What is the relationship between risk/hazard communication and ethics?

In early 2000, there was an outbreak of Severe Acute Respiratory Syndrome (SARS) in the Toronto, Canada area. This epidemic forced hard choices on people in Canada′s largest urban area. Medical and public health communities, federal, provincial and local governments, and ordinary citizens had to make difficult decisions, often with limited information and short deadlines. The cause of this disease outbreak was not known for a long time after it was first discovered. Health care providers were on the firing line, and were the most affected by the disease. Decision makers had to balance individual freedoms against the common good, fear for personal safety against the duty to treat the sick and economic losses against the need to contain the spread of a deadly disease. At times like this it is necessary to rely both on science and value systems to guide decisions. Lessons need to be learned from this outbreak, to ensure preparedness not only against the spread of SARS, but also for dealing with potential safety, health, and environmental issues at residential and public places and at manufacturing facilities. After a lengthy search, the cause of the disease was traced to infected poultry and other animal shipment from China. It was not known, at that time, what information was provided by China (or other entities) regarding the diseased bird. Are there conditions that justify lying about or withholding risk/hazard information? What is the relationship between risk/hazard communication and ethics?