The use of coal and furnace oil for power generation, effluent dumping by industry and automobiles having weak engines which burn lubricants, are the major sources of lead in the air. - File photo

KARACHI Major parts of the metropolis are exposed to acute lead pollution, which poses a serious threat to the health of citizens, a research study conducted at the University of Karachi has established.

'The research has found deposits of lead in significant quantities. This is indicative of the higher levels of lead content in the air, as studies have confirmed that uptake of soil-borne lead by plants is negligible and the presence of lead in plant leaves is due to the respiration from the stomata,' said Dr Nasiruddin Khan, who supervised the research conducted by MSc final-year students of the chemistry department.

The report titled, 'Assessment of lead toxicity in air with the help of bioindicator technique', was based on the method involving collection of leave samples from peepal trees (Ficus religiosa) from different areas of the city. The leaves were later examined in the lab. According to the study, the levels of lead found in leaves at different places were Quaidabad (14.51mg/kg), Sohrab Goth (3.42mg/kg), Sharea Faisal (1.25mg/kg), Kalapul (3.63mg/kg), Malir City (2.89mg/kg), Nazimabad Post Office (9.56mg/ kg), Nazimabad main road (2.63mg/kg), Saddar (10.49mg/kg), Model Colony (2.43mg/kg) and Gurumandir (21.43mg/ kg).

'Lead is a well-known neuro-toxin and it affects all systems within the body. Its presence in the air is much more dangerous for the health of the population compared to its presence in the soil,' said Dr Khan, describing the lead deposits ranging between 1.25mg/kg and 20.64mg/kg as very high.

The highest amount of lead deposits was found in the Gurumandir sample, which was almost 10 to 20 times higher than the lead levels in the air in major cities of developed countries.

He said that automobiles having weak engines which burn lubricants, leaded fuel, and the use of coal and furnace oil for power generation were major sources of lead in the air. 'Atmospheric emissions travel long distances and have the potential of affecting even the most remote regions,' he added.

When asked why the leaves of peepal were chosen for research, he said that the tree was common in Karachi, adding that its leaves were big and remained intact with the twigs for a longer duration as compared to other trees.

The KU chemistry department had earlier conducted tests to check the presence of lead in petrol. The samples were collected from the petrol pumps owned by four reputed fuel sellers of the country. It was found that all the samples contained low levels of lead (about 1mg/Lppm). 'The companies claim that their products are lead-free. But, this is not the case. The petrol being sold in the market by these companies has low levels of lead though it is contributing to damaging public health and the environment. It has a sort of accumulative effect and cannot be ignored,' he said.

The professor said smuggled petrol was extensively used in Karachi and highlighted the need for conducting research on its quality.

Study on blood lead levels

Referring to low-level lead exposure, Dr Zafar Fatmi, head of the environmental health sciences division and community medicine residency programme director at the Aga Khan University's department of community health sciences said 'Chronic low-level exposure of a large population to environmental lead is a great public health concern.
'A high level of lead in blood (80-100µg/dl), though rare nowadays, results in encephalopathy and death, while lower chronic level (10-80µg/dl) results in neuro-toxicity, hypertension, renal impairment and altered cognitive functions.'

He said effects of lead pollution on the human body, especially children, had been discussed in a study carried out by the AKU's department of community health in collaboration with the epidemiology and international health department of the University of Alabama in 2007.

The research titled, 'Status of children's blood lead levels in Pakistan implications for research and policy', says lead in petrol has caused public exposure to lead more than any other source. It adds that children are more vulnerable to lead exposure than adults because developing brains are more sensitive to the effects of lead exposure. Children can also be exposed to lead from mothers during gestation and breast-feeding.

Some relevant studies have shown that childhood exposure to low-level lead shifts the intelligence quotient distribution of an entire population towards lower values, leading to a decrease in the overall intellectual level and productivity of that population.

In those countries where lead is still used in petrol or has been recently phased out, the impact of lead exposure could be very high, the AKU study says.

In Pakistan, environmental lead was recognised as a problem in 1988. In 2001, the government encouraged refineries to phase out lead. Currently, the permissible limit of lead in petrol is 0.02g/l.

The study says that there has been a major decline in blood lead levels from 38.2µg/dl among schoolchildren in Saddar in 1989 to 16.5µg/dl among preschool children in 2000 and 10.8µg/dl among newborns in 2005-06 in the same area with high traffic density.

Though a major decline in blood lead levels has been noted, a large population of children still has a lead level in blood above the permissible limit, the study notes. In 2002, 80.5 per cent of children in Karachi had lead in blood above the current allowable limit of 10µg/dl.

The levels of lead in blood varied widely across and within cities, which may be at least partially explained by traffic density variations.

Paints, cosmetics and effluent

According to the study, paints containing lead are still being used in Pakistan. The flakes of such paint, which come off the buildings and are consumed by minor children, contribute to higher blood lead levels in them.

Eye cosmetics, such as surma and kohl, have been found to contain high levels of lead. A lab analysis has found that the concentration of lead in different types of surma in Pakistan ranges from 0.03 per cent to as high as 81.37 per cent.

Leaded pipes and industrial waste are also apparent causes of the high concentration of lead in water.

Summary with CM

Talking to Dawn, Sindh Environment Secretary Mir Hussain Ali highlighted the need for coordinated efforts to check the problem of lead pollution.

He said, 'Different departments need to get together to address the issue. For instance the Sindh Environment Protection Agency (Sepa), under the relevant act, can take action against those responsible for emissions from vehicles, but the police are already doing the job, though, inefficiently, since they lack equipment.

'Now, we have got the equipment and the staff trained for the purpose. We have submitted a summary to the chief minister, suggesting that Sepa should be asked to check vehicles for fitness certification and on the basis of its report, the police be authorised to issue a certificate,' he added.