It's actually quite hard to say, not least because this isn't much to do with photography, more to do with employment law, harassment and human rights, and largely beyond my knowledge. In principle this isn't much different from CCTV, which many employers use to monitor staff and customers. In UK there are supposed to be notices advising the public that this is happening, but for employees you will probably find that your contract of employment allows them to film or photograph you (except in private areas like cloakrooms). It's unlikely that a photo of you, because you were out of uniform, is going to be something you can object to, especially if you are required to wear uniform.

However, if it forms part of a wider pattern of intimidation or bullying, you may have a grievance - and the employer must have a published grievance procedure to deal with it, if they employ more than 5 people. If you are a union member, it would be worth asking for advice. If not, talk to HR, but be careful. Grievance procedures often blow back on the complainant. I don't say this to put you off complaining, just to warn you to get good and specific advice before proceeding.

Another issue is your concerns about a photo of your chest being circulated among colleagues for amusement or sexual interest. This would, I think, be completely illegal by numerous laws. You'd need to speak to a proper lawyer if this happens,  or looks like happening. You could discreetly warn the managers that they must not do this.

So: you probably can't object to a photo taken for legitmate management reasons and shared between the managers responsible for uniform policy, but anything beyond that, like one of those managers emailing the image around the company, could well be grounds for legal action.