Identification of atmospheric ozone generated from seismic activity during the occurrence of multiple earthquakes across Japan in 2022.

Ground-level atmospheric ozone (tropospheric ozone) is a well-known indicator of photochemical air pollution. Atmospheric ozone may also be an indicator of earthquake generation. Ground-level observations of atmospheric ozone at multiple sites were conducted in this study at the time of multiple earthquake occurrences in Japan in 2022. As the result of this study, ozone peaks of unknown origin were detected during the occurrence of multiple earthquakes across Japan in 2022. The level of these ozone peaks began to increase from a few days to a few hours before each earthquake, reaching a maximum concentration coincident with the time of earthquake generation. 'Unknown ozone' were detected at near earthquake epicentres, except in the case of deep earthquakes. The 'unknown ozone' were also associated with earthquake seismic intensities, which were monitored at seismograph stations in various Japanese cities, towns, and villages. A laboratory experiment by Baragiola et al. (2011) indicated that ppm levels of ozone can be generated in air by the crushing and grinding of terrestrial crustal rocks, generated by exo-electrons emitted by high electric fields, resulting from charge separation during rock fracture. Baragiola et al. (2011) proposed a hypothesis whereby atmospheric ozone could be generated via rock fracturing during the occurrence of earthquakes. This hypothesis could explain the ozone peaks correlating with multiple Japanese earthquakes observed in this study. The significance of atmospheric ozone generated by seismic activity is discussed in terms of it being a possible indicator of earthquake generation and prediction.

Prevalence and associated metabolic factors of nonalcoholic fatty liver disease in the general population from 2014 to 2018 in Japan: A large-scale multicenter retrospective study.

AIM: The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. The aim of this study was to determine the recent prevalence and clinical characteristics of NAFLD in Japan. METHODS: This study initially included 410 061 retrospectively enrolled adults from the medical health checkup registry for metabolic syndrome, chronic kidney disease, and fatty liver in Japan (MIRACLE-J; UMIN-CTR no. UMIN000049419), who were evaluated between 2014 and 2018 at 13 health centers in Japan. Individuals consuming >20 g of alcohol/day or with chronic liver disease were excluded. Fatty liver was diagnosed by ultrasonography. The probability of NAFLD with advanced fibrosis was estimated based on the fibrosis-4 index and NAFLD fibrosis score. RESULTS: A total of 71 254 participants were included in the final analysis. The overall prevalence of NAFLD was 25.8%. There was a significant, twofold difference in NAFLD prevalence between men (37.4%) and women (18.1%). Nonalcoholic fatty liver disease prevalence increased linearly with body mass index, triglycerides, and low-density lipoprotein cholesterol regardless of threshold values, even in the absence of obesity. Among patients with NAFLD, 14% had diabetes mellitus, 31% had hypertension, and 48% had dyslipidemia. The estimated prevalence of NAFLD with advanced fibrosis was 1.7% and 1.0% according to the fibrosis-4 index and NAFLD fibrosis score, respectively. CONCLUSIONS: The prevalence of NAFLD was approximately one-quarter of the general population in Japan. There was a linear relationship between NAFLD prevalence and various metabolic parameters, even in nonobese participants. The prevalence of NAFLD with advanced fibrosis was estimated to be 1%-2%.

Distribution and phylogeny of mercury methylation, demethylation, and reduction genes in the Seto Inland Sea of Japan.

Mercury (Hg) adversely affects human and environmental health. To evaluate the mercury (Hg) speciation (methylation, demethylation, and reduction) of microorganisms in coastal seawater, we analyzed the microbial functional gene sets involved in Hg methylation (hgcA and hgcB), demethylation (merB), and reduction (merA) using a metagenomic approach in the eastern and western parts (the Kii and Bungo channels, respectively) of the Seto Inland Sea (SIS) of Japan. We determined the concentration of dissolved total mercury (dTHg) and methylated mercury (dMeHg) in seawater. The metagenomic analysis detected hgcAB, merA, and merB in both channels, whereas the phylogenies of these genes differed between them. A correlation between Hg concentration (both dTHg and dMeHg) and the relative abundance of each gene was not observed. Our data suggests that microbial Hg methylation and demethylation could occur in the SIS and there could be a distinct microbial Hg speciation process between the Kii and Bungo channels.

