Geographical variations in arsenic contents in rice plants from Latin America and the Iberian Peninsula in relation to soil conditions.

Arsenic is a ubiquitous, toxic element that is efficiently accumulated by rice plants. This study assessed the spatial variability in the total As (tAs) contents and organic and inorganic forms in different types of rice, plant parts (husk, stem, leaves and phytoliths) and residues. Samples were collected in different countries in Latin America (Ecuador, Brazil and Peru) and the Iberian Peninsula (Spain and Portugal). The tAs content in commercial polished rice from the Latin American countries was similar (0.130-0.166 mg kg-1) and significantly lower than in the rice from the Iberian countries (0.191 ± 0.066 mg kg-1), and together, the tAs concentration in brown rice (236 ± 0.093 mg kg-1) was significantly higher than in polished and parboiled rice. The inorganic As (iAs) content in rice was similar in both geographical regions, and the aforementioned difference was attributed to dimethylarsinic acid (DMA). The relative abundance of organic species increased as the tAs content in rice grain increased. A meta-analysis of our and previously reported data confirmed the negative correlation between iAs/tAs and tAs. At low tAs concentrations, inorganic forms are dominant, while at higher values (tAs > 0.300 mg kg-1) the concentration of organic As increases substantially and DMA becomes the dominant form in rice grain. On the contrary, inorganic arsenic was always the dominant form, mainly as arsenate [As(V)], in leaves and stems. The presence in soils of high concentrations of amorphous Fe and Al oxides and hydroxides, which are capable of strongly adsorbing oxyanions (i.e. arsenate), was associated with low concentrations of As in rice plants. In addition, the presence of high concentrations of As(V) in stems and leaves, low concentration of As in phytoliths, and the As associated with organic matter in stems and husk, together suggest that rice plants take up more As(V) than As(III).

Cadmium bioaccumulation and gastric bioaccessibility in cacao: A field study in areas impacted by oil activities in Ecuador.

Cacao from South America is especially used to produce premium quality chocolate. Although the European Food Safety Authority has not established a limit for cadmium (Cd) in chocolate raw material, recent studies demonstrate that Cd concentrations in cacao beans can reach levels higher than the legal limits for dark chocolate (0.8 mg kg-1, effective January 1st, 2019). Despite the fact that the presence of Cd in agricultural soils is related to contamination by fertilizers, other potential sources must be considered in Ecuador. This field study was conducted to investigate Cd content in soils and cacao cultivated on Ecuadorian farms in areas impacted by oil activities. Soils, cacao leaves, and pod husks were collected from 31 farms in the northern Amazon and Pacific coastal regions exposed to oil production and refining and compared to two control areas. Human gastric bioaccessibility was determined in raw cacao beans and cacao liquor samples in order to assess potential health risks involved. Our results show that topsoils (0-20 cm) have higher Cd concentrations than deeper layers, exceeding the Ecuadorian legislation limit in 39% of the sampling sites. Cacao leaves accumulate more Cd than pod husks or beans but, nevertheless, 50% of the sampled beans have Cd contents above 0.8 mg kg-1. Root-to-cacao transfer seems to be the main pathway of Cd uptake, which is not only regulated by physico-chemical soil properties but also agricultural practices. Additionally, natural Cd enrichment by volcanic inputs must not be neglected. Finally, Cd in cacao trees cannot be considered as a tracer of oil activities. Assuming that total Cd content and its bioaccessible fraction (up to 90%) in cacao beans and liquor is directly linked to those in chocolate, the health risk associated with Cd exposure varies from low to moderate.

Digestibility of Quinoa (Chenopodium quinoa Willd.) Protein Concentrate and Its Potential to Inhibit Lipid Peroxidation in the Zebrafish Larvae Model.

