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.

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).

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.

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.

Zhang H 等 (2023). Epidemiology of foodborne bongkrekic acid poisoning outbreaks in China, 2010 to 2020. PLoS One 18(1):e0279957：「From 2010–2020, a total of 19 BA poisoning outbreaks were reported to the China National Foodborne Disease Outbreak Surveillance System. These outbreaks involved 146 illnesses, 139 hospitalizations, and 43 deaths, with a case-fatality rate of 29.5%.」https://doi.org/10.1371/journal.pone.0279957 ; Li H 等 (2021). Characteristics of Settings and Etiologic Agents of Foodborne Disease Outbreaks — China, 2020. China CDC Weekly 3(42):889-893. https://doi.org/10.46234/ccdcw2021.219 ; Yuan Y 等 (2020). A Foodborne Bongkrekic Acid Poisoning Incident — Heilongjiang Province, 2020. China CDC Weekly 2(51):975-978：「In October 2020, 9 persons in Jidong County, Heilongjiang Province died after consuming a homemade fermented corn flour product — sour soup — with a case fatality rate of 100%.」https://doi.org/10.46234/ccdcw2020.264 ; Liu Z 等 (2026). Controlling the Storage Time Is an Effective Measure to Reduce the Risk of Bongkrekic Acid Poisoning Caused by Wet Rice Noodles. Foodborne Pathog Dis 23(7):468-472（2025-05-12 网络首发）：「The annual average number of BKA poisoning cases in Guangdong Province dropped from 6.25 before implementing the code to 0.5 after implementing the code.」https://doi.org/10.1089/fpd.2024.0131 ; 北京市市场监督管理局 (2023). 关于米酵菌酸引发食物中毒的风险提示：「米酵菌酸对热稳定，经100℃煮沸和高压烹饪也不能被破坏」「目前，尚无米酵菌酸特效解毒药物」「隔天泡制的银耳、木耳及其加工制品不能食用」「耳片不成形、发粘、无弹性或有异臭味的不能食用」「尽快催吐，排出胃内容物，减少毒素的吸收量；及时送医院救治」. https://scjgj.beijing.gov.cn/hdjl/xfts/202309/t20230904_3248296.html ; 湖南省市场监督管理局 (2025). 【食安科普】米酵菌酸致命警告：「银耳冷水（室温）浸泡3~4小时，木耳冷水浸泡1~2小时，中途换水1~2次，去除微生物，泡发时长最长均不能超过8小时」「若浸泡后银耳、木耳摸起来黏黏的，弹性差，有酸臭异味，泡发水浑浊，是变质的表现，应立即丢弃」「当中毒发生时，应第一时间催吐，减少毒素的吸收；尽量保存可疑的致病食物，并及时就医」「吃了同样食物的人，不管有没有症状，都应送医院检查」. https://amr.hunan.gov.cn/amr/xxx/xtdtx/202506/t20250630_33725786.html ; 贵州省市场监督管理局 (2023). 关于谨防米酵菌酸中毒的食品安全警示：「选购银耳、木耳等相关食品时，要选择正规渠道，泡发不可过夜，应及时加工食用」. https://amr.guizhou.gov.cn/zfxxgk/fdzdgknr/tzgg_5626971/tzgg_5626972/202307/t20230728_81318622.html