Jarupong Boon-Long

Thailand is a country of 500,000 square kilometers with population of approximately 60 million, which is currently increasing at annual rate of about 2 percent. Thailand's agricultural sector is the foundation of the country's economy. About 70 percent of the working population is engaged in this sector which provides most of the country's current export earnings. During the last 2 decades general agricultural production has steadily increased. This has affected the expansion of area under cultivation. Thailand has also been in a period of industrialization and economic development which had the effect of increasing the number of registered industries from approximately 60,000 in 1978, 90,000 in 1988 and to 130,000 in 1997.

The demand for agricultural productivity and the expansion of industry caused a rapid increase in the use of chemicals. Most chemicals, organic and inorganic, are imported from approximately 40 countries including developing, developed and industrialized countries. The importation of chemicals, as reported, increased from 600,000 metric tons in 1978 to 3,000,000 metric tons in 1979. Pesticides form one of the major toxic groups of chemicals to be imported increasingly from approximately 5,000 metric tons of the active ingredients in 1971, 10,000 metric tons in 1981, 15,000 metric tons in 1991 to 25,000 metric tons in 1996. Particularly during the period 1950 to early 1970, most of the imported pesticides were organochlorine pesticides including those specified POPs chemicals such as DDT, toxaphene, drins, heptachlor and others. However, importation of almost all specified POPs chemicals have now been prohibited for all uses by final governmental regulatory action for human health and environmental reasons.

Information on the importation of the 12 specified POPs chemicals has not really been collected from the very beginning. The term "toxic chemicals" was not recognized at that time. The only term that the people heard and understood in that period was 'poison' from plants, snakes, mushrooms and other living things. Thailand was very conservative in this field and never introduced any toxic chemicals to the country in those days. The first report on the application of chemicals was learned about after the Second World War. That was in 1949 when [(1,1- (2,2,2- trichloroethylidene) - bis (4-chlorobenzene)], DDT was first introduced for a malaria control trial in Chiangmai Province. The Malaria epidemic in 1951 was very serious and killed over 40,000 Thai people at a mortality rate of 200/100,000. DDT has been widely applied at rate of 2 gm-a.i. / m² ever since. It proved capable of decreasing the mortality rate each year until it reached 1/100,000 in 1993. During those days, this toxic angel has not only been used for malaria control but also in agricultural for pest control. It was first applied to control the epidemic of corn grasshopper (Patanga) in 1953 and became widely known after 1955 when it was applied to control the cotton ball worm and tobacco insect pest.

Following DDT, the "drin family" was introduced in 1955. The Shell Company in Thailand imported dieldrin aldrin and endrin, and also at this time Yip In Soy, a local company imported BHC and toxaphene. Since 1959 all of these organochlorine pesticides have been widely applied for the pest control of almost all crops including casawa, fruit and vegetable crops. During 1960 - 1965, farmers applied a mixture of DDT + endrin, DDT + dieldrin and DDT + toxaphene and even DDT + toxaphene + methyl parathion instead of DDT only for the control of cotton pests and other plant pests.

The importation of POPs was first reported in 1971 when toxaphene DDT and BHC formed the largest volume of 621,968 and 17 metric tons respectively. The volume of Dieldrin, aldrin, endrin, chlordane and heptachlor were less, being 8, 6, 0.8, 3 and 1 metric tons respectively. The mixtures of DDT + toxaphene and DDT+ toxaphene + methyl parathion were also reported. The importation of such POPs increased for years and years. There were increases and decreases in volumes yearly but in general they increased until they were banned in specified years (Table 1, Figure 1) for the impact on human health and the environment. Only chlordane remained in use up until 1996.

Polychlorinated bi-phenyls (PCBs), have been used in small amount as industrial fluids for hydraulic systems and gas turbines, as lubricating oil, and as plasticizer. Imported volumes and the date it was first imported for these purposes have never been recorded. The other main purpose for which they were used in a relatively large quantity was as a dielectric fluid for electric capacitors and transformers known as askarel. No reports were made on when it was first imported either. It was recognized as a existing hazardous waste of concern in the electric utility industry as PCBs contaminated equipment. Importation of electric capacitors and transformers containing PCBs was totally banned in 1975. A report produced by the Electricity Generating Authority of Thailand (EGAT) in 1987 indicated their possession of 1,881 capacitors containing PCBs oil. Twenty eight percent of which have been retired from service and are awaiting the appropriate disposal measure (Table 10). Regarding transformers containing PCBs, EGAT has 33 transformers known to contain askarel oil of about 45,060 liters (Table 11). In this year, the Metropolitan Electricity Authority (MEA) had removed all of their 636 PCBs containing capacitors from service and stored in steel containers waiting for the appropriate disposal.

The Provincial Electricity Authority (PEA), responsible for all electricity services nationwide outside the Bangkok Metropolitan area, had a large number of transformers and capacitors (Table 12). Other than the MEA and PEA, some private firms also had electric equipment containing PCBs in relatively small amounts, connected directly to the MEA or PEA service system. A survey and study were again completed in 1992. The Pollution Control Department with cooperation from the MEA and PEA, reported the number of electric capacitors, transformers, and wastes containing PCBs. A total of 3,681 capacitors and transformers and another 109 drums both retired and in services of all together approximately 566 metric tons have been reported. From this amount, 1,195 capacitors and 65 transformers were still in services, another 2,396 capacitors, 29 transformers and 109 drums of contaminated PCBs wastes of all together approximately 211.25 metric tons were being kept for final disposal (Table 13).

