The Joint FAO/WHO Expert Committee on Food Additives (JECFA, 1990) assessed the compound together with six other cellulose derivatives and allocated a group acceptable daily intake (ADI) of ‘not specified’. The Scientific Committee for Food (SCF, 1994, 1999) who assessed five closely related cellulose derivatives, also allocated a group ADI of ‘not specified’. The most recent evaluation of cellulose and cellulose derivatives, including HPMC for their use as food additives was done in 2018 by the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) (EFSA ANS Panel, 2018), which concluded that there was no need to set a numerical ADI.
Substitution of cellulose with ethyl-, methyl-, hydroxypropyl-, hydroxypropyl-methyl- and carboxymethyl groups may increase the resistance of cellulose to degradation. Resistance increases with the degree of substitution and is greatest when the substituent groups are evenly dispersed along the polymer chain. Most cellulose of the additive under assessment will therefore pass the intestine undigested and will excreted unchanged via faeces. Even when a high cellulolytic activity is present, as in the rumen, ethyl cellulose remains sufficiently resistant to degradation to be used as enteric coatings designed to protect methionine from rumen release (EFSA FEEDAP Panel, 2012c). Subsequent degradation in the post-ruminal tract is most likely to lead to high molecule weight breakdown products, with little probability of absorption.