Contamination, dynamics, and health risk assessment of pesticides in seawater and marine samples from the Seto Inland Sea, Japan.

We assessed the contamination, dynamics, and health risks of the pesticides cyanazine, simetryn, fenarimol, isoprothiolane, diazinon, irgarol, fenitrothion, and diuron in marine samples (seawater, sediments, plankton, fish, and other edible organisms) at various locations in the Seto Inland Sea in Japan in 2016 and 2017. Pesticide concentrations were highest at sampling sites close to the coastline, and mean concentrations in seawater were slightly higher in surface water than in bottom water. All eight pesticides were detected in plankton. Diazinon concentrations (77-387 ng/g dw) were highest in sediments and cyanazine was the most frequently detected pesticide (88%, n = 17) in sediments. Only cyanazine (2.7-41.9 ng/g dw), simetryn (1.0-34.3 ng/g dw), and diazinon (6.3-308.8 ng/g dw) were detected in fish and other edible marine organisms. Based on the calculated bioconcentration factor, the results showed that plankton, fish, and marine animals bioaccumulated pesticides. The highest hazard quotients were calculated for diazinon in red seabream and greenling, indicating a possible risk to consumers. It is, therefore, imperative to promote strict implementation of pollution control, integrated pest management practices, and policy formulation on pesticides. Usage of diazinon must be controlled and monitored to ensure large residues do not reach aquatic ecosystems and marine coastlines.

Dynamics and Mass Balance of Polycyclic Aromatic Hydrocarbons in and Around the Seto Inland Sea, Japan.

Polycyclic aromatic hydrocarbons (PAHs) were analyzed to elucidate the distribution, ecological risk, pathways, and fluxes of these pollutants in and around the Seto Inland Sea, an industrialized coastal region of Japan. High molecular weight PAHs (5-6 rings) were primarily found in regions close to the bay estuaries, and their proportions decreased at distances further from the estuaries (offshore areas), where low molecular weight PAHs (2-4 rings) were more ubiquitous. Screening-level risk assessments revealed that the PAHs found in the sediments should have no adverse effects on benthic communities. A mass balance for PAHs in the Seto Inland Sea, calculated based on data collected in the field and published literature findings, showed the PAH flux into the Seto Inland Sea from atmospheric deposition were ca. 6 times higher than that from riverine inflows. Comparison of the amount of the PAH mass flux between the Seto Inland Sea and the sea of the Europe and Asian countries indicated that the Seto Inland Sea is less polluted than the Gulf of Lion, the Mediterranean Sea, and the Bohai Sea, China and more polluted than the Yellow Sea. This paper is the first to determine the fluxes of PAHs in the coastal region of Japan.

Optical properties of dissolved organic matter in Japanese rivers and contributions to photoformation of reactive oxygen species.

The optical properties of dissolved organic matter (DOM) from five rivers (Kokubu, Kurose, Ohta, Yamato, and Yodo) in Japan were investigated and contributions of DOM to photoformation of three reactive oxygen species (ROS) (hydroxyl radicals (OH), nitric oxide radicals (NO), and singlet oxygen (1O2)) were assessed. The lowest and highest mean dissolved organic carbon concentrations were for the Ohta River (0.95 (mg C) L-1) and Yamato River (2.85 (mg C) L-1), respectively, and the concentrations correlated with some optical parameters. Absorption ratios (e.g., the E2:E3 and A280/A350 ratios) and the spectral slope S275-295 indicated that DOM from the Yodo and Kokubu rivers had the lowest and highest molecular weights, respectively. PARAFAC models and DOM excitation-emission matrices were used to assess the sources and fates of DOM in the rivers. The PARAFAC model indicated that the main types of fluorescent DOM in the rivers were terrestrial humic-like (TH-L) and tryptophan-like (TP-L) substances. The Kokubu River contained other compounds such as fluorescent whitening agents, autochthonous humic-like substances, and extracellular polymeric substances. Statistically significant relationships between the dissolved organic carbon and TH-L, TP-L, and extracellular polymeric substance concentrations suggested that TH-L, TP-L, and extracellular polymeric substances are important contributors to total DOM in the rivers. TH-L and TP-L substances strongly contribute to ROS photoformation, but TH-L substances play roles in both ROS generation and scavenging. Comprehensive models for estimating the photoformation rates of different ROS (in M s-1) were established by integrating the contributions of the relevant major and minor sources. Examples are ROH (10-12) = 21.0 [NO2-]_µM + 0.460 [TH-L]_QSU + 10.9, RNO (10-12) = 67.9 [NO2-]_µM + 35.2 [a300]_m-1 - 2.51 [TH-L]_QSU - 0.765 [TP-L]_QSU - 8.14, and R1O2 (10-9) = 3.81 [a300]_m-1 - 0.101 [TP-L]_QSU + 11.1.

