External considerations ■ Bioaccumulation(生物集聚)or Bio-magnification(生物放大 It refers to the increase of tissue concentration of a chemical as it progresses up the food chain. 四大学化学学院 2002年7月26日
四川大学化学学院 2002年7月26日 11 External considerations ◼ Bioaccumulation（生物集聚）or ◼ Bio-magnification (生物放大): ◼ It refers to the increase of tissue concentration of a chemical as it progresses up the food chain
External considerations It is well known that certain chemicals. for example chlorinated pesticides and other chlorinated hydrocarbons, will be stored in the tissues of a wide range of living organisms and may accumulate to toxic level This phenomenon is exacerbated by the fact that the lower forms of life or the organism at lower trophic stages are subsequently ag consumed as food by fish, mammals and his birds These species in turn may be consumedly human 四大学化学学院 2002年7月26日
四川大学化学学院 2002年7月26日 12 External considerations ◼ It is well known that certain chemicals, for example chlorinated pesticides and other chlorinated hydrocarbons, will be stored in the tissues of a wide range of living organisms and may accumulate to toxic level. ◼ This phenomenon is exacerbated by the fact that the lower forms of life or the organism at lower trophic stages are subsequently consumed as food by fish, mammals and birds. ◼ These species in turn may be consumed by human
External considerations Hence, the substances of concern may both bioaccumulate in lower life forms and biomagnify or increase their concentration in higher life forms by oeders of magnitude as they accumulate and migrate up the food chain 四大学化学学院 2002年7月26日 13
四川大学化学学院 2002年7月26日 13 External considerations ◼ Hence, the substances of concern may both bioaccumulate in lower life forms and biomagnify or increase their concentration in higher life forms by oeders of magnitude as they accumulate and migrate up the food chain
The internal considerations They generally include approaches using molecular manipulations to facilitate Biodetoxication The avoidance of direct toxicity The avoidance of indirect biotoxicity or bioactivation 四大学化学学院 2002年7月26日
四川大学化学学院 2002年7月26日 14 The internal considerations ◼ They generally include approaches using molecular manipulations to facilitate: ◼ Biodetoxication ◼ The avoidance of direct toxicity ◼ The avoidance of indirect biotoxicity or bioactivation
Internal considerations -Prevention of toxic effects A. Facilitation of detoxication 1. Facilitation of excretion(排泄) a. selection of hydrophilic(亲水的) compounds b. facilitation of conjugation/acetylation conjugated with: glucuronic acid(葡萄糖醛酸) sulfate(硫酸盐, amino acid to accelerate urinary or biliary excretion C. other considerations 四大学化学学院 2002年7月26日
四川大学化学学院 2002年7月26日 15 Internal considerations-Prevention of toxic effects ◼ A. Facilitation of detoxication ◼ 1. Facilitation of excretion（排泄） ◼ a. selection of hydrophilic(亲水的) compounds ◼ b. facilitation of conjugation/acetylation ◼ conjugated with: glucuronic acid(葡萄糖醛酸) ◼ sulfate(硫酸盐), amino acid ◼ to accelerate urinary or biliary excretion ◼ c. other considerations