A contaminação dos solos por elementos potencialmente tóxicos (EPTs) provoca alterações na estrutura e no funcionamento dos ecossistemas, além de oferecer riscos à saúde pública. Os EPTs estão presentes naturalmente no ambiente, sendo constituintes de rochas e sedimentos. Entretanto, atividades antropogênicas como emissões industriais, uso de efluentes urbanos, dejetos de animais, biossólidos, fertilizantes e defensivos agrícolas podem contribuir para aumento da concentração dos EPTs. O solo é um dos principais meios de exposição dos EPTs aos seres humanos. Logo, é importante quantificar os teores dos EPTs nos solos e sua distribuição na microbacia para poder avaliar o risco a saúde humana. Os efeitos dos elementos tóxicos que chegam ao solo sobre a diversidade e funcionalidade da biota podem ser avaliados por meio de testes ecotoxicológicos. Alguns organismos são bons indicadores ambientais por participarem de processos biológicos importantes do solo. Os principais organismos utilizados são os colêmbolos, artrópodes terrestres com alta diversidade e abundância, sendo encontrado em todos os biomas. Nesse estudo, quantificaram-se os teores de Arsênio (As), Cádmio (Cd), Cobalto (Co), Cobre (Cu), Cromo (Cr), Chumbo (Pb), Níquel (Ni) e Zinco (Zn) em amostras de 15 solos da microbacia do Rio Guamium, localizada em Piracicaba, São Paulo. Foi realizado experimento em casa de vegetação com alface (Lactuca sativa L.), pepino (Cucumis sativus L.), beterraba (Beta vulgaris L.) e rúcula (Eruca sativus Mill.) para avaliar o risco a saúde humana. Foi avaliado também o efeito da aplicação de doses de As na reprodução dos colêmbolos. Para tanto, foram coletadas amostras de solos nas profundidades 0 - 0,1; 0,1 - 0,2; 0,2 - 0,3; 0,3 - 0,4; 0,4 - 0,6; 0,6 - 0,9 e 0,9 - 1,2 m. Foi realizada a extração dos EPTs pelo método EPA 3051a (0,5 g de solo + 9 ml HNO3 + 3 ml HCl com digestão assistida por forno microondas). Os EPTs que apresentaram as maiores concentrações foram o As (3 pontos) e Cu (1 ponto), sendo as concentrações superiores ou iguais ao valor de prevenção estabelecido pelo órgão ambiental paulista (Cetesb). O As apresentou elevado risco carcinogênico, enquanto o Cu apresentou risco à saúde humana apenas quando 100 % dos vegetais consumidos eram provenientes da área com elevado teor de Cu, sendo este o cenário mais restritivo. Houve diferença na disponibilidade de As entre o solo natural e o solo artificial tropical (SAT), composto por areia, caulinita e pó de fibra de coco. O SAT apresentou alta disponibilidade de As o que reduziu a taxa de reprodução dos colêmbolos. No SAT a LOEC (Lowest Observed Effect Concentration) foi 0,25 mg kg-1 e a NOEC (No Observed Effect Concentration) < 0,25 mg kg-1. No solo natural não foi possível determinar a NOEC, enquanto a LOEC foi 8,41 mg kg-1. / Soil contamination by potential toxics elements (PTEs) can change the ecosystem structure, its function and can cause risk to human health. PTEs occur naturally in the environment; however human activities such as industrial emissions, urban sewage, animal waste, biosolids, fertilizers and pesticides can increase their concentration. Soil is one of the main pathways to human exposure, so it is important to evaluate the contents of PTEs in soils and their distribution in the watershed in order to assess the human health risk. The effects of PTEs that reach the soil on the diversity and functionality of microorganisms can be evaluated by ecotoxicological tests. Organisms that take part of the biological process can be used as environment quality indicators. One of them is the springtails (Collembola) that are wide spread and have high diversity, being found in all ecosystems. In this study, we evaluated the Arsenic (As), Cadmium (Cd), Cobalt (Co), Copper (Cu), Chromium (Cr), Lead (Pb), Nickel (Ni) and Zinc (Zn) contents in 15 soil from Guamium watershed, located in Piracicaba, state of Sao Paulo, Brazil. To assess the human health risk lettuce (Lactuca sativa L.), cucumber (Cucumis sativus L.), sugar beet (Beta vulgaris L.) and rocket (Eruca sativus Mill.) were cultivated under greenhouse conditions. The effect of As rates on collembola reproduction was also evaluated. Soil samples were collected in the following depths: 0 - 0.1; 0.1 - 0.2; 0.2 - 0.3; 0.3 - 0.4; 0.4 - 0.6; 0.6 - 0.9 e 0.9 - 1.2 m. Contents of PTEs were obtained after microwave extraction by EPA 3051a method (0.5 g soil + 9 mL HNO3 + 3 mL HCl). As and Cu had the highest contents, and their concentration were close or higher than prevention value established by Sao Paulo state environmental agency (Cetesb). As showed high carcinogenic risk, otherwise Cu only represented risk to human health in the most restrictive scenario, when 100% of the vegetables consumed were taken from the contaminated area. There was difference in the As availability between natural soil and artificial soil (ArtS) which was composed by sand, Kaolinite and powdered coconut fiber. As availability was high in the ArtS and it decreased the collembola reproduction. The Lowest Observed Effect Concentration (LOEC) on SAT were 0.25 mg kg-1, while and the No Observed Effect Concentration (LOEC) were less than 0.25 mg kg-1. Otherwise, the LOEC were 8.41 mg kg-1 in the natural soil, but it was not possible to define the NOEC.

