Consume soaked black fungus (wood ear) and silver ear within the same meal without storing overnight, eat fresh wet rice noodles on the day of purchase, and never make fermented cornmeal at home

Black fungus and tremella (silver ear) soaked for extended periods, improperly stored fresh wet rice noodles, and home-fermented corn flour products can be contaminated by Burkholderia gladioli pathovar cocovenenans, producing bongkrekic acid—a lethal bacterial toxin. Bongkrekic acid cannot be broken down by 100°C boiling or pressure cooking, and there is no known medical antidote. Across nationwide foodborne outbreak surveillance in China over eleven years, nearly 30% of individuals poisoned by bongkrekic acid died.

Cost

Zero financial cost. Soak only the quantity of wood ear or silver ear needed for a single meal, and discard any leftovers. Buy only enough fresh wet rice noodles for same-day consumption. The primary difficulty is reluctance to discard surplus soaked fungus, and regional culinary habits of preparing homemade fermented cornmeal dishes (such as suantangzi).

Benefit

According to the China National Foodborne Disease Outbreak Surveillance System, between 2010 and 2020, 19 bongkrekic acid poisoning outbreaks were reported, involving 146 illnesses, 139 hospitalizations, and 43 deaths, representing a case-fatality rate of 29.5%. By food category: 9 outbreaks involved homemade fermented corn flour products, causing 33 deaths; 5 outbreaks involved wet rice noodles, causing 7 deaths; and 3 outbreaks involved soaked black fungus, resulting in 5 illnesses and 3 deaths. In 2020 nationwide food poisoning fatalities (143 deaths), bongkrekic acid caused 12 deaths, ranking behind wild poisonous mushrooms (80 deaths) and methanol (14 deaths). Market regulation safety alerts confirm bongkrekic acid is heat-stable and resistant to 100°C boiling and pressure cooking; currently no specific antidote exists. In Guangdong Province, regulatory mandates enacted in 2018 required wet rice noodles to be prepackaged, sealed in small portions, and clearly labeled with expiration dates; post-implementation surveillance showed average annual poisoning cases dropped from 6.25 to 0.5.

Notes

In October 2020 in Jidong County, Heilongjiang Province, family members consumed homemade fermented cornmeal noodles (suantangzi) for breakfast; all 9 individuals who ate the food died (100% case-fatality). Dried black fungus requires only 1 to 2 hours of cold-water soaking; market guidelines stipulate soaking should never exceed 8 hours. If soaked fungus feels slimy, loses elasticity, gives off a sour or unpleasant odor, or if soaking water becomes turbid, discard the entire batch immediately. If symptoms like vomiting, dizziness, or profound weakness appear after eating, induce vomiting immediately, preserve remaining food samples, and seek urgent hospital emergency care. Anyone who consumed the same food must undergo medical evaluation even if currently asymptomatic. Wild toxic mushrooms are covered in Chapter 1, Rule 5.

Sources · 7

1. Zhang H et al. (2023). Epidemiology of foodborne bongkrekic acid poisoning outbreaks in China, 2010 to 2020. PLoS One, 18(1), e0279957. doi.org/10.1371/journal.pone.0279957
2. Li H et al. (2021). Characteristics of Settings and Etiologic Agents of Foodborne Disease Outbreaks — China, 2020. China CDC Weekly, 3(42), 889-893. doi.org/10.46234/ccdcw2021.219
3. Yuan Y et al. (2020). A Foodborne Bongkrekic Acid Poisoning Incident — Heilongjiang Province, 2020. China CDC Weekly, 2(51), 975-978. doi.org/10.46234/ccdcw2020.264
4. Liu Z et al. (2026). Controlling the Storage Time Is an Effective Measure to Reduce the Risk of Bongkrekic Acid Poisoning Caused by Wet Rice Noodles. Foodborne Pathogens and Disease, 23(7), 468-472. doi.org/10.1089/fpd.2024.0131
5. Beijing Municipal Administration for Market Regulation (2023). Risk Warning on Food Poisoning Induced by Bongkrekic Acid. scjgj.beijing.gov.cn/hdjl/xfts/202309/t202309…
6. Hunan Provincial Administration for Market Regulation (2025). Food Safety Warning: Lethal Bongkrekic Acid. amr.hunan.gov.cn/amr/xxx/xtdtx/202506/t202506…
7. Guizhou Provincial Administration for Market Regulation (2023). Food Safety Warning on Preventing Bongkrekic Acid Poisoning. amr.guizhou.gov.cn/zfxxgk/fdzdgknr/tzgg_56269…