Health hazard evaluation report: HETA-2002-0014-2958, U.S. Department of Transportation, St. Lawrence Seaway Development Corporation, Massena, New York.
In October 2001, the National Institute for Occupational Safety and Health (NIOSH) received a joint labor/management request to conduct a health hazard evaluation (HHE) at the Dwight D. Eisenhower and Bertrand H. Snell Locks on the St. Lawrence Seaway, near Massena, New York. The request described "flu-like symptoms" and "general ill health" as concerns among workers exposed to stagnant water and decaying marine life during the annual winter inspection, cleaning, and repairs of the locks. Another impetus for the request was the collapse of one worker at the bottom of a lock during the previous winter. During site visits in 2002 and 2003, NIOSH investigators collected personal breathing zone (PBZ) and area air samples for endotoxins, hydrogen sulfide (H2S), carbon monoxide (CO), crystalline silica, and volatile organic compounds (VOCs). Endotoxin concentrations above relative limit values were measured on two workers. However, because these employees (both painters) left the worksite while wearing the monitoring equipment during part of their work shift, the exposures cannot be said to be work related. Peak PBZ H2S concentrations up to 87 parts per million (ppm) were measured while workers used pneumatic drills and jack hammers to remove deteriorating concrete from lock walls; the NIOSH recommended ceiling value is 10 ppm. Concentrations of CO, crystalline silica, and VOCs were below applicable NIOSH and OSHA occupational exposure limits. NIOSH investigators also concluded that the locks are confined spaces. NIOSH investigators identified 71 employees as having regular or intermittent exposure to the locks during winter work; 27 were interviewed or had information in their medical records that could be abstracted to identify disease trends or patterns. Most of the 27 workers reported a history of respiratory illness including bronchitis, pneumonia, or an aggravation of their asthma while working on the locks. Although several workers provided a history of seeing their health care provider for a winter illness, only two provided a history of having been hospitalized. Given the small percentage of workers who participated in this study, we cannot draw conclusions about the relationship between winter work activities and the risk of developing acute respiratory illnesses. NIOSH investigators conclude that some employees conducting winter work at the Dwight D. Eisenhower and Bertrand H. Snell Locks on the St. Lawrence Seaway are exposed to endotoxins, H2S, and VOCs. Acute respiratory illness due to H2S or VOC exposures at the levels measured during the NIOSH evaluation is unlikely. Recommendations are provided to consider the locks as confined spaces and to increase the ventilation inside the locks while winter work activities are conducted.