Mercury is considered one of the most toxic elements for plants and animals. Nevertheless, in the Middle East, Asia and Latin America, whitening creams containing mercury are being manufactured and purchased, despite their obvious health risks. Due to the mass distribution of these products, this can be considered a global public health issue. In Mexico, these products are widely available in pharmacies, beauty aid and health stores. They are used for their skin lightening effects. The aim of this work was to analyze the mercury content in some cosmetic whitening creams using the cold vapor technique coupled with atomic absorption spectrometry (CV-AAS). A total of 16 skin-lightening creams from the local market were investigated. No warning information was noted on the packaging. In 10 of the samples, no mercury was detected. The mercury content in six of the samples varied between 878 and 36,000 ppm, despite the fact that the U.S. Food and Drug Administration (FDA) has determined that the limit for mercury in creams should be less than 1 ppm. Skin creams containing mercury are still available and commonly used in Mexico and many developing countries, and their contents are poorly controlled.

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Bioavailability and hence bioaccumulation of heavy metals in fish species depends on seasonal conditions causing different risks levels to human health during the lifetime. Mercury, cadmium and lead contents in fish from Chihuahua (Mexico) water reservoirs have been investigated to assess contamination levels and safety for consumers. Muscle samples of fish were collected across the seasons. Lead and cadmium were analyzed by inductively coupled plasma-optical emission spectrometry, and mercury by cold-vapor atomic absorption spectrometry. The highest concentrations of cadmium (0.235 mg/kg), mercury (0.744 mg/kg) and lead (4.298 mg/kg) exceeded the maximum levels set by European regulations and Codex Alimentarius. Lead concentrations found in fish from three water reservoirs also surpassed the limit of 1 mg/kg established by Mexican regulations. The provisional tolerable weekly intake (PTWI) suggested by the World Health Organization for methyl mercury (1.6 µg/kg bw per week) was exceeded in the spring season (1.94 µg/kg bw per week). This might put consumers at risk of mercury poisoning.

Water reservoirs in Chihuahua County, Mexico, are affected by some punctual and non-punctual geogenic and anthropogenic pollution sources; fish are located at the top of the food chain and are good indicators for the ecosystems pollution. The study goal was to: (i) determine arsenic concentration in fish collected from the Chuviscar, Chihuahua, San Marcos and El Rejon water reservoirs; (ii) to assess if the fishes are suitable for human consumption and (iii) link the arsenic contents in fish with those in sediment and water reported in studies made the same year for these water reservoirs. Sampling was done in summer, fall and winter. The highest arsenic concentration in the species varied through the sampling periods: Channel catfish (Ictalurus punctatus) with 0.22 ± 0.15 mg/kg dw in winter and Green sunfish (Lepomis cyanellus) with 2.00 ± 0.15 mg/kg dw in summer in El Rejon water reservoir. A positive correlation of arsenic contents was found through all sampling seasons in fish samples and the samples of sediment and water. The contribution of the weekly intake of inorganic arsenic, based on the consumption of 0.245 kg fish muscles/body weight/week was found lower than the acceptable weekly intake of 0.015 mg/kg/body weight for inorganic arsenic suggested by FAO/WHO.

ResumenLa sustentabilidad de las ciudades debe basarse en gran medida por el capital ecológico que representa la vegetación, ya que constituye una alternativa para el estudio de la contaminación ambiental. Con el objetivo de determinar la capacidad de acumulación de azufre en cinco especies arbóreas fueron tomadas muestras de material foliar de 225 árboles ubicados en la ciudad de Chihuahua conforme a los usos de suelo comercial y servicio, industria mixta, industria pesada, residencial clase media-alta y residencial popular. A nivel de especie los niveles encontrados de azufre rebasaron los límites óptimos para su desarrollo. Con un análisis General Lineal se probaron las interacciones entre especie, sitio y temporada en el contenido de azufre en los árboles, determinando que la interacción significativa fue entre los factores temporada y sitio (P<0.0235). Con estos resultados se aportan elementos para la política ambiental urbana y la necesidad de contar con especies que determinen la calidad ambiental. Palabras clave: bioacumulador, desarrollo urbano, contaminación, uso de suelo Abstract Sustainability of cities should largely be based on the ecological capital represented by vegetation, which constitutes an alternative for the study of environmental pollution. In order to determine the capacity of sulfur accumulation in tree species, samples of leaf material were taken from 225 trees located in the city of Chihuahua taking into consideration commercial and land uses, mixed and heavy industry and low and middle class residential areas. At the species level, quantities of sulfur exceeded optimal levels for their development. Using General Linear Analysis interactions between species, site and season were tested for sulfur content in each tree, determining a significant interaction between season and site factors (P<0.0235). These results provide data for urban environmental policies and the need for finding species that determine environmental quality.