Blind alleys
The poisoned hearth
A study established that PCBs were posing a threat to human health in Delhi .
A DOCTORATE study submitted by Satya Prakash Saxena to the All India Institute of Medical Sciences ( aiims) 12 years ago presented evidence that highly toxic polychlorinated biphenyls ( pcbs) are present in high amounts in Delhi's environment. It recorded exceptionally high levels of these chemicals in samples of Delhi's population and in soil.
It should have immediately rung alarm bells. The entire government machinery should have been shaken, but not a leaf shook. It wasn't a case of ignorance, but of sheer carelessness about the threat to public health.
pcbs are persistent organic pollutants ( pops) - toxic chemicals that are difficult to break down into simpler, less harmful compounds by natural processes. Like other pops - dichlorodiphenyl trichloroethane ( ddt) is the best known - pcbs are highly stable. Once they get into an organism, they degrade very slowly. Since they are not very soluble in water, they can be transported by rivers over land into the sea and carried as vapour over long distances by the wind. The symptoms of pcb poisoning in humans and animals include a painful skin condition called chloracne, headaches, dizziness, fatigue, depression, sleep disorders as well as diseases of the liver and cancer (see box: Lethal cocktails ).
Saxena took a random sample from the general population not exposed to pcbs, and from occupationally exposed workers living in and around Delhi. He studied women with reproductive abnormalities like toxemia of pregnancy (where the blood of a pregnant woman becomes toxic), premature labour, spontaneous abortions (where no disease or disorder of the organs is known to have caused abortion). Tissues taken from cadavers (bodies) were also tested and high levels of pcbs found in the body fat.
The study found unusually high levels of pcbs - an average of 232 parts per billion - in the blood of workers engaged in manufacture, repair and maintenance of transformers. The level of pcb in the blood was found to be directly proportional to the duration of employment. It established that workers with high-exposure jobs like assembly, repair, packing and testing of transformers had higher levels of pcbs than workers in medium-exposure jobs (such as winding and case-making), and low-exposure jobs such as maintenance and sales.
People living close to industrial complexes had higher levels in their blood than residents in other areas. However, the difference in pcb levels found in the blood of the unexposed population was markedly lower than that found in the blood of exposed workers (see graph: Industrial disease ). Mean levels in general populations in developed countries where pcbs have been used most have ranged from 1.1 ppb to 8.3 ppb. The average of 17 ppb of pcbs found in the unexposed Delhi population was exceptionally high.
Women who had premature labour and toxemia of pregnancy showed higher pcbs levels than women with regular, full-term pregnancy. The levels in women with full-term pregnancy ranged from 6 ppb to 48 ppb, while pcbs in the blood of women in premature labour and with toxemia ranged from 8 ppb to 201 ppb. pcbs found in placental tissue and blood from umbilical cords of women undergoing normal pregnancy was in the range of 1-25 ppb and 4-28 ppb, respectively. On the other hand, women in premature labour had 14-125 ppb pcbs in placental tissue and 18-95 ppb in blood taken from umbilical cords.
pcbs in human whole milk in the sample ranged from 24 ppb to 156 ppb, a high level when compared with pcb levels found in other countries (see table: Milk of misery ).
Symptoms of pcb poisoning in occupa-tionally exposed workers studied by Saxena included muscular and joint pains, headaches, dizziness, fatigue and depression.
To his horror, Saxena found pcb s in all the 50 soil samples he took - from north, south, east and west Delhi (see graph: Dangerous distribution ). The highest levels were recorded near factories and the amount decreased with distance from the factory (see graph: Concentric concentration ). The highest concentration was in Okhla Industrial Area, measuring 9.62 ppm (9.62 mg of pcb per kg of soil).
In 1987, a young man who had just completed his PhD from the prestigious All India Institute of Medical Sciences based in New Delhi came to see me for a job in the Centre for Science and Environment (CSE). He said that he was a toxicologist and he was finding it difficult to get employment because there was little demand for toxicologists. Would an environmental NGO like CSE be interested in his services? He showed me his PhD thesis which had revealed high levels of polychlorinated biphenyls (PCBs) in the environment of Delhi. CSE, like most environmental NGOs, and I myself, were quite unaware of pollution issues, especially industrial pollution. I was also reluctant to get into pollution issues without knowing anything about them and, therefore, politely declined the offer. Ten years later, as my own consciousness about pollution issues began to grow, partly because of the extraordinary increase in air and water pollution that we have so visibly witnessed in the last decade and partly because of the two bouts of cancer I had, which could be related to pesticide exposure, I remembered the young man who had come to see me. He had said that PCBs were high in Delhi’s soils but I had not heard anybody mention anything about this. I did not even remember his name but I thought at least we could track down his PhD study and then locate the young man. And so began an interesting investigation, leading from one tale of disinterest to another — regardless of its implications for public health. Anil Agarwal, Director,Centre for Science and Environment. |
Recent tests by the Swedish Environmental Protection Agency ( sepa ) has sounded the alarm across Europe. sepa found 9 ppm pcb s in dry soil samples taken near an apartment block in Stockholm. A previous test in Sweden in 1973 had detected 15