Concise International Chemical Assessment Document 33

Barium and barium compounds

19

(2–10 mg/litre, 0.06–0.3 mg barium/kg body weight per

day assuming water consumption of 2 litres/day and

weight of 70 kg) or low levels of barium in drinking-water

(0.2 mg/litre, 0.006 mg barium/kg body weight per day).

Barium was the only drinking-water contaminant that

exceeded drinking-water regulations of the time in any of

the public drinking-water supplies. The communities

were matched for demographic characteristics and

socioeconomic status. Communities that were

industrialized or geographically different were excluded.

Although the study attempted to exclude communities

with high rates of population change, two of the four

high-barium communities had about 75% change in

population between 1960 and 1970; these were kept in

the study for lack of satisfactory replacements.

In the mortality study (Brenniman & Levy, 1984),

age-adjusted mortality rates for cardiovascular diseases

(combined), heart diseases (arteriosclerosis), and all

causes for both sexes together were significantly higher

in the elevated-barium communities compared with the

low-barium communities for the years 1971–1975. These

differences were largely confined to the population 65

years of age or older. This study did not measure the

barium exposure of individual subjects and did not

control for several important variables, such as popula-

tion mobility (approximately 75% turnover in two of the

four high-barium communities from 1960 to 1970), use of

water softeners that would remove barium from and add

sodium to the water supply, use of medication by study

subjects, and other risk factors, such as smoking, diet,

and exercise. As a result, it is not possible to assign a

causal relationship between mortality and exposure to

barium.

The morbidity study (Brenniman & Levy, 1984)

was conducted on two Illinois, USA, communities,

McHenry and West Dundee, which had similar demo-

graphic and socioeconomic characteristics, but a 70-fold

difference in barium concentrations in drinking-water.

The mean concentration in McHenry’s drinking-water

was 0.1 mg barium/litre, whereas the mean concentration

in West Dundee’s drinking-water was 7.3 mg

barium/litre. The levels of other minerals in the drinking-

water of the two communities were stated to be similar.

Subjects (2000) were selected randomly from a pool that

included every person 18 years of age or older in a

random sample of blocks within each community. All

subjects underwent three blood pressure measurements

(taken over a 20-min period with a calibrated electronic

blood pressure apparatus) and responded to a health

questionnaire that included such variables as sex, age,

weight, height, smoking habits, family history,

occupation, medication, and physician-diagnosed heart

disease, stroke, and renal disease. Data were analysed

using the signed rank test for age-specific rates, the

weighted Z test for prevalence rates, and analysis of

variance for blood pressures. No significant differences

in mean systolic or diastolic blood pressures or in

history of hypertension, heart disease, stroke, or kidney

disease (which included serum and urinary protein and

creatinine levels) were found for men or women of the

two communities. A more controlled study was con-

ducted on a subpopulation of the McHenry and West

Dundee subjects who did not have home water

softeners, were not taking medication for hypertension,

and had lived in the study community for more than 10

years. No significant differences were observed between

the mean systolic or diastolic blood pressures for men or

women of these subpopulations in the low-barium (0.1

mg barium/litre, 0.0029 mg barium/kg body weight per

day assuming water ingestion of 2 litres/day and 70-kg

body weight) and elevated-barium communities (7.3 mg

barium/litre, 0.21 mg barium/kg body weight per day).

The database on the toxicity of inhaled barium

compounds in humans consists primarily of studies of

occupational exposure to barium sulfate or barite ore or

to unspecified soluble barium compounds. Several case

reports (e.g., Pendergrass & Greening, 1953; Seaton et

al., 1986) and a prospective study conducted by Doig

(1976) have reported baritosis in barium-exposed

workers. Baritosis is considered to be a benign pneumo-

coniosis resulting from the inhalation of barite ore or

barium sulfate. The most outstanding feature of baritosis

is the intense radiopacity of the discrete opacities that

are usually profusely disseminated throughout the lung

fields; in some cases, the opacities may be so numerous

that they appear confluent. The Third Conference of

Experts on Pneumoconiosis (ACGIH, 1992) noted that

barium sulfate produced a non-collagenous type of

pneumoconiosis in which there is a minimal stromal

reaction that consists mainly of reticulin fibres, intact

alveolar architecture, and potentially reversible lesions.

The available human data on baritosis suggest that the

accumulation of barium in the lungs does not result in

medical disability or symptomatology. A decline in the

profusion and opacity density, suggesting a decrease in

the amount of accumulated barium in the lung, has been

observed several years after termination of exposure.

Doig (1976) reported on a series of cross-sectional

examinations of workers at a barite grinding facility.

During the initial investigation in 1947, five workers

employed for more than 3.5 years were examined. No

evidence of baritosis was observed in any of the

workers. In 1961, eight workers (26–45 years of age, mean

32 years) employed for 3.5–18 years (mean 9 years) were

examined (one of these workers was also examined in

1947). Seven of the workers reported no respiratory

symptoms; one worker reported a slight occasional 

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