Experimental and human studies on antimony metabolism: their relevance for the biological monitoring of workers exposed to inorganic antimony

Availability, Toxicology and Medical Significance of Antimony

Antimony has been known and used since ancient times, but its applications have increased significantly during the last two centuries. Aside from its few medical applications, it also has industrial applications, acting as a flame retardant and a catalyst. Geologically, native antimony is rare, and it is mostly found in sulfide ores. The main ore minerals of antimony are antimonite and jamesonite. The extensive mining and use of antimony have led to its introduction into the biosphere, where it can be hazardous, depending on its bioavailability and absorption. Detailed studies exist both from active and abandoned mining sites, and from urban settings, which document the environmental impact of antimony pollution and its impact on human physiology. Despite its evident and pronounced toxicity, it has also been used in some drugs, initially tartar emetics and subsequently antimonials. The latter are used to treat tropical diseases and their therapeutic potential for leishmaniasis means that they will not be soon phased out, despite the fact the antimonial resistance is beginning to be documented. The mechanisms by which antimony is introduced into human cells and subsequently excreted are still the subject of research; their elucidation will enable us to better understand antimony toxicity and, hopefully, to improve the nature and delivery method of antimonial drugs.

Occupational Exposure to Metals in Shooting Ranges: A Biomonitoring Study

Background

Lead (Pb) exposure in shooting ranges has been reduced by various measures such as jacketed ammunition and lead-free primers. Nevertheless, this may lead to exposure to other metals, potentially resulting in adverse health effects.

Methods

In a cross-sectional study, 35 subjects from seven different shooting ranges were studied: four shooting instructors, 10 police officers, 15 Special Forces, and six maintenance staff members. Metals and metalloids were determined in blood and urine by inductively coupled plasma–mass spectrometry.

Results

The concentrations of most elements did not differ significantly between groups or compared to reference values, except for Sb and Pt in urine and Pb in blood. Mean values for Sb were considerably higher in urine from the Special Forces (0.34 μg/L), the maintenance staff (0.13 μg/L), and shooting instructors (0.32 μg/L) compared to the police officers before shooting (0.06 μg/L) and a Belgian reference value (0.04 μg/L). For Pt, the Special Forces showed higher mean urinary concentrations (0.078 μg/L) compared to a Belgian reference value (<0.061 μg/L). Mean values for blood lead were markedly higher in the Special Forces (3.9 μg/dL), maintenance staff (5.7 μg/dL), and instructors (11.7 μg/dL) compared to police officers (1.4 μg/dL). One instructor exceeded the biological exposure index for blood Pb (38.8 μg/dL).

Conclusion

Since both Pb and Sb were found to be higher in shooting range employees, especially among frequent shooters, it is advisable to provide appropriate protective equipment, education, and medical follow-up for shooting range personnel in addition to careful choice of ammunition.

Tissue distribution of residual antimony in rats treated with multiple doses of meglumine antimoniate

Meglumine antimoniate (MA) and sodium stibogluconate are pentavalent antimony (Sb^V) drugs used since the mid-1940s. Notwithstanding the fact that they are first-choice drugs for the treatment of leishmaniases, there are gaps in our knowledge of their toxicological profile, mode of action and kinetics. Little is known about the distribution of antimony in tissues after Sb^V administration. In this study, we evaluated the Sb content of tissues from male rats 24 h and three weeks after a 21-day course of treatment with MA (300 mg Sb^V/kg body wt/d, subcutaneous). Sb concentrations in the blood and organs were determined by inductively coupled plasma-mass spectrometry. In rats, as with in humans, the Sb blood levels after MA dosing can be described by a two-compartment model with a fast (t1/2 = 0.6 h) and a slow (t1/2 >> 24 h) elimination phase. The spleen was the organ that accumulated the highest amount of Sb, while bone and thyroid ranked second in descending order of tissues according to Sb levels (spleen >> bone, thyroid, kidneys > liver, epididymis, lungs, adrenals > prostate > thymus, pancreas, heart, small intestines > skeletal muscle, testes, stomach > brain). The pathophysiological consequences of Sb accumulation in the thyroid and Sb speciation in the liver, thyroid, spleen and bone warrant further studies.

