An improved withdrawal interval calculation and risk assessment of doxycycline in crayfish (Procambarus clarkii) in the natural cultured environment.

[Display omitted] • Residue accumulation and risk assessment of doxycycline was studied in crayfish in the natural environment. • Statistical approaches were used to evaluate the homogeneity, linearity, and normality of errors for obtained data. • The dairy assessment indicated that hazard quotients were far less than 1 after post-doses for 5 days. • Reliable withdrawal times were determined in muscle (43 d) and hepatopancreas (89 d) of crayfish. Doxycycline is an important medicine in aquaculture for treating fish diseases. However, its excess use causes residue exceeding to threaten human health. So, this study aimed to estimate a reliable withdrawal time (WT) of doxycycline (DC) in crayfish (Procambarus clarkii) based on statistical approaches and conduct a risk assessment for human health in the natural environment. Samples were collected at predetermined time points and determined by high-performance liquid chromatography. A novel statistical method was used to process the data of residue concentration. The homogeneity and linearity of the regressed line of data were evaluated by Bartlett's, Cochran's, and F tests. Outliers were excluded by establishing the standardized residual versus their cumulative frequency distribution on a normal probability scale. The calculated WT was 43 days in muscle of crayfish based on China and European stipulations. After 43 days, estimated daily intakes of DC were ranged from 0.022 to 0.052 µg/kg/d. Hazard Quotients were ranged from 0.007 to 0.014, which were far less than 1. These results indicated that established WT could avoid health risks for humans resulting from DC's residue in crayfish. [ABSTRACT FROM AUTHOR]