Environmental Health Workforce Act of 2021 This bill requires the Department of Health and Human Services (HHS) to carry out certain activities related to the environmental-health workforce. It also requires the Government Accountability Office to report on state-based practices for training and credentialing environmental-health workers. Specifically, HHS must develop model standards and guidelines for credentialing environmental-health workers and a plan to ensure its programs and activities meet the future needs of the environmental-health workforce. The bill also specifies that environmental-health workers are eligible for public-service loan forgiveness.