Final answer:
Biosafety Level 4 (BSL-4) organisms are classified as high-risk organisms due to their potential to cause fatal diseases with no known treatments or vaccines, requiring the most stringent safety measures in labs.
Step-by-step explanation:
The Biosafety Level 4 (BSL-4) organisms are classified as high-risk organisms because they can be the most dangerous, are often fatal, and typically consist of exotic microbes that are easily transmitted by inhalation. These are agents for which there are no known treatments or vaccinations. Examples of BSL-4 pathogens include the Ebola and Marburg viruses. In laboratories that handle BSL-4 organisms, extreme precautionary measures are taken to protect laboratory workers and the community. These include requirements such as changing clothing upon entering, showering on exit, and decontaminating all materials when leaving the lab. Moreover, all work must either be done in a biological safety cabinet or while wearing a full-body, pressurized protective suit.