs to zebrafish embryos/larvae was evaluated, and a metabolomics approach was adopted to explore the impact of SCCPs exposure on the metabolism in zebrafish embryos. Exposure to SCCPs at concentrations of 1-200μg/L did not produce an observable effect on the hatching rate and morphological deformities of zebrafish embryos/larvae. However, the survival rate of zebrafish larvae in SCCPs exposure groups decreased in a concentration-dependent manner. The 13-day 50% lethal concentration (LC₅₀) value of SCCPs was calculated to be 34.4μg/L. Exposure to SCCPs induced a significant change of overall metabolism, even at environmentally relevant concentrations (1-5μg/L). The most relevant pathways affected by SCCPs exposure were glycerophospholipid metabolism, fatty acid metabolism and purine metabolism. Exposure to SCCPs at concentrations of 1-5μg/L had begun to accelerate the β-oxidation of unsaturated fatty acids and very long chain fatty acids, and affect the transformation of guanine to xanthine in the pathway of purine metabolism. Furthermore, when the exposure concentrations of SCCPs were increased to 50-200μg/L, the levels of phospholipids and amino acids were significantly raised; whereas the levels of fatty acids, carnitines and inosine were significantly decreased. In view of the significant effect on metabolism, the sub-chronic and chronic toxicity of SCCPs to fish should be concerned.

A metabolomics strategy to assess the combined toxicity of polycyclic aromatic hydrocarbons (PAHs) and short-chain chlorinated paraffins (SCCPs)

The combined toxicity of mixed chemicals is usually evaluated according to several specific endpoints, and other potentially toxic effects are disregarded. In this study, we provided a metabolomics strategy to achieve a comprehensive understanding of toxicological interactions between mixed chemicals on metabolism. The metabolic changes were quantified by a pseudotargeted analysis, and the types of combined effects were quantitatively discriminated according to the calculation of metabolic effect level index (MELI). The metabolomics strategy was used to assess the combined effects of polycyclic aromatic hydrocarbons (PAHs) and short-chain chlorinated paraffins (SCCPs) on the metabolism of human hepatoma HepG2 cells. Our data suggested that exposure to a combination of PAHs and SCCPs at human internal exposure levels could result in an additive effect on the overall metabolism, whereas diverse joint effects were observed on various metabolic pathways. The combined exposure could induce a synergistic up-regulation of phospholipid metabolism, an additive up-regulation of fatty acid metabolism, an additive down-regulation of tricarboxylic acid cycle and glycolysis, and an antagonistic effect on purine metabolism. SCCPs in the mixture acted as the primary driver for the acceleration of phospholipid and fatty acid metabolism. Lipid metabolism disorder caused by exposure to a combination of PAHs and SCCPs should be an important concern for human health.

Toxicity and occupational exposure assessment for Fischer-Tropsch synthetic paraffinic kerosene

Fischer-Tropsch (FT) Synthetic Paraffinic Kerosene (SPK) jet fuel is a synthetic organic mixture intended to augment petroleum-derived JP-8 jet fuel use by the U.S. armed forces. The FT SPK testing program goal was to develop a comparative toxicity database with petroleum-derived jet fuels that may be used to calculate an occupational exposure limit (OEL). Toxicity investigations included the dermal irritation test (FT vs. JP-8 vs. 50:50 blend), 2 in vitro genotoxicity tests, acute inhalation study, short-term (2-week) inhalation range finder study with measurement of bone marrow micronuclei, 90-day inhalation toxicity, and sensory irritation assay. Dermal irritation was slight to moderate. All genotoxicity studies were negative. An acute inhalation study with F344 rats exposed at 2000 mg/m³ for 4 hr resulted in no abnormal clinical observations. Based on a 2-week range-finder, F344 rats were exposed for 6 hr per day, 5 days per week, for 90 days to an aerosol-vapor mixture of FT SPK jet fuel (0, 200, 700 or 2000 mg/m³). Effects on the nasal cavities were minimal (700 mg/m³) to mild (2000 mg/m³); only high exposure produced multifocal inflammatory cell infiltration in rat lungs (both genders). The RD₅₀ (50% respiratory rate depression) value for the sensory irritation assay, calculated to be 10,939 mg/m^3, indicated the FT SPK fuel is less irritating than JP-8. Based upon the proposed use as a 50:50 blend with JP-8, a FT SPK jet fuel OEL is recommended at 200 mg/m³ vapor and 5 mg/m³ aerosol, in concurrence with the current JP-8 OEL.

