© 1986 Oxford University Press
research-article |
The Rate of Decline of Blood Lead in Lead Industry Workers during Medical Removal: The Effect of Job Tenure1
Department of Environmental Health, University of Cincinnati College of Medicine 3223 Eden Avenue, Cincinnati, Ohio 45267
The Rate of Decline of Blood Lead in Lead Industry Workers during Medical Removal: The Effect of Job Tenure. O'FLAHERTY, E. J. (1986). Fundam. Appl. Toxicol. 6, 372–380. Under the Occupational Safety and Health Administration (OSHA) standard for occupational exposure to lead, workers whose blood lead concentration has reached or exceeded a specified trigger level are removed from work areas where 8-hr time-weighted-average air lead concentration is equal to or in excess of a specified value, and are returned when two consecutive blood lead concentration measurements have been at or below the return trigger level. Initial removal and return triggers, of 80 and 60 µg/100 g respectively, instituted in 1979, were supplanted in a scheduled sequence by 70/50 and later by 60/40 triggers. This paper presents a descriptive summary of lead industry-wide experience with medical removals from high workplace-lead exposure as mandated by OSHA, and an examination of the influence of job tenure on length of removal. Median length of removal under the 80/60 triggers was 3.4 months; under the 70/50 triggers, it was 4.4 months. Median length of removal under the 60/40 triggers can only be estimated due to censoring of the data set, but was between 6 and 8 months for employees removed during the first 4 months after institution of the 60/40 triggers. Respirator use and company identity significantly influenced length of removal only under the 80/60 triggers. Job tenure did not influence length of removal of employees removed and returned within the 18-month limit. However, mean tenure of employees reaching 18 months on removal was significantly longer than mean tenure of employees removed and returned within 18 months, under all three sets of triggers. This result suggests that changes in industrial hygiene practices during the past 20–25 years have caused a shift of lead workers from a group with relatively high workplace-lead exposure during their early work experience to a group whose workplace-lead exposure has been relatively low throughout their employment history.