Efeito de metais pesados na alga Pseudokirchneriella subcapitata

O impacto dos metais pesados em ambientes aqu��ticos, incluindo ��guas residuais, �� vulgarmente determinado atrav��s de testes de toxicidade. A microalga Pseudokirchneriella subcapitata �� usada nos m��todos de toxicidade recomendados por organismos Internacionais como a EPA (Environmental Protection Agency) e a OCDE (Organiza����o para a Coopera����o e Desenvolvimento Econ��mico). O presente trabalho teve como objectivo avaliar o impacto do c��dmio e do zinco no crescimento, na autofluoresc��ncia e na actividade metab��lica da alga P. subcapitata. Para tal, a alga, em fase exponencial de crescimento, foi inoculada no meio de cultura contendo Cd (150, 500 ou 700 nmol/l) ou Zn (300, 1800 ou 6000 nmol/l). A concentra����o mais baixa de Cd e Zn n��o provocou qualquer efeito inibit��rio. Para uma concentra����o interm��dia de Cd e Zn, observou-se uma redu����o do crescimento, ao fim de 72 h, de 63 e 50 %, respectivamente. No caso da concentra����o mais elevada de Cd e de Zn, observou-se uma redu����o do crescimento, ao fim de 72 h, de 83 e 97 %, respectivamente. A perda de autofluoresc��ncia da alga, devido �� presen��a de Cd e de Zn, seguiu um padr��o similar ao efeito sobre o crescimento. Resultados preliminares mostraram que a exposi����o das c��lulas de P. subcapitata a 700 nmol/ de Cd, durante 1h, induziu uma inibi����o da actividade ester��sica de 52 %, enquanto que a incuba����o com 6000 nmol/l de Zn, durante 6 h, provocou uma redu����o da actividade ester��sica de ~ 50 %. Em conclus��o, os resultados obtidos mostram que o Cd �� mais t��xico que o Zn para a alga P. subcapitata. A perda de autofluoresc��ncia, devido �� exposi����o aos metais pesados em estudo, ocorreu segundo um padr��o similar ao efeito inibit��rio sobre o crescimento. O Cd e Zn provocaram uma r��pida perda (no espa��o de 6 h) da actividade ester��sica. Estes resultados sugerem que a avalia����o da actividade ester��sica da alga P. subcapitata poder�� constituir um indicador sens��vel na avalia����o da toxicidade.

Analysis of polycyclic aromatic hydrocarbons in atmospheric particulate samples by microwaveassisted extraction and liquid chromatography

A methodology based on microwave-assisted extraction (MAE) and LC with fluorescence detection (FLD) was investigated for the efficient determination of 15 polycyclic aromatic hydrocarbons (PAHs) regarded as priority pollutants by the US Environmental Protection Agency and dibenzo(a,l)pyrene in atmospheric particulate samples. PAHs were successfully extracted from real outdoor particulate matter (PM) samples with recoveries ranging from 81.4��8.8 to 112.0��1.1%, for all the compounds except for naphthalene (62.3��18.0%) and anthracene (67.3��5.7%), under the optimum MAE conditions (30.0 mL of ACN for 20 min at 110��C). No clean-up steps were necessary prior to LC analysis. LOQs ranging from 0.0054 ng/m3 for benzo( a)anthracene to 0.089 ng/m3 for naphthalene were reached. The validated MAE methodology was applied to the determination of PAHs from a set of real world PM samples collected in Oporto (north of Portugal). The sum of particulate-bound PAHs in outdoor PM ranged from 2.5 and 28 ng/m3.

Mercury, cadmium, lead and arsenic levels in three pelagic fish species from the Atlantic Ocean: intra- and inter-specific variability and human health risks for consumption

Three commonly consumed and commercially valuable fish species (sardine, chub and horse mackerel) were collected from the Northeast and Eastern Central Atlantic Ocean in Portuguese waters during one year. Mercury, cadmium, lead and arsenic amounts were determined in muscles using graphite furnace and cold vapour atomic absorption spectrometry. Maximum mean levels of mercury (0.1715 �� 0.0857 mg/kg, ww) and arsenic (1.139 �� 0.350 mg/kg, ww) were detected in horse mackerel. The higher mean amounts of cadmium (0.0084 �� 0.0036 mg/kg, ww) and lead (0.0379 �� 0.0303 mg/kg, ww) were determined in chub mackerel and in sardine, respectively. Intra- and inter-specific variability of metals bioaccumulation was statistically assessed and species and length revealed to be the major influencing biometric factors, in particular for mercury and arsenic. Muscles present metal concentrations below the tolerable limits considered by European Commission Regulation and Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO). However, estimation of non-carcinogenic and carcinogenic health risks by the target hazard quotient and target carcinogenic risk, established by the US Environmental Protection Agency, suggests that these species must be eaten in moderation due to possible hazard and carcinogenic risks derived from arsenic (in all analyzed species) and mercury ingestion (in horse and chub mackerel species).