Concentrations and inhalation risk assessment of short-chain polychlorinated paraffins in the urban air of Dalian, China

The concentrations of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China, were monitored from March to October 2010 and from September to October 2016 with active high-volume sampler. The total concentration of SCCPs (particulate phase + gas phase) ranged from 15.12 to 66.44 ng m^-3, with an average of 30.26 ng m^-3 in 2010, and 65.30 to 91.00 ng m^-3, with an average of 78.15 ng m^-3 in 2016. Hexa-chlorinated dodecane and hexa-chlorinated undecane are the predominant components in the gas phase, while octa-chlorinated undecane and hepta-chlorinated tridecane are dominant in the particulate phase. In 2010, 82.57-97.16% of the total SCCPs were found in the gas phase, except that in winter, where 63.11% of the total SCCPs were in the particulate phase; the air concentrations of SCCPs in gas phase were summer > autumn > spring > winter, which was positively correlated with the change of the average ambient temperature, while it was the contrary in particulate phase. In autumn, the gas phase and the total air concentration of SCCPs in 2016 were 2.57 times more than that in 2010, while the congener group patterns of SCCPs were similar. Spearman's rank correlation analysis between the concentrations of SCCPs with meteorological parameters was conducted. The gas-particle distribution was examined through the relationship of the logarithm of the gas-particle partition coefficient with that of the subcooled vapor pressure and the octanol-air partitioning coefficient of SCCPs. Results indicated that the absorption mechanisms contributed more to the partitioning process. The exposure risk of SCCPs was evaluated, which illustrated that the estimated exposure of SCCPs via the outdoor environment in Dalian did not exceed the health concern threshold of the European risk assessment.

Relative developmental toxicity of short-chain chlorinated paraffins in Zebrafish (Danio rerio) embryos

Short-chain chlorinated paraffins (SCCPs) are ubiquitous in the environment and might cause adverse environmental and human health effects. Little is known about the relative toxicity of different SCCP compounds especially during development. The objective of this study was to characterize and compare effects of seven SCCP groups at environmentally relevant levels, using a zebrafish (Danio rerio) model. Observations on malformation, survival rates at 96 h post fertilization (hpf), and hatching rates at 72 hpf indicated that the C_10- groups (C₁₀H₁₈Cl₄, 1,2,5,6,9,10-C₁₀H₁₆Cl₆ and C₁₀H₁₅Cl₇) were more toxic than the C_12- groups (C₁₂H₂₂Cl₄, C₁₂H₁₉Cl₇ and 1,1,1,3,10,12,12,12-C₁₂H₁₈Cl₈) and Cereclor 63L. The C_10- groups were also more potent than C_12- groups and Cereclor 63L in decreasing thyroid hormone levels. Among the three compounds within the C_10- group, the compounds with less chlorine content had stronger effects on sub-lethal malformations but less effects on triiodothyronine (T3) and tetraiodothyronine (T4). Only C₁₀H₁₈Cl₄ significantly decreased the mRNA expression of tyr, ttr, dio2 and dio3 at a dose-dependent manner suggesting that the specific mode of actions differ with different congeners. The mechanisms of disruption of thyroid status by different SCCPs could be different. C₁₀H₁₈Cl₄ might inhibit T3 production through the inhibition effect on dio2. These results indicate that SCCP exposure could alter gene expression in the hypothalamic-pituitary-thyroid (HPT) axis and thyroid hormone levels. The mechanisms of disruption of thyroid status by different SCCPs could be different. Our results on the relative developmental toxicities of SCCPs will be useful to reach a better understanding of SCCP toxicity supporting environmental risk evaluation and regulation and used as a guidance for environmental monitoring of SCCPs in the future.

Assessment of the endocrine-disrupting effects of short-chain chlorinated paraffins in in vitro models

Short-chain chlorinated paraffins (SCCPs), which are candidate persistent organic pollutants (POPs) according to the Stockholm Convention, are of great concern because of their persistent bioaccumulation, long-range transport and potential adverse health effects. However, data on the endocrine-disrupting effects of SCCPs remain scarce. In this study, we first adopted two in vitro models (reporter gene assays and H295R cell line) to investigate the endocrine-disrupting effects of three SCCPs (C10-40.40%, C10-66.10% and C11-43.20%) via receptor mediated and non-receptor mediated pathway. The dual-luciferase reporter gene assay revealed that all test chemicals significantly induced estrogenic effects, which were mediated by estrogen receptor α (ERα), in the following order: C11-43.20%>C10-66.10%>C10-40.40%. Notably, C10-40.40% and C10-66.10% also demonstrated remarkable anti-estrogenic activities. Only C11-43.20% showed glucocorticoid receptor-mediated (GR) antagonistic activity, with a RIC20 value of 2.6×10(-8)mol/L. None of the SCCPs showed any agonistic or antagonistic activities against thyroid receptor β (TRβ). Meanwhile, all test SCCPs stimulated the secretion of 17β-estradiol (E2). Both C10-66.10% and C11-43.20% increased the production of cortisol at a high level in H295R cell lines. In order to explore the possible mechanism underlying the endocrine-disrupting effects of SCCPs through the non-receptor pathway, the mRNA levels of 9 steroidogenic genes were measured by real-time polymerase chain reaction (RT-PCR). StAR, 17βHSD, CYP11A1, CYP11B1, CYP19 and CYP21 were upregulated in a concentration-dependent manner by all chemicals. The data provided here emphasized that comprehensive assessments of the health and ecological risks of emerging contaminants, such as SCCPs, are of great concern and should be investigated further.