Quinoa protein concentrate (QPC) was extracted and digested under in vitro gastrointestinal conditions. The protein content of QPC was in the range between 52.40 and 65.01% depending on the assay used. Quinoa proteins were almost completely hydrolyzed by pepsin at pH of 1.2, 2.0, and 3.2. At high pH, only partial hydrolysis was observed. During the duodenal phase, no intact proteins were visible, indicating their susceptibility to the in vitro simulated digestive conditions. Zebrafish larvae model was used to evaluate the in vivo ability of gastrointestinal digests to inhibit lipid peroxidation. Gastric digestion at pH 1.2 showed the highest lipid peroxidation inhibition percentage (75.15%). The lipid peroxidation activity increased after the duodenal phase. The digest obtained at the end of the digestive process showed an inhibition percentage of 82.10%, comparable to that showed when using BHT as positive control (87.13%).

Arsenic in rice agrosystems (water, soil and rice plants) in Guayas and Los Ríos provinces, Ecuador.

Geogenic arsenic (As) can accumulate and reach high concentrations in rice grains, thus representing a potential threat to human health. Ecuador is one of the main consumers of rice in South America. However, there is no information available about the concentrations of As in rice agrosystems, although some water bodies are known to contain high levels of the element. We carried out extensive sampling of water, soil, rice plants and commercial rice (obtained from local markets). Water samples were analysed to determine physico-chemical properties and concentrations of dissolved arsenic. Soil samples were analysed to determine total organic C, texture, total Fe and amorphous Fe oxyhydroxides (FeOx), total arsenic (tAs) and the bioavailable fraction (AsMe). The different plant parts were analysed separately to determine total (tAs), inorganic (iAs) and organic arsenic (oAs). Low concentrations of arsenic were found in samples of water (generally <10µgl-1) and soil (4.48±3mgkg-1). The tAs in the rice grains was within the usual range (0.042-0.125mgkg-1 dry weight, d.w.) and was significantly lower than in leaves (0.123-0.286mgkg-1 d.w.) and stems (0.091-0.201mgkg-1 d.w.). The FeOx and tAs and also AsMe in flood water were negatively correlated with tAs in the plants. However, the concentrations of As in stems and leaves were linearly correlated with tAs in the soil and flood water. The relationship between tAs and arsenic in the grain fitted a logarithmic function, as did that between tAs in the grain and the stem. The findings seem to indicate that high concentrations of arsenic in the environment (soil or water) or in the rice stem do not necessarily imply accumulation of the element in the grain. The iAs form was dominant (>80%) in all parts of the rice plants.

Processing of quinoa (Chenopodium quinoa, Willd): effects on in vitro iron availability and phytate hydrolysis.

The effect of different processing techniques was studied on in vitro iron availability and phytate hydrolysis in high and low saponin content quinoa (Chenopodium quinoa, Willd) seeds. Water slurries of ungerminated and germinated quinoa flour were processed by cooking, soaking, and fermentation using Lactobacillus plantarum as starter. Iron solubility under physiological conditions (in vitro) was measured and used as an estimation of iron availability. Phytate (inositol hexaphosphate/IP6) and its degradation products were analysed by an HPLC method. The IP6 + IP5 content was reduced by cooking with 4 to 8%, germination with 35 to 39%, soaking with 61 to 76% and by fermentation with 82 to 98%. The highest reduction, about 98%, was obtained after fermentation of the germinated flour. Cooking had no effect on the amount of soluble iron. Iron solubility increased, however, two to four times after soaking and germination, three to five times after fermentation and five to eight times after fermentation of the germinated flour samples and was highly correlated to the reduction of IP6 + IP5 (P < 0.001). There was no difference between the quinoa varieties with regard to phytate reduction and iron solubility. The pH in fermented samples was reduced from 6.5 to about 3.5, due to lactic acid formation.

Pilot study to detect neurologic disease in Ecuador among a population with a high prevalence of endemic goiter.

A census, uniform screening questionnaire, and simple screening neurologic examination were administered in a door-to-door survey to residents of Quiroga, Ecuador, a rural community in the Andes Mountains. The screening procedures had been pretested to assure a high level of sensitivity for detecting children and adults with major neurologic disease. A total of 1,113 participated in the study. Of these, 399 had responses or findings suggesting the presence of neurologic disease. These individuals were then examined by a neurologist, who used fixed diagnostic criteria. The prevalence ratios (per 1,000) for the most common neurologic conditions identified in this survey are: recurrent/persistent severe headache = 68.3, and epilepsy = 17.1.