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Heavy metal contamination in raw materials has spread widely in the United States. The high increased number of recalls in consumer products and the lack of stricter regulations in the raw materials to be used in the jewelry industry have raised concerns among consumers. Studies in low-cost jewelry have shown the presence and high content of heavy metals; this environmental problem led to a child's death after swallowing a charm containing elevated levels of lead (Pb). Exposure to heavy metals, through inhalation, mouth, and skin contact, causes adverse health effects in children and adults. Exposure to lead affects mainly the nervous system and brain development; exposure to cadmium (Cd) causes damage to liver, kidneys, and lungs, and potentially leads to cancer; exposure to nickel (Ni) causes severe dermatitis. Thus, the importance and impact of studies of this nature cannot be overstated. As heavy metal contamination has increased in the United States, this research fills an important knowledge gap between previous studies conducted on low-cost jewelry and fine jewelry. In this study, conducted in the Paso del Norte region, one hundred and forty-three pieces of fine jewelry were evaluated for the presence of heavy metals using X-ray fluorescence (XRF) spectroscopy. Our study showed that 61 samples (42.7 %) exhibited the presence of Ni in the metal alloy, prevailing in jewelry pieces with lower percentage of gold. Eighteen samples showed the presence of Pb in gemstones, 11 pieces of these samples (7.7 % total) had <33.3 % gold (≤10 K); however, none of the samples showed the presence of Pb in the metal alloy. Further research is needed to evaluate the bioaccessibility of Pb in these gemstones, which may pose a potential health hazard to children and adults in the US Paso del Norte region and throughout the world.

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The Juarez Valley is an important agricultural region in northern Mexico, conveniently organized into three modules (I to III). For decades, their soils have been exposed to organochlorine pesticides (OCPs) and also have been irrigated with wastewaters, which may contain heavy metals. Nowadays, there is very limited information regarding the presence of OCPs and heavy metals in these soils. Thus, the aim of this study was to diagnose these soils for OCPs and heavy metal content by using gas chromatography coupled with electron micro-capture detector and atomic absorption spectrometry, respectively. The results indicated that 4,4'-dichlorodiphenyldichloroethylene and 4,4'-dichlorodiphenyltrichloroethane were primarily disseminated across the three modules since they were found in 100% and 97% of the analyzed soils, respectively. According to international regulations, none of the determined OCP concentrations are out of the limits. Additionally, the Cu, Zn, Fe, Pb, and Mn were found in all sampled soils from the three modules. The highest concentration of Fe was found in module II (1902.7 ± 332.2 mg kg-1), followed by Mn in module III (392.43 ± 74.43 mg kg-1), Zn in module I (38.36 ± 26.57 mg kg-1), Pb in module II (23.48 ± 6.48 mg kg-1), and Cu in module I (11.04 ± 3.83 mg kg-1) (p ≤ 0.05). These values did not exceed the limits proposed by international standards. The Cd was detected in most of the analyzed soils and all their values, with an average of 2 mg kg-1, surpassed the Mexican standards (0.35 mg kg-1). This study has mapped the main OCPs and heavy metals in the Juarez Valley and can serve as a starting point to further monitor the behave of xenobiotics. Since these recalcitrant compounds might be bio-accumulated in biological systems, further analytical methods, as well as remediation techniques, should be developed.

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The Paso del Norte region is characterized by its dynamic industries and active agriculture. Throughout the years, urban and agricultural soils from this region have been exposed to xenobiotics, heavy metals, and excess of hydrocarbons. In this study, samples of urban [domestic workshops (DW)] and agricultural-intended (AI) soils from different sites of Ciudad Juárez, Mexico were evaluated for their fertility, element content, and microbial diversity. Chemical analyses showed that nitrites, nitrates, P, K, Mg, and Mn were predominantly higher in AI soils, compared to DW soils (p ≤ 0.05). The composition of soil microbial communities showed that Proteobacteria phylum was the most abundant in both soils (67%, p ≤ 0.05). In AI soils, Paracoccus denitrificans was reduced (p ≤ 0.05), concurring with an increment in nitrates, while the content of nitrogen was negatively correlated with the rhizobium group (r2 = -0.65, p ≤ 0.05). In DW soils, the Firmicutes phylum represented up to ~25%, and the relative abundance of Proteobacteria strongly correlated with a higher Cu content (r2 = 0.99, p ≤ 0.0001). The monotypic genus Sulfuricurvum was found only in oil-contaminated soil samples. Finally, all samples showed the presence of the recently created phylum Candidatus saccharibacteria. These results describe the productivity parameters of AI soils and its correlation to the microbial diversity, which are very important to understand and potentiate the productivity of soils. The data also suggest that soils impacted with hydrocarbons and metal(oid)s allow the reproduction of microorganisms with the potential to alleviate contaminated sites.

