Subject encyclopedias provide background information, key concepts, and, in many cases, a bibliography to lead you to additional sources.
When searching for background sources, think of your topic in broad terms and combine simple keywords and phrases. See examples, below.
"environmental justice" and health
transgender and health
"health care access"
eugenics (scroll down to Encyclopedia of Political Theory or Encyclopedia of Race, Ethnicity and Society)
"mental health" and politics
"genetic testing" and discrimination
"harm reduction coalition"
"breast cancer" and politics (scroll through the various entries, e.g. Health Policy and Breast Cancer Screening: The Politics of Research and Intervention)
"doctors without borders"
"public interest advocacy"
science and "public understanding"
climate and disease (scroll through to find relevant sources, such as Encyclopedia of Global Warming & Climate Change)