Toxicological profile for barium and barium compounds

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BARIUM AND BARIUM COMPOUNDS 

3.  HEALTH EFFECTS 

3.2.2.3  Immunological and Lymphoreticular Effects  

No studies were located regarding immunological effects in humans after oral exposure to barium.  

Several animal studies have examined potential lymphoreticular effects, particularly damage to the 

thymus, spleen, and lymph nodes.  Acute gavage exposure of rats to doses as high as 198 mg 

barium/kg/day as barium chloride for 1 or 10 days was not associated with any changes in thymus weight 

or any gross lesions of the thymus (Borzelleca et al. 1988).  Intermediate and chronic oral exposure of rats 

to nominal concentrations of barium in drinking water of 37.5 and 15 mg/kg/day, respectively, of an 

unspecified barium compound was not associated with lesions of the lymph nodes or thymus upon gross 

and histopathologic examination (McCauley et al. 1985).  No histopathological alterations were observed 

in the spleen or thymus of rats exposed to 180 or 60 mg barium/kg/day for an intermediate or chronic 

duration, respectively (NTP 1994).  In mice, thymic and splenic atrophy were observed at 450 mg 

barium/kg/day after intermediate exposure and lymphoid depletion in the spleen and decreased spleen 

weight were observed at 160 mg barium/kg/day after chronic exposure (NTP 1994).  These effects were 

probably secondary to the severe nephropathy and weight loss observed at these doses.   

No studies have assessed the potential of barium to impair immune function. 

The highest NOAEL values for lymphoreticular effects in each species and duration category are recorded 

in Table 3-1 and plotted in Figure 3-1. 

3.2.2.4  Neurological Effects 

Numbness and tingling around the mouth and neck were sometimes among the first symptoms of barium 

toxicity in humans (Lewi and Bar-Khayim 1964; Morton 1945).  Occasionally, these neurological 

symptoms extended to the extremities (Das and Singh 1970; Lewi and Bar-Khayim 1964).  Partial and 

complete paralysis occurred in severe cases, often accompanied by an absence of deep tendon reflexes 

(Das and Singh 1970; Diengott et al. 1964; Gould et al. 1973; Lewi and Bar-Khayim 1964; Morton 1945; 

Ogen et al. 1967; Phelan et al. 1984; Wetherill et al. 1981).  Post-mortem examination in one case of 

poisoning by ingestion of barium sulfide revealed brain congestion and edema (McNally 1925). 

Animal studies have not found significant alterations in brain weight or histopathology following acute 

gavage exposure of rats for 1 or 10 days to doses as high as 198 mg barium/kg/day as barium chloride 

(Borzelleca et al. 1988), intermediate oral exposure of rats to doses as high as 115 mg barium/kg/day in 

drinking water (McCauley et al. 1985; NTP 1994; Tardiff et al. 1980), intermediate-duration exposure of 

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54 

BARIUM AND BARIUM COMPOUNDS 

3.  HEALTH EFFECTS 

mice to doses less than 450 mg barium/kg/day as barium chloride in drinking water (NTP 1994), or 

chronic exposure of rats and mice to doses greater than 60 or 160 mg barium/kg/day as barium chloride in 

drinking water, respectively (NTP 1994).  Neurobehavioral performance (spontaneous motor activity, grip 

strength, tail flick latency, startle response, hindlimb foot splay) was evaluated in rats and mice exposed 

to barium chloride for 15 or 90 days (NTP 1994).  No alterations were observed in rats or mice following 

a 15-day exposure to 110 or 70 mg barium/kg/day.  Slight decreases in motor activity were observed in 

rats exposed to 10–115 mg barium/kg/day for 90 days; these changes were not considered to be 

biologically significant.  However, in female rats exposed to 180 mg barium/kg/day, spontaneous motor 

activity was 30% lower than controls; this difference was considered to be biologically significant.  In 

mice, the only alteration noted was a decrease in forelimb grip strength in females exposed to 495 mg 

barium/kg/day for 90 days; the investigators noted that this may have been due to debilitation.  The 

highest NOAEL values and reliable LOAEL values for neurological effects in each species and duration 

category are recorded in Table 3-1 and plotted in Figure 3-1. 

3.2.2.5  Reproductive Effects  

No studies were located regarding reproductive effects in humans after oral exposure to barium.  

However, limited data are available from acute, intermediate, and chronic animal studies in which certain 

reproductive organs were weighed and examined grossly and microscopically following oral barium 

exposure.  Gavage exposure of rats to doses of 198 mg barium/kg/day as barium chloride for 10 days 

resulted in decreased ovary weight and decreased ovary/brain weight ratio (Borzelleca et al. 1988); no 

alterations were observed after a single gavage dose with 198 mg barium/kg/day (Borzelleca et al. 1988).  

Neither study found changes in testicular weight, and no gross lesions of the ovaries or testes were 

observed at this dose.  No histological alterations were observed in the reproductive tissues of male and 

female rats and mice exposed to 110 mg barium/kg/day (rats) or 70/85 mg barium/kg/day (mice) as 

barium chloride in drinking water (NTP 1994).  Intermediate and chronic oral exposure of rats to barium 

in drinking water at doses of 200 mg barium/kg/day and lower was not associated with any gross or 

histopathologic lesions of the uterus, ovaries, or testes (Dietz et al. 1992; McCauley et al. 1985; NTP 

1994).  Similarly, no histopathological alterations were observed in reproductive tissues of mice exposed 

to 495 mg barium/kg/day and lower for an intermediate duration (NTP 1994) or 160 mg barium/kg/day or 

lower for a chronic duration (NTP 1994).  Additionally, no alterations in epididymal sperm counts, sperm 

motility, or sperm morphology were observed in rats or mice exposed to 200 or 205 mg barium/kg/day, 

respectively, as barium chloride in drinking water for 60 days (Dietz et al. 1992). 

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