Methylmercury is a potent toxicant, bioaccumulated and concentrated through the aquatic food chain, placing risks to human on the top of the chain. Based on the researches of adverse health effects exposed to methylmercury, several health risk assessment indexes (reference dose, provisional tolerable weekly intake, occupational mercury exposure assessment indexes ) and experiences on methylmercury exposure prevention (mainly on fish consumption) from the developed countries are presented in this paper.

OBJECTIVE:To study the absorption features of Silymarin enteric coated-polyllactic-co-glycolic acid (PLGA) nanoparticles in rat in situ intestine perfusion model and colonic adenoma Caco-2 cell model. METHODS:HPLC method was used to determine the content of silymarin. The absorption rate constant(Ka)and apparent absorption coefficient(Kapp)of Silymarin sus-pension,Silymarin PLGA nanoparticles and Silymarin enteric coated-PLGA nanoparticles were investigated in duodenum,jejunum, ileum and colon of rat in situ intestine perfusion model;the apparent permeability coefficient (Papp) of those drugs containing low-concentration,medium-concentration and high-concentration(20,40,60 μg/mL)of silymarin in Caco-2 cell model were also investigated. RESULTS:Compared with Silymarin suspension,Ka and Kapp of Silymarin PLGA nanoparticles and Silymarin enteric coated-PLGA nanoparticles were all increased in duodenum,jejunum,ileum and colon(P<0.05);compared with the correspond-ing concentration Silymarin suspension,two-way Papp of Silymarin PLGA nanoparticles and Silymarin enteric coated-PLGA nanopar-ticles containing low-concentration,medium-concentration and high-concentration of silymarin were all increased in Caco-2 cell model (P<0.05);there was no statistical significance between Silymarin PLGA nanoparticles and Silymarin enteric coated-PLGA nanoparticles (P>0.05). CONCLUSIONS:Silymarin enteric coated-PLGA nanoparticles can effectively increase the intestinal ab-sorption,cellular uptake and transmembrane transport rate of silymarin.