Get Toxic Substances Out of Schools Act of 2021 This bill addresses the provision of Environmental Protection Agency (EPA) grants to prevent and eliminate toxic substances, particularly in certain school environments. The EPA is authorized make grants to Indian tribes (in addition to the current authority to provide grants to states) to establish and operate programs to prevent or eliminate unreasonable risks associated with a chemical substance or mixture of which the EPA is unlikely to address during the 24-month period after the grant is made. The bill also authorizes the EPA to partner with the Department of Labor (with respect to enforcement of labor standards) to provide grants to states and Indian tribes to identify, prevent, or eliminate risks associated with the presence of a chemical substance or mixture in eligible facilities (i.e., public school facilities operated by a local educational agency, facilities operated by an early childhood education program, and center-based child care facilities operated by an eligible child care provider). The EPA has permanent authority to provide grants to Indian tribes (in addition to the current authority to provide such grants to states) to (1) provide technical assistance to local educational agencies, early childhood education programs, and eligible child care providers to address environmental concerns in eligible facilities; and (2) develop and implement state and tribal programs to support the remediation of toxic substances in eligible facilities. Under the bill, the EPA must also provide specified outreach and guidelines related to environmental hazards in eligible facilities.