It is now the responsibility of all concerned to critically analyse the whole issue to reach a logical conclusion. The various adverse effects of the smoke emitted from brickfields are scientifically proven facts. Accordingly, to reduce the smoke as well as to minimise the hazards, the Department of Environment have already enforced some obligatory measures including use of long chimney. However, I do not intend here to look at whether those measures are complied with or not. What I would like to communicate are some of the most important recent scientific reports related to the emissions from brickfields as well as other similar sources and the chemicals contained in those emissions, posing deadly effects on the environment including human lives.

The recent scientific report states the combustion of clay and fuels for making bricks in the brickfields produces dioxins and furans as byproducts, which first enter into the air from where the humans, birds and other animals either directly inhale or intake through different contaminated foodstuff both vegetable and animal origin. According to the Standard Toolkit prescribed by the United Nations Environment Programme (UNEP), under well-controlled processes 0.2 microgram TEQ (toxic equivalents) of dioxins and furans are emitted as byproduct into the air during the production of each tonne of brick. As per this emission rate, if each brickfield produces 2,550 tonnes of brick a year, then the reported 17 brickfields within 4-km around the worst affected village Baknai emit into air a total of 510 microgram TEQ dioxins and furans per year. Since the brickfields around Baknai or in Lalpur or for that matter in Bangladesh do not have well-controlled system and cleaning processes, they are likely to release much more quantity of dioxins and furans into the air.

Dioxins and furans emission and release into air take place from several other sources, too, such as, incineration of medical wastes, incineration or burning of municipality wastes, cremation, cigarettes and bidi smoking, burning of wood, straw, kerosene oil, coal, gas etc. for different purposes. The combustion processes of brickfields, glass, cement, ceramics factory etc., pulp and paper industry discharges, the manufacture of polyvinyl chloride (PVC) plastic, PCBs used in electrical transformers and other similar equipment etc. everyday are producing significant amount of dioxins and furans and releasing them into the air. But highly concentrated brickfields in a small area such as in Baknai/Lalpur are emitting dioxins and furans at a level, which, in combination with emissions from all other sources, might be enough to cause such hazards, which the people of Lalpur have noticed. May be, similar situations exist in many other places of the country, which are still beyond anybody's notice.

Dioxins (polychlorinated di-benzo-para -- dioxins) and furans (polychlorinated di-benzo-para -- furans) are two groups of several chlorinated organic chemical molecules. Dioxins have 75 molecules (congeners) while furans have 135. All these together are also called dioxins. All these dioxins are chlorine rich, persistent for years together, self-transportable from one place/country to another, bio-accumulative because of their strong affinity for fats, and thus increase manifold through the food chain and cause harms to the host lives. Since they accumulate much in mothers' breast milk, the nursing infants intake much more quantity of them.

Since the dioxins are partially soluble in fats, they accumulate in fat-rich organs and tissues of humans particularly in breast, uterus, intestine of women, in testes and adipose tissues of men and other similar organisms. These are highly persistent and thus magnify manifold in those organs and as deadly elements cause several adverse effects. They cause abnormally functioning thyroids and other hormone system dysfunctions, feminization of males and masculinization of females, compromised immune systems, behavioral abnormalities, neurobehavioral impairment including learning disorders, a shortened period of lactation in nursing mothers, endometriosis, increased incidence of diabetes, tumours and cancers, and gross birth defects. The other effects include loss of appetite, weight loss, nausea, headache, liver and renal damage, cardiac arrhythmias, allergic conjunctivitis, blepharitis, and retinal angiopathy.

In consideration the above hazardous effects, the WHO has prescribed 1-4 picogram (pg) TEQ/kg body weight (bw)/day (1 picogram=10-12 g) as the maximum limit of intake. A recent Dutch study reported that nursing infants typically consume about 112-118 pg/TEQ/kg bw/day, and adults typically take in only about 2.2 pg TEQ/kg/bw/day. But we do not know the quantity of daily intake of the people of Baknai, Lalpur or similar other places in Bangladesh. However, the quantity estimated based on the quantity of dioxins accumulated in air through years together and the population density of Baknai, Lalpur or Bangladesh as a whole may give a special kind of intake rate of dioxins.

However, the complexity of the issue and the deadly consequences of the causes deserve further detailed scientific investigation. Because till today Bangladesh doesn't have any well-organised set of information on the above issues. However, fortunately, Bangladesh, as a signatory and likely to be a party to the Stockholm Convention, has been implementing through Department of Environment in collaboration with Department of Agricultural Extension and Power Development Board, a project named Persistent Organic Pollutants (POPs): Bangladesh Preparations, financed by the Global Environment Facility through UNDP. Under this project, the basic activities are underway to generate a large set of good information and to prepare a national implementation plan on POPs, which, I believe, may address the dioxins and similar other POPs related issues very effectively in future, if the plan is appropriately prepared, well-organised and properly implemented.

Md Mahbubar Rahman is Professor, Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur