Gas stations are important emissions source of benzene (C 6 H 6 ), toluene (C 7 H 8 ), ethylbenzene (C 8 H 10 ), and ortho, meta and para-xylene (C 8 H 10 )-better known by the acronym BTEX. The objective of this study was to determine the concentrations of BTEX compounds in the ambient air of ten gas stations in the cities of Salvador and Feira de Santana, Bahia, Brazil and evaluate the health risks to workers. Passive samplers diffusive of the Radiello®, containing activated carbon as adsorbent, were used. The samplers were exposed for 8 h and then the analytes were recovered by chemical desorption with CS 2 and determined by GC-FID. The BTEX concentrations found in the ambient air of gas stations ranged from 46.72 -435.43 μg·m −3 for benzene;25.54 -342.46 μg·m −3 for toluene, 7.10 -30.07 μg·m −3 for ethylbenzene, 9.36 -89.73 μg·m −3 for m, p-xylene and 9.79 -52.29 μg·m −3 for o-xylene. The concentrations of toluene, ethylbenzene and xylenes found in gas stations were lower than the limits recommended by the US NIOSH and NR-15 of the Ministry of Labour of Brazil; however, it should be considered the risks due to chronic exposure of workers. Benzene concentrations in three gas stations were above the exposure limit recommended by NIOSH (3.20 × 10 2 μg·m −3). Samplings were also held outdoors at 250 m of two gas stations. The total concentrations of the BTEX compounds were equal to 24.97 and 35.51 μg·m −3

Lymphocytes activated by mitogenic lectins display changes in transmembrane potential, an elevation in the cytoplasmic Ca 2+ concentrations, proliferation and/or activation induced cell death. Low concentrations of ouabain (an inhibitor of Na + ,K + -ATPase) suppress mitogen-induced proliferation and increases cell death. To understand the mechanisms involved, a number of parameters were analyzed using fluorescent probes and flow cytometry. The addition of 100nM ouabain to cultures of peripheral blood lymphocytes activated with 5µg/ml phytohemagglutinin (PHA) did not modify the increased expression of the Fas receptor or its ligand FasL induced by the mitogen. However, treatment with ouabain potentiated apoptosis induced by an anti-Fas agonist antibody. A synergy between ouabain and PHA was also observed with regard to plasma membrane depolarization. PHA per se did not induce dissipation of mitochondrial membrane potential but when cells were also exposed to ouabain a marked depolarization could be observed, and this was a late event. It is possible that the inhibitory effect of ouabain on activated peripheral blood lymphocytes involves the potentiation of some of the steps of the apoptotic process and reflects an exacerbation of the mechanism of activation-induced cell death.

To show the risks and harm caused by the occupational exposure to the benzene, toluene, ethylbenzene and xylenes compounds (BTEX), the working conditions of 113 persons employed at gas stations in the cities of Riachão do Jacuipe, Feira de Santana and Salvador in the state of Bahia, Brazil were investigated by experts who correlated protection measures required by law and those applied to the workers. Data collection was performed by help of a questionnaire and non-participant observation record. The age groups of the workers in the three cities surveyed were between 18 to 25 years (30.08%) and 26 to 33 years (34.51%) of the total. The study revealed an association between occupational habits of workers at gas stations and the prevalence of symptoms due to the exposure to the BTEX compounds. Regarding the use of Personal Protective Equipment (PPE) most workers wear boots. The data show that these workers reported symptoms such as headache, rhinitis, leg pain, drowsiness, cough, fatigue, insomnia, tremors and palpitations. These disorders are related back to previous exposure to BTEX compounds which is associated with inadequate occupational habits of the workers which potentiate chemical contamination in their respective environment.

The medicinal plant Jatropha curcas exerts beneficial effects against ethanol toxicity in humans. In this work, we investigated the protective effect of three extracts (ethanol [Et], vegetal glycerin [VG], and propylene glycol [PG]) of J. curcas leafs against Et‐induced damage in human peripheral blood mononuclear cells. The cytotoxicity of the extracts alone or in combination with each other in mononuclear cells was also assessed. A thermodynamic and kinetic analysis of the protection assumed that the cells were in a metastable equilibrium of growth and death, and the mass action of the extracts was used to determine the optimal concentration for each extract. The PG and VG extracts were cytotoxic, with an efficiency index of protection (η) of approximately −20% and −41%, respectively. By contrast, η values of ∼220% were observed for Et extracts (0.625% vol/vol) and combined extracts (Et + PG) at concentrations of (0.375 + 0.250)% and (0.5 + 0.5)%, respectively. These results identify J. curcas as a promising source of bioactive compounds and show that appropriate modeling can provide a powerful system for determining the optimal conditions for drug action.

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