Gastric/lung bioaccessibility and identification of arsenic-bearing phases and sources of fine surface dust in a gold mining district

Marcos A Morais; Massimo Gasparon; Itamar D Delbem; Claudia L Caldeira; Erico T F Freitas; Jack C Ng; Virginia S T Ciminelli

doi:10.1016/j.scitotenv.2019.06.394

Gastric/lung bioaccessibility and identification of arsenic-bearing phases and sources of fine surface dust in a gold mining district

Sci Total Environ. 2019 Nov 1:689:1244-1254. doi: 10.1016/j.scitotenv.2019.06.394. Epub 2019 Jun 25.

Authors

Marcos A Morais¹, Massimo Gasparon², Itamar D Delbem³, Claudia L Caldeira⁴, Erico T F Freitas³, Jack C Ng⁵, Virginia S T Ciminelli⁶

Affiliations

¹ Universidade Federal de Minas Gerais, Belo Horizonte 31270901, MG, Brazil; Kinross Brasil Mineração, Paracatu 38609899, MG, Brazil.
² National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil; The University of Queensland, School of Earth and Environmental Sciences, Brisbane, QLD 4072, Australia.
³ National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil; Center of Microscopy, Universidade Federal de Minas Gerais, Brazil.
⁴ Universidade Federal de Minas Gerais, Belo Horizonte 31270901, MG, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
⁵ National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil; The University of Queensland, Queensland Alliance for Environmental Health Sciences (QAEHS), Brisbane, QLD 4102, Australia.
⁶ Universidade Federal de Minas Gerais, Belo Horizonte 31270901, MG, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil. Electronic address: ciminelli@demet.ufmg.br.

PMID: 31466163
DOI: 10.1016/j.scitotenv.2019.06.394

Abstract

Bioaccessibility (BAC) of fine surface dust (FSD, particle size ≤10 μm) and surface dust samples (particle size ≤250 μm) collected from a gold mining district was used as a tool to determine the portion of arsenic that would be available via simulated lung and gastrointestinal (G.I) fluids. BAC was considered low for both tests (lung 2.7 ± 1%, n = 5 and G.I 3.4 ± 2%, n = 14 for residential surface dust samples). An analytical procedure was developed to further identify arsenic-bearing phases found in FSD samples and analyze the main components that regulate arsenic solubility. Up to five different arsenic-bearing phases were identified among a total of 35 minerals surveyed by scanning electron microscopy-based automated image analysis (Mineral Liberation Analyzer - MLA). Arsenic-bearing Fe oxy-hydroxides and mixed phases comprised the main arsenic phases encountered in FSD samples, thus likely being responsible for regulating arsenic bioaccessibility. Transmission electron microscopy showed that the mixed phases comprised a mix of oriented nanostructure aggregates formed by hematite and goethite entangled with phyllosilicates. The main As-bearing phases identified in FSD samples are similar to those reported in soil samples in the same region. The predominant arsenic-bearing phase encountered in the ore was arsenopyrite, mostly in large particles (>10 μm in size), and therefore unlikely to be found in residential dust. Arsenic intake from both inhalation and ingestion were minimal when compared to total arsenic intake (considering food and water ingestion), which itself was <7% of the value established by the Food and Agriculture Organization of the United Nations Benchmark Dose Lower Confidence Limit (BMDL_0.5) of 3.0 μg per kg^-1 body weight per day. These results indicated that the relative risks associated with arsenic exposure by inhalation and oral ingestion in this region are low.

Keywords: Arsenic; Gastric/intestinal bioaccessibility; Health risk assessment; Lung bioaccessibility; Quantitative mineralogy; Surface dust.

MeSH terms

Arsenic / analysis*
Dust / analysis
Environmental Exposure / analysis*
Environmental Exposure / statistics & numerical data
Mining
Soil Pollutants / analysis*

Substances

Dust
Soil Pollutants
Arsenic