Occurrence, fate and ecological risk of chlorinated paraffins in Asia: A review

Chlorinated paraffins (CPs), complex mixtures of polychlorinated alkanes, are widely used in various industries and are thus ubiquitous in the receiving environment. The present study comprehensively reviewed the occurrence, fate and ecological risk of CPs in various environmental matrices in Asia. Releases from the production and consumption of CPs or CP-containing materials, wastewater discharge and irrigation, sewage sludge application, long-range atmospheric transport and aerial deposition have been found to be most likely sources and transport mechanisms for the dispersion of CPs in various environmental matrices, such as air, water, sediment, soil and biota. CPs can be bioaccumulated in biota and biomagnified through food webs, likely causing toxic ecological effects in organisms and posing health risks to humans. Inhalation, dust ingestion and dietary intake are strongly suggested as the major routes of human exposure. Research gaps are discussed to highlight the perspectives of future research to improve future efforts regarding the analysis of CPs, the environmental occurrence and elimination of CPs, the total environmental pressure, and the risks to organisms and populations.

Effects of short-chain chlorinated paraffins exposure on the viability and metabolism of human hepatoma HepG2 cells

Short-chain chlorinated paraffins (SCCPs) have attracted considerable attention for their characteristic of persistent organic pollutants. However, very limited information is available for their toxic effects at environmentally relevant doses, limiting the evaluation of their health risks. In this study, cell viability assay and targeted metabolomic approach was used to evaluate the environmental dose (<100 μg/L) effect of SCCPs on HepG2 cells. Cell viability was found to be decreased with increases in exposure dose of SCCPs. Exposure for 48 h to C10-CPs resulted in a significant reduction in cell viability compared with 24 h, even at 1 μg/L. SCCPs exposure altered the intracellular redox status and caused significant metabolic disruptions. As a kind of peroxisome proliferator, SCCPs specifically stimulated the β-oxidation of unsaturated fatty acids and long-chain fatty acids. Meanwhile, SCCPs exposure disturbed glycolysis and amino acid metabolism, and led to the up-regulation of glutamate metabolism and urea cycle. The toxic effects of SCCPs might mainly involve the perturbation of energy production, protein biosynthesis, fatty acid metabolism, and ammonia recycling.

Distillation fraction-specific ecotoxicological evaluation of a paraffin-rich crude oil

Crude oil is a complex mixture of petroleum hydrocarbons (PHC) with distinct chemical, physical and toxicological properties relevant for contaminated site risk assessment. Ecotoxicological effects of crude oil distillation fractions on luminescent bacteria (Vibrio fischeri), earthworms (Dendrobaena hortensis) and invertebrates (Heterocypris incongruens) were tested using two spiked soils and their elutriates. Fraction 2 (F2) had an equivalent carbon number (ECN) range of >10 to 16, and F3 from >16 to 39. F2 showed a substantially higher ecotoxicological effect than F3 for Vibrio and Dendrobaena. In contrast, severe inhibition of Heterocypris by the poorly soluble F3 is attributed to mechanical organ blockage. Immediate sequestration of PHC to the organic matter-rich soil effected reduced toxicity for all organisms. This study indicates that a more differentiated consideration (i) of PHC mixtures based on ECN range and (ii) of model soil properties employed for ecotoxicity testing should be included into PHC-contaminated site risk assessment.

[Preparation of rat model of systemic inflammatory response syndrome induced by zymosan]

OBJECTIVE

To establish a model of systemic inflammatory response syndrome (SIRS) in rats.

METHODS

SD rats were intraperitoneally injected with different concentrations of zymosan suspension. The general status, temperature, white cell count, tumor necrosis factor-α(TNF-α), interleukin-6(IL-6), interleukin-10 (IL-10) and the pathological changes of main organs were examined.

RESULTS

The conditions of rats receiving zymosan doses of 750 mg/kg and 1000 mg/kg were consistent with the criteria of SIRS model; however, the mortality of 1000 mg/kg group was higher than that of 750 mg/kg group.

CONCLUSION

The rat model of systemic inflammatory response syndrome has been successfully induced.

