Concise International Chemical Assessment Document 33
20
cough. No abnormal symptoms were noted during the
physical examination of seven of the workers;
crepitations dispelled by cough were observed in one
worker (not the same worker reporting an occasional
cough). Pneumoconiosis was detected in the
radiographs of seven workers. Three other workers
employed for 1 month to 1 year were also examined in
1961. Two of these workers reported having slight
coughs, but no abnormal findings were observed during
the physical examination, and the chest radiographs
were normal. The concentration of barium in the dust
was not measured. Barite samples were analysed for
quartz, silica, and iron content. No quartz was detected,
and the total silica and total iron (as iron oxide)
concentrations were 0.07–1.96% and 0.03–0.89%,
respectively.
Ten of the 11 workers examined in 1961 were re-
examined in 1963 (18 months later) (Doig, 1976). Two new
cases of pneumoconiosis were diagnosed. Thus, 9 of 10
workers exposed to barium sulfate for 1.5–19.5 years
(mean 8.2 years) had well-marked baritosis. Three of
these workers reported a slight or occasional cough, and
none had dyspnoea. Among the nine workers with
baritosis, three did not smoke, four smoked 1 pack/day,
and two smoked >1 pack/day. In six of the seven workers
with previously diagnosed baritosis, no significant
changes in the degree of pneumoconiosis were
observed; an increase in the number of opacities was
observed in the seventh worker. Spirometric lung
function tests (vital capacity, flow rate, and forced
expiratory volume) were performed in five workers. For
three of these workers, the results of the lung function
tests were similar to predicted normal values (89–119%
of predicted values). Lung function was below normal in
the other two workers (70–85% of predicted values). It is
questionable whether the impaired lung function was
related to barium exposure. One of the two workers was
an alcoholic and heavy smoker, and the other had a
fibrotic right middle lung lobe that probably resulted
from a childhood illness.
The barite grinding facility closed in 1964, and
follow-up examinations were performed in 1966, 1969,
and 1973 on five of the workers (Doig, 1976). Termination
of barium exposure resulted in a decline in the profusion
and density of opacities. In 1966, there was a slight
clearing of opacities; by 1973, there was a marked
decrease in profusion and density. No significant
changes in lung function were observed during this 10-
year period.
NIOSH (1982) conducted a health survey of past
and present workers at the Sherwin Williams Company’s
Coffeyville, Kansas, USA, facility. Work performed at
the facility included grinding, blending, and mixing
mineral ores. At the time of the study, four processes
were in operation: “ozide process,” which involved
blending several grades of zinc oxide; “ozark process,”
which involved bagging very pure zinc oxide powder;
“bayrite process,” which involved grinding and mixing
several grades of barium-containing ores; and “sher-tone
process,” which involved mixing inert clays with animal
tallow. A medical evaluation was performed on 61
current workers (91% participation). Information on
demographics, frequency of various symptoms
occurring during the previous 2 months, chemical expo-
sure, occupational history, and smoking history, as well
as history of renal disease, allergies, and hypertension,
was obtained from directed questionnaires. In addition,
spot urine and blood samples and blood pressure mea-
surements were taken. Exposures to barium, lead,
cadmium, and zinc were estimated from 27 personal
samples collected over a 2-day period. In the seven
personal breathing-zone samples collected from the
bayrite area, the levels of soluble barium ranged from
87.3 to 1920.0 mg/m
3
(mean 1068.5 mg/m
3
), lead levels
ranged from not detected to 15.0 mg/m
3
(mean
12.2 mg/m
3
, excluding two samples in which lead was not
detected), zinc levels ranged from 22.4 to 132.0 mg/m
3
(mean 72 mg/m
3
), and all seven samples had no
detectable levels of cadmium. Soluble barium was also
detected in breathing-zone samples in the ozark area
(10.6–1397.0 mg/m
3
, mean 196.1 mg/m
3
), ozide area
(11.6–99.5 mg/m
3
, mean 46.8 mg/m
3
), and sher-tone area
(114.3–167.5 mg/m
3
, mean 70.45 mg/m
3
).
Two approaches were used to analyse the results
of the health survey (NIOSH, 1982). In the first approach,
the workers were divided into five groups based on
current job assignments. Of the 61 current workers, 14
worked in the bayrite area (mean duration 3 years). No
statistically significant increases in the incidence of
subjective symptoms (e.g., headache, cough, nausea) or
differences in mean blood lead levels, number of workers
with blood lead levels greater than 39 mg/dl, mean free
erythrocyte protoporphyrin (FEP) levels, mean
haematocrit levels, mean serum creatinine levels, number
of workers with serum creatinine levels greater than 1.5
mg/dl, number of workers with blood urea nitrogen
(BUN) levels greater than 20 mg/dl, blood pressure, or
mean urine cadmium levels were observed between the
different groups of workers. In the second approach, the
workers were divided into seven groups based on past
job assignments. One group consisted of 12 workers
working in barium process areas (bayrite process and
other processes no longer in operation at the facility that
involved exposure to barium ores and barium carbonate)
for at least 5 years; barium exposure levels were not
reported for this group of workers. The results of the
health survey for the barium-exposed workers were