Pesticide Uptake in Potatoes: Model and Field Experiments

Abstract

A dynamic model for uptake of pesticides in potatoes is presented and evaluated with measurements performed within a field trial in the region of Boyacá, Colombia. The model takes into account the time between pesticide applications and harvest, the time between harvest and consumption, the amount of spray deposition on soil surface, mobility and degradation of pesticide in soil, diffusive uptake and persistence due to crop growth and metabolism in plant material, and loss due to food processing. Food processing steps included were cleaning, washing, storing, and cooking. Pesticide concentrations were measured periodically in soil and potato samples from the beginning of tuber formation until harvest. The model was able to predict the magnitude and temporal profile of the experimentally derived pesticide concentrations well, with all measurements falling within the 90% confidence interval. The fraction of chlorpyrifos applied on the field during plant cultivation that eventually is ingested by the consumer is on average 10(-4)-10(-7), depending on the time between pesticide application and ingestion and the processing step considered.

Organochlorine (chlordecone) uptake by root vegetables

“…The lack of chlordecone in airborne particles close to a former production site and its characteristic low vapor pressure and volatility but high affinity for organic matter (Dawson et al, 1979;Cabidoche et al, 2009), led us to hypothesize that the soil-air-plant pathway is much less important than uptake through the soil. This hypothesis is in accordance with reports in the literature that downward translocation of organochlorine pesticides with the same characteristics as CLD, via the phloem assimilation stream is negligible, and that the main uptake route for root vegetables is thus through the soil (Schroll et al, 1994;Fujisawa et al, 2002;Juraske et al, 2011).…”

“…With a K oc of between 1200 and 15,800 L kg À1 , depending on the soil type (Howard, 1991;Schüürmann et al, 2006;Fernandez Bayo et al, 2013) and a log K ow around 5 (United States Environmental Protection Agency, 2012), CLD uptake should thus be limited (Cabidoche et al, 2009), and this hypothesis was confirmed by our results. Once adsorbed by the skin of the root vegetable, lipophilic and organochlorine pesticides are then incorporated very slowly by diffusion through the skin into the inner tissues (Fujisawa et al, 2002;Trapp, 2002;Trapp et al, 2007;Juraske et al, 2011). Previous studies confirmed that the skin of the root vegetable remained the most highly contaminated by CLD compared to flesh (Cabidoche and Lesueur-Jannoyer, 2012;Clostre et al, 2014b).…”

Evaluation of models for dermal exposure assessment in farming systems in developing countries

“…Potato crops in this region are vulnerable to three major pests: the soil-dwelling larvae of the Andean weevil (Premnotrypes vorax), the late blight fungus (Phytophthora infestans) and the Guatemalan potato moth (Tecia solanivora) [22]. The pesticide management to control these pests is performed along three main activities: the preparation of the pesticide, the application itself, and the cleaning of the spraying equipment [18,21]. During the whole pesticide management, farmers use work clothing consisting of trousers, short sleeve shirts and plastic boots.…”

“…In developing countries this is of special interest because pesticide management activities face weak safety standards [2,12,13,17]. Studies in potato farming systems in Vereda La Hoya in Colombia [12,13,15,18,21,30]. Mojanda, Ecuador [31]; and El Angel, Ecuador [27] have shown that pesticide management in these countries has no particular knowledge foundation and is performed by trial and error, finding out what works out in practice.…”

Next generation of microbial inoculants for agriculture and bioremediation

“…Although little is known about this topic, we can infer that the crop plants are able to absorb these compounds from soil, representing a latent problem to the human health and environment. In fact, it has been demonstrated that some pesticides can be absorbed from soil by potatoes (Juraske et al ., 2011) and the highly recalcitrant compound TNT can be absorbed by maize plants (Van Dillewijn et al ., 2007). Nonetheless, something even more important, it will be determined if TNT is able to travel to maize fruits or just stay in the steam of the plants.…”