There are an enormous number of studies regarding this topic, but I'm only linking three. Feel free to tell me about more.
One disproves the notion that strippers and other "legitimate" sex workers are somehow immune to victimization by studying the rate at which strippers are assaulted and abused by customers, bosses, and the men being paid to protect them.
A second discusses the rate at which street-walking prostitutes use protection (about 25%) and discusses the extreme economic pressure that for most street prostitutes constitutes the primary driving force behind their "decision" to prostitute. In addition, the second study discusses the extremely low level of condom-use among street-walkers and the fact that the protection these women could be expecting from the police usually comes not in the form of referrals for help with drug addictions or employment aid, but in the form of demands for free sex in return for lack of arrests or convictions.
In case those of you who have watched "Sin City" a few too many times are still convinced that all street-working prostitutes have their own machine-guns, are karate experts, and are total experts at protecting themselves from everybody who therefore desire no protection ever, the third study discusses the rate at which street-walking prostitutes are violently victimized on a regular basis.
Given the reading, my answer is yes, though levels of danger vary enormously. Do I think it's dangerous to be a porn actress? If we're talking mainstream porn then yes, though not as much as with other types of work. Mainstream porn actresses are at a much-heightened risk of disease while the cameras are rolling, but in addition to that, they have to deal with their fame when the cameras have stopped. A woman who is payed to give men all over the world the illusion that she is fair game for any of their violent fantasies and remains sexually available to all of them at all times certainly has to worry a little bit more than the rest of us about who might recognize her when she's buying groceries.
Do I think it's dangerous to be a stripper? Of fucking course. First off, the place is run by straight men and secured by straight men, and I've seen some of those straight men display a lot more interest in whether a given stripper will have sex with them than in her safety. Second, even if the boss and security are respectful and on a dancer's side, the room is full of drunken men, some of whom are big enough assholes to attempt to follow a girl home to rape her. The security guys wouldn't be there if this wasn't the case. Perhaps it's safer with security guards present, but it's certainly not as safe as if one wasn't dancing in the first place, and security guards can't protect a woman from the customer who she accidentally runs into while off the clock.
Do I think it's dangerous to be an escort? I was raped repeatedly as an escort, so yes. Going into a bedroom or hotel room alone with a strange man and hoping he hands you a couple hundred after you have sex with him is just a bad idea. First off, exact boundaries are not negotiated ahead of time and some men very aggressively seek uncomfortable sexual acts or unprotected sex and will not take no for an answer. Second, agencies on the whole tend to have much worse security than strip clubs. If a girl gets in trouble while working outcall, there's not always a whole lot she can do but grit her teeth and bear it until the car shows back up. Essentially, escorts are trusting a total stranger not to rape or beat them for no reason other than that he claims to have the money and he might have shown their boss what may or may not have been his real ID. Oh, and he's already proven that he doesn't like women very much by requesting to see a prostitute in the first place.
Do I think it's dangerous to be a street-walker? I can't believe that people would even ask me this ridiculous question, but I've had people make the argument to me that it's safe because "the women look out for each other" or "police themselves," so I guess I have to mention the very obvious fact that they aren't doing a good job of it. Hookers are open to extreme violence and regularly experience it. Period. Men who want to assault a woman and run away will go for the women who it's easiest to do this to, and that's hookers. The fact that these women are sought out as a group by predators more than almost anybody else renders their situation dangerous, and it's hard for them to do much about that when their job requires that they get into cars or go into alleys with strangers and have sex with these strangers without ever seeing an ID.
There are other categories of sex workers, like dommes for example, who share most of the dangers that an escort does. However, it should be noted that the biggest danger faced by a lot of sex workers is that the police and courts are all staffed by people who hate them and believe they are getting what they deserve whenever a violent act is committed on them. The possible exceptions to this are fetish and porn models, porn actresses, and strippers, who are legitimized by arbitrary laws about which sex work is acceptable and which is not.