O'Malley Michael, Barry Terrell, Ibarra Mario, Verder-Carlos Marylou, Mehler Louise
Employee Health Services & Worker Health & Safety Branch, University of California Davis, 501 Oak Ave, 95616, USA.
J Agromedicine. 2005;10(4):27-42. doi: 10.1300/J096v10n04_06.
To evaluate the health effects of methyl isothiocyanate (MITC) and other byproducts resulting from the soil-incorporated (shank) application of 25,000 pounds of metam-sodium on July 8, 2002, near the community of Arvin, California.
Residents in a four-block area were interviewed regarding eye and upper respiratory irritation, non-specific systemic symptoms, and lower respiratory complaints. The distribution of cases was compared to results of Industrial Source Complex (ISC3) air dispersion modeling for the metam-sodium byproduct, methyl isothiocyanate (MITC). The 1-hour 200 ppb no-observed-effect- level (NOEL) and 800 ppb lowest-observed-effect level (LOEL) from a previous human eye irritation study were used to interpret the results of the air modeling estimates. Peak concentrations were compared to the 4-minute NOEL of 600 ppb and the LOEL of 1.9 ppm.
Two-hundred-fifty-two cases of irritant, non-specific systemic, and respiratory symptoms were associated with the metam-sodium application. These included 178 community residents or visitors and 74 employees of a carrot packing operation located in the affected neighborhood of Arvin. The most severe reported illness occurred in a community visitor with a history of pre-existing pulmonary disease, who was hospitalized for a week with respiratory distress. ISC3 Modeling indicated 1-hour MITC concentrations in the affected community ranged from 0.8-1.0 ppm, in the range of the LOEL, with peak concentrations between 2.4 and 3.2 ppm.
Estimated MITC concentrations during the episode exceeded both the 4-minute NOEL and 1-hourNOELby approximately four fold. The high concentrations of MITC present in the affected neighborhood may have been partially attributable to failure to immediately complete a required post-application water-treatment on 15 of the 100 treated acres. However, because of the limited area involved, the violation was unlikely to have accounted for the entire incident. Similar episodes may occur when metam-sodium fumigants are used adjacent to other rural communities.
评估2002年7月8日在加利福尼亚州阿尔文社区附近土壤中施用25000磅威百亩后产生的异硫氰酸甲酯（MITC）及其他副产物对健康的影响。
对一个四个街区区域内的居民进行访谈，询问眼部和上呼吸道刺激、非特异性全身症状以及下呼吸道不适情况。将病例分布与威百亩副产物异硫氰酸甲酯（MITC）的工业源复杂模型（ISC3）空气扩散模拟结果进行比较。利用先前一项人体眼部刺激研究中的1小时200 ppb无观察到效应水平（NOEL）和800 ppb最低观察到效应水平（LOEL）来解释空气模型估计结果。将峰值浓度与4分钟600 ppb的NOEL和1.9 ppm的LOEL进行比较。
252例刺激、非特异性全身和呼吸道症状与威百亩施用有关。其中包括178名社区居民或访客以及位于受影响的阿尔文社区内一家胡萝卜包装厂的74名员工。报告的最严重疾病发生在一名有既往肺部疾病史的社区访客身上，该访客因呼吸窘迫住院一周。ISC3模型显示，受影响社区内1小时MITC浓度在0.8 - 1.0 ppm之间，处于LOEL范围内，峰值浓度在2.4至3.2 ppm之间。
事件期间估计的MITC浓度超过了4分钟NOEL和1小时NOEL约四倍。受影响社区中存在的高浓度MITC可能部分归因于100英亩处理土地中的15英亩未能立即完成所需的施用后水处理。然而，由于涉及的区域有限，违规行为不太可能是整个事件的原因。在其他农村社区附近使用威百亩熏蒸剂时可能会发生类似事件。
