The authors examined the mortality and
cancer incidence of employees at a company which has manufactured, formulated, and sprayed 2 methyl-4 chlorophenoxyacetic
acid (
MCPA) and other phenoxy
acid herbicides. Ninety-eight percent of the 5,784 men employed by the company during 1947-1975 was traced to the end of 1983. The overall mortality of the cohort was less than that of the national population, as was mortality from
cancer. When allowance was made for rural residence, the deficit of
cancer deaths became a slight excess, but not statistically significantly so. Among workers whose jobs entailed potential exposure to
MCPA, there was one death from
soft tissue sarcoma (0.6 expected). No further cases of
soft tissue sarcoma were registered among living members of the cohort. Three potentially exposed workers died from nasal
carcinoma, but this
tumor has not previously been associated with phenoxy
herbicides and the cluster of cases may have occurred by chance. The findings do not exclude the possibility that
MCPA is a human
carcinogen, but they suggest that any risk of
soft tissue sarcoma is less than that indicated by earlier studies of
2,4,5-T (2,4,5-trichlorophenoxyacetic acid) and
2,4,5-trichlorophenol and is small in absolute terms.