Ecotoxicological and human health risk assessment of selected pesticides in Kurose River, Higashi-Hiroshima City (Japan).

This study conducted an integrated approach combining monitoring and risk assessment of pesticides in Kurose River and its catchment area, Japan. Water samples (n = 168) were collected every month for 1 year (March 2016 to February 2017). Pesticides (cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon) were extracted by Sep-Pack C18 cartridges and analyzed using a reversed-phase HPLC-UV system. The pesticides were also determined in non-target organisms Red algae (Audouinella sp.) and diatoms (Cocconeis placentula) from the river. Based on the residual concentrations, an ecotoxicological risk assessment was conducted using the risk quotient (RQ) index. The human health carcinogenic and non-carcinogenic risk assessments were evaluated using hazard quotients (HQ). Results showed that cyanazine was the most commonly detected (64%), followed by simetryn (58%), and diazinon (57%) in all the sample sites (n = 12). Except for isoprothiolane, the pesticides were highest in spring followed by summer, autumn and winter. Based on extreme values (ex), non-acceptable ecotoxicological risk was obtained for diazinon (RQex = 21.317), cyanazine (RQex = 3.129), simetryn (RQex = 8.577) and fenarimol (RQex = 10.855), while that of isoprothiolane (RQex  = 0.013) was negligible. Based on the HQ estimates, all the pesticides were below the threshold value of 1, hence pose no significant health risks to humans. PRACTITIONER POINTS: Pesticides affect non-target organisms in rivers and other aquatic systems Pesticides were frequently detected in spring and summer and accumulated in red algae and diatom The detected pesticides posed high ecotoxicological and human health risks.

Rotor Syndrome: Glucuronidated Bile Acidemia From Defective Reuptake by Hepatocytes.

Organic anion transporting polypeptide (OATP) 1B1 (gene, solute carrier organic anion transporter family member 1B1 [SLCO1B1]) and OATP1B3 (SLCO1B3) serve as transporters for hepatic uptake of important endogenous substances and several commonly prescribed drugs. Inactivation of both proteins together causes Rotor syndrome. How this OATP1B1/1B3 defect disturbs bile acid (BA) metabolism is largely unknown. In this study, we performed detailed BA analysis in 3 patients with genetically diagnosed Rotor syndrome. We found that BAs glucuronidated at the C-3 position (BA-3G) accounted for 50% or more of total BAs in these patients. In contrast but similarly to healthy controls, only trace amounts of BA-3G were detected in patients with constitutional indocyanine green excretory defect (OATP1B3 deficiency) or sodium-taurocholate cotransporting polypeptide (NTCP; gene, solute carrier family 10 member 1 [SLC10A1]) deficiency. Therefore, substantial amounts of BA-3G are synthesized in hepatocytes. The cycling pathway of BA-3G, consisting of excretion from upstream hepatocytes and uptake by downstream hepatocytes by OATP1B1/1B3 may exist to reduce the burden on upstream hepatocytes. Conclusion: Detailed BA analysis revealed glucuronidated bile acidemia in patients with Rotor syndrome. Further exploration of the physiologic role of glucuronidated BAs is necessary.

Photochemically generated nitric oxide in seawater: The peroxynitrite sink and its implications for daytime air quality.

