Assessment of chemical asphyxia caused by toxic gases generated from rigid polyurethane foam (RPUF) fires.

Rigid polyurethane foam (RPUF) is widely used for thermal and sound insulation owing to their low thermal conductivity and light weight. However, they have serious disadvantages, including flammability and toxic gas generation, which can cause chemical asphyxia during a fire. Carbon monoxide (CO) and hydrogen cyanide (HCN) are representative toxic gases formed by incomplete combustion and HCN, in particular, is closely related to polyurethane product fires. In this study, the risk of inhalation of toxic gases such as CO, HCN and NO2 during RPUF fires was demonstrated convincingly through the analysis of carboxyhemoglobin (COHb), cyanide (CN-) and methemoglobin (MetHb) in the postmortem blood samples of 38 victims of RPUF fires. To better understand the toxic gas poisoning and chemical asphyxia, we classified all cases into two groups based on the extent of injuries and location where the victim was found. Mean concentrations of COHb and cyanide in group 1 without injuries were approximately two times higher than in group 2 with severe injuries, while concentrations of free MetHb showing possibility of NO2 inhalation were approximately six times lower than in group 2. Furthermore, we presumed concentrations of cyanide at the time of death and five cases showed the possibility of cyanide poisoning.

Treatability of hexabromocyclododecane using Pd/Fe nanoparticles in the soil-plant system: Effects of humic acids.

Hexabromocyclododecane (HBCD) is a persistent organic pollutant that accumulates in soil and sediments, however, it has been difficult to degrade HBCD with developed remediation technologies so far. In this study, degradation of HBCD by bimetallic iron-based nanoparticles (NPs) under both aqueous and soil conditions considering the effects of humic acids (HAs) and tobacco plant was investigated. In the aqueous solution, 99% of the total HBCD (15 mM) was transformed by Pd/nFe (1 g L-1) within 9 h of treatment and the HBCD debromination by Pd/nFe increased with the addition of HAs. In the soil system, 13%, 15%, 41% and 27% of the total HBCD were removed by treatments consisting of plant only, plant with HAs, plant with NPs and plant + NPs + HAs, respectively, compared to the HBCD removal in an unplanted soil. The 221-986 ng/g of HBCD were detected inside the plant after the treatments, and HAs showed considerable influence on the selective bioaccumulation of HBCD stereoisomers in the plant. Overall, this approach represents a meaningful attempt to develop an efficient and eco-friendly technology for HBCD removal, and it provides advantages for the sustainable remediation of recalcitrant emerging contaminants in soils.

Photosensitized diastereoisomer-specific degradation of hexabromocyclododecane (HBCD) in the presence of humic acid in aquatic systems.

Humic acids (HA) are the most important photosensitizers in the ocean and generate highly reactive oxygen species (ROS), known as photochemically produce reactive intermediates (PPRI), which degrade organic pollutants. Thus, to reveal the fate of organic pollutants in an aqueous environment, it is important to understand the natural photodegradation phenomenon caused by HA. Three ROS generated from HA, 1O2, O2-, and OH, were measured using different probe compounds and instrumental techniques. In this study, HBCD (hexabromocyclododecane), a newly listed one of persistent organic pollutants (POPs) under the Stockholm Convention, was studied to understand the phototransformation mechanism, which has not been sufficiently investigated in terms of its environmental fate and transport, despite the distinctive features of its diastereoisomers. The results showed that the diastereoisomer-specific distributions of α-, ß-, and γ-HBCD were related to the acceleration and retardation of photodegradation in the presence of AHA (Aldrich Humic Acid) under simulated solar light, and only α-HBCD was rapidly photodegraded as the amount of AHA increased relative to the absence of AHA. This study provides the first characterization of the behavior of photosensitized HBCD degradation in aquatic systems.

Matrix-specific distribution and compositional profiles of perfluoroalkyl substances (PFASs) in multimedia environments.

This study investigated perfluoroalkyl substances (PFASs) in multimedia environments to confirm the effects of emission sources of PFASs and to elucidate their spatial distribution. The highest PFAS levels were detected from the samples of air (272.30 pg/m3) and surface water (36.54 ng/L) in an industrial complex area, meanwhile high PFAS levels were found from the samples of soil (8.80 ng/g) and sediment (84.98 ng/g) in urban areas and near wastewater treatment plants (WWTPs). Perfluorobutane sulfonate (PFBS) was primarily detected in water, influent and effluent, whereas long chain perfluorocarboxylic acids (PFCAs) and perfluorooctane sulfonate (PFOS) were dominant in dust, soil, sediment and sludge. While PFBS and neutral PFASs were dominant in air, PFCAs were primarily detected in plant and fish. The specific distribution patterns of PFASs in each matrix showed the influences of surrounding environments and different physicochemical characteristics of each congener. These findings suggest that the industrial complex and WWTP might be major emission sources to air and aquatic environments, respectively. This is the first study in which 6 neutral and 13 ionic PFASs were investigated simultaneously for nine different matrices in multimedia environments, and also it would be a good model study for future assessment of PFASs.

