One does read about stalking a silent killer like a man-eating Leopard and eliminating it. Jim Corbett the famous hunter of the yore killed many a man eaters by virtually stalking them. The story that unfolds today is also of a man eater of its kind, but tamed by other means.
Nature had created all the elements much before we came in to existence. Some of them are essential for our health and some are toxic. The advents of man lead to an interaction with the environment. Being on the highest echelon of evolution, his interactions over a period of time began to continuously modify the environment. For example man is the only animal that can produce fire. Naturally it affects the purity of the air we breathe in. The industrial revolution acted as a fuel to the fire and further contaminated the air. Man's interactions often lead to release of toxic elements, which would have otherwise remained wherever they were since they came in to existence.
Lead is one such element, which has been in use by the mankind for various purposes.
It was around 1920 after the automobile had been launched when lead was started to be used as an additive to the petrol to curb the knocking by the automobile engines. It was found that the vehicle exhaust is one of the worst polluter of the air and one of the root causes of lead in the air. Realizing the after effects of lead on their residents the USA stopped using lead in gasoline since 1974. By 1990 it was also observed that spurt in crime rate amongst young adults had come down by about 57%.
Lead is injurious: As per the World Health Organization (WHO) standards presence of lead in blood ≤10'g/dl is injurious. Axel Michaelowa, a German expert on Clean Development Mechanism in one of his papers (1997) said that in developing countries all children under two years and 80% of children between the ages of three and five years have levels of lead in blood exceeding the prescribed limits of the WHO and they may suffer permanent brain damage! How toxic lead can be in the blood is evident from the fact that at low levels lead impairs haem (iron) synthesis in body and psychological and neurobehavioral functions. At high levels a lead exposure can damage all organs and organ systems including the central nervous system and kidneys and blood, often leading to death. Lead in body system is also one of the main causes for abortions and damages to the fetal brain.
International efforts to curb poison in the air: Once it was realized that lead in petrol was the real culprit behind brain damage and falling health of the children various countries launched the damage control exercise. Japan was the first country to curb the use of lead in automobile fuel in 1970. Even after 26 years only 14 countries had phased out the addition of lead in petrol. By 1999 Bangladesh, China, Egypt, Haiti, Honduras, Hungary, Kuwait, Nicaragua, Malaysia and Thailand were able to phase out lead from petrol reported M. Lovei in a World Bank report.
Indian scenario: Better late than never goes the saying. In India lead was phased out in the first phase from petrol in metropolitan cities (Delhi, Mumbai, Kolkata and Chennai) from 1st April 1995 report A.K. Singh and Munendra Singh of Department of Environmental Sciences and Geology Department, respectively of Lucknow University, Lucknow in a paper published in Science Direct in June 2006. It is coincidental that around that time the growth of the country took rapid turns. There was no alternative but to curb use of lead as additive in petrol. The goal was achieved in the country by 1st April 2000.
Collecting data for a study directed towards the impact of removal of lead from petrol was quite a tough job. As already said, lead being one of the most widely distributed toxic elements in the environment can reach the human system. In their study the Singh duo had to ensure that their data is uncontaminated and unbiased. A scan of the literature took them to 14 internationally and one nationally published and acclaimed studies, which finally became the base of their research.
Armed with information about lead content of pre phase out period and post phase out period from Ganga River Water, urban air of Mumbai and Lucknow, Dalbergia sissoo tree species of Lucknow and urban children blood samples (collected from Mumbai, Chennai, Bangalore, Amritsar and Lucknow) they found what they were looking for.
Ganga River drains through one of the most populated agriculturally rich valley of Uttar Pradesh and Bihar. During the leaded petrol phase, total lead content in the River water ranged from 10-115 'g/l in 1988. Likewise water of the Indus River in Pakistan too had a concentration of lead ranging from 13-160 'g/l in 1991. The contents of a river depend upon the rate of erosion in the catchments, geology of the terrain it flows through and also upon the industrial and agricultural effluents dumped in the river along its journey to the sea.
Uluberia is a locality in the Ganga delta region and the total lead content there varied seasonally from 14 'g/l in pre-monsoon to 19 'g/l in post-monsoon period. Once lead was phased out from petrol the figures came down to 2.3 and 3.9 'g/l in the pre and post-monsoon periods respectively. It is generally presumed that atmosphere affects our systems only. It is not so. Even the river is exposed to the river and whatever is present is collected by the river too. That is why once the atmospheric lead content was lowered the river water also displayed a lower content of the poison in the delta region. It should also be noted that the lead content of the river does affect the aquatic biota and once the river meets the ocean the toxins in the water affect the marine biota too. A higher rate of erosion during monsoon increases the influx of sediments and along with them the toxins too rise.
One of the significant finds of the duo has been the impact of phase out of lead from petrol in the air of two major urban centers, viz. Lucknow and Mumbai. Based on the researches of various scientists, the Singh duo came to a conclusion that during the transition phase of leaded to unleaded petrol between 1988 and 1996 at Colaba, Deonar, Goregaon, Khar and Sion in Mumbai there was a general lowering of lead in the air. For example at Colaba it came down from 0.18 'g/m3 in 1988 to 0.11 'g/m3 in 1996.
With the withdrawal of lead from petrol, the urban air of Lucknow started showing decline in mean lead concentration from 1.6 'g/m3 in 1994 to 0.2 'g/m3 in 2001. Leaves of some trees are excellent pollution indicators. One such species Dalbergia sissoo, a tree that has been providing shade to the pedestrians since ages (alas, the wave of development has denuded Lucknow's skyline of those magnificent trees!) has shown a marked decline in the lead content in its leaves from 18.7 'g/g dry weight in 1994 to 8.3 'g/g dry weight in 2004.
They also collected data about the blood lead levels of children from Mumbai, Chennai, Bangalore, Amritsar and Lucknow. The outcome was positive; the lead content came down from 18.1 'g/dl in the leaded petrol phase to 12.1 'g/dl in the unleaded petrol phase. Though the lead content has come down, the picture is still gloomy because it is still above the permissible limits set by the WHO.
The future scenario: The study shows that sincere efforts on part of the society do pay dividends. Removal of lead from petrol has shown an improvement of air quality and also there is globally a marked improvement in terms of lead related ailments. Yet, there are multiple sources like drinking water, cosmetics, lead-glazed ceramics, industrial emissions, lead-based paints, lead-based batteries, and lead soldiered food containers through which lead can secretly enter our body. Lead is a metal that is most commonly used in our routine lives, including the insulation of electrical cables. Presence of higher levels of lead in children's blood in a growing economy like ours is a warning siren which should not be ignored. It is well established that lead in the minds of youngsters turns them criminals. We don't want our future to turn to crime. We don't want lead. Let's curb the use, find alternatives and do away with lead.