In this study, we experimentally investigated the magnitude of the peroxynitrite sink: a radical-radical consumption mechanism for photochemically generated nitric oxide (NO) in surface seawater that describes NO reactions with co-generated superoxide (O2-) to yield peroxynitrite (ONOO-). Measurements of photochemically generated NO, O2- and ONOO- were conducted on seawater samples obtained from the Seto Inland Sea, Japan. Nitrite, dissolved organic carbon, chromophoric dissolved organic matter and pH were also measured in the same samples using standard analytical methods. The average photoformation rates of NO, O2- and ONOO- were: 1.78 × 10-12 M s-1, 7.19 × 10-10 M s-1 and 9.0 × 10-10 M s-1, respectively, and the average steady-state concentrations were: 67.28 × 10-12 M, 2.69 × 10-12 M and 2.26 × 10-11 M, respectively. Further evaluation of the experimental data indicated that the existence of ONOO- in seawater strongly depends on, and is limited by, photoformed NO. Seawater alkalinity favored the consumption of photoformed NO· via the peroxynitrite sink. The magnitude of average sinks (%) calculated from kinetic estimates and experimental data were: 0.17% and 0.11%, respectively. These results show that the consumption of photochemically generated NO· via the peroxynitrite sink is not significant in surface seawater. Therefore, we propose that sea-to-air efflux across the marine boundary layer is the major sink of photochemical NO· and can be regarded as a non-anthropogenic contributor to daytime atmospheric NOx concentrations.

Heavy metals in urban dusts from Alexandria and Kafr El-Sheikh, Egypt: implications for human health.

A total of 23 road-dust and 9 house-dust samples were collected from Alexandria and Kafr El-Sheikh cities, Egypt in 2016 to investigate heavy metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination, spatial distribution, sources, and health risks. The mean concentrations (mg kg-1) of Cd (road-dust (RD) = 0.33, house-dust (HD) = 0.77), Cu (RD = 80, HD = 141), Pb (RD = 70, HD = 260), and Zn (RD = 169, HD = 771) in Alexandria and Zn (RD = 192, HD = 257) in Kafr El-Sheikh were higher than corresponding background (background refers to generic earth crust shale values given in the literature) levels. Whereas average concentrations (mg kg-1) of Co, Cr, Mn, and Ni (Alexandria: RD = 2.7, 24.3, 251, 14.4; HD = 3.2, 29.2, 237, 25.1 and Kafr El-Sheikh: RD = 6.6, 31.9, 343, 20.2; HD = 8.6, 33.4, 438, 23.2) in both cities were much lower than their background values. Spatially, for most heavy metals, the high concentrations were observed in areas characterized with increased anthropogenic activities, heavy traffic, and high population density. Contamination indices revealed moderate contamination (Cd and Cu) to high contamination (Pb: only house-dust from Alexandria), which posed low (most metals) to moderate ecological risk (Cd and Pb). Correlation analysis and factor analysis classified the studied metals in two groups as: natural input (Co, Cr, Mn, Ni, and Fe) and anthropogenic sources (Cd, Cu, Pb, and Zn). The noncancerous risks posed by studied metals ranged from 0.0001 (Cd) to 0.15 (Pb) and were insignificant. The cancerous risk of Pb (1.4 × 10-4) for children on exposure to house-dust form Alexandria exceeded the guideline values and was considered unacceptable, whereas the cancerous risks of other studied metals were acceptable for both subpopulations. The results of health risk revealed that children are facing higher risk than adults.

A fluorescence method for the determination of photochemically generated peroxynitrite in seawater.