Pollutant emissions from gasoline combustion. 1. Dependence on fuel structural functionalities

To study the formation of air pollutants and soot precursors (e.g., acetylene, 1,3-butadiene, benzene, and higher aromatics) from aliphatic and aromatic fractions of gasoline fuels, the Utah Surrogate Mechanisms is extended to include submechanisms of gasoline surrogate compounds using a set of mechanism generation techniques. The mechanism yields very good predictions of species concentrations in premixed flames of n-heptane, isooctane, benzene, cyclohexane, olefins, oxygenates, and gasoline using a 23-component surrogate formulation. The 1,3-butadiene emission comes mainly from minor fuel fractions of olefins and cyclohexane. The benzene formation potential of gasoline components shows the following trends as functions of (i) chemical class: n-paraffins < isoparaffins < olefins < naphthalenes < alkylbenzenes < cycloparaffins < toluene; (ii) carbon number: n-butane < n-pentane < n-hexane; and (iii) branching: n-hexane < isohexane < 2,2,4-trimethylpentane < 2,2,3,3-tetramethylbutane. In contrast, fuel structure is not the main factor in determining acetylene formation. Therefore, matching the benzene formation potential of the surrogate fuel to that produced by the real fuel should have priority when selecting candidate surrogate components for combustion simulations.

Effects of seven organic pollutants on soil nematode Caenorhabditis elegans

Caenorhabditis elegans is a free-living soil nematode that is commonly used as a model for toxicity tests. The aim of this study was to investigate the toxicity of seven organic pollutants: four azaarenes (quinoline, acridine, phenazine, and 1,10-phenanthroline), short-chain chlorinated paraffins, and two organochlorinated pesticides (toxaphene and hexachlorobenzene). The exposure to all chemicals was carried out in three test media (soil, agar, and aquatic medium), and adult mortality was evaluated after 24 and 48 h. Toxaphene was the most toxic substance with LC(50) (48 h) of 379 mg/kg in the soil and 0.2 mg/L in the aquatic medium. Quinoline was the most toxic chemical in agar test with LC(50) (48 h) of 10 mg/L. HCB showed a very low toxicity in all tests, maybe due to its very low water solubility. Longer than 24-h test duration was found necessary for getting more correct data on toxicity. In comparison with other studies, C. elegans was less sensitive than other soil invertebrates. Different response might be attributed to different exposure routes and shorter test duration. Equilibrium partitioning theory was used to calculate K(oc) from results of soil and aquatic tests but this approach was found not working. Our results suggest that the tests with nematode C. elegans should be included to the battery of tests for risk assessment of POPs in soil.

Dose–response feeding study of short chain chlorinated paraffins (SCCPs) in laying hens: Effects on laying performance and tissue distribution, accumulation and elimination kinetics

Technical short chain chlorinated paraffins (C10-C13 with 60% chlorine) were fed to 93 laying hens from 24 to 32 weeks of age in increasing concentrations of up to 100 mg/kg feed. No significant influence on health, relative organ weights or performance (laying intensity, egg weight, feed consumption) was noted. The chlorinated paraffin content of the tissues was linearly related to the concentration of short chain paraffins of the feed. The highest concentrations were found in abdominal fat, egg yolk and fatty tissues. Breast muscle, egg albumen and bile fluid contained minimal or no residues. Less than 1% of the chlorinated paraffins ingested were incorporated into the body (without head, feet, gut and feathers), whereas about 1.5% were eliminated with the egg yolk and 30% were excreted with urine and faeces. A six-week kinetic depuration study revealed a biphasic elimination with half-lifes of 4-40 min (liver, kidneys, legs, fat, blood) for the initial rapid phase, and 15-30 days (blood, fat, liver, yolk, kidneys, legs) for the terminal slow phase.

Hydrocarbon-based weapons maintenance compounds produce evidence of contact hypersensitivity in BALB/c mice

Unprotected dermal contact with weapons maintenance materials is highly probable during cleaning and maintenance of firearms. Several weapons maintenance materials of interest to the Department of Defense were evaluated for their irritating and sensitizing potential in a modified local lymph node assay (LLNA). Female BALB/c mice (n = 5) were topically exposed to Break-Free CLP, Royco 634, TW-25B, MC-25, or MC-2500. All compounds tested produced a positive response for irritancy and lymphocyte proliferation. Break-Free CLP and Royco 634 produced the greatest dermal irritation and highest LLNA stimulation index. Phenotyping of draining lymph node cells from animals treated with Break-Free CLP suggest that this material induces T-cell-mediated contact sensitization (Type IV hypersensitivity) in mice. These findings support the recommendation that persons handling or using weapons maintenance materials should protect their skin from repeated contact by wearing appropriate personal protective equipment.

Occupational paraffin-induced pulmonary fibrosis: a 25-year follow-up

Exogenous lipid pneumonia can exceptionally be caused by occupational exposure to paraffin. The authors report a case of severe interstitial pulmonary disease induced by occupational exposure to paraffin, leading to delayed fibrosis over a 25-year follow-up, despite cessation of exposure.

