# Risk Assessment of Metals in Black Fungus and Culture Substrates Based on Monte Carlo Simulation
## 3 Results
### Risk Assessment of Dietary Exposure to Heavy Metals in Black Fungus
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Population**} & \multirow{2}{*}{**Element Class**} & \multicolumn{6}{c}{**Risk Quotient**} \\ \cline{3-8}  & & **Mean** & **Mode** & **Std. Deviation** & **P50 * & **P97.5** & **P99** \\ \hline \multirow{4}{*}{**Juvenile**} & As & 0.1281 & 0.0058 & 0.1229 & 0.0904 & 0.4585 & 0.5708 \\  & Pb & 0.0315 & 0.0123 & 0.0243 & 0.0253 & 0.0943 & 0.1140 \\  & Cd & 0.0338 & 0.0191 & 0.0321 & 0.0265 & 0.1078 & 0.1511 \\  & Cr & 0.1326 & 0.0005 & 0.1328 & 0.0919 & 0.4894 & 0.6107 \\  & **THQ** & **0.3260** & _/_ & _/_ & 0.2341 & 1.1500 & 1.4466 \\ \hline \multirow{4}{*}{**Adult**} & As & 0.0766 & 0.0034 & 0.0735 & 0.0540 & 0.2741 & 0.3413 \\  & Pb & 0.0188 & 0.0074 & 0.0145 & 0.0151 & 0.0564 & 0.0682 \\ \cline{1-1}  & Cd & 0.0202 & 0.0114 & 0.0192 & 0.0158 & 0.0644 & 0.0903 \\ \cline{1-1}  & Cr & 0.0794 & 0.0003 & 0.0794 & 0.0549 & 0.2926 & 0.3651 \\ \cline{1-1}  & **THQ** & **0.1950** & _/_ & _/_ & **0.1399** & **0.6875** & **0.8649** \\ \hline \hline \end{tabular}  
* P50 is the 50 th percentile, that is, the value of the variable in order of size, which is 50% of the total number of variables. The same is true for P95 and P97.  
\end{table} 
Table 5: Hazard quotient statistics of heavy metal intake through _Auricularia heimuer_ in different populations. The average risk quotients of As, Pb, Cd and Cr ingestion in the Chinese adult population through black fungus pathway were 0.0766, 0.0188, 0.0202 and 0.0794, respectively, and the comprehensive pollution index was 0.1950, which was within the overall safety level. However, at the high exposure level of 99% sites, the risk quotient of single element was within the safe level, and the risk quotient of comprehensive pollution index was 0.8649, which was at the warning limit. Analysis and Simulation Distribution of Heavy Metals in Black Fungus Cultivation Medium 3.4.1. Analysis of Heavy Metal Content in Black Fungus Cultivation Medium  
Heavy metals As, Pb, Cd and Cr were detected on raw materials commonly used in black fungus bag cultivation. The residual distribution results of heavy metals in different black fungus cultivation substrates showed (Table 6) that from the point of view of detection rate, the detection rate of As and Cr in irrigation water was 2.94%, Pb and Cd were not detected, and all other raw materials were detected. From the qualification rate, the qualification rate of four heavy metals in culture medium, sawdust, soybean meal, wheat bran, corn flour and irrigation water, Pb and Cr in waste fungus rod, Pb and Cd and Cr in rice bran are 100%, the excess rate of As in waste fungus rod is 6.25%, the excess rate of Cd is 9.38%, and the excess rate of As in rice bran is 20%; no passing judgment). From the residual point of view, the heavy metals in culture medium, waste fungus sticks, sawdust, rice bran, wheat bran and corn flour showed Cr? Pb? As? Cd, the heavy metals in soybean meal showed Cr? Pb? Cd? As, and the heavy metals in lime and gypsum showed Cr? As? Pb? Cd. In terms of the residual amount of heavy metals, As was lime? gypsum? rice bran? waste fungus sticks? medium? sawdust? wheat bran? soybean meal? irrigation water. Pb in different raw materials is lime? sawdust? rice bran? waste fungus sticks? wheat bran? gypsum? medium? corn flour? soybean meal? irrigation water; Cd in different raw materials is waste fungus sticks? lime? gypsum? sawdust? medium? wheat bran? soybean meal? rice bran? corn flour? irrigation water; Cr in different raw materials is lime? rice bran? gypsum? sawdust? waste fungus sticks? medium? wheat bran? corn flour? soybean meal? irrigation water.