Consultant paediatric oncologist Victor Calvagna is “categorically denying” claims that a study he carried out shows the Delimara power station “is a hazard to the public because it increases the risk of cancer”.

The Marsa power station, as it was then, cannot not be compared to the Delimara power station

Dr Calvagna said “there was no way that one can extrapolate” the findings of his dissertation – which he wrote on the Marsa power station for his Master of Science postgraduate degree in 2005 – to the Delimara plant.

His dissertation focuses on two sources of environmental pollution – the Magħtab landfill and the Marsa power station – and examines the rates of cancer in their vicinity and how those rates vary with increasing distance.

The results showed there were no statistically significant changes in the rates of cancer from the Magħtab landfill.

“The same can be said for the Marsa power station except for the rate of change of lung cancer cases.

“Here there was a statistically significant decrease in lung cancer cases as one moved away from the power station,” he said.

Dr Calvagna’s study was mentioned several times last week as a link or evidence that the power stations, which use heavy fuel oil, cause cancer.

This link has been made by Labour leader Joseph Muscat, who described the Delimara power station as a “cancer and asthma factory”.

A grandmother of nine spoke in Marsaxlokk during a Labour event, saying eight of her grandchildren had asthma and a three-year-old grandchild had lung cancer.

However, the health authorities vehemently denied the allegations and Health Minister Joe Cassar called a press conference last week with six healthcare experts saying there was no such link.

Dr Calvagna said the results of his study could not be extrapolated to the Delimara power station because the “primary source of fossil fuel used to fire the turbines at Marsa from 1974 to 1995 was coal and not heavy fuel oil as is used at Delimara”.

To make matters worse, the coal was stored in the open air at Menqa wharf where it was exposed to the elements with the result that particulate matter, which was very fine dust, was distributed by the wind to the immediate surroundings, he added.

If one had to conclude that the Marsa power station was the “sole cause of the excess of cancers seen in that area”, then because of the long latency period associated with the development of these cancers, which was between 20 to 40 years, “one had to incriminate coal as the fossil fuel most likely to have resulted in this excess,” the study said.

However, Dr Calvagna pointed out that “even this conclusion may be biased”.

The area around Marsa power station is “heavily industrialised, vehicular traffic is high, and St Luke’s Hospital’s incinerator was in use at the time”.

These were all sources of environmental pollution that together may “raise the relative risk of a person living in that area to develop lung cancer”. The situation in Delimara and neighbouring Marsaxlokk “is completely different,” he said.

Also, the populations of the inner harbour area and Marsaxlokk may “differ in their smoking history, deprivation status and occupational history – all “are important in influencing the relative risk of cancer”.

Dr Calvagna said the Marsa power station, as it was then, could not be compared to the Delimara power station. The Marsa chimneys were of “inadequate height and prone to fumigate and downwash smoke on to neighbouring densely populated areas”.

The chimneys at Delimara were of “suitable height” and helped to reduce environmental pollution by dispersal into the atmosphere.

The electrostatic precipitators at Marsa “were not effective in removing particulate matter” and these were only refurbished in 2002 – something which was never the case at Delimara.

The Marsa power station was not equipped with systems to reduce the emission of sulphur dioxide, oxides of nitrogen, ozone and carbon monoxide “as is the Delimara power station,” Dr Calvagna said.

“In my opinion the results of my study are now outdated and do not apply to the current situation because, since joining the EU in 2004, Malta had to stringently comply with the Air Quality Standards Directive,” he added.