PFAS Testing Act of 2021 This bill requires the Environmental Protection Agency (EPA) to order comprehensive toxicity testing on all perfluoroalkyl and polyfluoroalkyl substances, commonly referred to as PFAS. These substances are man-made and may have adverse human health effects. A variety of products contain the compounds, such as nonstick cookware or weatherproof clothing. An order from the EPA for comprehensive toxicity testing for PFAS shall require the development of information by any person who manufactures, processes, or intends to manufacture or process PFAS. The bill also provides guidelines for the development of these orders, including the methodologies and protocols to be used. Additionally, the bill specifies when a PFAS may be exempt from testing or information submission. Each person who manufactures or processes PFAS must submit to the EPA (1) all records of significant adverse reactions to health or the environment alleged to have been caused by PFAS, and (2) all health and safety studies related to PFAS of which the person is aware. The EPA must make all such health and safety studies available to the public within four months of the enactment of this bill.