Good question! [Most] toads you’re likely to encounter are harmless and safe for human hands. They could only make you sick if you stuck them in your mouth. Anyone who tells you that they’ll give you warts is just parroting an old wives’ tale, toads cannot hurt you or make you sick.
If you encounter a toad in the wild and would like to hold them for a quick picture that’s fine, but you need to be mindful of the cleanliness of your hands and the duration that you handle them for. Frogs have very permeable skin that’s sensitive to chemicals and salts, so if you’ve been painting, exercising, or have sunblock on them, then you shouldn’t handle them. Likewise I always give my hands a good rinse before handling my pet toads to be safe. But if you’re just holding them briefly for a picture or to get them out of the way of danger then that’s fine, just be gentle!
You should also handle them properly. Do not turn them on their backs! They can’t breathe properly like that, and it’s stressful for them. Also, don’t hold by their limbs, push on their head, or squeeze them. Cup them in your hands, or hold them with one hand wrapped around them and their forelimbs hanging out of your hand. Basically, support the frog/toad as much as possible, don’t squish it, and don’t hold it for longer than you need to.
If it’s a toad, and you notice that it’s oozing white stuff out its back, put it down immediately and wash your hands very well. Cane toads secrete toxins, and a few other toad species secrete irritants.