Buy pre-packaged cooking oil with an SC code; avoid bulk, unregulated homemade peanut oil

The price difference isn’t huge if you shop elsewhere. Just check whether the packaging lists a food production licence number starting with “SC”. The real challenge is convincing older family members used to buying homemade oil.

Aflatoxin is a Group 1 carcinogen per the International Agency for Research on Cancer, meaning it definitely causes cancer, especially liver cancer. A Guangzhou study measured aflatoxin B1 levels in homemade peanut oil from small producers between 2010 and 2022. The median concentration was 1.29 μg/kg, with half of all samples falling between 0.12 and 6.58 μg/kg. After local rules for small producers took effect, toxin levels dropped by 2.865 μg/kg, then fell an additional 2.593 μg/kg each year. Concurrently, the proportion of local residents with abnormal liver function fell by 35% (PR 0.650, 95% CI 0.469–0.902). Another Guangxi study that followed 1611 pregnant women found 81.7% ate homemade peanut oil; the odds ratio for low birth weight among their babies was 1.9 (aOR 1.9, 1.1–3.2). The odds ratio for preterm birth was 1.8 (aOR 1.8, 1.1–3.0).

Lei J, Li Y, Wang Y, 等 (2024). The impact of small food workshops management regulations on aflatoxin B1 in home-made peanut oil and the liver function of high-consumption area residents: an interrupted time series study in Guangzhou, China. Frontiers in Public Health, 12. https://doi.org/10.3389/fpubh.2024.1484414；Zhong Y, Lu H, Jiang Y, 等 (2024). Effect of homemade peanut oil consumption during pregnancy on low birth weight and preterm birth outcomes: a cohort study in Southwestern China. Global Health Action, 17. https://doi.org/10.1080/16549716.2024.2336312；IARC (2012). Chemical Agents and Related Occupations. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 100F. https://publications.iarc.fr/123；国家卫生计生委、国家食品药品监督管理总局 (2017). 食品安全国家标准 食品中真菌毒素限量（GB 2761-2017）

Both studies are merely follow-up records and lack group controls. The endpoint for the Guangzhou study was liver function tests, not liver cancer or death. The median toxin level in self-pressed oil is actually lower than the national standard limit of 20 μg/kg for peanut oil; the risk comes from long-term consumption and individual high-level batches. National standard limits apply to all peanut oils, but pre-packaged oils must undergo production licensing and factory inspections, whereas small workshops are managed according to provincial regulations, and much fewer inspections are conducted. Regarding how to handle moldy peanuts, corn, or nuts stored at home, see item 46 of this section (if moldy, discard the entire package). The beneficiaries of this article are primarily you and the family members eating with you.