What to Do at Low Doses: A Bounding Approach for Economic Analysis

To quantify the health benefits of environmental policies, economists generally require estimates of the reduced probability of illness or death. For policies that reduce exposure to carcinogenic substances, these estimates traditionally have been obtained through the linear extrapolation of experimental dose-response data to low-exposure scenarios as described in the U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment (1986). In response to evolving scientific knowledge, EPA proposed revisions to the guidelines in 1996. Under the proposed revisions, dose-response relationships would not be estimated for carcinogens thought to exhibit nonlinear modes of action. Such a change in cancer-risk assessment methods and outputs will likely have serious consequences for how benefit-cost analyses of policies aimed at reducing cancer risks are conducted. Any tendency for reduced quantification of effects in environmental risk assessments, such as those contemplated in the revisions to EPA's cancer-risk assessment guidelines, impedes the ability of economic analysts to respond to increasing calls for benefit-cost analysis. This article examines the implications for benefit-cost analysis of carcinogenic exposures of the proposed changes to the 1986 Guidelines and proposes an approach for bounding dose-response relationships when no biologically based models are available. In spite of the more limited quantitative information provided in a carcinogen risk assessment under the proposed revisions to the guidelines, we argue that reasonable bounds on dose-response relationships can be estimated for low-level exposures to nonlinear carcinogens. This approach yields estimates of reduced illness for use in a benefit-cost analysis while incorporating evidence of nonlinearities in the dose-response relationship. As an illustration, the bounding approach is applied to the case of chloroform exposure.     

Dose-Response and Risk Assessment of Airborne Hexavalent Chromium and Lung Cancer Mortality

This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI).     

Valuation of childhood risk reduction: the importance of age, risk preferences, and perspective.

This article explores two problems analysts face in determining how to estimate values for children's health and safety risk reductions. The first addresses the question: Do willingness‐to‐pay estimates for health risk changes differ across children and adults and, if so, how? To answer this question, the article first examines the potential effects of age and risk preferences on willingness to pay. A summary of the literature reporting empirical evidence of differences between willingness to pay for adult health and safety risk reductions and willingness to pay for health and safety risk reductions in children is also provided. The second dimension of the problem is a more fundamental issue: Whose perspective is relevant when valuing children's health effects—society's, children's, adults‐as‐children, or parents'? Each perspective is considered, followed ultimately by the conclusion that adopting a parental perspective through an intrahousehold allocation model seems closest to meeting the needs of the estimation problem at hand. A policy example in which the choice of perspective affects the outcome of a regulatory benefit‐cost analysis rounds out the article and emphasizes the importance of perspective.     

对降低中国农业生产风险的方式探讨

农业生产领域因其要受气候条件、自然灾害、技术的改变、信息的不完全、国家政策的变动,有着不同于其他行业的特殊风险性,而我国农户大多又是风险规避者,所以,如何降低农业生产中的风险,及如何看待降低风险的方式在中国的实效性问题,成为目前解决“三农”问题关键所在。     

商业银行中间业务及风险管理的几点思考

我国商业银行在中间业务发展上与外资银行相比存在较大的差距。面对外资银行进军中国市场的事实,我国商业银行只有大力发展中间业务才能抵抗外资银行的冲击。发展中间业务必定伴随着风险的出现,特别是与业务发展相关的风险巨大,银行自身必须从内部做好相关的风险防范与管理;同时,银行监督管理部门也要从外部做好相关的风险管理工作,来保障和促进商业银行中间业务的发展。     

论当前的物欲型犯罪

当前的物欲型犯罪有其经济根源和直接原因 ,其动机、行为方式及侵害对象具有一些带规律性的特点 ;犯罪人在市场经济中的地位 ,决定了其犯罪动机和行为方式。尤其少部分身居高位、掌握实权的领导干部或国有企业负责人对个人财富、权力的不当追求 ,导致权钱交易、化公为私 ,造成国有财产的大量流失。这种犯罪不断发生的重要原因是 ,国有财产所有者虚位 ;应从源头上遏制此类犯罪的蔓延     

西部地区县乡财政状况与基层政权建设

近年来县乡基层政权在运转过程中出现了很多矛盾 ,其中财政收支是矛盾的焦点。县乡财政出现了收入大幅减少 ,支出刚性增加 ,债务负担沉重 ,风险加大等一系列问题。县乡基层政权组织的正常运转受到严重影响。解决这些问题和矛盾 ,既要从财税体制改革着眼 ,又要从经济发展环境着眼 ,更要从机构改革、政权体制改革着眼     

Benchmark Analysis: Shopping with Proper Confidence

We discuss the issue of using benchmark doses for quantifying (excess) risk associated with exposure to environmental hazards. The paradigm of low-dose risk estimation in dose-response modeling is used as the primary application scenario. Emphasis is placed on making simultaneous inferences on benchmark doses when data are in the form of proportions, although the concepts translate easily to other forms of outcome data.     

衍生金融工具风险:种类、成因与控制

衍生金融工具的风险问题已经引起了各国经济界和管理当局的广泛关注。本文将衍生金融工具的风险概括为市场风险、信用风险、流动性风险、营运风险和法律风险五类 ,探讨了各种风险的成因 ,并提出了防范和控制对策     

风险投资家的双重逆向选择风险规避机制

风险投资过程中,由于信息的不对称,投资者与风险投资家之间、风险投资家与风险企业家之间存在着双重逆向选择风险。在融资阶段的信号传递机制中,作为代理人的风险投资家,选择融资计划书信号,向作为委托人的投资者传递其能力信号,投资者据此修正自己的先验概率,然后根据后验概率,与风险投资家签定合同规避风险;在投资阶段的信息甄别机制中,作为中间委托人的风险投资家先提供合同,这时唯一可能是分离均衡,即不同类型的风险企业家选择不同的合同规避风险。