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ACS ES&T Water Aug 2021We investigated patterns of volatile organic compound (VOC) contamination in drinking water systems affected by the California 2018 Camp Fire. We performed spatial...
We investigated patterns of volatile organic compound (VOC) contamination in drinking water systems affected by the California 2018 Camp Fire. We performed spatial analysis of over 5000 water samples collected over a 17 month period by a local water utility, sampled tap water for VOCs in approximately 10% ( = 136) of standing homes, and conducted additional nontargeted chemical analysis of 10 samples. Benzene contamination was present in 29% of service connections to destroyed structures and 2% of service connections to standing homes. A spatial pattern was apparent. Tap water in standing homes 11 months after the fire contained low concentrations of benzene in 1% of samples, but methylene chloride was present in 19% of samples, including several above regulatory limits. Elevated methylene chloride was associated with greater distance from the water meter to the tap, longer stagnation time, and the presence of a destroyed structure on the service connection; it was inversely associated with certain trihalomethanes. Nontargeted analysis identified multiple combustion byproducts in the water at 2/10 homes. Our findings support the hypothesis that pyrolysis and smoke intrusion from depressurization contributed to the benzene contamination. Further research is needed to test the hypothesis that methylene chloride may be generated from the dehalogenation of disinfection byproducts stagnating in galvanized iron pipes.
PubMed: 34423333
DOI: 10.1021/acsestwater.1c00129 -
Risk Analysis : An Official Publication... Jul 2019We review approaches for characterizing "peak" exposures in epidemiologic studies and methods for incorporating peak exposure metrics in dose-response assessments that... (Review)
Review
We review approaches for characterizing "peak" exposures in epidemiologic studies and methods for incorporating peak exposure metrics in dose-response assessments that contribute to risk assessment. The focus was on potential etiologic relations between environmental chemical exposures and cancer risks. We searched the epidemiologic literature on environmental chemicals classified as carcinogens in which cancer risks were described in relation to "peak" exposures. These articles were evaluated to identify some of the challenges associated with defining and describing cancer risks in relation to peak exposures. We found that definitions of peak exposure varied considerably across studies. Of nine chemical agents included in our review of peak exposure, six had epidemiologic data used by the U.S. Environmental Protection Agency (US EPA) in dose-response assessments to derive inhalation unit risk values. These were benzene, formaldehyde, styrene, trichloroethylene, acrylonitrile, and ethylene oxide. All derived unit risks relied on cumulative exposure for dose-response estimation and none, to our knowledge, considered peak exposure metrics. This is not surprising, given the historical linear no-threshold default model (generally based on cumulative exposure) used in regulatory risk assessments. With newly proposed US EPA rule language, fuller consideration of alternative exposure and dose-response metrics will be supported. "Peak" exposure has not been consistently defined and rarely has been evaluated in epidemiologic studies of cancer risks. We recommend developing uniform definitions of "peak" exposure to facilitate fuller evaluation of dose response for environmental chemicals and cancer risks, especially where mechanistic understanding indicates that the dose response is unlikely linear and that short-term high-intensity exposures increase risk.
Topics: Acrylonitrile; Air Pollutants; Benzene; Environmental Exposure; Epidemiologic Studies; Ethylene Oxide; Formaldehyde; Humans; Leukemia; Lymphoma; Methylene Chloride; Neoplasms; Risk Assessment; Styrene; Trichloroethylene; United States; United States Environmental Protection Agency
PubMed: 30925210
DOI: 10.1111/risa.13294 -
Environmental Health Perspectives Feb 2015The U.S. EPA's Integrated Risk Information System (IRIS) completed an updated toxicological review of dichloromethane in November 2011. (Review)
Review
BACKGROUND
The U.S. EPA's Integrated Risk Information System (IRIS) completed an updated toxicological review of dichloromethane in November 2011.
OBJECTIVES
In this commentary we summarize key results and issues of this review, including exposure sources, identification of potential health effects, and updated physiologically based pharmacokinetic (PBPK) modeling.
METHODS
We performed a comprehensive review of primary research studies and evaluation of PBPK models.
