DF3, why is running in Bradford dangerous? Are you a habitual WUM? For sure areas like Manningham or Delph Hill are rough, but I'd sooner run there than say Soho Road or Lozells in Birmingham. It may surprise some but parts of Bradford aren't that bad, granted there are no Kensington, Little Aston or Four Oaks pockets of wealth but the BD postcode includes some nice rural areas.
The only time I've had any thing untowards happen is a McD's milkshake and a marker pen thrown from moving cars, both in nice areas of Birmingham. Like everyday life, act sensibly and be aware of your surroundings to reduce the risk. As Wilkie rightly says,I'm not running through the park in the dark because I don't want to trip, not because a nutter is waiting in the bushes on the off chance a middle aged mad trundles past.
I get more trouble from middle class dog owners in the park than chavs in hoodies comparing wheels on their Saxos.