Calypso (thiacloprid), Poncho (clothianidin), Gaucho (imidacloprid), and Jade (imidacloprid) are commercial neonicotinoid insecticides, a new class of agrochemicals in México. However, genotoxic and cytotoxic studies have not been performed. In the present study, human peripheral blood lymphocytes (PBL) were exposedin vitroto different concentrations of the four insecticides. The genotoxic and cytotoxic effects were evaluated using the alkaline comet and trypan blue dye exclusion assays. DNA damage was evaluated using two genotoxicity parameters: tail length and comet frequency. Exposure to9.5×10-6to5.7×10-5 M Jade;2.8×10-4to1.7×10-3 M Gaucho;0.6×10-1to1.4×10-1 M Calypso;1.2×10-1to9.5×10-1 M Poncho for 2 h induced a significant increase DNA damage with a concentration-dependent relationship. Jade was the most genotoxic of the four insecticides studied. Cytotoxicity was observed in cells exposed to18×10-3 M Jade,2.0×10-3 M Gaucho,2.0×10-1 M Calypso, 1.07 M Poncho, and cell death occurred at30×10-3 M Jade,3.3×10-3 M Gaucho,2.8×10-1 M Calypso, and 1.42 M Poncho. This study provides the first report of genotoxic and cytotoxic effects in PBL followingin vitroexposure to commercial neonicotinoid insecticides.

This work presents the results obtained when determining the priority polycyclic aromatic hydrocarbon (PAH) concentration contained in particulate matter 10 μm in aerodynamic diameter or less (PM₁₀) and in the gas phase in Mexico City’s atmosphere by means of a field study conducted during 2005. PM₁₀ and vapor-phase PAHs were collected on prebaked quartz fiber filters and PUF-XAD-4 resin and quantified by gas chromatography (GC)-mass spectrometry. Vapor-phase PAHs comprised 86–97% of the total PAH mass, and naphthalene was the most abundant PAH determined, contributing 84–93% to the total mass. The benzo[a]pyrene content was on average 7% of the PAHs’ particle phase and 0.2–1% of the gas phase. The PAH concentrations measured where large industrial areas are located were 2–8 times greater during the fall/winter months (dry-cold season), when winds bear north- north-easterly, than in spring and summer. In contrast, the largest partition gas/particle ratio occurred during the dry-warm season (March–May). The results of statistical analysis using multivariate techniques suggest that motor vehicles are the main PAH contributors. The toxicity equivalence factors (TEFs) related to the carcinogenic benzo[a]pyrene potency were used for the assessment of the carcinogenic potential risk because of the measured airborne PAHs. Benzo[a]pyrene equivalent (BAPeq) concentrations were determined through multiplication of the individual PAH concentrations by their corresponding TEF value. The estimated total BAPeq for the whole field study considering only PM₁₀ PAHs was 1085 pg m^-3.However, when taking into account the PAHs in both phases, the estimated total BAPeq was 1250 pg m^-3; in either case, the values were greater than the 1000-pg m^-3 limit proposed by European countries.

Deficient management of cinnabar mining left the San Joaquín region with high concentrations of mercury in its soils (2.4 – 4164 mg kg-1). Numerous cinnabar mines have contributed to the dispersion of mercury into agricultural (0.5 –314 mg kg-1) and forest (0.2 – 69 mg kg-1) soils. Sediments are a natural means of transportation for mercury, causing its spreading, especially in areas near mine entrances (0.6 – 687 mg kg-1). The nearness of maize crops to mines favors mercury accumulation in the different plant structures, such as roots, stems, leaves, and grain (0.04 – 8.2 mg kg-1); these being related to mercury volatilization and accumulation in soils. Mercury vapor present in the settlements could indicate a constant volatilization from lands and soils (22 – 153 ng m-3). The mercury levels found in the soils, in maize grain, and in the air resulted greater than the standards reported by the Official Mexican Norm (NOM) and the World Health Organization (WHO). Mercury in rainwater is due mainly to the presence of suspended atmospheric particles, later deposited on the surface (1.5 – 339 μg |-1). Mercury dissolution was found in the drinking water (10 – 170 ng |-1), with concentrations below those established by the NOM and the WHO. The contamination existing in the San Joaquín region does not reach the levels of the world’s greatest mercury producers: Almaden (Spain) and Idrija (Slovenia). It is, however, like that found in other important second degree world producers such as Guizhou (China). The population of San Joaquín, as well as its surrounding environment, are constantly exposed to mercury contamination, thus making a long term monitoring necessary to determine its effects, especially to people