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5.92 expected based on Rheinhessen-Pfalz rates, p < 0.05). An excess significant risk of lung cancer
remained after 78 cohort members from one factory who reported “contact with other substances since
proven to be carcinogenic” were removed from the calculations (9 observed, 4.37 expected based on
FRG mortality rates, p < 0.05); additionally, a significant excess risk of lymphatic cancer was seen (4
observed, 1.38 expected based on FRG mortality rates, p < 0.05).
US EPA (1983) noted that the members of the study cohort were exposed to a number of other
carcinogens, including vinyl chloride, and distillation residues including polycyclic aromatic
hydrocarbons, cadmium, ß-napthylamine, dimethyl sulfate and epichlorohydrin. Additionally, tobacco
smoking was a potential confounding factor; all lung cancer cases were smokers. However, US EPA
also noted that the lung cancer risk associated with exposure to acrylonitrile estimated from this study
could actually be an underestimate of the actual risk because 1) combining workers from 12 factories
between which acrylonitrile exposure levels varied could have lend to an underestimate of risk due to
the inclusion of unexposed or minimally exposed workers; 2) the “healthy worker” effect could have
resulted in an underestimate of risk; 3) followup on the relatively youthful cohort was insufficient, and did
not allow sufficient latency in the cohort segments most at risk - only 447.1 person-years were
accumulated in members over 64 years of age and 4) underascertainment of vital status (12% of the
study cohort were lost to followup) may have resulted in an undercount of observed deaths. US EPA
concluded that it was possible that exposure to acrylonitrile might be related to the excess risk of lung
cancer demonstrated by the study cohort of Theiss et al. (1980).
Werner and Carter (1981) studied the mortality of 1111 men who worked in acrylonitrile
polymerization and acrylic fiber production (6 plants, located in England, Northern Ireland, Scotland
and Wales) from 1950 to 1968; surveillance was continued to the end of 1978. An excess of total
cancer deaths was noted (21 observed, 18.6 expected) but was not statistically significant. Expected
deaths were calculated from mortality rates from England and Wales combined. Only 68 deaths from
all causes had occurred as of the end of 1978; 72.4 were expected. An excess of deaths from all types
of cancer combined was noted (21 observed, 18.6 expected), but this excess was not statistically
significant. Significant increases in deaths due to stomach cancer were noted in all age groups combined
(5 observed, 1.9 expected, p < 0.05), with deaths in the 55-64 age group comprising the largest
portion of those deaths (3 observed, 0.7 expected, p < 0.05). A statistically significant elevated risk of
lung cancer was also noted in the 15-44 age group (3 observed, 0.7 expected, p < 0.05), but not in
other age groups or in all age groups combined. The authors note the lack of acrylonitrile exposure
data, including potential differences in exposure levels between the 6 plants surveyed. US EPA (1983)
also notes the relatively short followup in the cohort subgroup which would be expected to have
incurred the greatest risk, the 158 men having the earliest exposure (during the 1950-1958 period). US
EPA (1983) concluded that because of the relative youth of the cohort resulting in a small number of
expected deaths, the lack of followup, and the lack of control for smoking, the findings of this study are
only suggestive.
A cohort mortality study of 327 white male workers employed for 2 or more years between January 1,
1940 and July 1, 1971 at a rubber manufacturing plant in Akron OH who were potentially exposed to
acrylonitrile was conducted by Delzell and Monson (1982). Acrylonitrile exposure levels were not
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