TevaWomen's Original Universal Sandal, Black, 7 M US

I’m a 6.5 not sure if i should get a 6 or a 7

If im in size 39 europe,what size should i buy?

Does anybody know what chemical in these is causing the California prop 65 warning to show up? There’s no materials list on the description

I’m a 9.5. Should I size up or down?