Impacts of dietary exposure to sodium or potassium salts of nitrate and nitrite on the development of Drosophila melanogaster

The effects of four food additives, namely sodium nitrite (NaNO₂), sodium nitrate (NaNO₃), potassium nitrite (KNO₂), and potassium nitrate (KNO₃), on animal development were evaluated by using Drosophila melanogster, a model organism. Adult male and female flies were allowed to breed in culture medium, each containing one of 4 concentrations, i.e.10, 20, 30 or 40 mM of the above mentioned salts. The concentration of 40 mM, NaNO₂ and KNO2 completely arrested the development of the flies. Of the different concentrations of the four salts tested, exposure of flies to 30 mM NaNO₂ exhibited only significant delays in the initial appearances of third instar larvae, pupae and young adults, along with huge reduction in the number of pupae and young adults compared to controls. Rearrangements like inversions, deletion looping, regional shrinking, as well as highly enlarged puffing, etc. were also observed in the polytene chromosomes of the third instar larvae exposed to 30 mM NaNO₂. Developmental outcomes of the flies exposed to varying concentrations of NaNO₃ and KNO3 did not differ significantly from the controls. Owing to the extensive genetic homology between Drosophila and human and the successful uses of this fly as models in developmental and toxicological studies, we speculate that the experimental results exhibited by this organism in our study strongly advocate for abstaining from the dietary use of NaNO₂ and KNO2 during human pregnancies to avoid possible negative developmental outcomes.