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The rice ingestion rate in Madagascar is among the highest globally; however studies concerning metal(loid) concentrations in Madagascar rice are lacking. For Madagascar unpolished rice (n = 51 landraces), levels of toxic elements (e.g., total mercury, methylmercury, arsenic and cadmium) as well as essential micronutrients (e.g., zinc and selenium) were uniformly low, indicating potentially both positive and negative health effects. Aside from manganese (Wilcoxon rank sum, p < 0.01), no significant differences in concentrations for all trace elements were observed between rice with red bran (n = 20) and brown bran (n = 31) (Wilcoxon rank sum, p = 0.06–0.91). Compared to all elements in rice, rubidium (i.e., tracer for phloem transport) was most positively correlated with methylmercury (Pearson's r = 0.33, p < 0.05) and total mercury (r = 0.44, p < 0.05), while strontium (i.e., tracer for xylem transport) was least correlated with total mercury and methylmercury (r < 0.01 for both), suggesting inorganic mercury and methylmercury were possibly more mobile in phloem compared to xylem.

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rubidium zinc strontium madagascar toxic substances phloem methylmercury compounds rice ingestion red bran phloem/xylem transport metal(loid)s methylmercury ...

National Agricultural Library - United States of America

Soil thresholds and a decision tool to manage food safety of crops grown in chlordecone polluted soil in the French West Indies Texto completo

2017

Clostre F. | Letourmy P. | Lesueur Jannoyer M.

Due to the persistent pollution of soils by an organochlorine, chlordecone (CLD also known as Kepone ©) in the French West Indies, some crops may be contaminated beyond the European regulatory threshold, the maximum residue limit (MRL). Farmers need to be able to foresee the risk of not complying with the regulatory threshold in each field and for each crop, if not, farmers whose fields are contaminated would have to stop cultivating certain crops in the fields concerned. To help farmers make the right choices, we studied the relationship between contamination of the soil and contamination of crops. We showed that contamination of a crop by CLD depended on the crop concerned, the soil CLD content and the type of soil. We grouped crop products in three categories: (i) non-uptakers and low-uptakers, (ii) medium-uptakers, and (iii) high-uptakers, according to their level of contamination and the resulting risk of exceeding MRL. Using a simulation model, we computed the soil threshold required to ensure the risk of not complying with MRL was sufficiently low for each crop product and soil type. Threshold values ranged from 0.02 ?gkg?1 for dasheen grown in nitisol to 1.7 ?gkg?1 for yam grown in andosol in the high-uptake category, and from 1 ?gkg?1 for lettuce grown in nitisol to 45 ?gkg?1 for the leaves of spring onions grown in andosol in the medium-uptake category. Contamination of non-uptakers and low-uptakers did not depend on soil contamination. With these results, we built an easy-to-use decision support tool based on two soil thresholds (0.1 and 1 ?gkg?1) to enable growers to adapt their cropping system and hence to be able to continue farming. (Résumé d'auteur)tttttt

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martinique antilles françaises

Centre de coopération internationale en recherche agronomique pour le développement - France