RISING levels of cancer-causing chromium have been found in vegetation in urban areas of Scotland.
Sampling carried out by environmental officials found that levels of chromium, a heavy metal, in a series of former industrial sites across the Central Belt were 4.5 times higher than at similar sites in England.
The Environment Agency, which co-ordinated the UK-wide investigation, is now planning further tests to pinpoint the source of the contamination.
Declan Barraclough, the geo-sytems science manager for the agency, said the "markedly elevated" chromium concentrations in urban vegetation in Scotland warranted further investigation.
"We will be looking for the potential sources," he said. "Chromium is a toxic element to humans or wildlife, and when you get elevated concentrations like this, then you need to find out why.
"We do not think there is any risk to health, but we need to carry out more detailed investigations."
The UK Soil and Herbage Survey, which has just been published, was carried out to build up a detailed picture of pollutants in the ground and in vegetation in non-agricultural areas across the country.
The investigators were looking for concentrations of 12 metals, including chromium, PCBs and dioxins, all mainly legacies of Britain's industrial past, in 122 rural, 28 urban and 50 industrial sites.
The sites sampled were in the west of Scotland, where chromium ore was used extensively in the once-thriving steel industry. Some companies are known to have dumped chromium waste from the manufacturing process in a number of locations up until the 1960s, as was then allowed under waste legislation. Plants may now be absorbing the underground dust.
Environmental groups welcomed the investigation. Duncan McLaren, chief executive of Friends of the Earth Scotland, said: "The existence of chromium waste dumps in Scotland has been known for some time.
"However, it is disturbing to learn that chromium levels being detected here are many times higher than those found elsewhere in the UK. Whether this is due to these dumps certainly warrants further investigation by the relevant authorities."
One of the biggest chromium factories in Glasgow was White's Chemical Works in Rutherglen, which offloaded industrial waste around the area in the 1950s.
The survey reflects concern by environmental groups that government attempts to clean up sites contaminated by industrial waste across Scotland are being starved of cash.
A survey by the Scottish Executive found that at least 171 sites across the country have been poisoned by pollutants from heavy industry and coalmining.
But although 7,600 hectares of urban Scotland are known or suspected to be contaminated, only 144 hectares of contamination were cleaned up between 2004 and 2005.