Diesel exhaust fumes ‘definitely’ cause cancer – should we be worried?.

On Friday 15th January 2016, I spend nearly one hour at the GPO bus Stop in the Central Business district (CBD) Nairobi. It is part of my annual ritual to use public transport at least once to-and from CBD.

I felt chocked and suffocated by the thick black smoke from the many buses that were stationery for nearly 10 minutes each with the engines running as they waited to fill up with passengers. I then recalled that diesel engine fumes cause human cancer.

I believe as a country we should worry given that large number of diesel engine vehicles that might not be well maintained and spew lots of carcinogen

In June 2012 Experts at the World Health Organization (WHO) concluded that diesel engine exhaust fumes can cause cancer in humans.

They said they belong in the same potentially deadly category as asbestos, arsenic and mustard gas.

The International Agency for Research on Cancer (IARC) – part of the World Health Organization – announced that it had reclassified diesel exhaust as a ‘definite carcinogen’ – putting it in its highest category (Category 1).

In other words, IARC’s expert panel assessed all the available scientific evidence and decided that exposure to diesel exhaust fumes can, and does, cause cancer in humans – specifically lung cancer (although there’s weak evidence they’re also linked to bladder cancer).

But what does this mean in practice? Is this something the general public should be worried about?

How do diesel exhaust fumes cause cancer?

When diesel burns inside an engine it releases two potentially cancer-causing things: microscopic soot particles, and chemicals called ‘polycyclic aromatic hydrocarbons’, or PAHs. According to Phillips, there are three possible ways these can cause cancer:

“Firstly, inhaled PAHs could directly damage the DNA in the cells of our lungs – leading to cancer.

“Secondly, the soot particles can get lodged deep inside the lungs, causing long-term inflammation, and thirdly this can increase the rate at which cells divide. So if any nearby lung cells pick up random mutations, this inflammation could, theoretically, make them more likely to grow and spread.

“Diesel exhaust may be carcinogenic by a combination of these effects – we know the particles are coated with the PAHs, delivering them deep into the lungs where they get stuck and, potentially, cause damage. I should stress, though, that we don’t know for certain which of these mechanisms is most important in practice.”