The US Govt's main portal for standards, technical reports, MSDS (Material Safety Data Sheets), and other agency-generated publications and statistics on workplace health and safety
National Institute for Occupational Safety & Health collections of information on chemicals, hazards, protective equipment/clothing, construction and agriculture
Developed by NIOSH for the emergency response community. "Contains accurate and concise information on high-priority chemical, biological and radiological agents that could be encountered by personnel responding to a terrorist event."