Thank you Mr. Chairman for introducing me. Good morning everyone.

First, I acknowledge to Japan fund global environment, Japan Offspring Fund and Consumers Association of Penang for inviting me in this symposium.

Today, first of all, I would like to touch on some basic information of PCBs and its related compounds, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs).

And then, I would like to talk about our resent study, regarding on Contamination by PCBs, PCDDs and PCDFs in soils from dumping sites of municipal and industrial waste in Malaysia.

Here I show the basic information of PCBs.

PCBs consist of 209 congeners with different numbers and positions of chlorine atoms on the biphenyl ring as shown here.

This chemical was firstly synthezed in 1881, and commercial production was started in 1929 in USA. Then after, Mass production was started in late 1940s for industrial proposes, such as heat transformer oils for transformers and capacitors, organic diluents, pesticide extenders, dust-reducing agent, cutting oils, flame retardants, carbonless copy paper and other.

PCBs have been detected from wild animals since 1966, and 2 case of mass poisoning caused by feeding rice oil contaminated with PCBs were occurred on 1968 and 1979. Because of these, Production and new usage was banned in Japan, western Europe and North America in 1970s, and in Russia and eastern Europe in early 1990s.

Recently, PCBs were classed into POPs (persistent organic pollutants), and UNEP request All the PCB usage should be stopped until 2025.

Until prohibition, PCBs were produced about 1.3 million tons in the world. As shown here, more than 30% of total production was in USA, followed by France, Germany, former Soviet Union, UK, and Japan. Production in other countries, such as Southeast Asia, Africa and south America, is less information.

Although most of production and new usage was terminated 30 years ago, why PCBs have been of a great concern as environmental contaminants, now?

This is answer.

PCBs have persistent nature in the environment, bioaccumulated in humans and wildlife, and transported on worldwide by air and water.
In addition, PCBs have been leakage from transformers and capacitors, which have been still used or stored.

As these results, PCBs have been detected in all the environmental media and biota at the highest level among POPs.

Furthermore, PCBs elicits various toxicities, such as body weight loss, dermal lesions, hepatotoxicity, suppression on immune system, endocrine disruption, reproductive and development toxicities, neurotoxicity and carcinogenicity.

These lead that PCBs have been of a great concern as environmental contaminants.

By the way, most of PCB toxicities are considered to be caused by coplanar PCBs and polychlorinated dibenzofurans (PCDFs), which are contained as impurities in commercial PCBs.

 

Coplanar PCBs, PCDFs and polychlorinated dibenzo-p-dioxin (PCDDs) are called dioxin-related compounds. These compounds are formed as unwanted byproducts during synthesis of a wide array of commercial chemical products, such as PCBs and organochlorine pesticides. In addition, a variety of combustion processes, for example burning of municipal waste, lead to continuous formation of dioxin-related compounds, especially PCDDs and PCDFs. Due to their persistent nature in the environment, bioaccumulation in high trophic animals, long-range transport on global scale by air and water, and highly toxic effects to human and wildlife, many developed nations have conducted comprehensive investigations, controlled emission sources, and applied the environmental standards for dioxin-related compounds. As these results, It made clear that environmental residue levels have been decreasing in recent past decades. However, in developing countries, fewer information are available on the pollution of these contaminants.

This is a view of the dumping site of municipal wastes in Phnom Penh, Cambodia.

This is a same view in India.
 
Large scale dumping of municipal wastes is common in the urban regions of many developing countries.
 
Variety of wastes including plastics, metals, papers, woods and raw materials are dumped in large open land areas.

The major problem here is burning of wastes at low temperatures due to the generation of methane gas.
 
As you guess now, the burning of wastes forms dioxin-related compounds.

Other problem in such dumping site is presence of slum.

Poor peoples form a slum near to the dumping site, collect the recyclable and usable items in this area, and keep them near their houses, as you can see here.

They are exposed to dioxin-related compounds here, because they spend most of their time here, and thus seem to be at risk of many toxic chemicals.

In addition, As you see here, some domestic animals, such as cows, feed in dumping site.

It can be expected that they are also exposed to dioxin-related compounds.

Consequently, People, who eat and drink food from these animals, is exposed to dioxin-related compounds.

From the slides I showed now, dumping sites of municipal wastes in Asian developing countries may be expected as the sites of secondary formation of dioxin-related compounds, because huge amounts of various wastes have been dumped daily and continuously burned under low temperature by spontaneous combustion or intentional incineration. Therefore, it is suspected that pollution sources are present in dumping sites. As results, DXNs from here will be contaminated surrounding fields, and many residents and wildlife around there might be exposed to these contaminants.

We have also found similar dumping site of municipal and Industrial wastes in Malaysia on last Survay.

This shows the combustion of solid waste in dumping site in Malaysia.

However, to our knowledge, there is no information on contamination by dioxin-related compounds in such field in Malaysia.