My patch tests showed allergies to nickel and fragrances (plus a few other things) but not the other chemicals you mention.
Nickel was not a surprise to me, as cheap jewellery causes me problems.
Dermatologist said that, day-to-day, nickel should not be a problem, because, most of the time, you don't handle it enough. Unless, of course, you're a cashier. You tend to react either through continuous exposure over several hours - the inside of a jeans button, for example - or eexposure of a defective skin barrier - already inflamed skin, or the inside of your earlobe, for example. So, once your ds's hands have healed, he should be far less vulnerable to nickel, and probably won't need to worry about it in day-to-day life.
Because fragrances are everywhere, they are likely to be continuously irritating his skin. I had lived with irritated skin for so long that I was astonished at the difference going strictly fragrance-free made to my life. Being scratchy had become normal!
To help your ds's skin to heal, your whole household will need to be fragrance-free. Everyone will have to wash in FF products, all your cleaning products will have to be FF, no 'air-fresheners', no essential oils, nothing, for several months. And you'll need to launder everything in his wardrobe. It's a hassle. BUT the result for me was worth every annoyance.
It took about 6-8w before I noticed an improvement in my skin, and about a year for my skin to heal up completely.
HTH. I found very little usable advice out there, so I'm more than happy to share my discoveries with you!