Pesticide Exposure And Neurologic Function In Farmworker

在过去50年中，用于农业和其他目的的农药使用量大大增加，对生产或使用农药的职业群体和一般人口构成越来越大的风险。农药神经毒性的临床表现是众所周知的，但越来越多的人担心农药也可能产生亚临床神经功能缺陷，特别是作为中毒发作的延迟后果或在慢性低水平暴露的情况下。这些影响可能会降低个体的生活质量，或者是临床可检测到的功能障碍或坦率的神经系统疾病的前奏。虽然农药中毒的病例报告很常见，并且中毒发作数年后神经功能缺损可能很明显，但很少有研究调查慢性低剂量暴露对神经系统的影响。在可能接触农药的职业群体中，农场工人是独一无二的。他们每天与处理过的作物密切接触，往往没有防护服或适当的卫生设施。监管它们暴露的法律可能不会得到执行。农场工人经常生活在杀虫剂处理过的地区或附近。难以获得医疗保健可能会加剧长期接触的影响。这一高度暴露人群的健康状况从未得到充分研究，部分原因是涉及后勤问题。农场工人经常搬家，他们可能不会说英语，也可能没有受过什么正规教育。这些因素使得很难在确定人群和良好反应率的情况下进行流行病学研究。为了解决农药神经毒性的科学问题，并调查农药对这一服务不足群体的健康影响，我们研究了佛罗里达州中部一组农场工人的农药暴露与神经功能障碍的关系。为了克服在农民工研究中经常遇到的后勤问题，我们确定了一个稳定的人口，并获得了当地一个农民工组织的合作。我们的研究在几个方面比以前的研究有了进步：我们从同一人群中招募了暴露的农场工人和未暴露的对照；我们使用了广泛的神经学测试来评估认知、运动和感觉功能；我们纳入了对慢性暴露的详细评估；我们将DNA存档以供基因分析。

Use of pesticides for agriculture and other purposes has increased greatly in the last 50 years, posing an increasing risk both to occupational groups manufacturing or using pesticides and to the general population. Clinical manifestations of pesticide neurotoxicity are well known, but there is growing concern that pesticides may also produce subclinical neurologic deficits, particularly as a delayed consequence of a poisoning episode or in situations of chronic, low-level exposure. Such effects might degrade an individual's quality of life or be a prelude to clinically detectable dysfunction or frank neurologic disease. Although case reports of pesticide poisoning are common, and neurologic deficits may be apparent years after a poisoning episode, few studies have investigated the neurologic effects of chronic low-dose exposure. Among occupational groups potentially exposed to pesticides, farmworkers are unique. They work in intimate contact with treated crops on a daily basis, often without protective clothing or adequate sanitary facilities. Laws regulating their exposure may not be enforced. Farmworkers often live in or near areas treated with pesticides. Poor access to medical care may compound the effects of chronic exposure. The health of this highly exposed group has never been adequately studied, partly because of the logistical problems involved. Farmworkers often move frequently, they may not speak English, and they may have little formal education. These factors make it difficult to conduct an epidemiologic study with a defined population and good response rates. To address the scientific issue of pesticide neurotoxicity and to investigate health effects of pesticides in this underserved group, we studied the relationship of pesticide exposure to neurologic dysfunction in a group of farmworkers in central Florida. In order to overcome the logistical problems often encountered in studies of migrant farmworkers, we identified a stable population and enlisted the collaboration of a local farmworker organization. Our study represents an advance over previous studies in several ways: we recruited exposed farmworkers and unexposed controls from the same population; we used a broad range of neurologic tests to assess cognitive, motor, and sensory function; we included a detailed evaluation of chronic exposure; and we archived DNA for genetic analyses. Working with a defined population in central Florida, we studied 283 farmworkers who had worked on one of three crops -- ornamental ferns, nursery plants, or citrus fruit -- and compared them to 51 unexposed controls. Information on farmwork history was collected using a structured questionnaire. Neurobehavioral performance was evaluated using a battery of seven tests adapted for use in Latino populations; some tests were implemented on a computer. Data were analyzed using logistic or linear regression, adjusted for potential confounders including age, sex, height, weight, education, acculturation, and alcohol use. The recruiting process was generally successful. The overall response rate was 72%. We compared eligible individuals who participated to those who did not. The two groups did not differ by age or sex. However, individuals who had done farmwork for 6 to 15 years were more likely to enroll than those who had done farmwork for either less or more time. Workers in one of the defined types of agriculture (nursery, citrus, or ferns) were more likely to enroll than either unexposed controls or those who had worked in various types of agriculture for 15 or more years. We have begun analyses to compare exposed farmworkers to unexposed controls. Fern work was associated with worse performance for digit span, symbol digit, tapping, Santa Ana, and postural sway; nursery and citrus work were associated with worse performance for tapping and postural sway. No changes in vibrotactile sensitivity or grip strength were related to farmwork. Deficits associated with farm work, when present, were comparable in size to those associated with less education or increased alcohol use. Dose-response for months of work was observed for fern work for tapping and Santa Ana; for nursery work for postural sway; and for citrus for tapping. We conclude that work with ferns, nursery plants, and citrus fruit may be associated with deficits in neurobehavioral performance reflecting cognitive, psychomotor, and integrated sensory-motor function.