Toxicity of three halogenated flame retardants to nitrifying bacteria, red clover (Trifolium pratense), and a soil invertebrate (Enchytraeus crypticus)

Halogenated flame retardants have a high sorption affinity to particles, making soils and sediments important sinks. Here, three of the most commonly used flame retardants have been tested for sub-lethal toxicity towards soil nitrifying bacteria, a terrestrial plant (seed emergence and growth of the red clover, Trifolium pratense), and a soil invertebrate (survival and reproduction of Enchytraeus crypticus). Tetrabromobisphenol A (TBBPA) was quite toxic to enchytraeids, with significant effects on reproduction detected already at the 10 mgkg(-1) exposure level (EC(10)=2.7 mgkg(-1)). In contrast, decabromodiphenyl ether (DeBDE) was not toxic at all, and short-chain chloroparaffins (CP(10-13)) only affected soil nitrifying bacteria at the highest test concentration (EC(10)=570 mgkg(-1)). Exposure concentrations were verified by chemical analysis for TBBPA and DeBDE, but not for CP(10-13), as a reliable method was not available. Based on the generated data, a PNEC for soil organisms can be estimated at 0.3 mgkg(-1) for TBBPA and 57 mgkg(-1) for short-chain chloroparaffins. No PNEC could be estimated for DeBDE. Measurements of TBBPA in soil are not available, but measured concentrations in Swedish sludge are all lower than the estimated threshold value for biological effects in soil.

Acute and subacute dermal toxicity of Break-Free CLP®: a weapons cleaning and maintenance compound

Break-Free CLP((R)) is a commercial cleaning, lubricating and preserving compound used in both the military and civilian sectors for maintenance of small- and large-caliber weapons. Like many commercial mixtures, there is very little information available on the toxicity of Break-Free CLP. Studies were conducted to characterize the biological effects of single or repeat dermal application of Break-Free CLP to the clipped backs of CD-1 mice. Break-Free CLP was applied neat, 50 microl three times of week for up to 2 weeks. Foci of epithelial ulceration were observed in skin sections from 22% of Break-Free CLP-treated animals in conjunction with markedly thickened epithelium suggesting that robust epithelial regeneration was occurring in these animals. Skin histopathology of Break-Free CLP-treated animals closely matched the histopathology from mice treated repeatedly with 2% croton oil in acetone (dermal irritation positive control). Serum alkaline phosphatase activity was significantly (P < 0.05) lower for mice treated with Break-Free CLP, 2% croton oil or 7,12-dimethylbenz[a]anthracene (DMBA) compared with negative and vehicle control mice. Skin nitric oxide (NO) levels were not significantly elevated for mice treated with Break-Free CLP but were significantly elevated for mice treated with dermal irritation positive control compound DMBA. The cumulative skin changes in Break-Free CLP-treated animals support conducting a subchronic dermal application study. The observed decreases in serum alkaline phosphatase activity suggest that future studies should include the liver and bone as possible target organs. Additionally, dermal penetration studies could provide key health risk assessment information for characterizing the potential health risks associated with chronic dermal exposure to Break-Free CLP.

Dose–response feeding study of chlorinated paraffins in broiler chickens: effects on growth rate and tissue distribution

Even with the highest additions of 100mg kg(-1) short-chain (C10-C13) chlorinated paraffins (CP) to feed, the health of broilers was not adversely affected during a 31-day feeding experiment. In addition, 1 and 3 weeks after the experiment started, growth rate and feed consumption of the young animals were not impaired. No significant influence on mortality, organ weight relative to live weight or performance (weight gain, feed consumption) was noted. The CP concentrations in abdominal fat, meat, liver and kidneys were related linearly to the CP concentration of the feed. The highest contents were analysed in fat and the faeces, and the lowest concentrations were found in blood, meat and bile fluid. Less than 5% of the CP amount consumed was incorporated into the body, without taking the head, gut, feet and feathers into account.

Oils activity against Melampsora epitea on willow

Willow trees cv. Iwa growing in open field conditions in the sandy soil and naturally infected with Melampsora epitea were used. Effectiveness of paraffin oil (Atpolan 80 EC) and plant oils (Olejan 85 EC, rape and sunflower) in the control of pathogen was evaluated. When first uredinia were seen on the lower leaf surface, plants were sprayed 2-times at 7-day intervals with tested compounds at concentration from 0.25 to 2%. Also Surfactant Tergitol (TM) 15-S-9 at conc. 0.3% was added to plant oil suspension. After 2 sprayings a number of uredinia per leaf and number of browned and destroyed uredinia were counted. In the first trial Atpolan 80 EC suppressed uredinia formation about 2-4-times whereas rape or sunflower oil about 1.8 to 3-times. Additionally about 11 to 30% of uredinia were dried. In the next trials effectiveness of tested oils was higher than in previous experiment. After 2-weeks of willow trees protection with Atpolan 80 EC formation of uredinia was inhibited from 7 to 17-times, whereas Olejan 85 EC suppressed their production about 4 to 14-times. Additionally about 9-62% (Atpolan 80 EC) or 10-25% (Olejan 85 EC) of uredinia were browned and dried depend on used concentration. In the third experiment after 2-week-protection of plants with Atpolan 80 EC inhibition of uredinia formation varied from 6 to 10-times. In the case of Olejan 85 EC about 2 to 10-times less uredinia were observed on protected plants than on control, untreated leaf blades. About 48-72% (Atpolan 80 EC) or 17-61% (Olejan 85 EC) of uredinia were dried.

