A person who passes the NCLEX is able to be licensed.
Does that qualify you to work as a company nurse? That really depends. Some places have little to do.
Yet the scope of practice of an OHN is rather broad.
You may be required to do
--hearing exams (audiometry) (requires training and certification)
--color blindnes exams
--spirometry (requires training and may require certification)
--Making decisions on FMLA requests
--Workers'compensation regulatory filing and oversight (a huge and complex area that can make you very, very valuable to a company)
--Hep B programs
--train AED/CPR/First Aid
--Rapid response including possible trauma situations, or poisonings
The list goes on...
The fee for the COHN is, I think $150, you have to work at least (I think) a year doing Occ-Med Nursing. I can't remember the current requiements. Search for COHN and you'll find everything you need.
So in short, usually, unless it is a very small and simple company, no, simply passing the NCLEX does not qualify you to be a company nurse.
However, I think that one of the best ways to get "into" O&E Nursing is to find a company who might hire you part time. They might train you to do post-hire physicals and pre-hire drug scans. Then they might use you to fill-in at companies, and over time your skill set will improve, and you will become more "in demand," and more skilled.
However the reality is that most corporations/companies of any size expect that you come from a critical care/Emergency Department background. Remember it will be you that someone comes running to with: "xxxx is down, I think she had a heart attack," or "come quick four workers have been exposed to poison gas..." (neither is imaginary, both have occurred during the past two years for me).
My recommendation is to do a stint in a basic Medical/Surgical Hospital, then spend a year or two in ED, and try to find some part-time occupational health work on the way. There really are not many jobs that do not expect their nurse to be experienced in the medical realm.
In any sub-specialty there is a sad element of: "We'd like to hire you but you aren't COHN" and then you realize that you can't become COHN unless you work in Occ Med. It's a catch 22. But there are jobs that qualify such as audio testing companies, or part-time occ health. Best of luck, and if you persevere you'll make it, but not overnight.
It's actually a huge body of knowledge. But I think it's a ton of fun.