Influence of exposure to perfluoroalkyl substances (PFASs) on the Korean general population: 10-year trend and health effects.

This study demonstrated the 10-year trend of 13 perfluoroalkyl substances (PFASs) serum levels among 786 adults living in Seoul, Korea. PFAS levels gradually increased from 2006 to 2013, decreasing thereafter. We found that PFAS levels were higher in male than in female participants and were positively correlated with age. PFASs were not significantly correlated with body mass index, although we observed positive correlations with total cholesterol, low-density lipoprotein cholesterol, and triglycerides and negative correlations with high-density lipoprotein cholesterol. Uric acid and free thyroxine (fT4) also showed positive correlations with major congeners while correlations between thyroid stimulating hormone and PFASs were inconsistent. We demonstrated significant correlations between fT4 and perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS), and perfluorodecanoic acid (PFDA). There were significant differences in PFHxS and perfluorododecanoic acid (PFDoDA) levels between participants with and without diabetes. Furthermore, principal component analysis suggested possible differences in disease manifestation based on the congener distribution of PFASs. This study is the first study of temporal trends of 13 PFAS congeners in serum samples obtained from the Korean general population; it is currently longest and largest scale study of this type.

Matrix-specific distribution and diastereomeric profiles of hexabromocyclododecane (HBCD) in a multimedia environment: Air, soil, sludge, sediment, and fish.

Hexabromocyclododecane (HBCD) contamination and its diastereomeric profile were investigated in a multi-media environment along a river at the local scale in air, soil, sludge, sediment, and fish samples. The spatial distribution of HBCD in each matrix showed a different result. The highest concentrations of HBCD in air and soil were detected near a general industrial complex; in the sediment and sludge samples, they were detected in the down-stream region (i.e., urban area). Each matrix showed the specific distribution patterns of HBCD diastereomers, suggesting continuous inputs of contaminants, different physicochemical properties, or isomerizations. The particle phases in air, sludge, and fish matrices were dominated by α-HBCD, owing to HBCD's various isomerization processes and different degradation rate in the environment, and metabolic capabilities of the fish; in contrast, the sediment and soil matrices were dominated by γ-HBCD because of the major composition of the technical mixtures and the strong adsorption onto solid particles. Based on these results, the prevalent and matrix-specific distribution of HBCD diastereomers suggested that more careful consideration should be given to the characteristics of the matrices and their effects on the potential influence of HBCD at the diastereomeric level.

Transformation of hexabromocyclododecane in contaminated soil in association with microbial diversity.

This study evaluated the transformation of 1,2,5,6,9,10-hexabromocyclododecane (HBCD) in soil under various conditions. Under anaerobic conditions for 21days, 34% of the total HBCD was reduced from rhizosphere soil containing humic acid, and 35% of the total HBCD was reduced from the non-rhizosphere soil; under aerobic conditions, 29% and 57-60% of the total HBCD were reduced from the same soil types after 40days. Three HBCD isomers (α-, ß-, and γ-HBCD) were separately analyzed for their isomeric effects on transformation. In the soils with added glucose as a carbon and energy source, the fraction of γ-HBCD was reduced due to the blooming microbial activity. The population of Gram-positive bacteria decreased during the aerobic treatments of HBCD, whereas the population of several Gram-negative bacteria (e.g., Brassia rhizosphere, Sphingomonas sp.) increased. Humic acid and glucose increased the HBCD removal efficiency and microbial diversity in both rhizosphere and non-rhizosphere soils.

Hexabromocyclododecane (HBCD) in the Korean food basket and estimation of dietary exposure.

