# Risk Assessment of Metals in Black Fungus and Culture Substrates Based on Monte Carlo Simulation
## 2 Materials and Methods
### Establishment of Risk Assessment Methods  
Exposure Assessment Model  
Exposure assessment is a qualitative or quantitative assessment of the biological, chemical and physical factors that may be exposed to humans or the environment through food intake or other relevant pathways. Exposure assessment describes the pathway by which the hazard enters the body and estimates the level of exposure to the hazard in different populations. The amount of human exposure to this chemical is calculated based on data from dietary surveys and surveys of exposure levels of chemical substances in various foods. The @Risk 8.0 (Palisade, NY, USA) software was used to conduct a non-parametric probability assessment of exposure to heavy metals in black auriculeus auriculeus, and heavy metal pollution data were randomly selected to calculate daily exposure per unit body weight of different populations. The simulation method was Monte Carlo simulation with 10,000 simulations. The distribution of daily exposure per unit body weight of black fungus heavy metals in different populations was obtained by calculation. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**RF Power/w**} & **Sampling** & **Flow Rate of** & **Compensated** & **Paristaltic** & **Atomizing** \\  & & **Depth/mm** & **Carrier** & **Gas Flow** & **Pump** & **Chamber** \\  & & **Gas/(L/min)** & **Rate/(L/min)** & **Speed/(r/min)** & **Temperature/\({}^{\circ}\)C** \\ \hline Set value & 1300–1500 & 6–9 & 6.0–10.0 & 0.4–0.6 & 0.1 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Tuning parameters of inductively coupled plasma mass spectrometer. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{2}{c}{**Mass Axis/\%**} & \multirow{2}{*}{**Mass Resolution \({}^{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \text{ \text{ \  
Risk description formula  
The health risk exposure of heavy metals in black fungus is calculated as follows:  
EDI = \(\frac{\text{EF}_{\text{r}}\times\text{ED}\times\text{F}_{\text{IR}}\times\text{ C}\times\text{F}_{\text{P}}\times\text{F}_{\text{m}}}{\text{W}_{\text{AB}} \times\text{AT}_{\text{n}}}\times 10^{-3}\)  
EDI [mg:(kgmg:L-1d)-1]: Assessment of daily exposure, EF\({}_{\text{r}}\) (d:a-1): exposure frequency, ED (a): Exposure persistence, F\({}_{\text{IR}}\) g-(d:person)-1: Per capita daily dietary intake of edible fungi, C: (mg:kg-1) black fungus heavy metal content, F\({}_{\text{P}}\): processing factor, Fm: variation factor, W\({}_{\text{AB}}\) (kg:person-1): Body weight per capita, A\({}_{\text{Th}}\) (d): Mean cancer-free response time. Exposure sources of assessment data  
Exposure frequency and duration: According to the relevant data in the _Risk Analysis Manual_ of the United States Environmental Protection Agency, the exposure frequency is 350 a\(\cdot\)d-1, and the lifetime duration of exposure is 70 a\(\cdot\)d-1 dietary intake of edible fungi. According to the data of the 2015 Report on Nutrition and Chronic Diseases of Chinese residents, the dietary intake of edible fungi of Chinese residents was 134.7 g\(\cdot\)d-1 for adults and 93.4 g\(\cdot\)d-1 for children, which was equivalent to 13.47 g\(\cdot\)d-1 for dried fungus for adults and 9.34 g\(\cdot\)d-1 for children. Heavy metal content in black fungus: calculated by the average value of the samples, and the undetected samples were assigned a uniform value of 1/2 LOD (limit of detection). The detection limit of total arsenic is 0.005 mg\(\cdot\)kg-1, cadmium detection limit 0.0005 mg\(\cdot\)kg-1, chromium detection limit 0.005 mg\(\cdot\)kg-1, detection limit of lead 0.01 mg\(\cdot\)kg-1, and detection limit of selenium 0.005 mg\(\cdot\)kg-1. Processing factor: refers to the proportion of its concentration decrease after cooking and other processing links, using the national general practice, and the default is 1.