Combined exposure to multiple mycotoxins in food: are we ready for risk assessment and risk management?

It is nowadays recognized that the risk of human co-exposure to multiple mycotoxins is real. In the last years, a number of studies have approached the issue of co-exposure and the best way to develop a more precise and realistic assessment. Likewise, the growing concern about the combined effects of mycotoxins and their potential impact on human health has been reflected by the increasing number of toxicological studies on the combined toxicity of these compounds. Nevertheless, risk assessment of these toxins, still follows the conventional paradigm of single exposure and single effects, incorporating only the possibility of additivity but not taking into account the complex dynamics associated to interactions between different mycotoxins or between mycotoxins and other food contaminants. Considering that risk assessment is intimately related to the establishment of regulatory guidelines, once the risk assessment is completed, an effort to reduce or manage the risk should be followed to protect public health. Risk assessment of combined human exposure to multiple mycotoxins thus poses several challenges to scientists, risk assessors and risk managers and opens new avenues for research. This presentation aims to give an overview of the different challenges posed by the likelihood of human co-exposure to mycotoxins and the possibility of interactive effects occurring after absorption, towards knowledge generation to support a more accurate human risk assessment and risk management. For this purpose, a physiologically-based framework that includes knowledge on the bioaccessibility, toxicokinetics and toxicodynamics of multiple toxins is proposed. Regarding exposure assessment, the need of harmonized food consumption data, availability of multianalyte methods for mycotoxin quantification, management of left-censored data and use of probabilistic models will be highlight, in order to develop a more precise and realistic exposure assessment. On the other hand, the application of predictive mathematical models to estimate mycotoxins’ combined effects from in vitro toxicity studies will be also discussed. Results from a recent Portuguese project aimed at exploring the toxic effects of mixtures of mycotoxins in infant foods and their potential health impact will be presented as a case study, illustrating the different aspects of risk assessment highlighted in this presentation. Further studies on hazard and exposure assessment of multiple mycotoxins, using harmonized approaches and methodologies, will be crucial towards an improvement in data quality and contributing to holistic risk assessment and risk management strategies for multiple mycotoxins in foodstuffs.

Vegetables production in NW Portugal, agriculture practices and groundwater quality

In NW of Portugal, the region between Esposende and Vila do Conde was established into a unique system called masseiras; masseiras are small fields that were created at the beginning of XX century by removing sand from dunes. Since the 80’s sand between closed masseiras has been removed giving way for larger fields, the “enlarged masseira with greenhouses”. This region is part of vulnerable zone nº1 (VZ1). Nowadays, the masseiras have almost disappeared; they had been replaced by “enlarged masseiras with plastic greenhouses” exploited by a new generation of growers. As water quality is an indicator of agriculture practices, 8 wells were selected and water samples were collected on four dates from September 2009 to May 2010. Laboratorial analysis was performed on nitrates and 28 pesticides. The results confirm that water in VZ1 is contaminated with nitrates (as it was expected) and also with pesticides. The water was contaminated in both dug wells and drilled wells all year round. Masseiras’ wells have more nitrates than greenhouses’ wells, probably due to poor agricultural practices used by growers who still employ high quantities of fertilizers and water. Pesticides detected in water samples include some that have been sprayed in the field and others that have not. Some forbidden substances were found. Our results confirm that, in VZ1, there is a diffusion contamination, which origin is unknown. In this communication, we put in picture the history of masseiras fields: how masseiras fields have been created and how they have disappeared; what trends exist in pest management strategies and the use of fertilizers, pesticides and water resources. These results reinforce the need to change the agricultural system in this region of traditional vegetable production.