Effects of Long-Term Low Level Hydrogen Sulfide Exposure

描述（由申请人提供）：硫化氢（H2S）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H2S影响最敏感的器官。在美国，大量的职业和社区长期暴露于H2S。来源包括集中的动物饲养操作、纸浆厂和天然气精炼厂。然而，暴露人群规模小，对H2S“臭鸡蛋”气味的恐惧，诉讼和赔偿问题可能导致的报告偏差，以及其他暴露的潜在混淆，使得对慢性H2S暴露是否造成健康影响的调查非常困难。罗托鲁瓦市（人口50万）位于新西兰的一个地热田，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，长期低水平暴露于H2S并将其视为日常生活中的事实（避免因恐惧引起的症状或未决诉讼而可能产生的偏见）的人口并不多。在对罗托鲁瓦人口样本进行横断面研究之前，有研究表明该市接触硫化氢可能对健康产生影响。研究样本将包括1800名年龄在18岁至65岁之间的成年人，他们居住在罗托鲁瓦地区，分别有高、中、低硫化氢暴露。我们将获得：(1)对调查问卷的回答，包括人口因素、症状学、居住和职业史等问题；(2)一系列神经行为功能测试的结果；(3)周围神经功能检查结果；(4)肺活量测定法肺功能检查结果；(5)眼科和视力检查结果，包括白内障和色觉障碍检查。暴露数据将基于Rotorua对H2S的广泛监测数据，并对整个城市的暴露进行空间建模。对于每个参与者，来自调查问卷的居住和工作历史以及日常运动模式的信息将与H2S建模结果相结合，以构建个人累积暴露指数。为了验证暴露估计，参与者样本将穿着个人H2S取样器三周。统计分析将寻求暴露指数与每一种健康影响指标之间的联系——神经行为、周围神经病变、呼吸和眼功能/视力。研究结果将要么证实美国目前的职业和环境H2S暴露标准的充分性，要么提供证据证明这些标准对健康的保护力度不够。

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.