Establishment of cumulative assessment groups of pesticides for their effects on the thyroid

Abstract

Cumulative assessment groups of pesticides have been established for two specific effects on the thyroid: firstly hypothyroidism, and secondly parafollicular cell (C-cell) hypertrophy, hyperplasia and neoplasia. Sources of uncertainties resulting from the methodological approach and from the limitations in available data and scientific knowledge have been identified and considered. This report supports the publication of a scientific report on cumulative risk assessment to pesticides affecting the thyroid, in which all uncertainties identified for either the exposure assessment or the establishment of the cumulative assessment groups are incorporated into a consolidated risk characterisation.

Integrating Selection and Risk Assessment of Chemical Mixtures: A Novel Approach Applied to a Breast Milk Survey

“…Our approach deals with substances belonging to different chemical classes and different regulatory silos, unlike previous methods based on TEFs [e.g., dioxin TEQs ( Van den Berg et al. 2006 )] focusing on one chemical class, or based on cumulative assessment groups developed for pesticide regulation ( EFSA 2013c ; EFSA Scientific Committee 2019 ). Importantly, in the context of a posteriori risk assessment, mixtures are driven by substances found in the environment and must be studied in a way that corresponds to the reality of current exposure ( Kortenkamp and Faust 2018 ; Sprong et al.…”

“…Therefore, in these particular cases, the HI would not have been such a conservative scenario. The HI or the RPI has been proposed to calculate cumulative risks ( EFSA 2019 ). However, because they are based on the most sensitive end point, which can be different from one substance to another (HI) or use a common generic UF (RPI), they were found to be rather conservative and can only be used in a tier 0 approach.…”

“…Based on scientific literature comparing the combined effects induced by exposure to multiple substances with similar and independent (dissimilar) actions ( Altenburger et al. 2013 ; Backhaus and Faust 2012 ; EFSA 2013a , 2013b , 2019 ; Faust 2003 , 2001 ; Jonker et al. 2004 ; Junghans et al.…”

“…2006 ; Kortenkamp et al. 2009 ), dose addition was established as the default hypothesis recommended by several institutions for mixture risk assessment ( EFSA 2013a , 2019 ; Meek et al. 2011 ; SCHER 2012 ; WHO 2009b ).…”

“…This approach can be used by considering addition of doses, addition of effects, or interactions. The component-based approach is the most commonly applied method and has resulted in the development of several metrics to calculate the risk related to mixtures ( EFSA 2019 ; Kortenkamp et al. 2009 ; Meek et al.…”