Assessment of melamine contamination in crop, soil and water in China and risks of melamine accumulation in animal tissues and products.

The scandal of melamine-adulterated infant formula in China in September 2008 demanded the need to assess the extent of melamine contamination in the environment and food products and possible risks of consuming melamine-contaminated diets. In this work, our extensive work tested water, soil and crop samples from 21 provinces in China. Soils nearby and waste waters from melamine-manufacturing factories were examined, and the highest melamine concentrations in waste water and soil samples were 226.766 and 41.136 mg/kg, respectively. Six of 94 irrigation water samples had melamine at a concentration of 21-198 microg/L. Only 1 sample collected from 124 farmlands farther than 150 km from melamine factories was detected for melamine at a content of 176 microg/L. Only 3 out of 557 crop samples contaminated more than 1mg/kg melamine, with the highest level of 2.05 mg/kg in a wheat sample. When basal diets contained 2mg/kg melamine were fed to various animals, deposition of melamine in animal tissues and products was all lower than 122 microg/kg. The melamine deposition was much higher (e.g., 4483 microg/kg in the kidney of chicken) when diets contained 100 mg/kg melamine but was found to be completely depleted after 96 h for all animals after switching to the basal diets. Our work may be valuable to regulate melamine production and monitor the safety of food and animal products.