Cytogenetic biomonitoring of oral mucosa cells of crack cocaine users

The aim of the present study was to comparatively evaluate genomic damage (micronucleus) and cellular death (pyknosis, karyolysis, and karyorrhexis) in exfoliated oral mucosa cells from crack cocaine users by micronucleus test. A total of 30 crack cocaine users and 30 health controls (non-exposed individuals) were included in this setting. Individuals had epithelial cells from cheek mechanically exfoliated, placed in fixative, and dropped in clean slides, which were checked for the above nuclear phenotypes. The results pointed out significant statistical differences (p?<?0.05) of micronucleated oral mucosa cells from crack cocaine users. Exposure to crack cocaine caused an increase of other nuclear alterations closely related to cytotoxicity such as karyolysis in oral cells as well. In summary, these data indicate that crack cocaine is able to induce chromosomal breakage and cellular death in oral mucosa cells of users.     

Effect of phenobarbital and polychlorinated biphenyls on the toxicity and disposition of 1,2,4,5‐tetrachlorobenzene in the rat

Soil avoidance by earthworms has been generally considered a relevant and sensitive endpoint for assessing soil contamination by xenobiotics. However, when pesticide ecotoxicological assessment is concerned, the sensitivity of the recently standardized avoidance assay has been questioned. We hypothesized that this controversy may be due to the specific pesticide mode of action of the chemicals used rather than reveal inconsistencies in the test feasibility, i.e. provided that no pesticides interfering with neuronal pathways are tested, this bioassay should keep expected high levels of sensitivity. In this study, the avoidance behaviour of the earthworm Eisenia andrei under exposure to the carbamate insecticide methomyl [S-methyl N-(methylcarbamoyloxy)thioacetimidate] was linked to the corresponding acetylcholinesterase (AChE) inhibition. Significant AChE inhibition occurred at lower concentrations (from 0.86 mg Kg^?1 onwards) than significant avoidance of spiked soil (from 5.62 mg Kg^?1 onwards). This indicates that assessments regarding pesticides that have neurotoxic activity may be biased if behavioral endpoints are selected. Despite theoretical hypothesis that have been raised, this should be the first study providing preliminary experimental evidence on such a link between avoidance behavior and neuronal impairment levels in earthworms. Further studies are ongoing that should refine conclusions of this study.     

Acute toxicity and ecotoxicological risk assessment of rice pesticides to Lithobates catesbeianus tadpoles

The objective of this study was to determine the acute toxicity of some pesticides used in irrigated rice farming to Lithobates catesbeianus tadpoles. The LC_50-96h for commercial formulations containing bentazon, penoxsulam, vegetable oil, permethrin and carbofuran, separately and their mixtures, were determined at the proportions commonly used in the field. The limits of risk concentrations of these products for the studied species were also established. The LC_50-96h for tadpoles was 4,530 mg L^?1 for bentazon; 7.52 mg L^?1 for penoxsulam + 145.66 mg L^?1 of vegetable oil; 81.57 mg L^?1 for vegetable oil; 0.10 mg L^?1 for permethrin; 29.90 mg L^?1 for carbofuran (active ingredients), and 38.79 times the dose used in the field for the mixture of these products. The environmental risk was determined only for permethrin, and care should be taken when using the vegetable oil.     

Ozone Formation in California's San Joaquin Valley: A Critical Assessment of Modeling and Data Needs

ABSTRACT

Data from the 1990 San Joaquin Valley Air Quality Study/ Atmospheric Utility Signatures, Predictions, and Experiments (SJVAQS/AUSPEX) field program in California's San Joaquin Valley (SJV) suggest that both urban and rural areas would have difficulty meeting an 8-hr average O₃ standard of 80 ppb. A conceptual model of O₃ formation and accumulation in the SJV is formulated based on the chemical, meteorological, and tracer data from SJVAQS/ AUSPEX. Two major phenomena appear to lead to high O₃ concentrations in the SJV: (1) transport of O₃ and precursors from upwind areas (primarily the San Francisco Bay Area, but also the Sacramento Valley) into the SJV, affecting the northern part of the valley, and (2) emissions of precursors, mixing, transport (including long-range transport), and atmospheric reactions within the SJV responsible for regional and urban-scale (e.g., downwind of Fresno and Bakersfield) distributions of O₃. Using this conceptual model, we then conduct a critical evaluation of the meteorological model and air quality model. Areas of model improvements and data needed to understand and properly simulate O₃ formation in the SJV are highlighted.     