Toxicity of chromated copper arsenate: a study in mice

Chromated copper arsenate (CCA) was widespread used as a chemical wood preservative with application in the construction of playground equipment, fences, jetties, and naval. Environmental protection agency (EPA) had limited the use of CCA-treated wood on 2002, due to probable implications on both human and environmental health. Although this fact, several industries pursue the use of this product within their manufactories. In addition, the durability of this wood for 60 years, makes these treated products an hazard to the public health. In the present work, studies were explored exposing mice to CCA, during 14, 24, 48, and 96 h for the assessment of acute toxicity of CCA. Kidney and liver were removed, prepared for histology and for metalloid, and copper content evaluation by high resolution inductively coupled plasma mass spectroscopy. The histological results evidenced apparently normal structures for control animals and group exposed to As2O5. On the contrary, the renal sections of the animals treated with CCA revealed epithelium cells desquamation, hyaline, and granular casts in renal tubules lumen. Furthermore, high levels of arsenic were detected in the kidney of animals treated with CCA over 14 and 48 h, being significantly greater than controls. Although this approach underlines the potential hazard of CCA on some vital organs, further testing may be required to establish the impacts on other functions.

Determina����o do teor de compostos arom��ticos polic��clicos de ��leos minerais isolantes para transformadores

Mestrado em Engenharia Qu��mica - Ramo Optimiza����o Energ��tica na Ind��stria Qu��mica

Trace metals in size-fractionated particulate matter in a Portuguese hospital: exposure risks assessment and comparisons with other countries

Hospitals are considered as a special and important type of indoor public place where air quality has significant impacts on potential health outcomes. Information on indoor air quality of these environments, concerning exposures to particulate matter (PM) and related toxicity, is limited though. This work aims to evaluate risks associated with inhalation exposure to ten toxic metals and chlorine (As, Ni, Cr, Cd, Pb, Mn, Se, Ba, Al, Si, and Cl) in coarse (PM2.5���10) and fine (PM2.5) particles in a Portuguese hospital in comparison with studies representative of other countries. Samples were collected during 1 month in one urban hospital; elemental PM characterization was determined by proton-induced X-ray emission. Noncarcinogenic and carcinogenic risks were assessed according to the methodology provided by the United States Environmental Protection Agency (USEPA; Region III Risk-Based Concentration Table) for three different age categories of hospital personnel (adults, >20, and <65 years) and patients (considering nine different age groups, i.e., children of 1���3 years to seniors of >65 years). The estimated noncarcinogenic risks due to occupational inhalation exposure to PM2.5-bound metals ranged from 5.88��10���6 for Se (adults, 55���64 years) to 9.35��10���1 for As (adults, 20���24 years) with total noncarcinogenic risks (sum of all metals) above the safe level for all three age categories. As and Cl (the latter due to its high abundances) were the most important contributors (approximately 90 %) to noncarcinogenic risks. For PM2.5���10, noncarcinogenic risks of all metals were acceptable to all age groups. Concerning carcinogenic risks, for Ni and Pb, they were negligible (<1��10���6) in both PM fractions for all age groups of hospital personnel; potential risks were observed for As and Cr with values in PM2.5 exceeding (up to 62 and 5 times, respectively) USEPA guideline across all age groups; for PM2.5���10, increased excess risks of As and Cr were observed particularly for long-term exposures (adults, 55���64 years). Total carcinogenic risks highly (up to 67 times) exceeded the recommended level for all age groups, thus clearly showing that occupational exposure to metals in fine particles pose significant risks. If the extensive working hours of hospital medical staff were considered, the respective noncarcinogenic and carcinogenic risks were increased, the latter for PM2.5 exceeding the USEPA cumulative guideline of 10���4. For adult patients, the estimated noncarcinogenic and carcinogenic risks were approximately three times higher than for personnel, with particular concerns observed for children and adolescents.

