Dangerous behaviour

He does have a chew toy, which he will take from me as a replacement for dangerous objects. He will even put it in his mouth himself just not all the time 

Hi, he will be six in July. He does love sensory play. I think food like berries or grapes could help. He does put things in his mouth then runs off laughing as if to say” come and take this out my mouth then”. 

Hitchhikers Guide rule #1: Don't Panic! (Take control)

NAS75657 said:

Because we panic when he does it, he laughs and it has become a game

He is misunderstanding your reaction and it's probably imperative to begin to contain your emotions, and eve have something on hand to give him in exchange. 

Frozen grapes and berries are quite a good thing - they don't go off, they're healthy and they have a sensory element to them. You might be able to start curbing this by giving him these to try occasionally and then when he puts something dangerous in his mouth, Don't React. Calmly and firmly open your hand and allow him agency to spit it out redirecting his attention toward the frozen berries / grapes you will give him in exchange. Ideally you want him to become bored with the 'game' and just ask for these lovely nuggets of vitamin C from the freezer if he's looking for something to chew on. 

with my twins everything goes in their mouth, they seeking something sensory its their way to explore so offer a safe item to him he can put in his mouth, if you go to the works they have plenty of items you can offer him, i normally carry these in the bag for when they get restless.

firstly how old is your child ? does he enjoy sensory play ? if so try and get him sensory toys, i keep my twins occupied with these on trips, anything squishy or something you think that sparks his interest, is he still in nappies, that seems to irritate them when on long trips, maybe stop in a safe place make him comfortable and offer a sensory toy, finger foods or one of his favourite items.

Thank you for your advice. These are certainly things to try. Another thing my Son has done for a while is occasionally put objects in his mouth. At first it was simply sensory I think. Because we panic when he does it, he laughs and it has become a game. Usually he is very good it’s just these moments where he is putting himself at very great risk   

Someone else just posted about this: https://community.autism.org.uk/f/parents-and-carers/26728/running-into-roads

I'd advise the same thing. It would be good to find ways for him to exhaust him self.

My father and brothers are all gamers and incredibly high achievers (physics, neurology, maths professor). I believe a few are also undiagnosed autistic. He bought my son a handheld device every time they came out. It turned out my son had dyslexia and Zelda was helping him really want to learn to read. Something to play with in the car is quite useful. I can time how long we would be in it, so he would have an idea of how much time he had to play. But in the society we now live in, where I couldn't afford to stay home and technological advances are part of our future, a focused activity can keep them safe. Once they arrive, they can leave the element in the car and run around the house a few times. I'd encourage ways for him to get this energy out.