Toxicological profile for barium and barium compounds

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21 

BARIUM AND BARIUM COMPOUNDS 

3.  HEALTH EFFECTS 

3.1 

INTRODUCTION 

The primary purpose of this chapter is to provide public health officials, physicians, toxicologists, and 

other interested individuals and groups with an overall perspective on the toxicology of barium.  It 

contains descriptions and evaluations of toxicological studies and epidemiological investigations and 

provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. 

A glossary and list of acronyms, abbreviations, and symbols can be found at the end of this profile. 

When evaluating the health effects of barium compounds, it is important to keep in mind that different 

barium compounds have different solubilities in water and body fluids and therefore serve as variable 

sources of the Ba

2+

 ion.  The Ba

2+

 ion and the soluble compounds of barium (notably chloride, nitrate, and 

hydroxide) are generally highly toxic to humans and experimental animals.  The insoluble barium 

compounds (notably sulfate) are inefficient sources of the Ba

2+

 ion and therefore are generally nontoxic.  

Although barium carbonate is insoluble in water, barium ions would be released from ingested barium 

carbonate in the acid milieu of the stomach.  Throughout the following section (3.2), the health effects by 

route of exposure of both soluble and insoluble barium compounds are discussed. 

3.2 

DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE  

To help public health professionals and others address the needs of persons living or working near 

hazardous waste sites, the information in this section is organized first by route of exposure (inhalation, 

oral, and dermal) and then by health effect (death, systemic, immunological, neurological, reproductive, 

developmental, genotoxic, and carcinogenic effects).  These data are discussed in terms of three exposure 

periods:  acute (14 days or less), intermediate (15–364 days), and chronic (365 days or more). 

Levels of significant exposure for each route and duration are presented in tables and illustrated in 

figures.  The points in the figures showing no-observed-adverse-effect levels (NOAELs) or lowest­

observed-adverse-effect levels (LOAELs) reflect the actual doses (levels of exposure) used in the studies. 

LOAELs have been classified into "less serious" or "serious" effects.  "Serious" effects are those that 

evoke failure in a biological system and can lead to morbidity or mortality (e.g., acute respiratory distress 

or death).  "Less serious" effects are those that are not expected to cause significant dysfunction or death, 

or those whose significance to the organism is not entirely clear.  ATSDR acknowledges that a 

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22 

BARIUM AND BARIUM COMPOUNDS 

3.  HEALTH EFFECTS 

considerable amount of judgment may be required in establishing whether an end point should be 

classified as a NOAEL, "less serious" LOAEL, or "serious" LOAEL, and that in some cases, there will be 

insufficient data to decide whether the effect is indicative of significant dysfunction.  However, the 

Agency has established guidelines and policies that are used to classify these end points.  ATSDR 

believes that there is sufficient merit in this approach to warrant an attempt at distinguishing between 

"less serious" and "serious" effects.  The distinction between "less serious" effects and "serious" effects is 

considered to be important because it helps the users of the profiles to identify levels of exposure at which 

major health effects start to appear.  LOAELs or NOAELs should also help in determining whether or not 

the effects vary with dose and/or duration, and place into perspective the possible significance of these 

effects to human health. 

The significance of the exposure levels shown in the Levels of Significant Exposure (LSE) tables and 

figures may differ depending on the user's perspective.  Public health officials and others concerned with 

appropriate actions to take at hazardous waste sites may want information on levels of exposure 

associated with more subtle effects in humans or animals (LOAELs) or exposure levels below which no 

adverse effects (NOAELs) have been observed.  Estimates of levels posing minimal risk to humans 

(Minimal Risk Levels or MRLs) may be of interest to health professionals and citizens alike. 

A User's Guide has been provided at the end of this profile (see Appendix B).  This guide should aid in 

the interpretation of the tables and figures for Levels of Significant Exposure and the MRLs. 

3.2.1 

Inhalation Exposure 

Studies evaluating the effects of barium following acute, intermediate, and chronic inhalation exposure 

are limited to several case reports of humans exposed occupationally (Doig 1976; Essing et al. 1976; 

Seaton et al. 1986; Shankle and Keane 1988), an experimental exposure to barium in welding fumes 

(Zschiesche et al. 1992), and three experimental studies with animals (Cullen et al. 2000; Hicks et al. 

1986; Tarasenko et al. 1977).  These case reports and animal studies are not adequate for firmly 

establishing the health effects of barium by inhalation because of a number of significant study 

limitations.  The case reports are generally inadequate because data were available for a limited number 

of exposed subjects and because exposure conditions (duration, frequency, dose) were not well 

characterized (Doig 1976; Essing et al. 1976; Seaton et al. 1986; Shankle and Keane 1988).  One of the 

animal studies was limited in that apparently no control animals were used, an inhalation chamber 

providing a controlled dose and environment was not used, and there was a lack of information regarding 

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