DISCUSSION
Hepatotoxicity was observed in oral and inhalation exposure studies in several studies in animals; neurological effects were also identified as a potential area of concern. Dichloromethane was classified as likely to be carcinogenic in humans based primarily on evidence of carcinogenicity at two sites (liver and lung) in male and female B6C3F1 mice (inhalation exposure) and at one site (liver) in male B6C3F1 mice (drinking-water exposure). Recent epidemiologic studies of dichloromethane (seven studies of hematopoietic cancers published since 2000) provide additional data raising concerns about associations with non-Hodgkin lymphoma and multiple myeloma. Although there are gaps in the database for dichloromethane genotoxicity (i.e., DNA adduct formation and gene mutations in target tissues in vivo), the positive DNA damage assays correlated with tissue and/or species availability of functional glutathione S-transferase (GST) metabolic activity, the key activation pathway for dichloromethane-induced cancer. Innovations in the IRIS assessment include estimation of cancer risk specifically for a presumed sensitive genotype (GST-theta-1+/+), and PBPK modeling accounting for human physiological distributions based on the expected distribution for all individuals 6 months to 80 years of age.
CONCLUSION
The 2011 IRIS assessment of dichloromethane provides insights into the toxicity of a commonly used solvent.
Topics: Carcinogens, Environmental; Environmental Pollutants; Humans; Lung Neoplasms; Methylene Chloride; Models, Theoretical; Mutagenicity Tests; Neoplasms; Risk Assessment; United States; United States Environmental Protection Agency
PubMed: 25325283
DOI: 10.1289/ehp.1308030 -
Polymers Mar 2021Conformal coating is typically composed of polymeric film and is used to protect delicate electronic components such as printed-circuit boards. Without removing...
Conformal coating is typically composed of polymeric film and is used to protect delicate electronic components such as printed-circuit boards. Without removing conformal coating, it would be difficult to repair these complicated electronics. Methylene chloride, also called dichloromethane (DCM), has a widespread usage in conformal coating stripper products. The high toxicity of DCM increases human health risk when workers are exposed to DCM during the conformal coating removal processes. Therefore, the replacement of DCM would be beneficial to greatly improve the overall safety profile for workers in the electronics and coating industries. This research identified and evaluated alternative chemicals for replacing DCM used in acrylic conformal coating stripping operations. The solubility of an acrylic conformal coating was measured and characterized using Hansen solubility parameters (HSP) theory. Coating dwell time tests using various solvent blends verified the accuracy of the created HSP solubility sphere. A data processing method was also developed to identify and screen potential alternative solvent blends in terms of safety, toxicity, and cost-effectiveness. The identified safer solvent blends were demonstrated to provide equivalent stripping performance as compared to DCM based coating strippers within an acceptable cost range. The results of this research will be of value to other types of conformal coatings, such as silicone and polyurethane, where DCM is commonly used in similar coating stripping operations. By safely removing conformal coating, delicate electronics would be available for re-manufacturing, enabling a circular economy.
PubMed: 33803712
DOI: 10.3390/polym13060937 -
Annals of Dermatology May 2011Bacteria associated with marine invertebrates are a rich source of bioactive metabolites.
BACKGROUND
Bacteria associated with marine invertebrates are a rich source of bioactive metabolites.
OBJECTIVE
The effects of marine bacteria extracts on pigmentation were investigated to find novel whitening agents.
METHODS
The marine bacteria collected near Gangwha Island in Korea were isolated and extracted using organic solvent. The organic extracts were screened and selected using the cell free tyrosinase activity. The whitening effects of the selected extract were further investigated using cultured melanocytes, cultured skin and in vivo zebrafish. The whitening mechanism of the marine extract was also investigated.
RESULTS
The marine bacterial methylene chloride extract reduced the pigmentation of Melan-a cells, human melanocytes, cultured skin and in vivo zebrafish. The decrease in pigmentation was due to the inhibition of tyrosinase activity and the expression of tyrosinase and microphthalmia-associated transcription factor protein. These bacteria were identified as a novel Pseudomonas species.
CONCLUSION
The methylene chloride extract of marine pseudomonas species possesses a whitening effect. Further chemical isolation and characterization of the active compounds from this marine bacterial extract are needed.
