Bioaccessibility and Relative Bioavailability of Metals

In risk assessment, metals are evaluated conservatively, as if they exist in the environment as a pure metal or a specific chemical, such as a soluble salt; however, bioavailability and toxicity are well recognized to vary relative to the solubility of the metal ion in biological fluids (e.g., gastric fluid, lung fluid). In many matrices, including alloys and slags and mine tailings, metal ions are not readily released into biological fluids and are determined to have limited bioaccessibility and bioavailability. In vitro bioaccessibility (IVBA) is a test method based on simulated biological fluids, that is used to estimate in vivo conditions. It has been used by US regulators for risk assessment and is also under consideration by the European Chemicals Agency (ECHA) for read-across.

ToxStrategies’ Relevant Published Work:

ToxStrategies’ Test Method Development:

  • ToxStrategies participated in the Bioelution Working Group of the EURL ECVAM (European Union Reference Laboratory for Alternatives to Animal Testing) Scientific Advisory Committee in 2019, to review the scientific validity of a proposed bioelution test method to assess the relative IVBA of metals and metalloids in inorganic metal compounds and materials (published in 2020).
  • ToxStrategies is participating in the OECD panel of international experts from Europe, the United States, Canada, and Japan to develop a new Test Guideline to determine relative metal release using a simulated gastric fluid.

ToxStrategies’ Experience

Source Metals Evaluated Environmental Media1 IVBA Exposure Pathway Evaluated
Titanium & steel forge CrVI, total Cr, Co, Mo, Ni, V Soil and dust Oral
Specialty steel foundry As, CrVI, total Cr, Co, Ni Baghouse dust, soil Oral, Inhalation
Steel mill As, Cd, CrVI, total Cr, Co, Pb, Mn, Ni EAF and LF slags, furnace dust Oral, Inhalation
Specialty steel forge Co, Ni Soil and dust Oral, Inhalation
Steel slag processors Al, Sb, As, Ba, Be, Cd, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Hg, Mo, Ni, P, Se, Si, Ag, T, Sn, V, Zn EAF, BOF, and BF slags Oral
Steel slag processor CrVI, total Cr, Mn Aged and fresh EAF slag mixed with soil Oral

1 EAF = electric arc furnace, LF = ladle furnace, BOF = basic oxygen furnace, BF = blast furnace


Review our numerous publications on metals here.

See more on our Bioaccessibility and Relative Bioavailability of Metals experts:

Deborah Proctor, Managing Principal Scientist

Mina Suh, Senior Epidemiologist

Ann Verwiel, Senior Managing Scientist

Rayetta Henderson, Managing Scientist