Effects of some controversial food additives on zebrafish embryonic development

Background information: The rising concerns about potential hazardous properties of food additives requires extensive, yet animal-minimized, testing strategies. For that purpose, the zebrafish embryo is the ideal model system which is amenable to high-throughput in vivo assays.

Method: In this study, we exposed zebrafish wildtype and transgenic fluorescent embryos to different concentrations of ten controversial food additives: the preservative Sodium benzoate (SB); the flavour enhancer Monosodium glutamate (MSG), the sweetener Aspartame (Asp), and colouring agents Tartrazine (TTZ), Quinoline yellow (QY), Sunset yellow (SY), Azorubine (Az), Ponceau 4R (P4R), Allura red AC (AR), and Brilliant blue (BB). Data was recorded and analysed for morphological and lethal effects, remarkable biological/functional outcomes are further investigated with emphasis on neurodevelopment and neurobehaviour.

Results: Effects of each substance on zebrafish embryonic morphology and lethality were determined as well as the corresponding concentration-response relationship. Calculated toxicological indexes (LC50, EC50, and teratogenic index TI) revealed that SB belongs to Cat.3 aquatic toxicity class, while QY and BB are highly teratogenic. Remarkably, adverse effects of BB and P4R present a multiphasic dependence on concentration, with BB appearing to weaken the embryonic yolk sac. SB exposure decreased the zebrafish motoneuron differentiation rate, while Az exposure stimulated the hatching rate. Behavioural studies revealed a synergistic effect on locomotive activity due to a mixture of Asp/MSG.

Conclusion: Our results demonstrate that the zebrafish embryo is a cost-effective model for high throughput screening of food additives¿ safety and toxicity. This in vivo model allows systematic detection of biological effects, especially those unexpected by targeted in vitro and in silico models. Also, our data suggest the need to reconsider the safety of food additives SB, BB, and QY as well as other controversial food additives in further studies.