US EPA

1017907 

Journal Article 

The effect of residence time and fluid volume to soil mass (LS) ratio on in vitro arsenic bioaccessibility from poorly crystalline scorodite 

Laird, BD; Peak, D; Siciliano, SD 

2010 

1 

Journal of Environmental Science and Health, Part A: Toxic/Hazardous Substances & Environmental Engineering
ISSN: 1093-4529
EISSN: 1532-4117 

Taylor & Francis Group Ltd., 2 Park Square Oxford OX14 4RN UK 

England 

45 

6 

732-739 

English 

20401772 

10.1080/10934521003648958 

WOS:000284097000004 

Percent arsenic bioaccessibility is occasionally dependent upon arsenic concentration; however, the mechanism(s) of this relationship has not yet been defined. To evaluate the mechanism of this relationship, the arsenic bioaccessibility from freshly synthesized poorly crystalline scorodite was measured in the stomach, small intestine, and colon stages of the Simulator of the Human Intestinal Microbial Ecosystem (SHIME). The shape of the arsenic dissolution isotherms were different between stages (stomach: linear; small intestine: exponential rise to maxima; colon: sigmoidal). These results indicate that arsenic bioaccessibility may be limited by either in vitro GI fluid saturation or in vitro GI model residence time, depending upon the chemical/microbiological conditions of the model. Gastrointestinal microorganisms increased arsenic bioaccessibility of scorodite up to two-fold in the SHIME colon; however, this was dependent upon the sample arsenic concentration. Up to 40% of the bioaccessible arsenic was reduced to arsenite; however this process was neither mediated by GI microorganisms nor associated with increased arsenic bioaccessibility. 

Environmental factors; Small intestine; Stomach; Microorganisms; Model Studies; Models; Soil; Dissolution; Saturation; Isotherms; Shape; Simulators; Colon; Arsenite; Ecosystems; Arsenic; Environmental Engineering; Residence time; Intestines