Brazilian hair straightening while BF - advice please!

[Messing]

Since getting pg and having DD (now 10 months), I have stopped having my hair straightened and as such now resemble Worzel Gummidge.
I am going back to work in 4 weeks and would REALLY like to have straightening done before then, but I've heard it isn't suitable when breastfeeding.

I'm currently only feeding DD 3-4 times in 24 hours and expect that will reduce further in the next month - so would it be so bad to have it done?
Can anyone explain what exactly the issue is - do the chemicals actually get into breast milk?!

TIA

Simply purchase a reputable At-Home "Permanent".Put your
Cape on with a small towel tucked in.Follow directions,Only
Comb your hair Straight for the length of time stated-don't Stop
Combing.Following directions-when the "Fixitive"is now on your
hair,comb it Straight...keep combing.At the appointed Time-do
Not put hair into rollers.Condition.This application will have less
"Chemicals" and Less Impact on your body chemistry.

Thanks Japple. So basically, an at-home kit is safer to use than a salon treatment? Although probably still not 100% safe.