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Barium and barium compounds

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Barium and barium compounds

21

compared with results for 25 workers who stated that

they had never worked in barium process areas. No

statistically significant differences in mean age, number

of years employed, number of current or past smokers,

prevalence of subjective symptoms, mean FEP levels,

mean haematocrit levels, mean urine cadmium levels,

mean 


$

-2-microglobulin levels, or the prevalence of

workers with elevated serum creatinine, BUN, or urine

protein levels were observed between the two groups.

The number of workers with elevated blood pressure

(defined as systolic pressure >140 mmHg [>18.7 kPa] or

diastolic pressure >90 mmHg [>12 kPa] or taking

medication for hypertension) was significantly higher in

the barium-exposed group than in the comparison group.

The number of workers in the barium group with blood

lead levels of >39 mg/dl was lower than in the

comparison group; however, the difference was not

statistically significant. Additionally, there was no sig-

nificant difference between mean blood lead levels in the

barium-exposed workers (24 mg/dl) and the comparison

group (32 mg/dl).

The health effects associated with occupational

exposure to barium during arc welding with barium-

containing stick electrodes and flux-cored wires were

investigated by Zschiesche et al. (1992). A group of

18 healthy welders not using barium-containing

consumables in the past 10 days was divided into three

groups: group A (n = 8, mean age 30.4 years) performed

arc welding with barium-containing stick electrodes,

group B (n = 5, mean age 43.6 years) performed arc

welding with barium-containing self-shielded flux-cored

wires, and group C (n = 5, mean age 32.0 years)

performed arc welding with barium-containing self-

shielded flux-cored wires using welding guns with built-

in ventilation systems. All welders performed welding

with barium-free consumables on Thursday and Friday

of the first week of the study. Barium-containing

consumables were used during week 2 of the study and

on Monday of week 3. The subjects welded for an

average of 4 h/day. The average barium concentrations

in the breathing zones were 4.4 (range 0.1–22.7), 2.0

(0.3–6.0), and 0.3 (0.1–1.5) mg/m

3

 for groups A, B, and C,

respectively. No exposure-related subjective adverse

health symptoms or neurological signs were found. No

significant differences between pre- and post-shift

electrocardiogram, pulse rate, whole-blood pH, base

excess and standard bicarbonate, or plasma concen-

trations of sodium, magnesium, and total and ionized

calcium were observed. During week 2, decreases in

plasma potassium concentrations were observed in

groups A and C; the levels returned to the normal range

under continuation of barium exposure and were not

statistically different from levels during week 1 (no

barium exposure). This drop in serum potassium levels

was not observed in group B, which had a barium

exposure level similar to that of group A.

10. EFFECTS ON OTHER ORGANISMS IN

THE LABORATORY AND FIELD

10.1

Aquatic environment

Toxicity of barium to selected aquatic organisms is

summarized in Table 2. A 48-h no-observed-effect level

(NOEL) of 68 mg/litre was calculated for water fleas

(Daphnia magna) exposed to various concentrations of

barium (LeBlanc, 1980). In contrast, Biesinger &

Christensen (1972) reported 48-h and 21-day LC

50

 values

of 14.5 and 13.5 mg/litre, respectively, a 16% impairment

of reproduction at 5.8 mg/litre, and a 50% impairment at

8.9 mg/litre during the 21-day tests. Khangarot & Ray

(1989) reported 24- and 48-h EC

50

 (the concentration

resulting in 50% immobilization) values of 52.8 and 32.0

mg/litre, respectively, for daphnids exposed to barium

sulfate. A reported 48-h EC

50

 value for developmental

effects in the mussel Mytilus californianus was 0.189

mg/litre (Spangenberg & Cherr, 1996). For two aquatic

amphipod species (Gammarus pulex and Echinogammarus berilloni), Vincent et al. (1986)

reported 24-, 48-, 72-, and 96-h LC

50

 values of 3980, 395,

255, and 238 mg/litre and 336, 258, 162, and 122 mg/litre,

respectively, in eucalcic water; LC

50

 values in oligocalcic

water were 1260, 533, 337, and 227 mg/litre and 308, 197,

151, and 129 mg/litre, respectively. The 30-day LC

50

values for two species of crayfish ranged from 39 to 61

mg/litre; the 96-h values were comparable (Boutet &

Chaisemartin, 1973). Heitmuller et al. (1981) reported a

NOEL in the sheepshead minnow (Cyprinodon variegatus) of 500 mg/litre. 

Growth of Anacystis nidulans (a cyanobacterium)

in an environment containing 50 mg barium chloride/litre

was similar to that of controls. Higher concentrations of

barium resulted in a concentration-related increase in

growth inhibition; almost complete inhibition was

reported at barium chloride concentrations 

$

750 mg/litre

(Lee & Lustigman, 1996). Wang (1986) reported a 96-h

EC

50

 (growth) of 26 mg barium/litre in duckweed (Lemna minor) in deionized water. However, in river water,

barium showed no toxic effect on growth of duckweed.

The lack of an adverse effect in the river water was

shown to be due to precipitation of barium from the river

water as sulfate. Stanley (1974) investigated the toxic

effects of barium on the growth of Eurasian watermilfoil

(Myriophyllum spicatum). Root


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