Mortality in a cohort of orchard workers exposed to lead arsenate pesticide spray.

During the period from 1890 to 1940, lead arsenate was the major pesticide used in apple orchards to control the coddling moth. In the Wenatchee area of Washington State, lead arsenate spray was used for longer periods and in larger quantities than in other areas of the United States. In 1938, a cohort of 1,231 people who lived in this area was selected for a study to determine the effects of exposure to lead arsenate spray and residue. This same cohort was re-examined to determine whether there was excess mortality that could be attributed to the lead arsenate exposure. Three levels of exposure (i.e., orchardist, intermediate, consumer) were defined, based upon the use of lead arsenate pesticide spray before and during the 1938 apple growing season. Age-adjusted hazard ratios for all causes of mortality were elevated for both male orchardists and male intermediates. The only significantly increased age-adjusted hazard ratio (1.94) was heart disease in male intermediates. No significantly elevated age-adjusted hazard ratios were observed for women in any exposure group. The lack of evidence that supported an increase in mortality from respiratory cancer in this cohort may have resulted from the lower cumulative concentration of arsenic exposure, the type of arsenical compound, and the small number of study subjects.