Incidental ingestion of As-contaminated soils and housedust is an important non-dietary As exposure contributor for children living nearby contaminated sites, while consumption of rice has been recognized as the most important dietary contributor. However, to accurately assess the health risk associated with soil and dust ingestion and rice consumption, determination of total concentration and oral bioavailability of As are both important. However, compared to soils, assessment of As relative bioavailability (RBA) in housedust and rice is limited. In addition, the suitability of in vitro bioaccessibility assays to predict As bioavailability has not been compared between different exposure scenarios. Recently, by combining in vivo mouse bioassay and in vitro bioaccessibility assays, we measured As-RBA (relative to the absorption of sodium arsenate) in samples of contaminated soils, slightly-contaminated housedust, co-contaminated housedust, and rice. Results showed that As-RBA in these media showed significant variation among individual samples, suggesting the need to incorporate bioavailability to accurately assess the associated health risk. In addition, by establishing in vivo-in vitro correlations, the most suitable in vitro assay to predict As-RBA varied with the target media, suggesting the need of developing specific methodologies to predict As-RBA in different environmental media.