Novel miniaturized exposure to evaluate the toxicity of Enniatin B1 on Daphnia magna.

Enniatins (ENNs) are a heterogenous group of mycotoxins that are commonly detected in several commodity items, food and feedstock. Although this class of compounds shows several toxicological properties, studies so far mainly investigated the effects of ENN B, neglecting other prevalent molecules such as ENN B1, one of the most detected mycotoxins in food. Despite ENNs have been detected in freshwater, regulatory efforts have only focused on limiting the levels of these molecules in food, while limited investigations assessed their toxicity towards organisms. This study aims at expanding the knowledge on the effects of ENN B1 through a miniaturized in vivo approach using the freshwater cladoceran Daphnia magna as model organism. A 7-day exposure was performed under miniaturized conditions to assess the effects of two concentrations of ENN B1 (i.e., 0.25 and 1.5 µM). After the exposure, effects on survival, activity of antioxidant and detoxifying enzymes, body size, reproductive outcomes (i.e., presence of eggs in the brood chamber) and swimming activity were investigated. Whilst EEN B1 did not affect survival and enzyme activities, significant changes in body length and egg appearance were observed. These findings highlight the potential toxicity of ENN B1 on a freshwater species suggesting the need of further studies to assess its risk for aquatic organisms.