Oils activity in the control of rose powdery mildew

The efficacy and eventual phytotoxicity of oils from rape, sunflower seed (vegetable oil) and paraffin (Atpolan 80 EC) in the control of Sphaerotheca pannosa var. rosae were evaluated on roses grown in greenhouse or plastic tunnel. Oils were applied curativelly as plant spray 4-times at 7-day-intervals in concentrations from 0.25 to 4%. All used oils, gave as good effect as triforine (standard) or even better. On shrubs protected with oils at concentrations 0.25% and 0.5%, disease symptoms were noted only sporadically. Rose shrubs sprayed with higher concentration of oils were almost completely protected. Efficacy of tested oils increased with their concentrations. Paraffin oil was better in the control of S. pannosa var. rosae than vegetable oils. After 2 oil applications at conc. 2% or higher, first phytotoxicity symptoms on leaves were noted, particularly during warm and sunny days. Observations of treated leaves, 24 h after spraying under microscope, showed that all tested oils caused hyphae and spores degeneration or their visible deformation suggesting partial loss of turgidity. Depends on oil concentrations used, sporadically regular and unchanged shape hyphae and spores were visible.

Assessment of the acute pulmonary toxicity of lamp oil aspiration in the isolated perfused rat lung

Mainly among children incidental ingestion of conventional lamp oils (paraffin oil) is responsible for casual intoxications with severe pulmonary toxicity and fatal consequences. On the basis of the isolated blood-free perfused rat lung we developed a model to study the acute toxic effects of lamp oil. Three oils were studied: conventional paraffin lamp oil (kinematic viscosity 1.62 10(-6) m(2)/sec), the methyl ester Edenor ME C12 70 (2.7 10(-6) m(2)/s) and another ester Edenor LPL (4.5 10(-6) m(2)/s). The oils were instilled into the trachea of isolated rat lungs and the changes in lung mechanics (tidal volume, pulmonary compliance and pulmonary conductance) as well as edema formation (increase in lung weight) studied. Instillation of as little as 10 microl paraffin oil caused complete failure of lung functions within 20 min and even 2 microl caused noticeable edema. Similar results were obtained with Edenor ME C12 70, which appeared to be even more toxic than paraffin oil, while Edenor LPL was less toxic. We conclude that tracheal instillation of oils into isolated perfused rat lungs may be a useful model to study the toxicity of lamp oils in vitro. Our findings further suggest that Edenor LPL may be a safer alternative for use as a lamp oil than paraffin oil.

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and chlorinated paraffins (CPs) in rats-testing interactions and mechanisms for thyroid hormone effects

The effects of the polybrominated diphenyl ether (PBDE) congener 2,2'4, 4'-tetrabromodiphenylether (DE-47), and technical preparations of polychlorinated biphenyls (PCBs; Aroclor 1254) and chlorinated paraffins (CPs; Witaclor 171P) on thyroid hormone (TH) levels were examined in rats. To study possible interactive effects, also combinations of the three compounds were used. Thus, female Sprague-Dawley rats, 7 weeks old, were treated with approximately isomolar doses (ca. 30 micromol/kg bw per day) of DE-47 (6.0 mg/kg per day), Aroclor 1254 (4.0 mg/kg per day) and Witaclor 171P (6.8 mg/kg per day), alone or in combinations, daily for 14 days by gastric intubation. DE-47 was also administered in a higher (18 mg/kg per day) and lower (1.0 mg/kg per day) dose. In order to test possible mechanisms behind the TH effects, microsomal enzyme (cytochrome P-450 isozymes and uridine diphosphoglucuronyl transferase-UDPGT) activity (indicating both metabolic activation and/or biliary clearance), ex vivo-binding of 125I-T4 to plasma proteins (suggesting effects on peripheral TH transport) and light microscope morphology of the thyroid gland were studied. The observed degree of TH reduction after Aroclor 1254 and DE-47 exposure corresponded with a decrease in the ex vivo binding of 125I-T4 to the plasma TH-transporter transthyretin (TTR), and with induction of the microsomal phase I enzymes (ethoxy- and methoxy-resorufin dealkylases, EROD and MROD). The phase II enzyme UDPGT was also elevated, but only moderately. The thyroid morphology showed an activation of the epithelia, but no degenerative alternations, that was correlated to exposure to Aroclor 1254. In our model, the observed effects match the hypothesis that the T4 decrease is chiefly due to disturbances in serum transport, caused by binding of in vivo-formed Aroclor 1254 and DE-47 metabolites to TTR. However, decreased plasma TH levels due to increased glucuronidation activity may also be of some importance. The thyroid gland hyperactivity is probably a feed-back consequence of the T4 decrease, in spite of the lack of TSH alterations. In the mixed DE-47 and Witaclor 171P group synergistic effects were indicated on free T4 (FT4) and EROD induction levels, results that may suggest that such effects should be considered in risk assessment of mixtures of persistent organohalogens.