The exposure to and health effects of antimony

CONTEXT

This minireview describes the health effects of antimony exposure in the workplace and the environment.

AIM

To collate information on the consequences of occupational and environmental exposure to antimony on physiological function and well-being.

METHODS

The criteria used in the current minireview for selecting articles were adopted from proposed criteria in The International Classification of Functioning, Disability and Health. Articles were classified from an acute and chronic exposure and toxicity thrust.

RESULTS

The proportion of utilised and non-utilised articles was tabulated. Antimony toxicity is dependent on the exposure dose, duration, route (breathing, eating, drinking, or skin contact), other chemical exposures, age, sex, nutritional status, family traits, life style, and state of health. Chronic exposure to antimony in the air at levels of 9 mg/m(3) may exacerbate irritation of the eyes, skin, and lungs. Long-term inhalation of antimony can potentiate pneumoconiosis, altered electrocardiograms, stomach pain, diarrhea, vomiting, and stomach ulcers, results which were confirmed in laboratory animals. Although there were investigations of the effect of antimony in sudden infant death syndrome, current findings suggest no link. Antimony trioxide exposure is predominant in smelters. Mining and exposure via glass working, soldering, and brazing are also important.

CONCLUSION

Antimony has some useful but undoubtedly harmful effects on health and well-being and measures need to be taken to prevent hazardous exposure of the like. Its biological monitoring in the workplace is essential.

Antimony: an unlikely confounder in the relationship between well water arsenic and health outcomes in Bangladesh

Recent in vitro studies have suggested a potential role for antimony as a confounder in human health studies related to arsenic in drinking water. We measured tube-well water concentrations of antimony and arsenic in the Pabna region of Bangladesh, where arsenic concentrations are known to be elevated and the concentrations of antimony have not yet been thoroughly documented. Two hundred forty-five tube-well water samples were collected from various regions in Pabna, Bangladesh, as part of an ongoing case-control study. Water samples were analyzed for arsenic and antimony concentrations by inductively coupled plasma-mass spectrometry using U.S. Environmental Protection Agency method 200.8. The arsenic concentrations in the tube-well water samples ranged from < 1 microg/L to 747 microg/L. All 245 water samples had antimony concentrations < 1 microg/L. Based on consideration of the concentrations used the in vitro studies compared with field-observed concentrations, our results do not support the hypothesis that antimony would be a significant confounder in observed relationships between arsenic exposure through drinking water and potential health outcomes in Pabna, Bangladesh.

Human biomonitoring of arsenic and antimony in case of an elevated geogenic exposure

Part of the northern Palatinate region in Germany is characterized by elevated levels of arsenic and antimony in the soil due to the presence of ore sources and former mining activities. In a biomonitoring study, 218 residents were investigated for a putative increased intake of these elements. Seventy-six nonexposed subjects in a rural region in south lower Saxony were chosen as the reference group. Urine and scalp hair samples were obtained as surrogates to determine the internal exposures to arsenic and antimony. The analyses were performed using graphite furnace atomic absorption spectrometry except for arsenic in urine, which was determined by the hydride technique. This method does not detect organoarsenicals from seafood, which are not toxicologically relevant. In the northern Palatinate subjects, slightly elevated arsenic contents in urine and scalp hair (presumably not hazardous) could be correlated with an increased arsenic content in the soil. On the other hand, the results did not show a correlation between the antimony contents in the soil of the housing area and those in urine and hair. Except for antimony in scalp hair, age tended to be associated with internal exposures to arsenic and antimony in both study groups. Consumption of seafood had a slight impact on the level of urinary arsenic, which is indicative of the presence of low quantities of inorganic arsenicals and dimethylarsinic acid in seafood. The arsenic and antimony contents in scalp hair were positively correlated with the 24-hr arsenic excretion in urine. However, antimony in scalp hair was not correlated with seafood consumption as was arsenic in scalp hair and in urine. This indicated the existence of unidentified common pathways of exposure contributing to the alimentary body burden. Short time peaks in the 24-hr excretion of arsenic in urine, which could not be assigned to a high consumption of seafood, were detected for six study participants. This suggests that additional factors relevant in the exposure to arsenic are still unidentified.