Aflatoxin exposure — DTM&H MCQ

Correct answer: A — Aflatoxin from Aspergillus-contaminated grain

The correct answer is A, aflatoxin from Aspergillus-contaminated grain. Aflatoxin B1, produced by Aspergillus flavus and A. parasiticus on poorly dried or stored maize and groundnuts, is a potent hepatocarcinogen that causes p53 mutations in codon 249, and its effect is markedly synergistic with chronic hepatitis B infection, multiplying hepatocellular carcinoma risk far beyond either exposure alone. This synergy explains the clustering of young-onset hepatocellular carcinoma in hepatitis B-endemic communities with poor grain storage, exactly as described in the stem. Visibly mouldy home-stored maize is a classic clue for aflatoxin exposure in sub-Saharan Africa, where humid storage conditions favour fungal growth and toxin production. Why the other options are wrong: C. Ciguatoxin in reef fish: causes an acute neuro-gastrointestinal illness (ciguatera fish poisoning) after eating contaminated reef fish, with no established link to chronic liver carcinogenesis. B. Lead in ceramic glaze: causes neurotoxicity, anaemia, and nephrotoxicity through chronic heavy metal accumulation, not hepatocellular carcinoma. D. Cyanide in cassava after soaking: adequately soaked cassava has reduced cyanogenic glycoside content, and even inadequate processing causes acute cyanide toxicity or chronic conditions like konzo, not liver cancer. E. Mercury in river fish: causes neurological toxicity (paraesthesia, ataxia, visual disturbance) from methylmercury bioaccumulation, unrelated to hepatocarcinogenesis. Key point: Aflatoxin exposure and chronic hepatitis B act synergistically, not merely additively, to dramatically raise hepatocellular carcinoma risk, making contaminated grain storage a critical, modifiable co-factor in endemic regions.

Reference: Food Standards Agency (UK), Mycotoxins guidance (aflatoxins and health effects including liver cancer risk), food.gov.uk/business-guidance/mycotoxins; supported by IARC Group 1 classification of aflatoxin B1 as a human carcinogen and its documented synergy with hepatitis B virus in hepatocarcinogenesis.