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Bulk Cu compounds such as Cu(OH)2 are extensively used as pesticides in agriculture. Recent investigations suggest that Cu-based nanomaterials can replace bulk materials reducing the environmental impacts of Cu. In this study, stress responses of alfalfa (Medicago sativa L.) seedlings to Cu(OH)2 nanoparticle or compounds were evaluated. Seeds were immersed in suspension/solutions of a Cu(OH)2 nanoform, bulk Cu(OH)2, CuSO4, and Cu(NO3)2 at 25 and 75 mg/L. Six days later, the germination, seedling growth, and the physiological and biochemical responses of sprouts were evaluated. All Cu treatments significantly reduced root elongation (average = 63%). The ionic compounds at 25 and 75 mg/L caused a reduction in all elements analyzed (Ca, K, Mg, P, Zn, and Mn), excepting for S, Fe and Mo. The bulk-Cu(OH)2 treatment reduced K (48%) and P (52%) at 75 mg/L, but increased Zn at 25 (18%) and 75 (21%) mg/L. The nano-Cu(OH)2 reduced K (46%) and P (48%) at 75 mg/L, and also P (37%) at 25 mg/L, compared with control. Confocal microscopy images showed that all Cu compounds, at 75 mg/L, significantly reduced nitric oxide, concurring with the reduction in root growth. Nano Cu(OH)2 at 25 mg/L upregulated the expression of the Cu/Zn superoxide dismutase gene (1.92-fold), while ionic treatments at 75 mg/L upregulated (∼10-fold) metallothionein (MT) transcripts. Results demonstrated that nano and bulk Cu(OH)2 compounds caused less physiological impairments in comparison to the ionic ones in alfalfa seedlings.

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The effects of nCeO2 on food quality are not well known yet. This research was performed to determine the impact of nCeO2 on radish (Raphanus sativus L.). Plants were cultivated to full maturity in potting soil treated with nCeO2 at concentrations of 0, 62.5, 125, 250, and 500 mg/kg. Germination, growth, photosynthesis, ionome, and antioxidants were evaluated at different growth stages. Results showed that at 500 mg/kg, nCeO2 significantly retarded seed germination but did not reduce the number of germinated seeds. None of the treatments affected gas exchange, photosynthesis, growth, phenols, flavonoids, and nutrients' accumulation in tubers and leaves of adult plants. However, tubers' antioxidant capacity, expressed as FRAP, ABTS(•-) and DPPH, increased by 30%, 32%, and 85%, respectively, in plants treated with 250 mg nCeO2kg(-1) soil. In addition, cerium accumulation in tubers of plants treated with 250 and 500 mg/kg reached 72 and 142 mg/kg d wt, respectively. This suggests that nCeO2 could improve the radical scavenging potency of radish but it might introduce nCeO2 into the food chain with unknown consequences.

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We identified contaminants associated with the Cata mine tailing depot located in the outskirts of the city of Guanajuato, Mexico. We also investigated strategies for their phytomanagement. Silver and antimony were present at 39 and 31 mg kg(-1), respectively, some twofold higher than the Dutch Intervention Values. Total and extractable boron (B) occurred at concentrations of 301 and 6.3 mg L(-1), respectively. Concentrations of B in soil solution above 1.9 mg L(-1) have been shown to be toxic to plants. Plant growth may also be inhibited by the low concentrations of extractable plant nutrients. Analysis of the aerial portions of Aloe vera (L. Burm.f.) revealed that this plant accumulates negligible concentrations of the identified contaminants. Calculations using a whole system model (Phyto-DSS) showed that establishing a crop of A. vera would have little effect on the drainage or leaching from the site. However, this plant would reduce wind and water erosion and potentially produce valuable cosmetic products. In contrast, crops of poplar, a species that is tolerant to high soil B concentrations, would mitigate leaching from this site. Alternate rows of trees could be periodically harvested and be used for timber or bioenergy.