Peroxynitrite (ONOO-) is a reactive species which can degrade several classes of organic compounds via both oxidation and nitration reactions. Despite the fact that the photochemical precursors; superoxide (O2·-) and nitric oxide (NO·) radicals, have been measured in seawater under simulated solar radiation, there is no published report on actual measurements of photoformed peroxynitrite in seawater. Hence, this attempt was made to develop a fluorescence method by using coumarin boronic acid (CBA) as a chemical probe. CBA reacts with ONOO- to yield fluorescent 7-hydroxycoumarin (COH). COH was determined by reversed‒phase isocratic HPLC with fluorescence detection at excitation/emission wavelengths of 332/475 nm, respectively. COH standards calibration is linear in range of (0.25-100) × 10-9 M. The detection limit, defined as 3σ of the lowest ONOO- photo-formation rates obtained within 10- min irradiation, was 1.66 × 10-12 M s-1. This method is very precise as coefficient of variation for triplicate measurements of COH photo-formation rates was a maximum of 0.052. Experimental procedures were optimized to handle potential interference by hypochlorite, and the method was applied to measure ONOO- in 13 surface seawater samples obtained from the Seto Inland Sea, Japan. ONOO- photo-formation rates, steady‒state concentrations and lifetimes were determined to be (0.06-5.13) × 10-9 M s-1, (0.98-6.11) × 10-11 M and (0.01-0.16) s, respectively.

A simple, inexpensive method for gas-phase singlet oxygen generation from sensitizer-impregnated filters: Potential application to bacteria/virus inactivation and pollutant degradation.

Airborne infectious diseases such as the new Coronavirus 2019 (COVID-19) pose serious threat to human health. Indoor air pollution is a problem of global environmental concern as well. Singlet oxygen (1O2) is a reactive oxygen species that plays important role in bacteria/virus inactivation and pollutant degradation. In this study, we found that commercially available filters typically deployed in air purifier and air conditioning units, when impregnated with Rose Bengal (RB) as a 1O2 sensitizer, can be used for heterogeneous gas-phase generation of 1O2. It was confirmed that irradiation of the RB filter under oxygen gas stream produced 1O2, which was measured using furfuryl alcohol trapping method followed by HPLC analysis. It was also observed that the amount of 1O2 generated increases as the light intensity increased. Similarly, the sensitizer loading also positively influenced the 1O2 generation. The heterogeneous gas-phase generation of 1O2 can find potential applications in air purifier and air conditioning units for the purpose of bacteria/virus inactivation and/or pollutant degradation thereby improving indoor air quality.

Heterogeneity and potential aquatic toxicity of hydrogen peroxide concentrations in selected rivers across Japan.

Hydrogen peroxide (H2O2) is a reactive oxygen species formed in natural water. It is reportedly toxic to aquatic organisms with a predicted no-effect concentration (PNEC) of about 380 nM. In this study, a countrywide investigation of H2O2 concentrations in selected rivers across Japan was conducted to identify rivers that pose toxicity concerns. Twelve rivers with a total catchment area of 13,646 km2 were selected from different prefectures. Spatial and temporal variation studies showed that the H2O2 concentrations (avg. 320 nM, n = 111) varied by two orders of magnitude (range 21-2929 nM) across the rivers. The Yamato River in Osaka and Nara prefectures and the Kokubu River in Chiba Prefecture had the highest concentrations at 276-669 nM and 236-2929 nM, respectively. >75% of the data from the two rivers were either close to or exceeded the PNEC. Most of the results for the other rivers were less than the PNEC. There was a clear seasonal variation in the H2O2 concentrations, with the highest values obtained in summer because of high solar irradiation. The H2O2 concentration had the highest positive correlation (r = 0.61, p < 0.01, n = 111) with the product of dissolved organic carbon and solar radiation intensity, which suggests that these two factors in combination are important in determining the H2O2 concentrations in river water. It was also observed that bigger rivers had lower H2O2 concentration and vice-versa. This shows that the size of a river may influence its H2O2 concentration. This study is the first countrywide survey of H2O2 concentrations in different rivers and evaluation of their relationship with the PNEC. The data provide insight on the factors influencing the concentrations of H2O2 in river water.

Singlet Oxygen Photogeneration in Coastal Seawater: Prospect of Large-Scale Modeling in Seawater Surface and Its Environmental Significance.

