tailieunhanh - The principles of toxicology environmental and industrial applications 2nd edition phần 5

Hai lĩnh vực quan trọng để điều tra bổ sung là: 1) phát triển các công cụ tốt hơn để điều tra chức năng nhận thức và khả năng của con người và 2) mô tả mối quan hệ giữa các đặc điểm doseresponse của động vật thí nghiệm và con người chì. | 236 REPRODUCTIVE TOXICOLOGY Two important areas for additional investigation are 1 developing better tools for investigating human cognitive function and abilities and 2 characterizing the relationship between the doseresponse characteristics of experimental animals and that of humans for lead. These questions are important in terms of both public health and economics. In general the scientific and regulatory communities have regarded the clear and dramatic drop in children s blood lead levels since the 1970s as a real public health improvement realized through the control of lead from gasoline and paints. If neurocognitive development turns out to be as sensitive as some suggest to the effects of lead much tougher questions about whether and how to address exposures down to the range associated with naturally occurring lead will be up for consideration. Without obvious and readily replaceable major exposure sources like gasoline or paint the costs associated with additional incremental reductions in lead exposure for the population as a whole may be dramatic. SUMMARY This chapter has outlined the toxic responses of the male and female reproductive systems and the developing fetus. Some of the mechanisms of toxicity generally described using experimental toxicants have been presented to illustrate the types of responses and effects that should be considered. In most cases however the experimental toxicants have limited direct application to human health effects. Especially for occupational exposures the gap between toxic potential and demonstrated effects is large. Examples of actual human reproductive and developmental toxicants have been pointed out so that those chemicals which are currently known to represent a risk to humans can be identified. Some of the key points in the chapter included The differential sensitivity of various tissues and cell types in the male and female reproductive organs to certain types of toxicants. The functional and .