 This combines microfabrication techniques with modern tissue engineering and mimics the complicated mechanical and biochemical behaviours of a human lung.Toxicity testing typically involves studying adverse health outcomes in animals subjected to high doses of toxicants with subsequent extrapolation to expected human responses at lower doses.The system relies on the use of a 40+year-old patchwork of animal tests that are expensive (costing more than $3B per year), time-consuming, low-throughput and often provide results of limited predictive value for human health effects.