Chromophoric-dissolved organic matter (CDOM) acts as the precursor to singlet oxygen (1O2) in natural waters, while water acts as the main scavenger. In this study, we showed that 1O2 in coastal seawater can be successfully predicted from CDOM parameters. The 1O2 steady-state concentration [1O2]ss and photoformation rate (R1O2) varied by a factor of 6 across 13 sampling stations in the Seto Inland Sea, Japan, ranging from 1.2 to 8.2 × 10-14 M and 3.32 to 22.7 × 10-9 M s-1, respectively. Investigation of CDOM optical properties revealed that CDOM abundance measured as the absorption coefficient at 300 nm (a300) had the strongest correlation (r = 0.96, p < 0.001) with [1O2]ss, while parameters indicative of CDOM quality (e.g., spectral slope) did not influence [1O2]ss. A linear relationship between [1O2]ss and a300, normalized to a sunlight intensity of 0.91 kW/m2, was derived as [1O2]ss (10-14 M) = 2.12(a300) + 0.48. This was then used to predict [1O2]ss using a300 values from a subsequent, independent sampling exercise conducted 2 years after the first sampling. There was a good agreement (r = 0.93, p < 0.001) between the predicted values and the experimentally determined values based on a 95% prediction interval plot. Kinetic estimations using [1O2]ss suggest that 1O2 mediates the degradation of tetrabromobisphenol A in surface seawater (t1/2 = 0.63 days) while also contributing to the indirect photolysis of methyl mercury. The findings from this study suggest that large-scale modeling of 1O2 generation in surface seawater from CDOM parameters is possible with useful environmental significance for determining the fate of pollutants.

Carbaryl residue concentrations, degradation, and major sinks in the Seto Inland Sea, Japan.

The fate of carbaryl in the Seto Inland Sea (west Japan) was predicted using a mass distribution model using carbaryl concentrations in river and sea water samples, degradation data, and published data. The predicted carbaryl concentrations in water in Kurose River and the Seto Inland Sea were 4.320 and 0.2134 µg/L, respectively, and the predicted concentrations in plankton, fish, and sediment were 0.4140, 2.436, and 1.851 µg/g dry weight, respectively. The carbaryl photodegradation and biodegradation rates were higher for river water (0.330 and 0.029 day-1, respectively) than sea water (0.23 and 0.001 day-1, respectively). The carbaryl photodegradation rates for river and sea water (0.33 and 0.23 day-1, respectively) were higher than the biodegradation rates (0.029 and 0.001 day-1, respectively). The hydrolysis degradation rate for carbaryl in sea water was 0.003 day-1, and the half-life was 231 days. Land (via rivers) was the main source of carbaryl to the Seto Inland Sea. The model confirmed carbaryl is distributed between sediment, plankton, and fish in the Seto Inland Sea. Degradation, loss to the Open Ocean, and sedimentation are the main carbaryl sinks in the Seto Inland Sea, accounting for 43.81, 27.90, and 17.68%, respectively, of total carbaryl inputs. Carbaryl source and sink data produced by the model could help in the management of the negative impacts of carbaryl on aquatic systems and human health.

Factors controlling the degradation of hydrogen peroxide in river water, and the role of riverbed sand.

Diurnal changes of H2O2 in river water during mid-summer were investigated. H2O2 in river water increased with the increase in intensity of solar radiation in the morning, and reached a maximum at 14:00, although solar radiation reached a maximum around 12:00. In the afternoon, a gradual decrease in H2O2 was observed, and H2O2 reached a minimum just before sunrise. Degradation rate constants determined using unfiltered river water samples were 0.081-0.161 h-1, corresponding to a half-life of 4.3-8.5 h. We simulated diurnal changes in H2O2 using a simple formation, accumulation, and degradation model for static water using formation and degradation rate constants. The results of the modeling suggested that in situ degradation rate constants in rivers could be faster than those determined for unfiltered river water samples. Experiments using river sand indicated that riverbed sand could play an important role in H2O2 decay in rivers. We discussed the decomposition process of H2O2 in rivers.

Photoformation of reactive oxygen species and their potential to degrade highly toxic carbaryl and methomyl in river water.

