Recommendations for the Conduct of Acute Inhalation Limit Tests

This paper reviews the scientific issues related to exposureconcentrations and particle sizes used in acute inhalation limittests. The current United States Environmental Protection Agency(USEPA) recommended exposure concentration for such tests is5 mg/liter, while this level is very high, it is often achievable.On the other hand, its toxicological relevance is questionable.The USEPA recommendation that 25% of the particle distributionbe less than 1 µm is a more difficult issue to address.Physical laws for aerosol particle generation and behavior limitthe minimum size of particles in an exposure atmosphere at aconcentration of 5 mg/liter. Particle size also influences depositionsite in the respiratory tract. Since damage to any region ofthe respiratory tract can produce lethality, and it is not possibleto predict, a priori, the most responsive region of the tractor the most harmful particle size of an untested agent, acutelimit testing should employ particles in a size range that depositsthroughout the entire rodent respiratory tract. Particles between1 and 4 µm mass median aerodynamic diameter (MMAD) arewell suited for such studies. It is, therefore, recommendedthat the limit test concentration should be the highest concentration(up to 5 mg/liter) that can be achieved while still maintaininga particle size distribution having an MMAD between 1 and 4µm.     

中医疲劳术语整理研究

以疲劳术语系列中的“倦类”为代表进行释义并阐述了整理疲劳术语的意义的目的。其意义和目的为：阐明中医疲劳的病因，病机，规范描述疲劳的术语，为探讨中医抗疲劳及调治亚健康的方药提供线索与依据。     

大理市1986年～2000年孕产妇死亡分析

目的:为进一步降低孕产妇死亡率提供科学依据,总结大理市孕产妇系统管理工作的经验教训.方法:回顾性分析大理市15a孕产妇死亡病例.结果:大理市15a孕产妇死亡率逐年下降,从1986年的127.4/10万降至2000年的49.4/10万.死亡原因前五位依次为产科出血、妊高症、产褥感染、羊水栓塞、妊娠合并心脏病.结论:本市的孕产妇死亡原因主要与医疗保健人员知识技能水平相关、家庭个人知识水平及经济状况相关.