How do I keep my grandson from dying from huffing solvents?

This is really hard. It’s a nightmare. My nineteen year old grandson, unlike his cousins, has had a horrible life of rejection by both parents, being cold at night in bed, being hungry and seeing his mother, so to speak, having sex for money, and begging to live with other people. We began keeping him for entire school years in elementary school then his mother, my older daughter, would want him back and he’d go. Then all summer she’d be fooling around with much older men, some poor some rich but they’d come over at times. He was expelled in the tenth grade. I wish we had adopted him. He came to visit us a month ago and of all things my younger daughter made sure he got enrolled in our junior college (he got a GED on his own)and he’s making A’s and may go to summer Christian camp. He needs ten to twelve thousand dollars in dental work. He showed up here with a bottle or two of Ronson’s benzene. Since he’s in the dorm now I took the lid off and inside is a piece of tissue paper with pale tan streaks on it. I found a new large can of paint thinner in our garage which I threw out. But we have over a dozen cans of solvents and paint thinners in there. He is vaping with his aunt’s blessing (my younger daughter) but I know my husband won’t put up with it indoors. Last time I saw him he was fifteen and he still rearranges my things, puts our things under his bed here, looks all through my desk drawers when we’re asleep and I’ve had to hide my money and jewelry. His aunt says to heap praises on him due to his past, never criticize him , and not to hide paint thinners since he can buy more. She gives him $20 a week allowance. We bought him all new clothes, he has gained weight and his complexion is clearing up. He qualified for his first Pell Grant for school at 14K dollars. But what should I do about this huffing? I’ve read they can die with the first huff. He denies everything; he won’t budge. HIs dental receptionist even invited him to church. How can I save his life or is my daughter wrong in saying I can’t since the solvents are legal? His mother is certified “Neglectful” and she has lost her mind from drugs/poor nutrition and her teeth are chipped from chewing ice. Of course, I have left out a lot but thank you if you’ve read this far. My other grandkids are as good as they get. Please don’t lay a guilt trip on me for not adopting him. My husband is not his grandfather and when he got cancer we left the state and , with that, my grandson ten years ago.