Thomas Hartung, MD, Johns Hopkins Bloomberg School of Public Health, delivers an insightful overview of his work studying toxicity testing improvements, organoids, and advancing technologies. Dr. Hartung has departmental affiliations with the Environmental Health and Engineering and Molecular Microbiology and Immunology departments at Johns Hopkins. Dr. Hartung’s work is heavily focused on creating a paradigm shift in toxicity testing to improve overall public health. Dr. Hartung has been an integral part of the implementation of the 2007 NRC vision document known as, “Toxicity Testing in the 21st Century – a vision and a strategy.” Dr. Hartung discusses his background, and the road he has taken to arrive at his current place as a leading voice in the discussions concerning toxicity and animal testing. He explains that the technological opportunities have advanced significantly in the last few years. Dr. Hartung discusses ‘organ on a chip’ technologies and other advanced tissue, etc. work. As he explains, this field is permanently moving. The advancement of organoids, which are small, self-organized 3D tissue cultures that are actually derived from stem cells, is changing the way research is done. The research doctor talks about the importance of toxicity testing, cellular communication and tissue technology, as well as genomics and metabolomics, discussing nutrients, types of cells, and the coming research that will certainly advance the field. Learning from current experiences, he explains that the ‘human on a chip’ technologies will continue to change as more research is done. Organoids are being used to test various compounds to observe the relative toxicity, but they are utilized for other reasons as well, such as modeling diseases. As Dr. Hartung states, the future will likely bring these types of systems into all kinds of toxicity testing, and replace animal testing altogether if possible.