If peanuts, corn, nuts or rice and flour at home have gone moldy, throw out the whole bag and don't pick out the moldy parts and eat the rest; spit out any nut that tastes bitter right away

Cost

Throwing out a bag of peanuts or nuts, or a sack of rice or flour, costs a few to a few dozen CNY. Store grain and nuts in a dry, ventilated, cool place, buy small packages, and don't stockpile. The hard part is not wanting to throw things out, especially persuading the older people in your family.

What you get

Aflatoxin is a Group 1 carcinogen (known to cause cancer in humans) as classified by the International Agency for Research on Cancer, and it causes liver cancer. It is most common in peanuts and corn, and ordinary cooking such as stir-frying, boiling and deep-frying is hard pressed to destroy it. A Shanghai study followed 18244 middle-aged men from 1986, each leaving one urine sample at enrollment. Over about 70,000 (7万) person-years of follow-up, 55 cases of liver cancer were found. 50 of them were compared with 267 men from the same group who did not get the disease. Those with aflatoxin found in the urine had about 3.4 times the risk of liver cancer (RR 3.4, 95% CI 1.1–10.0, the plausible range). Those positive for hepatitis B surface antigen had about 7.3 times (2.2–24.4). Those with both had about 59.4 times (16.6–212.0), compared with people with neither. In an earlier analysis of the same group, after accounting for hepatitis B, smoking, drinking and education, those with the toxin found had about 3.8 times the risk (1.2–12.2). Qidong, Jiangsu used to be a high-rate area for liver cancer, and from the 1980s the main staple there was switched from corn to rice. The median of the toxin marker in residents' blood fell from 19.3 pg/mg in 1989 to undetectable in 2009 (below 0.5). Liver cancer mortality among residents under 35 fell by half or more across the cohorts born from the 1960s to the 1980s. These cohorts were all born before the hepatitis B vaccine was given to newborns universally. The authors estimate that about 65% of the fall in liver cancer deaths can be attributed to eating less of the toxin, and 83% of that fell among people infected with hepatitis B. By global estimates, for the same amount of toxin eaten, a hepatitis B carrier's cancer risk from it is about 30 times that of a person without the virus. In China each year a number of liver cancers can be attributed to this toxin. About 5300 to 14400 of them are in hepatitis B carriers, and about 1990 to 4430 are in people without the virus.

Notes

The numbers in the benefit field measure the link between “how much toxin you take in” and liver cancer; no study has directly measured how much liver cancer is prevented by “throwing out moldy things at home.” The Shanghai study tested urine only once, at enrollment. The intake estimated from a diet questionnaire showed no link to liver cancer, which shows that questionnaires cannot estimate it well and lab tests are needed. By 2009 the toxin marker in Qidong residents was undetectable. Most households today probably take in far less than back then; that is a judgment, and there is no national figure. So the size of the benefit was not mechanically set at large because of the 3.4 times, and was set at medium on judgment. Why throw out the whole bag: the Guangdong Provincial Health Commission (广东省卫健委) advises that if nuts or peanuts smell off when you open them, throw out the whole bag, so that mold spores don't scatter when you shake it out. Food with a moldy smell should be firmly thrown away. The U.S. Department of Agriculture's food safety guidance states that moldy peanut butter, beans and nuts must all be thrown out, and so must cooked rice and noodles and bread. Only hard vegetables with little water, such as cabbage and carrots, can be eaten after cutting off at least 2.5 centimeters around the mold spot. The Ministry of Agriculture and Rural Affairs (农业农村部) advises that moldy peanuts taste bitter and off in the mouth, and if you eat one by mistake, spit it out right away and rinse your mouth. The stacking of risk is most obvious for hepatitis B carriers; if you have never been tested for hepatitis B, see §1.14 (get the hepatitis B two-and-a-half tests). For buying oil, see §2.40 (don't buy loose home-pressed peanut oil from small workshops); this item is about the grain and nuts you keep at home. Acute poisoning from soaked wood ear and fermented rice and corn flour is a different toxin; see §1.48 (don't ferment corn or rice flour at home). Nuts that are not moldy are still worth eating; see §2.22 (eat a small handful of nuts a day). The beneficiary of this item is mainly you and the family who eat with you.

Evidence grade

B : Supported by research but without a precise number, or based on small or single studies.

Sources

1. IARC (2012). Aflatoxins. In: Chemical Agents and Related Occupations. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 100F, 225-248. https://publications.iarc.fr/123
2. Qian GS, Ross RK, Yu MC, 等 (1994). A follow-up study of urinary markers of aflatoxin exposure and liver cancer risk in Shanghai, People's Republic of China. Cancer Epidemiology, Biomarkers & Prevention, 3(1), 3-10. https://pubmed.ncbi.nlm.nih.gov/8118382/
3. Ross RK, Yuan JM, Yu MC, 等 (1992). Urinary aflatoxin biomarkers and risk of hepatocellular carcinoma. Lancet, 339(8799), 943-946. https://doi.org/10.1016/0140-6736(92)91528-G
4. Chen JG, Egner PA, Ng D, 等 (2013). Reduced aflatoxin exposure presages decline in liver cancer mortality in an endemic region of China. Cancer Prevention Research, 6(10), 1038-1045. https://doi.org/10.1158/1940-6207.CAPR-13-0168
5. Liu Y, Wu F (2010). Global burden of aflatoxin-induced hepatocellular carcinoma: a risk assessment. Environmental Health Perspectives, 118(6), 818-824. https://doi.org/10.1289/ehp.0901388
6. 农业农村部油料产品质量安全风险评估实验室（武汉）(2020). 农产品及食品中黄曲霉毒素污染识别与预防. 农业农村部农产品质量安全监管司科普天地. https://jgs.moa.gov.cn/kptd/202011/t20201110_6356097.htm
7. 广东省卫生健康委员会 (2015). 勿吃霉变食物 谨防黄曲霉素中毒. https://wsjkw.gd.gov.cn/gkmlpt/content/2/2129/post_2129622.html
8. USDA Food Safety and Inspection Service. Molds on Food: Are They Dangerous? https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/molds-food-are-they-dangerous

Translated from the Chinese original. Original book, section 2, tip 46. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer