Toxicological profile for barium and barium compounds

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3.  HEALTH EFFECTS 

(Cullen et al. 2000; Tarasenko et al. 1977).  The Tarasenko et al. (1977) study examined systemic, 

reproductive, and developmental end points.  However, interpretation of the results is limited by poor 

reporting of the study design and results.  The Cullen et al. (2000) study only examined the respiratory 

tract.  As these studies were considered inadequate for development of an inhalation MRL, additional 

studies examining a variety of end points are needed to identify the critical targets of barium toxicity and 

to establish concentration-response relationships.   

One human experimental study examined the cardiovascular toxicity of barium (Wones et al. 1990) 

following oral exposure; no adverse effects were found.  Several animal studies also examined the oral 

systemic toxicity (McCauley et al. 1985; NTP 1994; Perry et al. 1983, 1985, 1989; Tardiff et al. 1980), 

neurotoxicity (NTP 1994), reproductive toxicity (Dietz et al. 1992), and developmental toxicity (Dietz et 

al. 1992; Tarasenko et al. 1977) of barium.  The results of these studies suggest that the kidney is the most 

sensitive target of toxicity following intermediate-duration oral exposure.  An intermediate-duration oral 

MRL based on kidney effects in rats exposed to barium chloride for 13 weeks (NTP 1994) has been 

derived. 

Information on the oral toxicity of barium following intermediate-duration exposure comes from a human 

experimental study examining cardiovascular toxicity (Wones et al. 1990) and several animal studies 

examining systemic toxicity (McCauley et al. 1985; NTP 1994; Perry et al. 1983, 1985, 1989; Tardiff et 

al. 1980), neurotoxicity (NTP 1994), reproductive toxicity (Dietz et al. 1992; NTP 1994), and 

developmental toxicity (Dietz et al. 1992).  The human study did not find significant alterations in blood 

pressure or ECG readings in adults exposed to fairly low doses (Wones et al. 1990).  Effects observed in 

the animal studies include increased blood pressure (Perry et al. 1983, 1985, 1989), kidney damage 

(glomerular alterations consisting of fused podocytes and thickening of the capillary basement membrane 

and mild to moderate nephropathy) (McCauley et al. 1985; NTP 1994), and developmental toxicity 

(decreased pup birth weight) (Dietz et al. 1992).  The increase in blood pressure was observed at the 

lowest adverse effect level; however, two other studies (McCauley et al. 1985; NTP 1994) did not find 

significant alterations in blood pressure or ECG readings in rats exposed to higher doses of barium.  The 

low-mineral diet used in the Perry et al. (1983, 1985, 1989) studies may have influenced the results.  The 

calcium content of the rye-based diet was 3.8 mg/kg, which is lower than the concentration recommended 

for maintenance, growth, and reproduction of laboratory rats (NRC 1995).  Additional studies are needed 

to support this hypothesis.  The results of the McCauley et al. (1985) and NTP (1994) studies suggest that 

the kidney is the most sensitive target of toxicity in rats and mice following intermediate-duration oral 

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BARIUM AND BARIUM COMPOUNDS 

3.  HEALTH EFFECTS 

exposure; an intermediate-duration oral MRL was derived based on kidney effects observed in rats 

exposed to barium chloride for 13 weeks (NTP 1994). 

No studies have examined the toxicity in humans or animals following intermediate-duration dermal 

exposure.  Studies are needed to assess the potential toxicity of various barium compounds and to 

establish whether dermal exposure would result in remote toxicity. 

Chronic-Duration Exposure and Cancer.

    The toxicity of barium following chronic-duration 

inhalation exposure is limited to three occupational exposure studies (Doig 1976; Essing et al. 1976; 

Seaton et al. 1986).  These studies focused on potential respiratory tract effects and are limited by co­

exposure to other compounds, small number of tested workers, and/or lack of a comparison group.  Well-

designed studies examining a number of potential end points are needed to identify the critical targets of 

barium toxicity and establish concentration-response relationships.  These studies would be useful for 

deriving a chronic-duration inhalation MRL for barium. 

Three groups of investigators have examined the effect of living in a community with elevated barium 

levels in the drinking water and the risk of mortality and cardiovascular effects (Brenniman and Levy 

1985; Brenniman et al. 1979a, 1979b, 1981; Elwood et al. 1974; Schroeder and Kraemer 1974).  These 

studies are limited by a number of factors including the lack of information on barium ingestion levels 

and the possible use of water softeners, which may have removed barium from the drinking water and 

increased the sodium content of the water.  Several studies in rats and mice have examined the chronic 

toxicity of barium (NTP 1994; Perry et al. 1989; Schroeder and Mitchener 1975a, 1975b).  The Perry et 

al. (1989) study found significant increases in systolic blood pressure in rats fed a relatively low 

concentration of barium in the diet; however, the contribution of the low mineral basal diet to the 

observed effect is not known.  Several rat studies did not find adverse effects at the highest doses tested 

(McCauley et al. 1985; NTP 1994; Schroeder and Mitchener 1975a).  Marked renal nephropathy was 

observed in mice (NTP 1994); this study and effect were the basis of the chronic-duration MRL for 

barium.  The available toxicokinetic data suggest that barium accumulates in bone; it is not known if this 

accumulation would result in adverse effects.  Studies designed to test the possible association between 

high levels of barium in bone and adverse bone effects would be useful. 

Data on the dermal toxicity of barium are limited to a skin tumor promotion study using barium 

hydroxide extract from tobacco plants (Van Duuren et al. 1968); the study did not examine noncancerous 

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