Effects of Long-Term Low Level Hydrogen Sulfide Exposure

描述(申请人提供)：硫化氢气体具有很高的急性毒性，但对长期、低水平暴露的影响知之甚少。目前的证据表明，神经系统、呼吸系统和眼睛是对硫化氢影响最敏感的器官。在美国，职业和社区长期接触硫化氢的情况很多。来源包括集中的动物饲养作业、纸浆厂和天然气精炼厂。然而，接触硫化氢的人口规模较小，硫化氢“臭鸡蛋”气味引起的恐惧，诉讼和赔偿问题可能产生的报告偏差，以及其他暴露可能造成的混淆，使得调查长期接触硫化氢是否会对健康造成影响非常困难。位于新西兰地热田的罗托鲁瓦市(人口50,000人)为研究长期接触硫化氢是否会对健康造成影响提供了一个独特的机会。在没有其他潜在有毒气体的情况下，长期低水平接触硫化氢，同时将气味作为日常生活的一种事实接受(避免因恐惧引发的症状或未决诉讼而可能产生的偏见)，不存在其他大量人口。这项对罗托鲁瓦人口样本的横断面研究是在早先的研究之后进行的，该研究表明，该市接触硫化氢可能会对健康造成影响。研究样本将包括1800名成年人，年龄在18岁至65岁之间，生活在高、中、低硫化氢暴露的罗托鲁瓦地区。我们将获得：(1)对问卷的回答，包括人口统计因素、症状学以及居住和职业史的问题；(2)一系列神经行为功能测试的结果；(3)周围神经功能检查的结果；(4)肺功能测试的结果；(5)眼睛和视力测试的结果，包括白内障和色觉障碍的检查。暴露数据将基于广泛的Rotorua硫化氢监测数据，并对全市的暴露进行空间建模。对于每个参与者，调查问卷中关于居住和工作历史以及日常活动模式的信息将与硫化氢建模结果相结合，以构建个人累积接触指数。为了验证暴露估计，参与者的样本将佩戴个人硫化氢采样器三周。统计分析将寻求暴露指数与健康影响的每一项指标--神经行为、周围神经病变、呼吸和眼功能/视力--之间的联系。研究结果将确认当前美国职业和环境中硫化氢暴露标准的充分性，或者提供证据表明它们对健康的保护不足。

DESCRIPTION (provided by applicant): Hydrogen sulfide (H2S) gas has high acute toxicity, but little is known about the effects of long-term, low-level exposures. Current evidence indicates the nervous system, the respiratory system and the eye are the most sensitive organs to effects of H2S. Substantial chronic occupational and community exposures to H2S occur in the United States. Sources include concentrated animal feeding operations, pulp mills, and gas refineries. However, small exposed population sizes, fears caused by the "rotten eggs" odor of H2S, potential reporting biases from litigation and compensation issues, and potential confounding by other exposures have made very difficult investigations into whether health effects are caused by chronic H2S exposures. Rotorua city (population >50,000), situated on a geothermal field in New Zealand, presents a unique opportunity to investigate whether chronic H2S exposure causes health effects. No other large population exists where chronic low-level exposures to H2S, in the absence of other potentially toxic gases, coincide with acceptance of the odor as a fact of daily life (avoiding possible biases from fear-induced symptoms or pending litigation). This cross-sectional study of a sample of the Rotorua population follows earlier research suggesting possible health effects associated with H2S exposure in the city. The study sample will consist of 1,800 adults, aged 18 to 65, living in Rotorua areas with high, medium and low exposures to H2S. We will obtain: (1) responses to a questionnaire, including questions on demographic factors, symptomatology, and residential and occupational histories; (2) the results of a battery of tests of neurobehavioral function; (3) the results of an examination of peripheral nerve function; (4) the results of lung function testing by spirometry; and (5) the results of ocular and vision testing including examination for cataract and color vision impairment. Exposure data will be based on extensive Rotorua monitoring data for H2S, with spatial modeling of exposures across the city. For each participant, the information from the questionnaire on residential and work histories and daily movement patterns will be combined with the H2S modeling results to construct individual cumulative exposure indices. To validate exposure estimates, a sample of participants will wear personal H2S samplers for three weeks. Statistical analysis will seek associations between the exposure indices and each of the measures of health effect - neurobehavioral, peripheral neuropathy, respiratory and ocular function/vision. Study results will either confirm the adequacy of current U.S. occupational and environmental exposure standards for H2S or provide evidence that they are insufficiently health protective.