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The objective of this study was to examine how changes in the benthic macroinvertebrate community structure and a variety of abiotic variables, such as conductivity and sediment metal concentrations, are modified along the Forgotten River stretch of the Rio Grande. This stretch receives industrial effluent, raw sewage, and agricultural return flow from the El Paso (TX, USA)-Ciudad Juárez (CHI, Mexico) metroplex and then flows relatively undisturbed for 320 km before its next significant input. The high degree of use, followed by the 320-km undisturbed stretch, makes the Forgotten River a unique study site to examine downstream attenuation of contaminants and other abiotic variables to determine their potential effects on macroinvertebrates. Five different sites along the Forgotten Stretch were sampled over a 2-year period. Metal concentrations were low throughout the stretch and were predominantly correlated to percent sediment organic matter rather than explained spatially. Several sensitive invertebrate species, such as Leptophlebiidae, increased in relative abundance downstream, whereas the percentage of tolerant invertebrates decreased. Nonmetric multidimensional scaling separated the macroinvertebrate communities upstream from those downstream, with the more sensitive species being found predominantly downstream and more tolerant taxa associated upstream. Additionally, there was a distinct seasonal gradient to the community. The most important drivers of the community assemblage appear to be distance downstream and seasonality, as well as water conductivity and concentrations of sediment cadmium, which was the only metal that exceeded protective criteria. This study did not provide evidence of the downstream attenuation of heavy metals in the sediments in the Forgotten Stretch; however, downstream changes in macroinvertebrates toward more sensitive taxa suggests that other, unmeasured contaminants might be affecting biological communities in this isolated stretch of an international waterway.

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This report shows, for the first time, the effectiveness of the phytohormone kinetin (KN) in increasing Cr translocation from roots to stems in Mexican Palo Verde. Fifteen-day-old seedlings, germinated in soil spiked with Cr(III) and (VI) at 60 and 10 mg kg(-1), respectively, were watered every other day for 30 days with a KN solution at 250 µM. Samples were analyzed for catalase (CAT) and ascorbate peroxidase (APOX) activities, Cr concentration, and Cr distribution in tissues. Results showed that KN reduced CAT but increased APOX in the roots of Cr(VI)-treated plants. In the leaves, KN reduced both CAT and APOX in Cr(III) but not in Cr(VI)-treated plants. However, KN increased total Cr concentration in roots, stems, and leaves by 45%, 103%, and 72%, respectively, compared to Cr(III) alone. For Cr(VI), KN increased Cr concentrations in roots, stems, and leaves, respectively, by 53%, 129%, and 168%, compared to Cr(VI) alone. The electron probe microanalyzer results showed that Cr was mainly located at the cortex section in the root, and Cr distribution was essentially homogeneous in stems. However, proven through X-ray images, Cr(VI)-treated roots and stems had more Cr accumulation than Cr(III) counterparts. KN increased the Cr translocation from roots to stems.

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OBJECTIVE: To establish the degree of contamination by arsenic in drinking water in the Los Altos de Jalisco (LAJ) region of west-central Mexico, and to estimate the levels of exposure that residents of the area face. METHODS: Total arsenic concentration (the sum of all arsenic forms, organic and inorganic) was determined for 129 public water wells in 17 municipal capitals (cabeceras municipales) of the LAJ region, using inductively coupled plasma-optical emission spectroscopy. For most of the wells, water samples were taken in both November 2002 and October 2003. The levels of exposure to arsenic were estimated for babies (10 kg), children (20 kg), and adults (70 kg). RESULTS: Mean concentrations of arsenic higher than the Mexican national guideline value of 25 æg/L were found in 44 (34 percent) of the 129 wells. The mean concentration of total arsenic for the 129 wells ranged from 14.7 æg/L to 101.9 æg/L. The highest concentrations were found in well water samples collected in the cities of Mexticacán (262.9 æg/L), Teocaltiche (157.7 æg/L), and San Juan de los Lagos (113.8 æg/L). Considering the global mean concentration for all the wells in each of the 17 cities, the mean concentration of arsenic exceeded the Mexican guideline value in 7 of the cities. However, the global mean concentration in all 17 cities was higher than the World Health Organization guideline value of 10 æg/L for arsenic. The range of the estimated exposure doses to arsenic in drinking water was 1.1-7.6 æg/kg/d for babies, 0.7-5.1 æg/kg/d for children, and 0.4-2.7 æg/kg/d for adults. CONCLUSIONS: At the exposure doses estimated in the LAJ region, the potential health effects from chronic arsenic ingestion include skin diseases, gastrointestinal effects, neurological damage, cardiovascular problems, and hematological effects. While all the residents may not be affected, an important fraction of the total population of the LAJ region is under potential health risk...