New methodological improvements in the Microtox® solid phase assay

The classic Microtox® solid phase assay (MSPA) based on the inhibition of light production of the marine bacteria recently renamed Aliivibrio fischeri suffers from various bias and interferences, mainly due to physico-chemical characteristics of the tested solid phase. To precisely assess ecotoxicity of sediments, we have developed an alternative method, named Microtox® leachate phase assay (MLPA), in order to measure the action of dissolved pollutants in the aqueous phase. Two hypotheses were formulated to explain the observed difference between MSPA and MLPA results: a real ecotoxicity of the solid phase or the fixation of bacteria to fine particles and/or organic matter. To estimate the latter, flow cytometry analyses were performed with two fluorochromes (known for their ability to stain bacterial DNA), allowing correction of MSPA measurements and generation of new (corrected) IC50. Comparison of results of MLPA with the new IC50 MSPA allows differentiating real ecotoxic and fixation effect in classic MSPA especially for samples with high amount of fines and/or organic matter.     

Contribution of sociodemographic characteristics, occupation, diet and lifestyle to DDT and DDE concentrations in serum and adipose tissue from a Bolivian cohort

The organochlorine pesticide p,p′-Dichlorodiphenyltrichloroethane (DDT) was widely used in the early 1960s-70s for vector control in tropical and subtropical areas of South America. Due to its persistence, DDT has a high potential to bioaccumulate in the food chain and living organisms and is a major public health concern, especially in South America.The main purpose of the present study was to investigate predictors of serum and adipose tissue concentrations of p,p′-DDT and its main metabolite, p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE), in an adult cohort (n = 112) from Santa Cruz de la Sierra, Bolivia, using multiple linear regression models. These models explained 29.3-47.8% of the variability in adipose tissue concentrations of p,p′-DDT and p,p′-DDE, respectively, and 32.9-47.0% of that in serum. Main exposure predictors included age, occupational class, residence, diet, smoking habit, and accumulated breastfeeding time.This is one of the few studies to explore predictors of human exposure to these chemicals using a multivariate approach in a South American population. Results show that predictors of human exposure to p,p′-DDT and p,p′-DDE in Santa Cruz de la Sierra may diverge from those found in other populations of the world, due to particular sociodemographic and lifestyle characteristics of this region.     

A multi-biomarker approach to assess the impact of farming systems on black tiger shrimp (Penaeus monodon)

This study examined the advantages of the use of biomarkers as an early warning system by applying it to different shrimp farming systems in Soctrang and Camau provinces, main shrimp producers in Mekong River Delta, Vietnam. Shrimp were collected at 15 different farms divided into four different farming systems: three farms were converted from originally rice paddies into intensive shrimp farming systems (IS1, IS2, IS3); three farms were rice-shrimp integrated farming systems (RS4, RS5, RS6); three farms were intensive farming systems (IS7, IS8, IS9); six farms were extensive shrimp farming systems (From ES1 to ES6). Lipid peroxidation (LPO) and total glutathione (GSH) were measured as well as catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST) and acetylcholinesterase activities (ACHE). Organ specificity was observed between gills and hepatopancreas with generally higher activity of GST in gills (GSTG) whereas the contrary was observed for LPO level in gills (LPOG). Hierarchical clustering and principal component analysis clearly indicated that shrimp reared in extensive culture system formed a distinct group from those reared in intensive or rice-shrimp integrated systems. CAT in gills (CATG), GPX in gills (GPXG) and hepatopancreas (GPXHP) and ACHE in muscle (ACHEM) of shrimp collected in extensive farms showed a general higher level than those in intensively farmed shrimp. On the contrary, we observed clear high levels of GSTG and GST in hepatopancreas (GSTHP) and LPOG and hepatopancreas (LPOHP) of shrimp sampled in intensive and rice-shrimp integrated systems. Thus, we propose that LPO and CAT, GPX, GST and ACHE can be used as a set of biomarkers for the assessment of health condition and can discriminate between shrimp cultivated in different farming systems. These findings provide the usefulness of integrating a set of biomarkers to define the health status of shrimp in different shrimp culture systems.     

