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Lead poison along National Highway No. 1
Aditi Tandon
Tribune News Service

Chandigarh, September 9
Not all is well with the health of National Highway-1 in Punjab.
Right from Ambala to Amritsar (Wagah), the north-south highway is in the grip of toxic lead that has accumulated in roadside soil following years of enhanced exposure to motor vehicle exhaust. The use of tetraethyl lead-free fuel being a recent practice, the damage has long been done and it persists.

In the first-ever study on the problems associated with lead pollution along NH-1 passing through Punjab, soil experts from Punjab Agricultural University (PAU), Ludhiana, have made startling revelations. They have found that the soil samples taken from near the road have a much higher concentration of lead as compared to samples taken from sites located even 50 metres away from the highway. The soil sample collected from Mandi Gobindgarh has the highest concentration of toxic lead –- 38.75 mg per kg.

Not just that, plant samples (leaf tissues of wheat crops and eucalyptus tree) collected from the edges of the national highway further show that the concentration of lead is much higher than the permissible limit of 10 mg per kg. This explains why people living close to roadsides suffer serious medical problems — sterility, abortions, chronic nephritis, discolouration of lips and premature development of arteriosclerosis being major ones among them.

There are several reported cases of abortions and sterility among women living near the edges of NH-1 as it runs across Punjab. Medical experts endorse the hazards of prolonged exposure to lead. A Chandigarh-based physician, Dr Jasjit Singh, points out: “On being inhaled, lead forms small deposits in lungs. From there it gets circulated in the whole body along with blood whose oxygen enrichment takes place in the lungs. Lead exposure can be damaging, especially where the metal has stayed in the atmosphere, soil and plants for long.”

Past studies show that although lead is not readily translocated to edible portions of most plants but in areas of rapid urban expansion where farms and homes are intermixed with heavily travelled highways, like the NH-1, lead concentration in soils and plants can reach unusually high levels. Most of the lead from gasoline exhausts gets deposited along the edges of highways as soluble chlorobromide.

Lead pollution is thus of major concern due to its long persistence in soil and its possible association with disruptions in the cognitive development of children who live close to polluted areas. No wonder several countries have set limits for lead in fuels to reduce its build-up in the environment as well as the food chain.

As regards the cause of lead accumulation — the use of tetraethyl lead as an anti-knock agent in vehicle fuel has been known to cause general increase in the content of lead both in atmosphere and soil. A study conducted in 2005 in India proved that even when no tetraethyl lead was used in fuel, lead pollution still happened because traces of the heavy metal were found in unleaded gasoline. These traces made it to the atmosphere on being emitted in motor vehicle exhaust.

These findings have however been confirmed for the first time in context with NH-1 in Punjab. For the purpose of investigation, the highway was divided into two zones depending on the traffic load.

To the surprise of investigators, soil samples collected from the edges of Ludhiana-Ambala road – a heavy traffic zone – had greater concentration of lead than those taken from the Ludhiana-Amritsar road, with a comparatively lower traffic density.

An average of 53, 000 vehicles pass through NH-1 between Ludhiana and Ambala daily. The corresponding figure for NH-1 between Ludhiana and Amritsar is 42, 000 vehicles.

Sharing other findings of the study, Prof H.S. Hundal from PAU’s Department of Soils said: “As the distance from the road increased the lead concentration in soil samples decreased. We, however, did not limit the study to soil surface samples, which we took from 135 locations along the north-south highway in Punjab. We also examined leaf samples of wheat and eucalyptus.”

Vegetation samples, like soil samples, were collected from three sites — roadsides, 50 metres away from the road and 100 metres away from the road.

Lead concentration in vegetation followed the same pattern as soils. In wheat crop and eucalyptus tree lead was in higher concentration than permissible limits – dangerous for human beings who inhale lead from the atmosphere and become susceptible to respiratory disorders.

The study has, for the first time, exclusively established that lead accumulation in roadside soils and plants along NH-1 has occurred due to vehicular emission from automobiles. Industrial activity in Mandi Gobindgarh (whose soil sample has the highest lead concentration as compared to others collected from elsewhere in Punjab) has exacerbated the situation by contributing more lead to soil and plants.



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