OBJETIVOS: Determinar el grado de contaminación con arsénico del agua potable en la región de Los Altos de Jalisco (LAJ), en la parte centrooccidental de México, y estimar el nivel de exposición que enfrentan los habitantes de esa zona. MÉTODOS: Se determinó la concentración total de arsénico (la suma de todas las formas de arsénico, tanto orgánicas como inorgánicas) en 129 pozos de agua públicos en 17 cabeceras municipales de LAJ, mediante espectroscopia de emisión óptica con plasma inductivamente acoplado. En la mayoría de los pozos se tomaron muestras en noviembre de 2002 y en octubre de 2003. En los restantes se tomó la muestra en uno de esos dos momentos. El nivel de exposición al arsénico se estimó para lactantes (10 kg), niños (20 kg) y adultos (70 kg). RESULTADOS: En 44 (34 por ciento) de los 129 pozos se encontraron concentraciones media de arsénico superiores al límite de 25 æg/L, establecido en la norma nacional mexicana. Las concentraciones media de arsénico total en los 129 pozos estuvieron entre 14,7 æg/L y 101,9 æg/L. Las mayores concentraciones se encontraron en las muestras de agua colectadas en los pozos de Mexticacán (262,9 æg/L), Teocaltiche (157,7 æg/L) y San Juan de los Lagos (113,8 æg/L). Si se toma en cuenta la concentración general de todos los pozos de cada una de las 17 ciudades, la concentración media de arsénico fue superior a lo establecido en la norma mexicana en 7 ciudades. La concentración media general en las 17 ciudades fue superior al valor de 10 æg/L establecido en los lineamientos de la Organización Mundial de la Salud. Los niveles estimados de las dosis de exposición al arsénico por el agua potable fue de 1,1-7,6 æg/kg/d en los lactantes, de 0,7-5,1 æg/kg/d en los niños y de 0,4-2,7 æg/kg/d en los adultos. CONCLUSIONES: Según la dosis de exposición estimada en la región de LAJ, la ingestión continuada de arsénico puede afectar a la salud y causar enfermedades de la piel, trastornos gastrointestinales, daños...

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OBJECTIVE: To establish the degree of contamination by arsenic in drinking water in the Los Altos de Jalisco (LAJ) region of west-central Mexico, and to estimate the levels of exposure that residents of the area face. METHODS: Total arsenic concentration (the sum of all arsenic forms, organic and inorganic) was determined for 129 public water wells in 17 municipal capitals (cabeceras municipales) of the LAJ region, using inductively coupled plasma-optical emission spectroscopy. For most of the wells, water samples were taken in both November 2002 and October 2003. The levels of exposure to arsenic were estimated for babies (10 kg), children (20 kg), and adults (70 kg). RESULTS: Mean concentrations of arsenic higher than the Mexican national guideline value of 25 micro g/L were found in 44 (34%) of the 129 wells. The mean concentration of total arsenic for the 129 wells ranged from 14.7 micro g/L to 101.9 micro g/L. The highest concentrations were found in well water samples collected in the cities of Mexticacán (262.9 micro g/L), Teocaltiche (157.7 micro g/L), and San Juan de los Lagos (113.8 micro g/L). Considering the global mean concentration for all the wells in each of the 17 cities, the mean concentration of arsenic exceeded the Mexican guideline value in 7 of the cities. However, the global mean concentration in all 17 cities was higher than the World Health Organization guideline value of 10 micro g/L for arsenic. The range of the estimated exposure doses to arsenic in drinking water was 1.1-7.6 micro g/kg/d for babies, 0.7-5.1 micro g/kg/d for children, and 0.4-2.7 micro g/kg/d for adults. CONCLUSIONS: At the exposure doses estimated in the LAJ region, the potential health effects from chronic arsenic ingestion include skin diseases, gastrointestinal effects, neurological damage, cardiovascular problems, and hematological effects. While all the residents may not be affected, an important fraction of the total population of the LAJ region is under potential health risk due to the ingestion of high levels of arsenic. Epidemiological studies to determine the arsenic levels in the blood, hair, and nails of humans should be conducted in the LAJ region to help assess the relationship between the prevalence of health problems and the chronic ingestion of arsenic.

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