Cationic solid-lipid nanoparticles can efficiently bind and transfect plasmid DNA

The suitability of cationically modified solid-lipid nanoparticles (SLN) as a novel transfection agent was investigated. SLN were produced by hot homogenisation using either Compritol ATO 888 or paraffin as matrix lipid, a mixture of Tween 80 and Span 85 as tenside and either EQ1 (N,N-di-(beta-steaorylethyl)-N,N-dimethylammonium chloride) or cetylpyridinium chloride as charge carrier. The resulting particles were approximately 100 nm in size and showed zeta potentials around +40 mV at pH 7.4. DNA binding was tested by agarose gel electrophoresis. The resulting SLN-DNA complexes were further characterised by AFM and zeta potential measurements. Only the SLN batch SII-13, composed of 4% Compritol, 4% Tween/Span and 1% EQ1, was able to form stable complexes with DNA. Typical complexes were 300 to 800 nm in size. Cytotoxicity and transfection efficiency was tested in vitro on Cos-1 cells. Cationic SLN produced by modification with EQ1 were well tolerated, with LD50 values >3 mg/ml in the LDH release assay and >0.6 mg/ml in the WST-1 assay. Further, SLN-DNA complexes containing between 10 and 200 weight equivalents of SII-13 (matrix lipid) efficiently transfected the galactosidase expression plasmid pCMVbeta in the absence and presence of the endosomolytic agent chloroquine.

Examination of the behavior and liver and thyroid histology of juvenile rainbow trout (Oncorhynchus mykiss) exposed to high dietary concentrations of C(10)-, C(11)-, C(12)- and C(14)-polychlorinated n-alkanes

Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to high dietary concentrations of six polychlorinated n-alkane (PCAs) (C(10)H(15.5)C(6.5), C(10)H(15.3)Cl(6.7),C(11)H(18.4)Cl(5.6),C(12)H(19.5)Cl(6.5),C(14)H(24.9)Cl(5.1) and C(14)H(23.3)Cl(6.7)) for 21 to assess their effects on behavior and liver and thyroid histology and for 85 days to assess histology for a longer term exposure. This is the first histological work using PCAs of known carbon chain length and chlorine content and the first effort to examine the histopathology of fish exposed to PCAs. PCAs, also known as chlorinated paraffins, are complex industrial products for which there is a lack of toxicological data on individual congeners. With the exception of trout exposed to C(14)H(24.9)Cl(5.1), which had much lower exposure concentrations, many of the trout exposed to the PCAs (whole fish concentrations 0.22-5.5 microg g(-1)) showed a diminished or no startle response, loss of equilibrium, and developed a dark coloration. These responses are indicative of a narcotic toxicological mode-of-action. Histopathological lesions were observed in the livers of trout from each exposure group. However, the most severe histopathologies were observed in the livers of fish exposed to C(10)H(15.3)Cl(6.7) and C(11)H(18.4)Cl(5.6) (whole fish concentrations 0.92 and 5.5 microg g(-1), respectively), in which extensive fibrous lesions were present that were not observed in any other exposure group. Other alterations observed in all treatment groups included hepatocyte necrosis, sites of inflammation, and glycogen/lipid depletion. The relative sizes of hepatocytes of PCA exposed trout were smaller than control trout, although only a few of the observed differences were statistically significant. No lesions were present in the thyroid, although trout exposed to C(10)H(15.5)Cl(6.5) (whole fish concentration 0.84 microg g(-1)) had slightly more active thyroids, as indicated by an increased mean thyroid epithelium cell height relative to controls. It would appear that PCA toxicity is inversely related to carbon chain length, as has been observed in similar studies using mammals. The concentrations in the fish from this experiment were at levels that have been reported in invertebrates and fish from contaminated sites in the Great Lakes. However, the exposure concentrations were likely much greater in these experiments compared with the environment and require further study.

