How carcinogenic is your CAR?

Do you want a country full of cars? Cars cause cancer. Scientists can even measure the cancer potency levels of the cars we ride. The so-called cancer potency index has emerged as an important tool for risk assessment the world over. But think twice before you buy a diesel car over a petrol car. Swedish consultants at Ecotraffic found potency levels of diesel exhaust from Indian cars to be more than twice that from petrol. A German government finds diesel cars to be even worse. Meanwhile, more evidence has emerged that diesel emission is not only cancer-causing but can also trigger serious allergies and affect the poor the most. Down To Earth presents the findings of the three studies on the subject

Published: Monday 15 May 2000

How carcinogenic is your CAR?

imageIn a study conducted for the Centre for Science and Environment, Swedish consultants Peter Ahlvik and Ake Brandberg at Ecotraffic have found that after taking into account all the toxic components in emissions the cancer potency level of diesel cars is double that of petrol cars in India. If only particulate emissions are compared from different car models then the cancerous effect of diesel particulate matter (PM) from one new diesel car is equal to that of 24 new petrol cars and 81 compressed natural gas (CNG) cars on roads. The results of this study are further supported by evidence from another study conducted by the German Federal Environment Agency (UBA). They have found diesel to be several dozen times more cancer-causing than petrol. Diesel particles alone constitute as much as 95 per cent of the cancer-causing potential of all diesel emissions, it reported. Differences in the cancer potency of vehicles can arise because of different fuel quality, engine technology and local temperatures.

Following the spate of epidemiological studies linking PM from diesel exhaust to increased lung cancer risk, the California Air Resources Board (CARB) in 1998 labelled diesel particles as ‘toxic air contaminant and probable human carcinogen’. The United States Environmental Protection Agency (US EPA) is also in the process of making a similar declaration. A recent study from the South Coast Air Quality Management District of California concluded that vehicles were responsible for approximately 90 per cent of the cancer risk in the South Coast Air Basin, but 70 per cent of the total cancer risk was attributable to diesel particulates.

Alarmed by these findings, the State and Territorial Air Pollution Programme Administrators (STAPPA) and the Association of Local Air Pollution Control Officials (ALAPCO) have sought to extend the evaluation of cancer risk from diesel particulate to other cities across the country and to estimate how many cancers nationwide are the result of exposure to diesel particulates. Their findings are no less frightening: the soot spewed by diesel engines is responsible for a shocking 125,000 cancers in the US.

What further adds to the risk from diesel fumes is their ability to trigger and exacerbate a wide range of noncancerous effects including allergy, asthma, and other respiratory problems. A summary of scientific evidence prepared by Susannah Foster for the Boston Public Health Commission and Harvard Medical School, USA, clearly shows why diesel exhaust is a cause of concern, especially for the poor. Unfortunately, the evolving science of pollution has completely eluded Indian air quality regulators. They have failed to develop precise strategies to phase in cleaner fuels and technology by taking into account these health parameters of risk assessment.

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