Worker exposure to endotoxin, phenolic compounds, and formaldehyde in a fiberglass insulation manufacturing plant

Worker exposures in a fiberglass wool insulation manufacturing plant were studied. The plant used a continuous process and operated at full production during a six-week study. Area samples were used to characterize spatial variability of contaminant levels. Repeated personal samples were used to characterize the distribution and to explore within- and between-worker variability of exposures. The greatest potential for exposure to each of the contaminants was restricted to specific areas of the plant. Area geometric mean concentrations were 1 to 390 ng/m3 for endotoxin and 22 to 414 micrograms/m3 for formaldehyde. There was considerable within-area variation of endotoxin (geometric standard deviation [GSD] 2.6 to 5.5) and formaldehyde (GSD 2.0 to 4.5). Concentrations of phenolic compounds were correlated with endotoxin and were influenced by a relatively high limit of detection. The ranges of personal GM exposures across homogeneous groupings were smaller than the range for the corresponding areas (endotoxin 5.8 to 36.4 ng/m3; formaldehyde 18.1 to 67.4 micrograms/m3). Variability in personal exposure was high. Individual GSDs ranged up to 10, with the mean individual GSD of 3.4 for endotoxin, and up to 12 with mean 3.7 for formaldehyde. Suggested thresholds for acute respiratory effects of endotoxin exposure were frequently exceeded (46% of 8-hr personal samples > 10 ng/m3, 7% > 100 ng/m3). No personal samples exceeded the Occupational Safety and Health Administration permissible exposure level or the American Conference of Government Industrial Hygienists' threshold limit value for formaldehyde; however, 34% were greater than 60 micrograms/m3 and 11% were greater than 120 micrograms/m3. Thus, exposures fell in a range where important exposure-response relationship could be examined.