In August, a huge forest fire ravaged the San Lorenzo Valley north of Santa Cruz, California, destroying nearly 1,500 structures and exposing many others to extreme heat. Before the fire was extinguished, laboratory tests revealed benzene levels of up to 9.1 parts per billion in residential water samples, nine times the state’s maximum safety level.
This isn’t the first time the carcinogen has been following forest fires: California water managers found unsafe levels of benzene and other volatile organic compounds or VOCs in Santa Rosa after the Tubbs Fire in 2017 and in Paradise after the Camp Fire in 2018 .
Scientists suspected that, among other possibilities, plastic drinking water pipes exposed to extreme heat released chemicals (SN: 13/11/20). Now, laboratory experiments show that it is possible.
Andrew Whelton, an environmental engineer at Purdue University in West Lafayette, Indiana, and colleagues subjected commonly available pipes to temperatures of 200 ° C to 400 ° C. Those temperatures, hot enough to damage but not destroy the pipes, can occur at radiate the heat of nearby flames, says Whelton.
Andrew Whelton / Purdue University (CC-BY-ND)
When researchers submerged the pipes in water and cooled them, varying amounts of benzene and VOCs – more than 100 chemicals in some tests – leachate from 10 of the 11 types of water pipes, the team reported on Dec. 14 in Environmental Science: Research and water technology.
“Some contamination from past fires has probably originated from thermally damaged plastics,” Whelton says. It is impossible to do experiments in the midst of a raging fire to pinpoint the exact source of the contamination, he says, but inspecting the damaged pipes after the fact may suggest what temperatures they may have experienced.
Exposure to benzene can cause immediate health problems, such as skin and throat irritation, dizziness, and long-term effects such as leukemia. The team suggests testing drinking water if the fire gets close to your property and, if possible, replacing any plastic in a home’s water system with heat-resistant metal.