HK at risk from deadly chemicals
DEADLY airborne chemicals which can cause cancer and other health dangers are present in Hongkong, some in levels which exceed recommended standards.
The toxins are believed to come from industrial sources like electroplating and are released either by burning or the disposal of fume-producing solvents.
Of particular concern are the chemical ethylene dichloride, whose levels exceed recommended American guidelines, and benzo-alpha-pyrene, whose levels are believed to have risen 50 per cent since 1989.
The figures were obtained through preliminary Environmental Protection Department (EPD) studies.
Principal environmental protection officer, Mr Raymond Leung Pak-ming, said ethylene dichloride has caused cancer in experimental animals and benzo-alpha-pyrene is also linked to the disease.
Both chemicals arise from combustion, particularly in factories, although ethylene dichloride is also an additive in leaded petrol.
Mr Leung said the study of toxic air contaminants was relatively new world-wide and standards varied widely so it was difficult to say whether levels were high or low, but carcinogens at any level were a worry.
''It is very difficult to say what is a safe level because for carcinogens, you are talking of increased risk of cancer,'' he said.
''Even if they're at a very low level, you still have a risk.'' Other toxic air substances that have been measured are arsenic, beryllium, cadmium, chromium, lead and mercury, as well as polychlorinated biphenyls and seven volatile organic compounds, but all were within acceptable limits.
Mr Leung said there was a long list of potentially harmful chemicals, but the EPD had concentrated on the most common because of limited resources.
For instance, it has not studied dioxin, which is toxic even at low concentrations, because it is difficult to measure and is not expected to be widespread in Hongkong.
''There are a whole lot of chemicals emitted from factory and combustion processes, with very different and adverse effects on health,'' Mr Leung said.
''Cancer is one effect and it's a big concern. There are also birth defects, neurological damage and other fatal diseases.'' The EPD will commission a consultancy study in the next few months to trace the main sources of the toxins and how they can be controlled.
Mr Leung said surveys over the past four years had been rough, being taken only once a month which made them more vulnerable to wide variations such as the increase in benzo-alpha-pyrene levels, but the industrial sources needed to be investigated nonetheless.
The consultant will be asked to look at industrial practices and chemical imports to pinpoint the problems.
For instance, the study will determine why ethylene dichloride levels did not drop after unleaded petrol was introduced in April 1991. The EPD now suspects its main source is industrial, as about 100 tonnes of the chemical are imported each year for use in carpet cleaners and solvents, and for cleaning metals.
Mr Leung said the department hoped by the end of the year to have a clearer idea of the problem and how it might tackle it.
Ms Mary Riley, who chairs the environment group Friends of the Earth, welcomed the EPD's efforts on the problem, but called on tertiary institutions to devote more resources to studying pollution because the EPD did not have the resources to do all the work on its own.