Evaluation of a detailed model of secondary organic aerosol formation from α-pinene against dark ozonolysis experiments

BOREAM, a detailed model for the gas-phase oxidation of α-pinene and its subsequent formation of Secondary Organic Aerosol (SOA), is tested against a large set of SOA yield measurements obtained in dark ozonolysis experiments. For the majority of experiments, modelled SOA yields are found to agree with measured yields to within a factor 2. However, the comparisons point to a general underestimation of modelled SOA yields at high temperatures (above 30 °C), reaching an order of magnitude or more in the worst cases, whereas modelled SOA yields are often overestimated at lower temperature (by a factor of about 2). Comparisons of results obtained using four different vapour pressure prediction methods indicate a strong sensitivity to the choice of the method, although the overestimated temperature dependence of the yields is found in all cases. Accounting for non-ideality of the aerosol mixture (based on an adapted UNIFAC method) has significant effects, especially at low yields. Our simulations show that the formation of oligomers through the gas-phase reactions of Stabilised Criegee Intermediates (SCI) with other molecular organic products could increase the SOA yield significantly only at very low relative humidity (below 1%). Further tests show that the agreement between model and measurements is improved when the ozonolysis mechanism includes additional production of non-volatile compounds.     

Characterisation of PM10 emissions from woodstove combustion of common woods grown in Portugal

A series of source tests was performed to evaluate the chemical composition of particle emissions from the woodstove combustion of four prevalent Portuguese species of woods: Pinus pinaster (maritime pine), Eucalyptus globulus (eucalyptus), Quercus suber (cork oak) and Acacia longifolia (golden wattle). Analyses included water-soluble ions, metals, radionuclides, organic and elemental carbon (OC and EC), humic-like substances (HULIS), cellulose and approximately l80 organic compounds. Particle (PM₁₀) emission factors from eucalyptus and oak were higher than those from pine and acacia. The carbonaceous matter represented 44–63% of the particulate mass emitted during the combustion process, regardless of species burned. The major organic components of smoke particles, for all the wood species studied, with the exception of the golden wattle (0.07–1.9% w/w), were anhydrosugars (0.2–17% w/w). Conflicting with what was expected, only small amounts of cellulose were found in wood smoke. As for HULIS, average particle mass concentrations ranged from 1.5% to 3.0%. The golden wattle wood smoke presented much higher concentrations of ions and metal species than the emissions from the other wood types. The results of the analysis of radionuclides revealed that the ²²⁶Ra was the naturally occurring radionuclide more enriched in PM₁₀. The chromatographically resolved organics included n-alkanes, n-alkenes, PAH, oxygenated PAH, n-alkanals, ketones, n-alkanols, terpenoids, triterpenoids, phenolic compounds, phytosterols, alcohols, n-alkanoic acids, n-di-acids, unsaturated acids and alkyl ester acids.     

Using diatom indices for water quality assessment in a subtropical river, China

Diatoms have been regularly used as bioindicators to assess water quality of surface waters. However, diatom-based indices developed for a specific geographic region may not be appropriate elsewhere. We sampled benthic diatom assemblages in the upper Han River, a subtropical river in China, to evaluate applicability of 14 diatom-based indices used worldwide for water quality assessment. A total of 194 taxa from 31 genera were identified in the dry season and 139 taxa from 23 genera in the wet season. During the dry season, significant relationships were found for all but one of the diatom-based indices (Index Diatom Artois–Picardie) with one or more physical and chemical variables including nutrients and ion concentrations in river waters. The Biological Diatom Index (IBD) and diatom-based eutrophication/pollution index (EPI-D) were strongly related to trophic status and ionic content, while Watanabe’s Index was related to organic pollution and conductivity. Yet, the diatom indices showed weak relationships with physical and chemical variables during the wet season. It suggests that diatom-based indices developed in Europe can be applied with confidence as bioindicators of water quality in subtropical rivers of China, at least during base-flow conditions.