The fast lane of northbound Interstate 95 in Arbutus was closed for more than six hours yesterday after the load of a truck hauling 20 tons of used car batteries shifted, saturating the road with acid, authorities said.

The spill occurred about 6 p.m. between the exits for I-195 and the Beltway. The left lane and its shoulder were closed as hazardous-materials crews cleaned up and the batteries were put onto another truck.

The driver was treated for minor injuries, police said.