The chemical contaminating homes at Clovelly Park is trichloroethylene (TCE) – a group 2a carcinogen, meaning that it probably causes cancer in humans.

Here, we look at the health risks of TCE and find out how concerned Clovelly Park residents should be.

What are the health risks?

TCE has been linked with a host of adverse health impacts on the central nervous system, kidney, liver, immune system and male reproductive system.

The chemical also poses an increased risk of congenital heart defects in newborns, if pregnant women are exposed at high enough levels during pregnancy.

The most concerning of the long-term health effects relate to cancer and impacts on the central nervous system and liver.

The chemical’s classification as a cancer-causing substance is based on limited evidence in humans and sufficient evidence in other animals, according to the World Health Organisation.

Studies from Europe and the United States have found evidence that TCE increases the risk of liver cancer, non-Hodgkin’s lymphoma and cervical cancer.

TCE has also been associated with more than a six-fold increase to the risk of developing Parkinson’s disease in men.

The long-term effects of TCE on humans are not as well understood as those on animals, such as mice.

Because the available evidence indicates that TCE is genotoxic and carcinogenic, the World Health Organisation says no safe level of exposure can be recommended, but that, as a guideline, levels of TCE over 2 micrograms/cubic metre should be avoided.

How dangerous is TCE at Clovelly Park?

According to SA Health, the exposure of Clovelly Park residents to TCE vapour is slightly above the WHO guideline.

This means that residents are at a risk in the long term, but that there isn’t an immediate risk to residents’ health now.

“Based on the soil vapour data we have seen it is possible for the chemical to find its way into houses and expose residents to levels higher than is acceptable for residential indoor air,” said Director of Public Health, Dr Kevin Buckett.

“The relocation of residents over the next few months while further testing and analysis is done is the safest way to prevent ongoing exposure.”

Associate Professor of Environmental Health at Flinders University Richard Bentham told InDaily that sites like Clovelly Park demonstrate the ability of TCE to seep from the groundwater to the soil, and from there, into buildings.

“The vapour creeps up through the soil and it will follow the route of least resistance, like vapours do, which means it ends up concentrating in buildings,” he said.

“Any exposure that residents have had is probably at low levels and has not been for a long enough duration to be causing any serious health effects within the people within those houses.

“The reason they’ll be moving them is saying that if they were to stay there, then the long-term exposure may result, or could possibly result in adverse health effects.”

Peter Dolan of the Environmental Protection Authority said more testing was required to understand the nature of the soil and groundwater contamination at Clovelly Park.

“Sampling undertaken in February and March 2013 identified three residential properties of an 11 properties tested with TCE in indoor air slightly above the World Health Organisation guideline of 2ug/m3,” he said.

“Further investigations need to be undertaken to delineate the nature and extent of site contamination south in Clovelly Park and west in Mitchell Park, and further data needs to collected from the homes in the relocation area. This is a precautionary measure to allow that work to be undertaken and remediation options investigated.”

TCE was used until the late 1970s as an anaesthetic similar to chloroform. It was also used in dry cleaning.

Though many uses for TCE – in pharmacuticals and food, for example – have now been banned, the chemical is still used as an industrial solvent.