External considerations Molecular designs that reduce or impede(妨碍) absorption by man, animals and aquatic life (水生生物) also represent important external 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 5 External considerations ◼ Molecular designs that reduce or impede（妨碍） absorption by man, animals and aquatic life （水生生物） also represent important external considerations