You should assume that all blood and other potentially infectious materials (OPIM) are infectious, regardless of the source. It doesn’t matter if the person appears healthy, has no known diagnosis, or claims to be disease-free. Every sample of blood and every body fluid classified as OPIM gets treated as though it carries a bloodborne pathogen. This single assumption is the foundation of universal precautions, and it drives nearly every safety protocol in workplaces where exposure is possible.
Why the Assumption Exists
The Centers for Disease Control and Prevention introduced universal precautions in 1985, during the early years of the HIV epidemic. At the time, healthcare workers had no reliable way to know which patients carried HIV or hepatitis B before lab results came back. The solution was simple and effective: stop trying to guess who is infectious and treat every exposure as dangerous.
This approach works because many people carrying bloodborne pathogens don’t know they’re infected. Hepatitis B, hepatitis C, and HIV can all circulate in someone’s blood for months or years without causing obvious symptoms. You cannot identify an infected person by looking at them, reviewing their history, or relying on their self-report. The assumption removes that guesswork entirely.
What Counts as OPIM
Blood is the most obvious risk, but OSHA’s Bloodborne Pathogens Standard covers a specific list of other body fluids classified as OPIM. These include semen, vaginal secretions, cerebrospinal fluid, synovial fluid (from joints), pleural fluid (from the lungs), pericardial fluid (from around the heart), peritoneal fluid (from the abdomen), and amniotic fluid. Saliva counts during dental procedures. Any body fluid visibly contaminated with blood also qualifies, as does any fluid in situations where you can’t tell what type it is.
Several common body fluids are not considered OPIM on their own: urine, feces, nasal secretions, sputum, tears, vomit, and saliva outside of dental settings. However, the moment any of these contain visible blood, they fall under the same protective assumption. In practice, if you’re unsure whether something contains blood, you treat it as though it does.
The Diseases You’re Protecting Against
The three primary bloodborne pathogens behind these precautions are hepatitis B (HBV), hepatitis C (HCV), and HIV. Of the three, hepatitis B poses the highest transmission risk from a single needlestick or sharp injury. HBV is remarkably resilient and can survive on surfaces outside the body for up to seven days, still capable of causing infection. Hepatitis C and HIV are transmitted less efficiently through needlestick injuries, but the consequences of infection are serious enough that even a small risk justifies full precautions every time.
What This Assumption Looks Like in Practice
Treating all blood and OPIM as infectious means using the right protective equipment every time contact is possible. At a minimum, that means gloves whenever you might touch blood, OPIM, mucous membranes, or broken skin. If splashing is likely, you add eye protection such as goggles or a face shield. Gowns or aprons protect your clothing and skin during procedures or cleanup tasks that could involve larger amounts of fluid.
The assumption also shapes how you handle waste. Anything contaminated with blood or OPIM goes into properly labeled biohazard containers. Sharps like needles, scalpels, and broken glass go into rigid, puncture-resistant containers that are leak-proof and clearly marked. These containers have a fill line at three-quarters full, and you stop adding to them once they reach that point. You never reach into a sharps container, bend or recap a used needle, or transfer sharps between containers by hand.
OSHA’s Legal Requirements for Employers
OSHA’s Bloodborne Pathogens Standard (29 CFR 1910.1030) makes this assumption a legal obligation for any workplace where employees could be exposed to blood or OPIM. Employers must create a written Exposure Control Plan that identifies which workers are at risk, spells out protective measures, and explains what happens after an exposure incident. This plan has to be reviewed and updated annually.
Employers are also required to offer the hepatitis B vaccine at no cost to workers with occupational exposure. The vaccine must be made available within 10 days of starting a job that involves potential exposure, and only after the worker has received training. Workers can decline the vaccine, but if they change their mind later, the employer still has to provide it for free as long as the exposure risk remains. There is no equivalent vaccine for hepatitis C or HIV, which makes the “assume everything is infectious” approach even more critical.
If an Exposure Happens
Even with precautions, accidents occur. If you get a needlestick or cut from a contaminated sharp, wash the area immediately with soap and water. If blood or OPIM splashes into your eyes, flush them with clean water, saline, or a sterile eyewash. Splashes to your nose, mouth, or skin get flushed with water. Don’t scrub aggressively or use harsh chemicals like bleach on your skin.
After first aid, report the exposure to your supervisor right away. Prompt reporting starts the medical evaluation process, which can include blood tests and, depending on the pathogen involved, preventive treatment that works best when started within hours. Delays reduce the effectiveness of these options significantly.
Universal Precautions vs. Standard Precautions
You may see two terms used in training materials. Universal precautions, the original CDC framework from 1985, specifically addresses blood and OPIM. Standard precautions, introduced in 1996, expand on that concept to cover a broader range of body fluids including urine, feces, nasal secretions, sputum, and vomit, whether or not blood is visible. Standard precautions are now the recommended practice in healthcare settings because they protect against a wider range of infections, not just bloodborne pathogens.
OSHA’s Bloodborne Pathogens Standard still uses the universal precautions framework. In practical terms, workplaces that follow standard precautions are meeting and exceeding OSHA’s requirements. The core assumption remains identical in both systems: you never rely on appearance, patient history, or your own judgment to decide whether blood or body fluids are safe. You assume they are not, and you protect yourself accordingly.