Why would there be?
Is there anything special about the materials being transported to and from fracking sites that makes them unusually prone to being spilled? Is there anything notably different about the sorts of containers and vehicles used, or the quantities involved?
No, not that we can see.
Harmful construction chemicals are shipped around the country every day on lorries, eventually reaching the shelves of B&Q. Billions of litres of petrol and diesel are moved in road tankers every year, from refineries to filling station forecourts. Water treatment chemicals like Hydrochloric Acid and Sodium Hypochlorite are transported in 1,000 litre IBC's to swimming pools and leisure centres. Wastes that are much more hazardous than fracking flowback are taken away from industrial facilities to treatment and disposal centres.
According to the Department for Transport (DfT) last year saw 9,873 Million Tonne Kilometres of dangerous goods transported on roads around Britain, of all classes. This includes products that are flammable, toxic, infectious and corrosive.
This is going on around us all of the time, but you don't regularly hear news of major spillages do you?
That's because the transport of hazardous materials is very well regulated. Vehicles are selected that are appropriate for the loads they will be carrying, containers have to meet certain regulatory standards (including for leakproofness in an accident) and drivers receive detailed mandatory training that's refreshed every few years.
We're not saying there's zero risk of something going wrong, but it's a very low risk if done properly.
Like everything, it's important to view the risks in perspective - compared with, say, petrol and diesel transport, there will be significantly fewer hazardous goods loads created by fracking and the materials involved will themselves also be less dangerous to people and the environment in the case of a road spillage. Fewer loads means fewer opportunities for things to go wrong and therefore a lower likelihood of spills; less dangerous materials means lesser consequences if something does go wrong. Together, those factors (low likelihood and low consequence) add up to a low risk.