These ptwis represent a tolerable weekly intake for life - time exposure and that occasional short - term excursions above the ptwis would have no major health consequences provided that the average intake over long periods is not exceeded 这些重金属的摄取量即使超过暂定每周可容忍摄入量，也未必会损害健康。暂定每周可容忍许摄入量是指人于一生中每周可以接受的摄入水平。