In the past 20 years, improved governmental policy has resulted in better control of pesticide management including legislation and monitoring. Several government agencies have routinely monitored and reported the persistence of toxic chemicals mainly heavy metals and pesticides in water, soil, sediment, aquatic organisms, foods, meats, commodities and human blood. The level of pesticide residues in few samples was higher than the recognized international safety standards. Since 1977, thousands samples of different source were collected and analyzed each year. In summary, relatively small amounts of organochlorine pesticides such as aldrin, dieldrin, endrin, DDT, heptachlor were found in different percentages of all samples (Table 2 - Table 7). During 1972-1987, organochlorine pesticides at different levels were detected in more than 50 percent of each sample source except in human blood. During 1988-1992, such pesticide residues were still detected in relatively lower levels and percentages. Since 1993, the situation regarding organochlorine pesticide persistence has been getting better and better. Most samples were reported at a very few part per million (ppm) or part per billion (ppb) or even at non-detectable (ND) level.

The most current collection on the routine monitoring of the organochlorine pesticides in the environment made by the Pollution Control Department during the rainy and dry seasons in 1997 has illustrated remaining persistence in a small amount. Most pesticides have been detected in a part of billion in both soil and water (Table 8, Table 9).

Monitoring for the persistence of PCBs was not done as often as for other organochlorine compounds. It was first monitored by the Asian Institution of Technology in 1971 and was found in sediment of Chao Praya river from ND to 0.152 ppm. The second monitor was done in 1976 by the Department of Agriculture and found 0.0003-0.0029 ppm in Chao Praya river sediment and average of 0.05 ppb in water. In the same year PCBs were also found in fish and squid at 5.3-106.2 ppb and 58.7-69.0 ppb respectively. In 1992, Monthip Tabucanon of the Environmental Research and Training Center, studied the behavior of PCBs around a storage of used capacitors and transformers in Thailand. Air and surface soil samples were monitored and PCBs ranged from 160 to 1,400 ng/m³ and 0.09 to 127 mg/g respectively.

Ever since the early 1960s, Thailand has been busy tackling the occupational health and environmental problems systematically and at national level. At present, there are many government agencies responsible in the field of chemical control and management. The Pollution Control Department (PCD) formerly part of the Office of National Environment Board, has developed policies, strategies and action plans in protecting the environment and other living systems. Recommendations have been made concerning environmental quality standards with regard to the control of pollution and also toxic chemicals as protective measures under the Enhancement and Conservation of National Environmental Quality Act 1975, 1978 and as amended in 1992.

The Ministry of Industry (MOI) has established quality standards and control for industries and factories involved with chemicals, particularly those generating hazardous or toxic chemicals under the provision of the Factory Act 1969, 1978 and the amended 1992 and of the Hazardous Substance Act 1967, 1973 and the amended 1992.

The Ministry of Agriculture and cooperatives (MOA) has the authority to control toxic substances in agriculture (pesticides) under the Hazardous Substances Act 1967, 1973 and the amendment of 1992. Under the same Act, the Ministry of Public Health (MPH) also controls the toxic substances used as consumer products and some purposes for human health. The MOI, MOA and MPH issued a lot of hazardous substances in the Ministerial Notification periodically following the evaluation of such substances, either old or newly introduced. In addition, the PCD, MOA and MPH have done a great deal of monitoring and analysis of residues of chemicals including those POPs chemicals.

Under these brief descriptions of the relative government agencies responsible, chemicals including POPs life cycle have been managed more or less in a sound manner under the circumstances in Thailand. Import, export, manufacture and the possession of hazardous substances have been controlled under the Hazardous Substances Act 1992. Banning of the importation or severely restricted uses of chemicals have been notified in the Ministerial Notification following the consideration of the National Hazardous Substances Committee. In particular the specified POPs, most pesticides were banned for importation in the 1980s. (Table 14) Hexachlorobenzene was the first one in 1980, followed by endrin in 1981 and toxaphene in 1982. DDT has been used both in agriculture and for malaria control it was banned in agricultural uses in 1983 and for malaria control in 1994 following the available of other alternatives. Dieldrin was banned in 1986 followed by aldrin and heptachlor in 1988. Chlordane was the last one to be banned in 1996. Most POPs chemicals were banned for their effects on human health and the hazard to wild life and the environment.

PCBs were banned for importation even before the others mentioned, in 1975. However, problems related to the use of PCBs were still bad enough to call attention to the government to spend hundreds million Bahts for the final disposal of the electric capacitors and transformers containing PCBs. In this regard, the Electricity Generating Authority of Thailand had to spend almost 50 million Bahts to purchase non-PCBs capacitors and transformers but still could not replace all existing ones. Exporting capacitors and transformers containing PCBs and PCBs wastes has been done for years and years, depending on the budget available because Thailand does not have disposal facilities. In 1992, Thailand exported 153 metric tons of such hazardous wastes to dispose at the EMC Service, PEC TREDI, in Saint-Vulbus, France (Table 13). For the rest in storage, the EGAT exported 240 metric tons during 1994-1996, MEA exported 166.22 metric tons in 1994 to France, and the Ekarat Engineering CO., LTD. Exported 30 metric tons in 1996 to United Kingdom.