Reactive oxygen species (ROS) including singlet oxygen (1O2) and hydroxylradicals (OH) photogenerated in natural waters play important roles in indirect photolysis of man-made pollutants. This study was conducted to investigate how the generation of these two ROS influences the degradation of two highly toxic insecticides (methomyl and carbaryl) in river water. To accomplish this, the reaction rate constants of 1O2 and OH with carbaryl and methomyl were determined; the degradation rate constants of the tested insecticides in ultrapure water (direct photolysis) and in river water in the presence and absence of 1O2 and OH scavengers were also measured. The rate constants for the reaction of OH with carbaryl and methomyl were found to be (14.8 ±â€¯0.64) × 109 and (4.68 ±â€¯0.52) × 109 M-1 s-1, respectively. The reaction rate constant of 1O2 with carbaryl (2.98 ±â€¯0.10) × 105 M-1 s-1, was much higher than that of methomyl (<104 M-1 s-1). Indirect photolysis by OH accounted for 63% and 62%, while 1O2 accounted for 26% and 30% and direct photolysis accounted for 1.4% and 7% of methomyl and carbaryl degradation, respectively. The high degradation rate in river water demonstrated by both insecticides suggests that indirect photolysis mediated by OH is an important means of their degradation in river water. In addition, kinetic calculations of OH-mediated degradation rate constants of the compounds agrees with their experimentally-determined values thereby confirming the importance of OH towards their degradation.

Temporal trends in organophosphorus pesticides use and concentrations in river water in Japan, and risk assessment.

We reviewed organophosphorus pesticide use in Japan between 1982 and 2016 using data from the National Institute of Environmental Studies. Organophosphorus pesticide concentrations in river water throughout Japan were taken from the literature, and risk assessments were performed for some organophosphorus pesticides based on risk quotients and hazard quotients. Assessments were performed for 20 common pesticides, including insecticides, fungicides, and herbicides. The amounts used decreased in the order: insecticides > herbicides > fungicides. Organophosphorus insecticide and fungicide use have decreased over the last four decades, but organophosphorus herbicide use has increased. During this period, annual organophosphorus pesticide use was the highest for chlorpyrifos (105,263 tons/year) and the lowest for glyphosate-sodium (8 tons/year). The ecotoxicological risk assessment indicated that diazinon and fenitrothion posed strong risks to the Japanese aquatic environment, and chlorpyrifos and malathion have moderate risks. None of the pesticides that were assessed posed significant risks to humans. Continued use of organophosphorus pesticides in Japan may cause strong risks to aquatic environments. These risks should be reassessed periodically.

Polycyclic aromatic hydrocarbons in urban road dust, Afghanistan: Implications for human health.

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in road and aerial dust to assess their concentration, composition profile, distribution, emission sources, and potential human health risks. Sixteen priority PAHs and Benzo [e]pyrene (BeP) were analyzed in 13 aerial dust samples from Jalalabad, and 78 road dust samples from Kabul and Jalalabad cities, Afghanistan. The mean concentration of ∑17PAHs in road dust from Kabul and Jalalabad were 427  µg kg-1 and 288  µg kg-1, respectively whereas ∑17PAHs in aerial dust from Jalalabad averaged 200  µg kg-1. Fluoranthene (Flu), Chrysene (Chr), Benzo [b]fluoranthene (BbF), Benzo [k]fluoranthene (BkF) and BeP were major individual PAH species. The composition patterns of the PAHs were dominated by 5-6-ring PAHs (51% in road dust from Kabul; 44% in road dust from Jalalabad; and 44% in aerial dust) followed by 4-ring and 2-3-ring PAHs. Source apportionment of the road dust PAHs by the molecular diagnostic ratios (MDR) and principal component analysis (PCA), indicated signatures of PAHs sources (including vehicular exhaust, coal/wood combustion and oil spill). The Benzo [a]pyrene (BaP) toxicity equivalent values (BaPeq17PAHs) for road dust were 75  µg kg-1 (Kabul) and 36 µg kg-1 (Jalalabad); and 35 µg kg-1 for aerial dust (Jalalabad). BaP and Dibenz [a,h]anthracene (DahA) together contributed > 50% of the BaPeq associated cancer risk. All incremental lifetime cancer risk (ILCR) due to human exposure to road and aerial dust PAHs were in the order of 10-7, which is one-fold lower than the threshold (10-6). The noncancerous risk (Hazard Index < 1) on exposure to dust was also negligible for both subpopulations.