Scientific Opinion on Risk Assessment for a Selected Group of Pesticides from the Triazole Group to Test Possible Methodologies to Assess Cumulative Effects from Exposure through Food from these Pesticides on Human Health

International experience in addressing combined exposures: increasing the efficiency of assessment

More efficient methodology for assessing the impact of combined exposures to multiple chemicals has been considered in a project of the World Health Organization (WHO) International Programme on Chemical Safety (IPCS). Recommendations regarding terminology and the status of development of the framework, its content, review and application are described. Evolving experience in its application is illustrated by example (polybrominated diphenyls) with special emphasis on the critical content of problem formulation, the role of predictive tools in grouping of chemicals for consideration and the importance of explicit delineation of relative uncertainty and sensitivity for tiered assessment. Priorities in increasing the efficiency of risk assessment not only for combined exposures, but more generally based on experience acquired in developing the framework and its application in case studies are identified and recommendations included.

Total diet study on pesticide residues in France: levels in food as consumed and chronic dietary risk to consumers

Chronic dietary exposure to pesticide residues was assessed for the French population using a total diet study (TDS) to take into account realistic levels in foods as consumed at home (table-ready). Three hundred and twenty-five pesticides and their transformation products, grouped into 283 pesticides according to their residue definition, were sought in 1235 composite samples corresponding to 194 individual food items that cover 90% of the adult and child diet. To make up the composite samples, about 19,000 food products were bought during different seasons from 2007 to 2009 in 36 French cities and prepared according to the food preparation practices recorded in the individual and national consumption survey (INCA2). The results showed that 37% of the samples contained one or more residues. Seventy-three pesticides were detected and 55 quantified at levels ranging from 0.003 to 8.7mg/kg. The most frequently detected pesticides, identified as monitoring priorities in 2006, were the post-harvest insecticides pirimiphos-methyl and chlorpyrifos-methyl-particularly in wheat-based products-together with chlorpyrifos, iprodione, carbendazim and imazalil, mainly in fruit and fruit juices. Dietary intakes were estimated for each subject of INCA2 survey, under two contamination scenarios to handle left-censored data: lower-bound scenario (LB) where undetected results were set to zero, and upper-bound (UB) scenario where undetected results were set to the detection limit. For 90% of the pesticides, exposure levels were below the acceptable daily intake (ADI) under the two scenarios. Under the LB scenario, which tends to underestimate exposure levels, only dimethoate intakes exceeded the ADI for high level consumers of cherry (0.6% of children and 0.4% of adults). This pesticide, authorised in Europe, and its metabolite were detected in both cherries and endives. Under the UB scenario, that overestimates exposure, a chronic risk could not be excluded for nine other pesticides (dithiocarbamates, ethoprophos, carbofuran, diazinon, methamidophos, disulfoton, dieldrin, endrin and heptachlor). For these pesticides, more sensitive analyses of the main food contributors are needed in order to refine exposure assessment.

Risk Assessment of Human Exposure to Pesticides in Food

U ovome preglednom radu prikazane su metode procjene rizika od akutne i kronične izloženosti ljudi ostacima pesticida unesenih hranom. U hrani su često prisutni ostaci više različitih pesticida. Međutim rizik od istodobne izloženosti ostacima različitih pesticida nije moguće utvrditi jer trenutačno ne postoji međunarodno prihvaćeni postupak kumulativne procjene rizika. Stoga se procjena rizika temelji na toksikološkoj procjeni pojedinačnog spoja u određenoj vrsti hrane. Za izračun akutnog unosa najčešće se upotrebljava tzv. međunarodna procjena kratkoročnog unosa (engl. international estimation of short-term intake, IESTI). Model izračuna IESTI temelji se na tzv. metodi najgoreg scenarija uz pretpostavke da će osoba u kratkom vremenu konzumirati veliku količinu hrane koja sadržava najveći određeni maseni udio pesticida te uzimajući u obzir i nehomogenost distribucije ostataka pesticida u hrani. Kronična izloženost ostacima pesticida procjenjuje se uz primjenu tzv. determinističkog modela koji je analogan izračunu maksimalnoga dnevnog unosa.

Comparison of the mouse Embryonic Stem cell Test, the rat Whole Embryo Culture and the Zebrafish Embryotoxicity Test as alternative methods for developmental toxicity testing of six 1,2,4-triazoles

The relatively high experimental animal use in developmental toxicity testing has stimulated the search for alternatives that are less animal intensive. Three widely studied alternative assays are the mouse Embryonic Stem cell Test (EST), the Zebrafish Embryotoxicity Test (ZET) and the rat postimplantation Whole Embryo Culture (WEC). The goal of this study was to determine their efficacy in assessing the relative developmental toxicity of six 1,2,4-triazole compounds,(1) flusilazole, hexaconazole, cyproconazole, triadimefon, myclobutanil and triticonazole. For this purpose, we analyzed effects and relative potencies of the compounds in and among the alternative assays and compared the findings to their known in vivo developmental toxicity. Triazoles are antifungal agents used in agriculture and medicine, some of which are known to induce craniofacial and limb abnormalities in rodents. The WEC showed a general pattern of teratogenic effects, typical of exposure to triazoles, mainly consisting of reduction and fusion of the first and second branchial arches, which are in accordance with the craniofacial malformations reported after in vivo exposure. In the EST all triazole compounds inhibited cardiomyocyte differentiation concentration-dependently. Overall, the ZET gave the best correlation with the relative in vivo developmental toxicities of the tested compounds, closely followed by the EST. The relative potencies observed in the WEC showed the lowest correlation with the in vivo developmental toxicity data. These differences in the efficacy between the test systems might be due to differences in compound kinetics, in developmental stages represented and in the relative complexity of the alternative assays.

[Plant protection products and their residues : Aspects of consumer safety in context of the new EU regulations]

The law regulating plant protection products (PPP) in the European Union (EU) was fundamentally revised through the introduction of Regulation (EC) No. 1107/2009 which is due to enter into force on 14 June 2011. EU-wide harmonized maximum residue levels (MRLs) for the active substances of PPP in foods are laid down in Regulation (EC) No. 396/2005 and apply since entry into force of the regulation on 1 September 2008. The goal of both regulations is to strengthen the level of consumer protection. PPP are subject to a strict assessment of active substances, which is regulated at the EU level as well as an authorization procedure in the EU Member States. Prior to application for authorization of a PPP, the active substance(s) it contains must be included in a positive list. Tests regarding the toxicity and residue behavior of PPP must be conducted by the applicant, and the respective documents must be submitted to the authorities for evaluation. Following review of the required data, toxicological threshold values are derived, consumer exposure is assessed, and the risk to health is evaluated. The goal of this evaluation is to ensure that the use of PPP according to good plant protection practice does not have any harmful effects on human health.