I am in an industry that is open 7 days a week. I was recently told that because I am a salaried (exempt) employee, my boss can force me to work 7 days a week without providing any comp. time , alternative days off or other allowences. I work in Massachusetts. Is this true?

Under Massachusetts "blue laws", the state places restrictions on the working on Sundays. You can review the website at this link to see if the laws apply to you: http://www.mass.gov/dlwd/bluelaws.html

Comp time is not required by either Federal or Massachusetts law. If you are correctly classified as exempt comp time is permissable but not mandatory - it's up to the employer whether to offer it or not.

Although Massachusetts has a one-day-of-rest-in-seven law, it is limited to only certain industries.

http://www.mass.gov/legis/laws/mgl/149-48.htm