Firstly, it's not based at a recycling centre, it's a piece of waste ground being used as a dump (1988, book was written) so tipping was still prevalent.
Secondly, my DD knows that little girls with red cloaks don't meet wolves for a chat in the woods and that bears don't eat porridge etc. Plus, sleeping beaty pricking her finger illustrates how you shouldn't play with needles.
I wasn't meaning to be overdramatic/overprotective and of course I realise about fiction (I am soon to start a GTP course and become a primary teacher!).
In the book, the waste ground became a building site and the kids still wanted to play there, with lorries, cement mixers, concrete pipes everywhere etc.
At the beginning they said how it was a safe place to play. Old mattresses could have needles in them, pipes could fall/roll, ground is unstable etc.
All I'm saying is the theme of the book (not the reading ability) was aimed at a much higher age group (9/10/11) and said they didn't want to play at the playpark where there was a slide, swings, see-saw etc (all the things my DD loves playing on).
It said it was ok and safe to play on waste ground being used as a tip.