As part of my sound-dampening procedures for my Defender 110 CSW, I’ve been considering the use of Bituplus Modified Waterproofing membrane to reduce vibration in the floors, side panels and roof.

Of course, bitumen (asphalt) contains carcinogens. While there is most danger to (e.g.) roofing workers, Bituplus membrane on the floor of a vehicle would be subject to some (perhaps considerable) temperature change, as would parts of the vehicle exposed to constant, strong sunlight.

we spend many hours in the vehicle, including sleeping. The presence of potentially toxic fumes does appear to be an issue.

Any thoughts on this from layman or expert?

MATERIAL SAFETY DATA SHEET
SBS MODIFIED BITUMEN
WATERPROOFING MEMBRANE

Bitumen membrane. Asphalt odour. Under normal use, this product is not expected to create any health or environmental hazard.
Inhalation of dust or of asphalt fumes can cause a respiratory irritation and/or a congestion.

WARNING! This product may contain substances known by the State of California that could cause cancer (asphalt, crystalline
silica, fibreglass, antimony trioxide).

if you aint eating it there wont be a problem.Dont heat it.If cutting it do it outside in a ventilated area.UV deformation wont be an issue.Alspo try not to catch it alight.Although the health issues are apprent if that happens.