*2.6. Statistical Analysis*

Toxicity equivalent (TEQ) calculations are based on the revised WHO-TEF values from 2005. All of the TEQ concentrations are reported according to upper, median, and lower limits. The TEQs of the PCDD/Fs and DL-PCBs in Chinese mitten crab were calculated according to Formulas (1)–(6):

$$\text{TEQ}\_{i} = \text{TEF} \times \text{c}\_{i} \tag{1}$$

$$\text{TEQ}\_{\text{PCDDs}} = \Sigma \text{TEF}\_{\text{iPCDDs}} \times \text{c}\_{i\text{PCDDs}} \tag{2}$$

$$\text{TEQ}\_{\text{PCDFs}} = \Sigma \text{TEF}\_{\text{iPCDFs}} \times \text{c}\_{\text{iPCDFs}} \tag{3}$$

$$\text{TEQ}\_{\text{PCDD/Fs}} = \text{TEQ}\_{\text{PCDDs}} + \text{TEQ}\_{\text{PCDFs}} \tag{4}$$

$$\text{TEQ}\_{\text{DL-PCBs}} = \Sigma \text{TEF}\_{\text{iDL-PCBs}} \times \text{c}\_{\text{iDL-PCBs}} \tag{5}$$

$$\text{TEQ}\_{\text{(PCDD/Fs} + DL-PCBs)} = \text{TEQ}\_{\text{PCDD/Fs}} + \text{TEQ}\_{DL-PCBs} \tag{6}$$

where *TEQi*—dioxin toxic equivalent (*TEQ*) of the congeners of *PCDD*/*Fs* or *DL-PCBs* in food in micrograms per unit kg (μg/kg); *TEFi*— toxicity equivalent factors of congeners in *PCDD*/*Fs* or *DL-PCB*s; *ci*—concentrations of *PCDD*/*Fs* or *DL*-*PCBs* congeners in food in micrograms per kilogram (μg/kg); the remaining subscripts are specific combinations of *PCDD*/*Fs* or *DL-PCBs*.
