Tissue Distribution of Tungsten in Mice Following Oral Exposure to Sodium Tungstate

Abstract

Heavy metal tungsten alloys have replaced lead and depleted uranium in many munitions applications, due to public perception of these elements as environmentally unsafe. Tungsten materials left in the environment may become bioaccessible as tungstate, which might lead to population exposure through water and soil contamination. Although tungsten had been considered a relatively inert and toxicologically safe material, recent research findings have raised concerns about possible deleterious health effects after acute and chronic exposure to this metal. This investigation describes tissue distribution of tungsten in mice following oral exposure to sodium tungstate. Twenty-four 6-9 weeks-old C57BL/6 laboratory mice were exposed to different oral doses of sodium tungstate (0, 62.5, 125, and 200 mg/kg/d) for 28 days, and after one day, six organs were harvested for trace element analysis with inductively coupled plasma mass spectrometry (ICP-MS). Kidney, liver, colon, bone, brain, and spleen were analyzed by sector-field high-resolution ICP-MS. The results showed increasing tungsten levels in all organs with increased dose of exposure, with the highest concentration found in the bones and the lowest concentration found in brain tissue. Gender differences were noticed only in the spleen (higher concentration of tungsten in female animals), and increasing tungsten levels in this organ were correlated with increased iron levels, something that was not observed for any other organ or either of the two other metals analyzed (nickel and cobalt). These findings confirmed most of what has been published on tungsten tissue distribution; they also showed that the brain is relatively protected from oral exposure. Further studies are necessary to clarify the findings in splenic tissue, focusing on possible immunological effects of tungsten exposure.

Accumulation of persistent tungsten in bone as in situ generated polytungstate

“…As there remains a lack of toxicological data, tungsten was nominated as an emerging contaminant for further investigation by the US Environmental Protection Agency and National Toxicity Program. 4 When mice ingest solubilized tungsten in the form of orthotungstate (WO 4 2− ), it rapidly accumulates in their bones 5 . Other bone-accumulating metals, such as lead and strontium 6 , substitute for calcium in hydroxyapatite, the calcium-phosphate matrix of bone, and can be removed using standard chelation therapy 7 .…”

Sodium Tungstate for Promoting Mesenchymal Stem Cell Chondrogenesis

“…Studies have been performed to investigate the toxicity of tungsten or Na 2 WO 4 [43,44]. The concentration of Na 2 WO 4 used to evaluate the antidiabetic effect was around 6 mM [18,19].…”

Inductively Coupled Plasma Mass Spectrometry

“…The distribution of tungsten in the body of mice 24 h after oral uptake of sodium tungstate was studied by Guandalini et al 321 They used highresolution ICP-SFMS to quantify the metal in several organs such as liver, kidney, colon, spleen, brain and bone, which were digested using HNO 3 and H 2 O 2 prior to analysis. It could be shown that tungstate predominantly accumulates in bone and spleen.…”