Discussion on a "Dynamic model to conceptualize multiple environmental pathways to the epidemic of Chronic Kidney Disease of unknown etiology (CKDu)"

Abstract

Jayasinghe et al. [Science of the Total Environment, 705 (2020) 135766] propose a 'dynamical' model of Chronic Kidney Disease of Unknown etiology (CKDu) wherein CKDu arises as an emergent property of a complex system where they claim that weak multiple environmental factors contribute. They criticize the usual approaches as being "reductionist". We use their model as a basis of a discussion on the possibility of treating CKDu as an emergent property resulting from the interaction of multiple weak environmental factors with the organism. The model does not reveal anything beyond what is already known from simple considerations of well-known feed-back loops, but has the merit of re-stating those issues in a different format. If a proper weighting of the possible environmental factors is included, most proposed environmental factors drop out and what Jayasinghe et al. call the "reductionist" approach naturally arises due to the weight of evidence. The theory that the consumption of water containing fluoride and magnesium ions as found in water from regolith aquifers drawn via house-hold wells is found to clearly hold within this model when proper weighting is included. However, we show by examples that such models can be easily misused, leading to completely misleading conclusions. A response formalism useful in the theory of complex systems and emergent modes is presented in the context of the current problem. In addition to there being a lack of adequate data to fully implement such a theory, it is seen that such elaborations are unnecessary and misleading in the present context.