Bioaccessibility and bioavailability of As and Pb in housedust

Reliable assessment of human health risks from exposure to As and Pb in housedust depends on their bioavailability. In vivo animal assays to estimate As and Pb relative bioavailability are costly so in vitro assays have been... [ view full abstract ]

Reliable assessment of human health risks from exposure to As and Pb in housedust depends on their bioavailability. In vivo animal assays to estimate As and Pb relative bioavailability are costly so in vitro assays have been developed. However, they need be correlated to in vivo animal data before they can be used to estimate As/Pb bioavailability. The <150 µm fractions of 24 housedust samples containing 4.48–38.2 mg kg–1 As and 25.0–738 mg kg–1 Pb were analyzed using gastric and intestinal phases of four in vitro assays including SBRC, IVG, DIN, and PBET. Twelve housedust samples were assessed for As and Pb relative bioavailability (RBA) using a mouse blood AUC model. Both As and Pb bioaccessibility varied significantly with in vitro assays. In the gastric phase, the SBRC produced the highest As and Pb bioaccessibility (73 and 78%) compared to IVG (68 and 70%), DIN (53 and 46%), and PBET (49 and 41%) assays. Lead bioaccessibility in the intestinal phase of the 4 assays were considerably lower. Based on the mouse blood model, As-RBA was 22-86% with samples containing low Fe and high OC having higher As-RBA, while Pb-RBA was 29-60%. Strong in vivo–in vitro correlations were found between As-RBA and As bioaccessibility for SBRC and DIN (r2=0.63–0.85). Similarly, Pb bioaccessibility based on the gastric phase of SBRC and DIN assays was correlated with Pb-RBA (r2 = 0.68 and 0.85). Our data suggested that both SBRC and DIN had potential to assess As and Pb bioavailability in housedust samples.