1,2,5,6,9,10-hexabromocyclododecane (HBCD) is a brominated flame retardant that is used worldwide in expanded and extruded polystyrene foam and simultaneously emitted to the environment. HBCD can easily accumulate in animals and humans and cause neurotoxicity, thyroid hormone disruption, and reproductive disorders. Therefore, it is essential to monitor the HBCD concentrations in foods and estimate the human exposure through the diet. In this study a total of 521 food samples from eight food categories were sampled and analyzed for their HBCD content. Based on consumption data, the average dietary intake of the general Korean population and specific subgroups was calculated. The highest levels of HBCD were found in fish and shellfish (0.47 ng g(-1) ww), and this was attributed to natural exposure to the contaminated marine environments and the HBCD bioaccumulation. In addition, the use of expanded polystyrene buoys in aquaculture was also found to be a potential source of HBCD in bivalves. The high solubility of α-HBCD in water and the persistence of this diastereomer compared to ß- and γ-HBCD in biological tissues, led to higher accumulation of α-HBCD in animal-based foods. In contrast, the diastereomeric selectivity and lower metabolic capacity in plants compared with animals led to the predominance of γ-HBCD in plant-based foods. The dietary intake of HBCD was estimated to be 0.82 ng kg(-1) bw d(-1) in the general population and 2.89 ng kg(-1) bw d(-1) in children up to 5 years of age. The high HBCD intake in children was found to be a result of their lower body weight and their high consumption of milk and homemade Korean baby foods that usually contain fish.

Occurrence of Dechlorane compounds and polybrominated diphenyl ethers (PBDEs) in the Korean general population.

Dechlorane compounds, including Dechlorane Plus (DP), mirex, and Dechlorane (Dec) 602, 603 and 604, were measured in 61 serum samples collected from a Korean urban area (Seoul) in 2013. Dechlorane Plus and Dec 602 were dominant in most samples, whereas Dec 604 was not detected in any samples. The median value of DP was 0.75 ng/g lipid, which was comparable with the levels observed in Europe and Canada, but lower than that observed in China. Statistically significant correlations among Dechlorane compounds were observed. The median anti-isomer fractional abundance (fanti) was 0.74, and a negative correlation between fanti and the DP concentration in serum samples was observed. Polybrominated diphenyl ethers (PBDEs) were also measured for comparison with Dechlorane compounds, and BDE-153 was found the most abundant congener with a median value of 1.43 ng/g lipid. A time trend of Dechlorane compounds was investigated in 7 pooled serum samples to cover the period from 2006 to 2013. A distinct trend of Dechlorane compounds was not observed, while PBDEs steadily decreased with time.

Occurrence of Legacy and New Persistent Organic Pollutants in Avian Tissues from King George Island, Antarctica.

Legacy and new persistent organic pollutants (POPs), including polychlorinated naphthalenes (PCNs), Dechlorane Plus (DPs) and related compounds (Dechloranes), hexabromocyclododecanes (HBCDs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs), were analyzed in avian tissue samples from King George Island, Antarctica. The avian species consisted of the Gentoo penguin (Pygoscelis papua), the Adelie penguin (Pygoscelis adeliae), the South polar skua (Stercorarius maccormicki), and the Brown skua (Stercorarius antarcticus). HBCDs were detected in all samples and ranged from 1.67-713 pg/g-lipid. In the penguin samples, the concentrations of PCNs ranged from 0.69-2.07 ng/g-lipid, whereas those in the skua samples ranged from 7.41-175 ng/g-lipid. The levels of Dechloranes ranged from 0.60-1.30 ng/g-lipid in the penguin samples and from 6.57-47.4 ng/g-lipid in the skua samples. The concentrations and congener distributions of OCPs and PCBs were similar to the results of previous reports. The three new POPs were detected in all samples, and this study was one of the first reports on the occurrence of these pollutants in the Antarctic biota. Because Antarctica is one of the most pristine places on Earth, the detection of new POPs in the Antarctic birds, especially penguins, is direct evidence of the long-range transport of pollutants. Furthermore, the concentration ratios of the penguin to the skua samples (BMFs-p) were greater than 1 in most legacy and new POPs, and the BMFs-p values of the new POPs were comparable to those of some OCPs, suggesting a possibility of biomagnification. Despite the small sample size, the results of this study identified POP contamination of the Antarctic avian species and long-range transport and biomagnification of HBCDs, Dechloranes, and PCNs.

Diastereoisomer- and species-specific distribution of hexabromocyclododecane (HBCD) in fish and marine invertebrates.

