What a curious thread. There are two separate questions to address. The first is if it is generally a good idea, or reasonably necessary, to do FM or another residency before doing Occupational and Environmental Medicine (OEM) residency.
No.
If you are fortunate enough to be exposed to OEM in medical school and want to pursue residency training in OEM, then you should absolutely apply to go directly from medical school into OEM residency. Just like any other specialty. OEM residency will teach you everything you need to know to be competent working in the field.
Don’t a lot of people in OEM have additional residency training or board certification? Sure. But this is mostly because OEM is so under the radar. They simply didn’t know about OEM coming out of medical school, so transitioned into OEM later in their career after being unhappy with their initial choice of specialty. Many of them, could they do it over again, would simply have gone straight into OEM and skipped the unhappy years in whatever they quickly became burned out in. I certainly know OEM physicians who went straight into OEM training from med school, and they are loving their life in OEM practice. One example is
here.
Wouldn’t I be more marketable if I had dual training in OEM in another specialty? I suppose that all other things being equal, having completed FM or another residency in addition to completing OEM will look better on paper, give you a broader clinical skill set, and may set you up better for some jobs that look for this specific combination. But OEM training, as with any other specialty, is sufficient to stand on its own. The limited upside hardly seems worth the years of additional residency training.
Should I have FM training just in case, as a fallback plan? This is quite a ridiculous question. Sure, you would have a solid fallback option if you completed another residency first, but this would be true no matter what specialty you went into. Should general surgeons do FM residency first, just in case it doesn’t work out with general surgery, or they realize later on in life that they don’t really like general surgery? I strongly recommend to focus your efforts on picking the right specialty for you, the first time around. Which should be obvious to everyone. If you made a bad choice initially, then I would focus on getting it right the second time around. Make the shortest path to achieve your goals.
Wouldn’t having FM training make me a much better OEM doc? There is a common misconception among those who are not OEM-trained that FM has a lot of similarities and overlap with OEM. It doesn’t. Of course there is some overlap, but the two specialties are really apples and oranges. I personally know people that have gone into OEM after years in FM practice. Some think that their FM training and experience makes them a better OEM doc. A good example can be found
here. I would say that most people tend to say this, though I believe there is a substantial incentive for them to think this way. Nobody wants to think or admit that they wasted years of their medical career. I do however, know some brutally honest ones who think that their FM training added nothing useful or was even a detriment, in the sense that they had to unlearn much of what they picked up in FM training in order to be a good OEM physician. I have personally seen physicians that tried to transition from primary care to OEM, without doing OEM residency training, and floundered.
You can absolutely find many good job opportunities in with residency training and board certification in OEM alone. I believe it would be accurate to say that transitioning into OEM is a good "fallback" option for unhappy FPs. However, since there are so few unhappy OEM docs to begin with, and a diverse range of plentiful OEM jobs available, FP is not a serious fallback option for those in OEM. Sure, some FPs out there probably dabble in OEM just a bit, maybe take a bottom-tier OEMish job that OEM-trained physicians would never take, and don’t like it. But it would be exceedingly rare to find somebody residency trained in OEM that willingly chose to go into FP (or back into FP). I know of none.