PubMed: 21747611
DOI: 10.5021/ad.2011.23.2.144 -
Environmental Health Perspectives Aug 1996During a 2-year chronic inhalation study on methylene chloride (2000 or 0 ppm; 6 hr/day, 5 days/week), gas-uptake pharmacokinetic studies and tissue partition... (Comparative Study)
Comparative Study
During a 2-year chronic inhalation study on methylene chloride (2000 or 0 ppm; 6 hr/day, 5 days/week), gas-uptake pharmacokinetic studies and tissue partition coefficient determinations were conducted on female B6C3F1, mice after 1 day, 1 month, 1 year, and 2 years of exposure. Using physiologically based pharmacokinetic (PBPK) modeling coupled with Monte Carlo simulation and bootstrap resampling for data analyses, a significant induction in the mixed function oxidase (MFO) rate constant (Vmaxc) was observed at the 1-day and 1-month exposure points when compared to concurrent control mice while decreases in glutathione S-transferase (GST) rate constant (Kfc) were observed in the 1-day and 1-month exposed mice. Within exposure groups, the apparent Vmaxc maintained significant increases in the 1-month and 2-year control groups. Although the same initial increase exists in the exposed group, the 2-year Vmaxc is significantly smaller than the 1-month group (p < 0.001). Within group differences in median Kfc values show a significant decrease in both 1-month and 2-year groups among control and exposed mice (p < 0.001). Although no changes in methylene chloride solubility as a result of prior exposure were observed in blood, muscle, liver, or lung, a marginal decrease in the fat:air partition coefficient was found in the exposed mice at p = 0.053. Age related solubility differences were found in muscle:air, liver:air, lung:air, and fat:air partition coefficients at p < 0.001, while the solubility of methylene chloride in blood was not affected by age (p = 0.461). As a result of this study, we conclude that age and prior exposure to methylene chloride can produce notable changes in disposition and metabolism and may represent important factors in the interpretation for toxicologic data and its application to risk assessment.
Topics: Administration, Inhalation; Age Factors; Animals; Female; Methylene Chloride; Mice; Models, Biological; Monte Carlo Method; Time Factors
PubMed: 8875160
DOI: 10.1289/ehp.96104858 -
International Journal of Molecular... Jul 2020Microglial hyperactivation and neuroinflammation are known to induce neuronal death, which is one of the main causes of neurodegenerative disorders. We previously found...
Microglial hyperactivation and neuroinflammation are known to induce neuronal death, which is one of the main causes of neurodegenerative disorders. We previously found that Aquilariae Lignum extract attenuated both neuronal excitotoxicity and neuroinflammation in vivo and in vitro. For further analysis, we extracted the methylene chloride fraction of Aquilariae Lignum to determine the bioactive compounds. In this study, we investigated the anti-neuroinflammatory effects and underlying mechanisms of the Aquilariae Lignum fraction (ALF) using lipopolysaccharide (LPS)-stimulated BV2 microglial cells. BV2 cells were pretreated with ALF (0.5, 1, and 2.5 μg/mL) before treatment with LPS (1 μg/mL). Pretreatment with ALF significantly attenuated the LPS-induced overproductions of nitric oxide (NO), cyclooxygenase-2 (COX-2), prostaglandin E (PGE), and interleukin (IL)-1β. These anti-inflammatory effects were supported by ALF-mediated modulation of the nuclear factor-kappa B (NF-κB) pathway. Furthermore, ALF exerted strong anti-inflammasome effects, as shown by IL-1β-specific inhibitory activity, but not activity against tumor necrosis factor (TNF)-α, along with inhibition of caspase-1 activity and NACHT, LRR, and PYD domain-containing protein 3 (NLRP3)-related molecules. These results indicate the potent anti-neuroinflammatory activity of ALF and that its underlying mechanism may involve the regulation of NLRP3 inflammasome-derived neuroinflammation in microglial cells.
Topics: Animals; Anti-Inflammatory Agents; Cyclooxygenase 2; Dinoprostone; Gene Expression Regulation; Heme Oxygenase-1; Humans; Inflammation; Interleukin-1beta; Lipopolysaccharides; Methylene Chloride; Microglia; NF-kappa B; Nitric Oxide; Signal Transduction; Thymelaeaceae; Tumor Necrosis Factor-alpha
PubMed: 32751738
DOI: 10.3390/ijms21155465 -
Acta Pharmacologica Sinica Mar 2002The potential toxicants in food are derived from natural or industrial sources. Compounds like lectins and glycoalkaloids that are toxic to man are naturally present in... (Review)
Review
The potential toxicants in food are derived from natural or industrial sources. Compounds like lectins and glycoalkaloids that are toxic to man are naturally present in some vegetables like potatoes or legumes. A wide variety of marine toxins mostly produced by dinoflagellates occurring secondarily in molluscs and mussels are usually ingested by human beings causing poisoning. On the other hand, toxic compounds find their way into food during manufacture, storage, or transportation. These include largely the industrial contaminants, persistent organic pollutants (POP), pesticides, heavy metals, and toxins of fungal and bacterial origin. Further, toxic compounds like higher alcohols may be produced as byproducts during processing. Migration of compounds from packaging materials into packaged food like contamination with lead from solder in certain metal cans is well known. Additives (emulsifiers, preservatives, and antioxidants) could also influence the quality of foods. Solvent residues may find their way into food as a result of their use in extraction processes like the use of trichloroethylene and methylene chloride in decaffeination of coffee. In addition, poor hygiene, storage, and preparation may also lead to food contamination by various microbes and ova or cysts of nematodes. The problem of food contamination can be overcome to a great extent by regular surveillance and monitoring programmes and strict implementation of food and adulteration act. In the present review some of these aspects of food contamination have been discussed in detail.
