Mahaffey K R
Environ Health Perspect. 1974 May;7:107-12. doi: 10.1289/ehp.747107.
Although the quantities of lead (Pb) to which individuals are exposed vary widely, susceptibility of an individual to the effects of a specific level of exposure is another highly important factor in development of lead toxicity. For example, susceptibility to lead toxicity can be modified by several dietary factors. Low dietary intakes of calcium or iron (20% of recommended levels) substantially increase the toxicity of the same level of lead exposure to rats. In the studies of calcium effect, when calcium was fed to rats at (1/5) of the recommended intake, 12 mug Pb/ml drinking water produced the same degree of toxicity as did 200 mug Pb/ml with a normal calcium diet. The maximal dose for a 10-week period that does not impair heme synthesis or renal function in the rat has been established to be 200 mug Pb/ml drinking water. The role of low calcium diet on increasing susceptibility to lead has been confirmed in several species. Mechanisms explaining the effect of calcium on lead toxicity may be related to absorption of lead from the gastrointestinal tract or renal tubule or to function of the parathyroid. Preliminary histological investigations on the parathyroids of control and lead-treated rats on normal and low calcium diets show no effect of lead. Studies are currently underway to evaluate the lead, calcium and iron contents of the diets of children with normal and elevated concentrations of blood lead.
尽管个体接触铅（Pb）的量差异很大，但个体对特定暴露水平影响的易感性是铅中毒发展的另一个非常重要的因素。例如，铅中毒的易感性可受多种饮食因素影响。低钙或低铁饮食摄入量（推荐水平的20%）会大幅增加相同铅暴露水平对大鼠的毒性。在钙效应研究中，当以推荐摄入量的（1/5）给大鼠喂食钙时，12微克/毫升铅的饮用水产生的毒性程度与正常钙饮食下200微克/毫升铅的饮用水相同。已确定大鼠在10周内不损害血红素合成或肾功能的最大剂量为200微克/毫升铅的饮用水。低钙饮食增加铅易感性的作用已在多个物种中得到证实。解释钙对铅毒性影响的机制可能与胃肠道或肾小管对铅的吸收或甲状旁腺功能有关。对正常钙饮食和低钙饮食下对照大鼠和铅处理大鼠甲状旁腺的初步组织学研究表明铅无影响。目前正在进行研究，以评估血铅浓度正常和升高的儿童饮食中的铅、钙和铁含量。