Evaluation of hepatoprotective activity of Cassia fistula leaf extract

Hepatoprotective activity of the n-heptane extract of Cassia fistula leaves was investigated in rats by inducing hepatotoxicity with carbon tetrachloride:liquid paraffin (1:1). The extract has been shown to possess significant protective effect by lowering the serum levels of transminases (SGOT and SGPT), bilirubin and alkaline phosphatase (ALP). The extract of C. fistula at a dose of 400 mg/kg showed significant hepatoprotective activity which was comparable to that of a standard hepatoprotective agent.

Alteration of Kupffer cell function and morphology by low melt point paraffin wax in female Fischer-344 but not Sprague-Dawley rats

This study was conducted to compare the effects of 60-day dietary exposure (2%) to low melt point paraffin wax (LMPW) on both general liver morphology and Kupffer cell (KC) function and morphology in female F-344 and Sprague-Dawley (SD) rats. Livers from only F-344 rats fed LMPW had granuloma formation/lymphoid cell aggregates with small areas of necrosis. Significant increases in serum alanine and aspartate aminotransferase as well as gamma-glutamyltransferase activities were detected only in treated F-344 rats. Additionally, detectable amounts of LMPW were present only in livers of treated F-344 rats. Because KC can be involved in granuloma formation, their morphology and function were examined. Electron microscopy revealed the presence of large, irregularly shaped, membrane-associated vacuoles in cells isolated from F-344 rats exposed to LMPW. These vacuoles were not seen in KC from control rats and rarely detected in KC isolated from LMPW-exposed SD rats. Moreover, indices of KC function including phagocytic activity and nitric oxide and superoxide anion production were significantly increased by KC isolated from F-344 rats exposed to LMPW (1.6-, 36-, and 2.2-fold increases, respectively) over untreated controls. In contrast, LPS-stimulated production of TNF and LTB4 was significantly decreased only in KC of LMPW-fed F-344 rats. No significant changes in these functions were observed in KC isolated from SD rats exposed to LMPW or from KC isolated from control F-344 or SD rats. These data provide evidence that dietary LMPW alters the morphology and functional capacity of KC of F-344 but not SD rats and these changes may ultimately lead to granuloma formation.

Partial liquid ventilation in a child on extracorporeal life support

A 14 month old child was referred for management of acute respiratory distress syndrome after aspiration of paraffin lamp oil. Initial management with conventional ventilation and subsequent management with high frequency oscillatory ventilation produced pulmonary air leaks, further compromising clinical management. After initiating extracorporeal life support and low pressure ventilation, pulmonary air leaks subsided. The patient was then successfully managed by a protocol including partial liquid ventilation with perfluorocarbon. This case report details the authors' experience with the first child with respiratory failure to be managed with partial liquid ventilation while on extracorporeal life support.

Variable responses of species and strains to white mineral oils and paraffin waxes

Recent dietary studies on mineral hydrocarbon (MHC) white oils and waxes have shown inflammatory effects in Fischer 344 (F-344) rats, but not in other rat strains or dogs. Histopathologic effects seen in F-344 rats include mesenteric lymph node histiocytosis, liver granulomas, and inflammation of the mitral valve (only seen with paraffin waxes). Human ingestion of MHC can result in noninflammatory lipogranulomas (oil droplets) in tissues which are regarded as clinically unimportant. It is speculated that inherent interspecies differences in pharmacokinetics and/or immune function may contribute to the differential response to MHC seen in F-344 rats. The F-344 rat retains greater amounts of MHC in target tissues compared to other rat strains and dogs and appears to be more sensitive immunologically to MHC than other species, including humans. This strain may be predisposed to these effects as indicated by a high background incidence of inflammatory granulomatous lesions in control female F-344 rats. Because of its apparently unique sensitivity, relevance of effects seen in F-344 rat to human health is questionable and requires further investigation.

Mechanistical studies of the inhibition of intercellular communication by organochlorine compounds

Many hydrocarbons are environmental pollutants that, due to their lipophilicity and chemical stability, accumulate in biological systems including milk and body fat. A number of investigations have demonstrated that many organochlorine compounds can act as tumour promoters in vivo and inhibit gap junctional intercellular communication between cells in culture. In the present study we have investigated the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), different polychlorinated biphenyls, chlorinated paraffins and the pesticide endosulfan. Using techniques of scrape loading dye/transfer and Western blot analysis the function, expression and phosphorylation of different connexins in vitro and in vivo were studied. The results show a good correlation between the ability to act as a tumour promoter and to interfere with gap junctional intercellular communication. All tested compounds inhibited the intercellular communication in a liver derived cell line (IAR 20). However, the results show that the time to inhibition varies between the different agents. Endosulfan and chlorinated paraffins inhibit the communication within one hour, whereas dioxin like substances need to expose the cells for 48 hours before the communication is affected.