The levels and distributional characteristics of hexabromocyclododecane (HBCD) diastereoisomers have been largely reported for various fish and select shellfish. In this study, we reclassified a number and variety of marine invertebrates, including shellfish, to further contribute to the comprehensive understanding of the effects and assessment of human exposure to HBCD. Overall, 30 marine invertebrate species (n=188) were investigated and the following order of ∑2HBCD (α- and γ-HBCD) was observed: fish>chordata>cephalopoda>echinodermata>bivalve>crustacea. The marine invertebrates that were reclassified into nektonic and benthic organisms showed similar concentration of ∑2HBCD. The feeding habits and modes of the marine organisms were considered to compare the degree of bioaccumulation and diastereoisomer-specific distribution of HBCD due to the effects of the environment in and around pollution sources, as well as the organisms' metabolic capacities. To the best of our knowledge, this is the first study to examine the species-specific distribution patterns of HBCD for both fish and marine invertebrates. We expect to significantly expand the understanding of the environmental fate of HBCD for marine organisms.

Partitioning behavior of heavy metals and persistent organic pollutants among feto-maternal bloods and tissues.

Heavy metals and persistent organic pollutants (POPs), including Pb, Cd, T-Hg, MeHg, PCDD/Fs, PCBs, PBDEs, PCNs, and PBDD/Fs, were analyzed in 20 paired samples of cord blood, maternal blood, maternal urine, and placenta. The samples were collected from pregnant mothers and neonates from South Korea in 2010. The distribution of heavy metals among the samples varied with their physicochemical characteristics. The concentrations of Pb and Hg in the maternal and the cord blood samples were significantly correlated each other, implying efficient transplacental transport (TPT). Cd and Hg were accumulated in the placenta, forming protein conjugates, and T-Hg was higher in the cord blood samples than the maternal blood samples due to the binding affinity of Hg with fetal proteins. POPs generally showed the highest concentrations in the maternal serum samples, and the POPs levels in the cord serum and the placenta samples were dependent on the degree of halogenation. The TPT of POPs was seemingly related to lipoprotein transportation. Some PBDE congeners, however, showed their highest concentrations in the cord serum samples, suggesting an additional TPT mechanism. This is the first study to detect PCNs and PBDD/Fs in the cord serum samples, showing that the PCN levels were comparable to other POPs. According to the principal component analysis (PCA) results of the contaminant levels, POPs and heavy metals showed significantly different characteristics, whereas PBDEs had an intermediate attribute. Despite the limited number of participants, the comprehensive analysis of trace contaminants in the paired sample sets enabled us to infer the distribution and TPT mechanism of various contaminants.

Assessment of Dechlorane compounds in foodstuffs obtained from retail markets and estimates of dietary intake in Korean population.

A total of 175 samples, composed of 35 different foodstuffs, were obtained from retail markets in Korea and analyzed to investigate the contamination status and dietary intake of Dechlorane compounds. The concentrations of Dechlorane Plus (DP), mirex, Dechlorane (Dec) 602 and 603 ranged from ND to 169.85 pg/g wet weight (ww), 107.30 pg/g ww, 20.81 pg/g ww, 0.41 pg/g ww, respectively, while Dechlorane (Dec) 604 was not detected in any samples. Strong correlations between anti- and syn-DP and between mirex and Dec 602 were observed. The average anti-isomer fractional abundance (fanti) was 0.78±0.11 which was larger than the technical DP value (fanti=0.75). The estimated dietary daily intake of DP, 11.2×10(3) pg/day, was one to three orders of magnitude higher than other Dechloranes. Grain was the most contributed food group to dietary daily intake of DP for Korean population.

Assessment of the daily intake of 62 polychlorinated biphenyls from dietary exposure in South Korea.

The dietary intake of polychlorinated biphenyls (PCBs) was estimated using the sum of 62 PCB congeners (∑(62)PCBs), including seven indicator PCBs and 12 dioxin-like PCBs, in the South Korea. In this study, 200 individual food samples belonging to 40 different foodstuffs were investigated to estimate the distribution of PCB congeners in five sampling cities. PCB exposure was estimated using Korean dietary habits as established by the National Health and Nutrition Examination Survey (NHANES). The PCB concentrations in rice, the most frequently consumed food in Korea, was relatively low in whole food samples. The mean PCB levels measured in fish were the highest in this study, but each fish is consumed in relatively small amounts by the general population. Therefore, the daily dietary intake should also be considered with regard to human exposure to PCBs, especially with the consumption of contaminated foods. Dioxin-like PCB levels were also calculated using TEF values that were established in 2005. The average levels (pg TEQ/g) were 0.0002 for rice and 0.0098 for fish. The dioxin-like PCBs accounted for a relatively small percentage of the total PCBs, compared to previous studies. According to our research, the health risks associated with exposure to PCBs could be estimated using the tolerable daily intake (TDI) of the general population.