Petroleum refineries emit a variety of airborne substances which may be harmful to human health. HEIDI II (Health Effects Indicators Decision Index II) is a computer-based decision analysis tool which assesses airborne emissions from Canada's oil refineries for reduction, based on ordinal ranking of estimated health impacts. The model was designed by a project team within NERAM (Network for Environmental Risk Assessment and Management) and assembled with significant stakeholder consultation. HEIDI II is publicly available as a deterministic Excel-based tool which ranks 31 air pollutants based on predicted disease incidence or estimated DALYS (disability adjusted life years). The model includes calculations to account for average annual emissions, ambient concentrations, stack height, meteorology/dispersion, photodegradation, and the population distribution around each refinery. Different formulations of continuous dose-response functions were applied to nonthreshold-acting air toxics, threshold-acting air toxics, and nonthreshold-acting CACs (criteria air contaminants). An updated probabilistic version of HEIDI II was developed using Matlab code to account for parameter uncertainty and identify key leverage variables. Sensitivity analyses indicate that parameter uncertainty in the model variables for annual emissions and for concentration-response/toxicological slopes have the greatest leverage on predicted health impacts. Scenario analyses suggest that the geographic distribution of population density around a refinery site is an important predictor of total health impact. Several ranking metrics (predicted case incidence, simple DALY, and complex DALY) and ordinal ranking approaches (deterministic model, average from Monte Carlo simulation, test of stochastic dominance) were used to identify priority substances for reduction; the results were similar in each case. The predicted impacts of primary and secondary particulate matter (PM) consistently outweighed those of the air toxics. Nickel, PAH (polycyclic aromatic hydrocarbons), BTEX (benzene, toluene, ethylbenzene and xylene), sulphuric acid, and vanadium were consistently identified as priority air toxics at refineries where they were reported emissions. For many substances, the difference in rank order is indeterminate when parametric uncertainty and variability are considered.

Benzene is an important toxic chemical in urban air and known human carcinogen released substantially by mobile sources. It's important to understand the spatial variation of benzene concentrations in order to understand exposures of susceptible sub-populations such as children and minority groups. Current monitoring networks use large and expensive air samplers that require electricity and restrict the location and number of samplers, not allowing for fine spatial resolution data. The goals of this study are to develop and evaluate protocols for passive sampling and analysis of ambient benzene concentrations, and conduct a pilot study investigating small-scale variations over an area where children are likely to be exposed. Protocols were developed for the use and analysis of the Radiello RAD130 passive sampler for field sampling over the spatial scale of a city park adjacent to an elementary school. A pilot study was conducted from 4/27/11-5/4/11, where 11 samplers were exposed for a seven day sampling period at the park. After sampler exposure, benzene concentrations were determined through solvent desorption followed by analysis using a Varian gas chromatograph with mass spectrometer. Co-location with the existing regulatory active sampler in the county and of two samplers at the same site was done to evaluate the accuracy and precision of the methods, respectively. Health risk estimates were calculated using risk assessment guidance from the U.S. and California Environmental Protection Agencies. Concentrations over the park were found to range from 0.23 0.34 µg m^-3 with a coefficient of variation of 11%. A relative percent difference of 3% was found between the co-located sampler and the active sampler, and a 14% relative percent difference was found between the two duplicate samplers. The variation in health risk from concentration variation due to sampler placement contributed less to the overall uncertainty in the estimates than the uncertainty built in to the calculation parameters of inhalation unit risk and cancer potency factor, as estimated by the U.S. EPA and California EPA, respectively. These results suggest that the exposure of an individual at the park would be characterized sufficiently for standard health risk analysis through the use of one sampler. Further research is necessary into using passive samplers over both the same spatial scale in other areas, as well as on a larger scale to determine intra-urban benzene concentration distributions. The protocols developed here will be used in a future planned study of benzene concentration measurements to characterize neighborhood-scale exposures in Hillsborough County.

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