I worked in a graduate biology lab as a college freshman.  I used to wash scintillation vials that had contained toluene, a solvent.  It wasn't until the second year that I was told, "Oh, you should be using gloves...!" 

I do think of all the lawn chemicals our parents used - and I work at a university that uses a lot of pesticides, although they are now trying to cut back.  There was one summer when something they used made my breathing funny...

The trouble is, what do you do after the fact?  I guess try to get a lot of antioxidants and get rid of 'free radicals' that cause cell damage.  Exercise.  Healthy food ... and hope for the best.

RA runs in my family, but not everyone has it, not even the rheumatoid factor.  I apparently take after my grandmother (my mother implied that once, long before RA, something made her say I reminded her of her mom.  It was just before my marriage, 35 years ago...I have 4 sisters, none with RA, though 2 now have PMR (polymyalgia rheumatica).

My mother-in-law was an avid house-cleaner, her home always looked pristine, and she used a lot of cleansers.  I have wondered about her cancer - but she had also smoked for a long time, though she quit 7 years before the cancer  - salivary gland cancer, a rather rare one.  Household chemicals can be pretty nasty - my daughter is one of the 'greenies' going back to vinegar & baking soda, she's probably going to be healthier than her parent's generations!