Avalia����o do papel da glutationa e do vac��olo como mecanismos de defesa contra a toxicidade induzida pelo chumbo na levedura Saccharomyces cerevisiae

A presen��a de metais pesados no meio ambiente deve-se, principalmente, a actividades antropog��nicas. Ao contr��rio do Cu e do Zn, que em baixas concentra����es s��o essenciais para o normal funcionamento celular, n��o se conhece para o chumbo nenhuma fun����o biol��gica. O chumbo apresenta efeitos t��xicos, e considerado poss��vel agente carcinog��neo, sendo classificado como poluente priorit��rio pela Agencia de Protec����o Ambiental dos EUA (US-EPA). O presente trabalho teve como objetivo avaliar o papel da glutationa e do vac��olo, como mecanismos de defesa, contra os efeitos t��xicos induzidos pelo chumbo, usando como modelo a levedura Saccharomyces cerevisiae. A levedura S. cerevisiae quando exposta a varias concentra����es de chumbo, durante 3h, perde a viabilidade e acumula esp��cies reativas de oxig��nio (ROS). O estudo comparativo da perda de viabilidade e acumula����o de ROS em c��lulas de uma estirpe selvagem (WT) e de estirpes mutantes, incapazes de produzir glutationa devido a uma defici��ncia no gene GSH1 (���gsh1) ou GSH2 (���gsh2) mostrou que as estirpes ���gsh1 ou(���gsh2 n��o apresentavam um aumento da sensibilidade ao efeito toxico do chumbo. No entanto, o tratamento de c��lulas da estirpe WT com iodoacetamida (um agente alquilante que induz a deple����o de glutationa) aumentou a sensibilidade das c��lulas a presen��a de chumbo. Pelo contr��rio, o enriquecimento em GSH, atrav��s da incuba����o de c��lulas WT com glucose e uma mistura de amino��cidos que constituem a GSH (acido L-glut��mico, L-ciste��na e glicina), reduziu o stress oxidativo e a perda de viabilidade induzida por chumbo. A import��ncia do vac��olo, como mecanismo de defesa, foi avaliada atrav��s da utiliza����o de um mutante sem qualquer estrutura vacuolar (���vps16) ou de mutantes deficientes na subunidade catal��tica A (���vma1) ou B (���vma2) ou no proteol��tico - subunidade C (���vma3) da V-ATPase. As c��lulas da estirpe ����vps16 apresentaram uma elevada suscetibilidade a presen��a de chumbo. As c��lulas das estirpes deficientes na subunidade A, B ou c da V-ATPase, apresentaram uma maior perda de viabilidade, quando expostas a chumbo, do que as c��lulas da estirpe WT, mas menor do que a da estirpe ���vps16 Em conclus��o, os resultados obtidos, no seu conjunto, sugerem que a glutationa esta envolvida na defesa contra a toxicidade provocada por chumbo; todavia, a glutationa, por si s��, parece n��o ser suficiente para suster o stress oxidativo e a perda de viabilidade induzida por chumbo. O vac��olo parece constituir um importante mecanismo de defesa contra a toxicidade provocada por chumbo. A V-ATPase parece estar envolvida na compartimenta����o de chumbo no vac��olo.

Exposure to polycyclic aromatic hydrocarbons and assessment of potential risks in preschool children

As children represent one of the most vulnerable groups in society, more information concerning their exposure to health hazardous air pollutants in school environments is necessary. Polycyclic aromatic hydrocarbons (PAHs) have been identified as priority air pollutants due to their mutagenic and carcinogenic properties that strongly affect human health. Thus, this work aims to characterize levels of 18 selected PAHs in preschool environment, and to estimate exposure and assess the respective risks for 3���5-year-old children (in comparison with adults). Gaseous PAHs (mean of 44.5��������12.3 ng m���3) accounted for 87 % of the total concentration (��PAHs) with 3���ringed compounds being the most abundant (66 % of gaseous ��PAHs). PAHs with 5 rings were the most abundant ones in the particulate phase (PM; mean of 6.89��������2.85 ng m���3) being predominantly found in PM1 (78 % particulate ��PAHs). Overall child exposures to PAHs were not significantly different between older children (4���5 years old) and younger ones (3 years old). Total carcinogenic risks due to particulate-bound PAHs indoors were higher than outdoor ones. The estimated cancer risks of both preschool children and the staff were lower than the United States Environmental Protection Agency (USEPA) threshold of 10���6 but slightly higher than WHO-based guideline.