Letter Health Consultation: Follow-Up to June 2010 Letter Health Consultation. Phosphine Gas and Human Exposures from Pond 15S, FMC Site, Eastern Michaud Flats, Chubbuck and Pocatello, Idaho

摘要

This letter is a follow up to the letter health consultation prepared by the Department of Health and Welfare, Division of Public Health, Bureau of Community and Environmental Health (BCEH) on June 2, 2010 under a cooperative agreement with ATSDR. BCEH has completed an evaluation of the latest ambient air sampling data from May 7, 2010 through July 31, 2010 for the Pond 15S Resource Conservation and Recovery Act (RCRA) area of the FMC Eastern Michaud Flats Superfund site near Chubbuck and Pocatello, Idaho. We conclude that during the period of June 1 to July 31, breathing zone levels of phosphine gas (PH3) being released to ambient air from Pond 15S were not expected to harm peoples health. Phosphine levels began to decline in mid-May, and did not increase again for the remainder of the sampling period. The real-time meters (Draeger PacIII) used to measure phosphine in ambient air at breathing zone height near the Pond 15S lift station number 1 (LS1) were the same ones used in previous sampling efforts. During the May-July sampling period, samples were generally taken 3-4 times per 24-hours at approximately 4 to 6 hour intervals. Readings at LS1 adjacent to Pond 15S were in the range of 0 to 0.29 parts per million (ppm) for the June 2010 period, and 0 to 0.07 ppm for the July 2010 period, as shown in Table 1. For comparison, the Occupational Safety and Health Administration Permissible Exposure Limit (OSHA PEL) is 0.30 ppm time-weighted over an 8 hour work shift.