Topics: Animals; Food Additives; Food Contamination; Food Microbiology; Humans; Insecticides; Metals, Heavy; Mycotoxins; Organophosphorus Compounds; Polychlorinated Biphenyls; Polycyclic Aromatic Hydrocarbons
PubMed: 11918841
DOI: No ID Found -
Journal of Pharmacological Sciences 2010Glehnia littoralis (Umbelliferae) has been used traditionally in Korean, Japanese, and Chinese medicine for the treatment of immune-related diseases; however, its... (Comparative Study)
Comparative Study
Glehnia littoralis (Umbelliferae) has been used traditionally in Korean, Japanese, and Chinese medicine for the treatment of immune-related diseases; however, its anti-inflammatory activity and underlying mechanism remain to be defined. We investigated the anti-inflammatory effect and inhibitory mechanism on inflammation by the methylene chloride fraction from Glehnia littoralis extract (MCF-GLE), which was more effective than Glehnia littoralis extract (GLE). MCF-GLE inhibited 12-O-Tetradecanoyl-phorbol-13-acetate (TPA)-induced inflammation in an inflammatory edema mouse model. Also, MCF-GLE strongly inhibited the releases of nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) and significantly suppressed the mRNA and protein expression of inducible nitric oxide synthase and cyclooxygenase-2 in lipopolysaccharide-stimulated RAW 264.7 macrophage cells in a dose-dependent manner. Furthermore, MCF-GLE suppressed NF-kappaB activation and IkappaB-alpha degradation. MCF-GLE also attenuated the activation of ERK and JNK in a dose-dependent manner. These results indicate that MCF-GLE has an inhibitory effect on the in vivo and in vitro inflammatory reaction and is a possible therapeutic agent. Our results suggest that the anti-inflammatory properties of MCF-GLE may result from the inhibition of pro-inflammatory mediators, such as NO, PGE(2), TNF-alpha, and IL-1beta via suppression of NF-kappaB- and mitogen-activated protein kinases-dependent pathways.
Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Apiaceae; Cell Line; Cell Survival; Edema; Male; Methylene Chloride; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinases; NF-kappa B; Plant Extracts; Plant Roots; Protein Kinase Inhibitors
PubMed: 20093788
DOI: 10.1254/jphs.09168fp -
European Journal of Epidemiology Mar 2020Studies of occupational solvent exposures and amyotrophic lateral sclerosis (ALS) have been conflicting. We conducted a population-based case-control study of mixed...
Studies of occupational solvent exposures and amyotrophic lateral sclerosis (ALS) have been conflicting. We conducted a population-based case-control study of mixed occupational solvent exposures and ALS. Using the Danish National Patient Registry, we identified ALS cases in Denmark from 1982 to 2013, and matched them to 100 controls based on sex and birth year. We estimated cumulative exposures to solvents (benzene, methylene chloride, toluene, trichloroethylene, perchloroethylene, and 1,1,1-trichloroethane) via job exposure matrices and applied them to occupational history from the Danish Pension Fund. Sex-stratified conditional logistic regression analyses revealed higher adjusted odds of ALS for men with exposure to benzene (aOR = 1.20; 95% CI 1.02, 1.41) and methylene chloride (aOR = 1.23; 95% CI 1.07, 1.42). We used weighted quantile sum regression to explore combined solvent exposures and risk of ALS in exposed subjects and found increased odds of 26 to 28% in all exposure lag periods for every one-unit increase in the mixture index in men. Weights of methylene chloride predominated the mixture index in all lag periods. Our study suggests an increased risk of ALS in men exposed to multiple solvents, with the greatest influence being from methylene chloride. These findings highlight the need to utilize mixtures analysis when considering co-occurring exposures.
Topics: Adult; Aged; Amyotrophic Lateral Sclerosis; Case-Control Studies; Denmark; Female; Humans; Male; Methylene Chloride; Middle Aged; Occupational Diseases; Occupational Exposure; Population Surveillance; Risk Factors; Solvents
PubMed: 32193761
DOI: 10.1007/s10654-020-00624-5