Saturday, July 28, 2007

Malaysia issue- Time to weed out POPs from Malaysia

The long-term effects also involved other organs: the heart, the lungs and even the blood. Chronic neurotoxic effects associated with low-level exposures to the chlordane were further substantiated in a study in 1995 on protracted neurotoxicity from chlordane sprayed to kill termites. The deficits identified included that of balance, reaction time, and verbal recall. Studies too have confirmed that in animals the chemicals can cause reduced fertility and caused neurological defects in their offsprings.

In Malaysia, the choice for using chlordane is said to be because of its relative cost as compared to other available alternatives. Also, it is perceived as effective since its residue can persist in the ground for up to 40 years once it is pumped in. On the contrary this is in fact one of the major setback of chlordane because of the risk that Malaysians could be exposed to due its persistent nature in the environment. It is therefore high time that such chemicals be removed from our market as soon as possible.

The ban on the manufacture and importation of chlordane however has also raised some larger questions. Foremost, chlordane belongs to a group of chemicals generally known as "persistent organic pollutants" or POPs for short. They include similar organochlorine compounds like DDT, PCBs, furans, heptachlor, aldrin, dieldrin and endrin. Some of these are still common found in Malaysia. Many of them are used in or arise from industry, agriculture and disease vector control. They may also be created unintentionally, as by-products. As such all of them can result in environmental health risks. Because of their persistent nature, over a period of time, their concentrations can increase to levels that eventually effect health.

Dangers of other POPs
The best known example is perhaps DDT, which has been widely used for many years for vector control around the world. It has a low acute toxicity in humans and for a while was regarded as 'safe'. However, it is now recognised that DDT has a number of long-term effects including acting as "endocrine disruptor" namely in mimicking steroid hormones in the human body. Moreover, the reports of high concentrations of DDT found in human breast milk especially in developing countries point to the possibility of environmental accumulation of DDT. One prospective study based on the New York University Women's Health Study in fact, showed a significant association between body stores of the DDT metabolite, DDE, and breast cancer.

On the other hand, eldrin, another POP, is even more hazardous. As a comparison, it is reported to be between two to four times more toxic than DDT (LD 50: 16-43 mg/kg in rats), despite endrin being more readily meta-bolised. Food contamination with endrin has caused several clusters of illness worldwide especially with regard to poisoning in children. But these are often overlooked because the symptoms resembles those of encephilitis, making the cause not immediately apparent.

Yet another group of great concern is the polychlorinated biphenyls (PCBs). They have been around since 1929 but was banned more that 20 years ago in the US. PCBs are made up of more than 200 related compounds which because of their many ideal characteristics are used in a number of industrial applications, especially as insulators. Their wide acceptance have "insulated" them from being made a focus of potential health and environmental problems.
The extent to which PCBs can affect us today cannot be overemphasied since at time of their discovery as environmental and health hazards, they had been produced and used extensively for more than 3 decades.

Like most POPs, PCBs too can accumulate in the fatty tissue, and over the years it becomes clear that PCBs have been detected in food samples from all over the world. They can enter the food chains and disrupted them. The higher the level of the food chain, the greater the concentration of PCBs. Some have been passed on to eggs (for birds and fishes) as well as milk (for mammals), and eventually humans. Indeed, PCBs can be traced to humans by consuming such contaminated food, and through breast milk in the case of infants. One report submitted to the UK Department of Health stated the "[b]reast fed infants are receiving up to 17 times the tolerable amounts of dioxins and polychlorinated biphenyls (PCBs)."

PCBs and IQ
One of the most alarming exposure effects of PCBs, however is the lowering of IQ, a subtle and devastating impact. It was recently confirmed that children exposed to the low levels of PCBs in the womb grow up with low IQs, poor reading comprehension, attention deficit as well as memory problems. Even at the age of 11, maternal exposures to PCBs were correlated with lower overall IQ and lower verbal IQ score. About 11 percent of the children whose mothers has highest exposures now have IQs 6.2 points lower than average. Other researchers suggested that the mechanism of harm of PCB involves with interference with the thyroid hormones, which are essential for development of the brain.

Children exposed to PCBs in the womb at levels regarded as "background levels" in the US have also been reported to experience loss of muscle tone, poor reflexes at birth, delays in psychomotor development at ages of 6 and 12 months, and diminished visual recognition memory at 7 months. Others have reported of findings like "balky, uncooperative behaviour" suspected to be linked to exposure of higher levels of PCBs. All these invariably are related to the presence of PCBs in the environment - be it in storage, landfills, in sediment of lakes, rivers, or even oceans - apart of the larger proportion that are in use, estimated at 70 percent of the total. Given all these findings, it is therefore not suprising that a ban was imposed on PCBs by the US Congress - outlawing the manufacture, sale and distribution - as early as 1976, except in "totally enclosed" systems. Even then, although their use in heat transfer and hydraulic systems can be regarded as "closed," there is always the risk of leakage and exposure.

The question of safety
Thus, while the banning of chlordane can be seen as a step in the right direction, it by not means the only substance of concern. Many more should follow suit in the immediate future. We must continue to weed out as many POPs as possible in the shortest time frame possible until they no longer pose potential risks to the population. In fact, in a recent WHO report (1997) as part of the review five years after the Earth Summit, considerable attention has recently been focused on POPs (see box). The report commented that the use of such substances cannot be considered sustainable. Increasing evidence of the long-range transport in the environment of these substances and the consequent threats they pose to the whole globe, has prompted the international community to call for urgent global action to reduce and eliminate releases and emissions of these chemicals.

Among the twelve POPs under initial consideration for international action, DDT is the only insecticide still in use for public health purposes, notably vector control. DDT has made major impact to the eradication, or virtual eradication of malaria from a number of countries, including Malaysia. Even then the use has declined following development of vector-resistance, reduction in its global production and adverse recent findings.
In other words, the POPs is fast losing its 'popularity' and Malaysians should be spared of any potential hazardous that could arise from being accessible to such hazardous substances. The only way that this can happen for certain is by eliminating all of them from our mwrektt as soon as possible.N

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