Comparative Studies on the Detoxification of Aflatoxins by Sodium Hypochlorite and Commercial Bleaches

Abstract

Cultures of Aspergillus flavus and aflatoxins were destroyed by a commercial bleach (Clorox; active ingredient, NaOCl) or analytical reagent grade NaOCl at 7.0 × 10 -3 M NaOCl in 5 days. Addition of Clorox or NaOCl at 2.8 × 10 -3 M to the fungal growth medium prior to inoculation completely inhibited the fungal growth. Aflatoxin production was inversely proportional to the logarithm of NaOCl concentration and time of treatment. Clorox and NaOCl were equally effective on aflatoxins, but fungal cells were lysed more readily by Clorox than by NaOCl. Mycelia older than 8 days lysed more readily than younger ones. Most conidia survived concentrations below 1.4 × 10 -3 M. The lowest effective concentration for a 2-hr treatment was 8.8 × 10 -3 M which is well below the Clorox concentration recommended for routine laboratory decontamination of aflatoxins. Mice and rats injected with aflatoxins and aflatoxins incompletely destroyed by Clorox died within 72 hr and had typical liver and kidney damage caused by aflatoxins. However, animals injected with NaOCl or Clorox or Clorox-destroyed aflatoxin extracts survived and showed no obvious liver or kidney damage.