If you write about environmental health issues, the searchable WONDER data system online at the Centers for Disease Control and Prevention (CDC) may help you do your job.
WONDER is a single portal for using a variety of databases related to public health that are maintained by CDC. CDC has a mandate to collect and compile statistics on many subjects, and a surprising number of these are relevant to the environment beat. Examples include asthma and allergy prevalence, lung disease, cancer, agricultural safety, pesticides, occupational exposure, chemical hazards, waterborne disease, foodborne disease, and adverse vaccine events.
The main access point for WONDER is here.