Sister chromatid exchanges in Vicia faba induced by arsenic-contaminated drinking water from Zimapan, Hidalgo, Mexico

Arsenic in waters, soils, sediments, and biota from Mexico: An environmental review

We reviewed over 226 studies dealing with arsenic (As) in water bodies (124 sites or regions; 5,834 samples), soils (44; 2,700), sediments (56; 765), rocks (6; 85), mine waste (25; 582), continental plants (17 (77 species); 571), continental animals (10 (32 species); 3,525) and aquatic organisms (27 (100 species) 2,417) in Mexico. In general, higher As concentrations were associated with specific regions in the states of Hidalgo (21 sites), San Luis Potosi (SLP) (19), Baja California Sur (15), Zacatecas (5), and Morelos (4). High As levels have been detected in drinking water in certain locations of Coahuila (up to 435 μg L^-1) and Sonora (up to 1004 μg L^-1); in continental surficial water in Puebla (up to 780 μg L^-1) and Matehuala, SLP (up to 8684 μg L^-1); in groundwater in SLP (up to 16,000 μg L^-1) and Morelia, Michoacán (up to 1506,000 μg L^-1); in soils in Matehuala, SLP (up to 27,945 μg g^-1) and the Xichú mining area, Guanajuato (up to 62,302 μg g^-1); and in sediments in Zimapán, Hidalgo (up to 11,810 μg g^-1) and Matehuala, SLP (up to 28,600 μg g^-1). In contaminated arid and semi-arid areas, the plants P. laevigata and A. farnesiana exhibit the highest As levels. These findings emphasize the human and environmental risks associated with the presence of As in such regions. A synthesis of the available techniques for the removal of As in water and the remediation technologies for As contaminated soils and sediments is given. The As occurrence, origin (geogenic, thermal, mining and anthropogenic) and evolution in specific regions is summarized. Also, the mobilization and mechanisms to explain the As variability in continental environments are concisely given. For future research, a stratified regional sampling is proposed which prioritizes critical sites for waters, soils and sediments, and biota, considering the subpopulation of foods from agriculture, livestock, and seafood. It is concluded that more detailed and comprehensive studies concerning pollution levels, as well as As trends, transfer, speciation, and toxic effects are still required.

Vicia faba bioassay for environmental toxicity monitoring: A review

Higher plants are recognized as excellent genetic models to detect cytogenetic and mutagenic agents and are frequently used in environmental monitoring studies. Vicia faba (V. faba) bioassay have been used to study DNA damages i.e., chromosomal and nuclear aberrations induced by metallic compounds, pesticides, complex mixtures, petroleum derivates, toxins, nanoparticles and industrial effluents. The main advantages of using V. faba is its availability round the year, economical to use, easy to grow and handle; its use does not require sterile conditions, rate of cell division is fast, chromosomes are easy to score, less expensive and more sensitive as compared to other short-term tests that require pre-preparations. The V. faba test offers evaluation of different endpoints and tested agents can be classified as cytotoxic/genotoxic/mutagenic. This test also provides understanding about mechanism of action, whether the tested agent is clastogenic or aneugenic in nature. In view of advantages offered by V. faba test system, it is used extensively to assess toxic agents and has been emerged as an important bioassay for ecotoxicological studies. Based on the applications of V. faba test to assess the environmental quality, this article offers an overview of this test system and its efficiency in assessing the cytogenetic and mutagenic agents in different classes of the environmental concerns.

Arsenic and fluoride in the groundwater of Mexico

Concentrations of arsenic and fluoride above Mexican drinking water standards have been detected in aquifers of various areas of Mexico. This contamination has been found to be mainly caused by natural sources. However, the specific processes releasing these toxic elements into groundwater have been determined in a few zones only. Many studies, focused on arsenic-related health effects, have been performed at Comarca Lagunera in northern México. High concentrations of fluoride in water were also found in this area. The origin of the arsenic there is still controversial. Groundwater in active mining areas has been polluted by both natural and anthropogenic sources. Arsenic-rich minerals contaminate the fractured limestone aquifer at Zimapán, Central México. Tailings and deposits smelter-rich fumes polluted the shallow granular aquifer. Arsenic contamination has also been reported in the San Antonio-El Triunfo mining zone, southern Baja California, and Santa María de la Paz, in San Luis Potosí state. Even in the absence of mining activities, hydrogeochemistry and statistical techniques showed that arsenopyrite oxidation may also contaminate water, as in the case of the Independencia aquifer in the Mexican Altiplano. High concentrations of arsenic have also been detected in geothermal areas like Los Azufres, Los Humeros, and Acoculco. Prevalence of dental fluorosis was revealed by epidemiological studies in Aguascalientes and San Luis Potosí states. Presence of fluoride in water results from dissolution of acid-volcanic rocks. In Mexico, groundwater supplies most drinking water. Current knowledge and the geology of Mexico indicate the need to include arsenic and fluoride determinations in groundwater on a routine basis, and to develop interdisciplinary studies to assess the contaminant's sources in all enriched areas.

