How does a synthetic preservative used in processed foods affect development?

The synthetic antioxidant, tert-Butylhydroquinone (tBHQ), is used to prevent food products from oxidative deterioration. In the United States, it is estimated that people exceed the acceptable daily intake by up to 80%. Some studies suggest that short-term tBHQ exposure has chemoprotective properties, as it is a nuclear factor erythroid 2-related factor 2 (Nrf2) activator. Other studies show tBHQ plays a role in developmental impairment, DNA damage, and carcinogenicity. This study investigates the effect of chronic dietary tBHQ exposure on zebrafish growth parameters and organ development. Since the zebrafish genome is similar to that of humans, the results from this study could indicate the adverse effects of chronic tBHQ exposure in the human population. Nrf2a wildtype and mutant larvae were exposed to a 5% tBHQ or control diet for five months. Growth parameters and survival were assessed at 20 weeks-post-fertilization. To examine the effects of pancreas and liver development, a 10-day dietary exposure was conducted between 5 and 15 days-post-fertilization. The survival of the tBHQ-fed adult zebrafish was 50-83% less than that of the control group, with the Nrf2a mutant strains having the lowest survival. The tBHQ-fed zebrafish were also significantly smaller than the control group. The tBHQ-diet was associated with a decreased secondary islet development and increased rate of abnormal primary islet morphology. The findings from this study show that chronic dietary tBHQ exposure may affect pancreas development, and impair growth and survival in a Nrf2a dependent manner.