Residential exposure to drinking water arsenic in Inner Mongolia, China

In the Ba Men region of Inner Mongolia, China, a high prevalence of chronic arsenism has been reported in earlier studies. A survey of the arsenic contamination among wells from groundwater was conducted to better understand the occurrence of arsenic (As) in drinking water. A total of 14,866 wells (30% of all wells in the region) were analyzed for their arsenic-content. Methods used to detect arsenic were Spectrophotometric methods with DCC-Ag (detection limit, 0.5 microg of As/L); Spot method (detection limit, 10 microg of As/L); and air assisted Colorimetry method (detection limit, 20 microg of As/L). Arsenic-concentrations ranged from below limit of detection to 1200 microg of As/L. Elevated concentrations were related to well depth (10 to 29 m), the date the well was built (peaks from 1980-1990), and geographic location (near mountain range). Over 25,900 individuals utilized wells with drinking water arsenic concentrations above 20 microg of As/L (14,500 above 50 microg of As/L-the current China national standard in drinking water and 2198 above 300 microg of As/L). The presented database of arsenic in wells of the Ba Men region provides a useful tool for planning future water explorations when combined with geological information as well as support for designing upcoming epidemiological studies on the effects of arsenic in drinking water for this region.

Sister chromatid exchange analysis in smelting plant workers exposed to arsenic

There are many studies documenting the genotoxic effects of environmental exposure to arsenic. Nevertheless, few data are available on the genotoxic risks of occupational arsenic exposure. In the present study, we have evaluated whether or not occupational exposure to arsenic in a copper smelting plant results in a significant increase in the frequency of sister chromatid exchange (SCE). SCE frequencies, proliferation rate index (PRI), and high frequency cells (HFCs) were evaluated in peripheral blood lymphocytes from a group of 105 arsenic-exposed workers from a Chilean smelting plant (exposed group). Similar assays were conducted on a group of 55 workers employed at the same mine but involved in administrative jobs (internal control), and on 48 workers of another mine, with no significant levels of arsenic (external control). Small but significant increases in SCE frequency were observed in the arsenic-exposed workers compared with the external control group (6.28+/-0.09 vs. 5.84+/-0.14 SCE/cell; P<0.01). Also, significantly higher frequencies of HFCs were observed in the exposed group (2.21%+/-0.20%) than in either the external control group (1.20+/-0.23; P=0.002) or the internal control group (1.30+/-0.24; P=0.008). However, there was no relationship between arsenic levels in the urine of the subjects and SCE or HFC frequency. The results of the study indicate that copper smelting results in slightly increased levels of DNA damage. However, our data were not consistent with arsenic exposure being the cause of the increase.

Genetic toxicology of a paradoxical human carcinogen, arsenic: a review

Arsenic is widely distributed in nature in air, water and soil in the form of either metalloids or chemical compounds. It is used commercially, as pesticide, wood preservative, in the manufacture of glass, paper and semiconductors. Epidemiological and clinical studies indicate that arsenic is a paradoxical human carcinogen that does not easily induce cancer in animal models. It is one of the toxic compounds known in the environment. Intermittent incidents of arsenic contamination in ground water have been reported from several parts of the world. Arsenic containing drinking water has been associated with a variety of skin and internal organ cancers. The wide human exposure to this compound through drinking water throughout the world causes great concern for human health. In the present review, we have attempted to evaluate and update the mutagenic and genotoxic effects of arsenic and its compounds based on available literature.

In vivo and in vitro promutagen activation by Vicia faba of thiocarbamate herbicides molinate and butylate to products inducing sister chromatid exchanges in human lymphocyte cultures

Molinate and butylate treatments for 4 h of Vicia faba root tip meristems, showed that both thiocarbamate herbicides increased significantly SCE frequency. Direct treatments of molinate and butylate on human lymphocytes applied 24 h after the beginning of culture did not induce SCE. When S10 extracts of the Vicia roots, treated for 4 h with molinate and butylate (in vivo activation) were added to lymphocytes (24 h after of the beginning of culture), SCE were induced in a concentration-response manner. The in vitro assays, in which molinate and butylate was added at 48 h lymphocyte cultures for 4 h, showed a negative response, however, in the treatment where the S10 metabolic mix was added the SCE frequencies were significantly different to the control, and the concentration-response relationship was not observed with molinate, but it was obtained with butylate. The results showed that both herbicides needed the V. faba metabolism to produce SCE in human lymphocyte culture.