Benzene is the simplest aromatic chemical (called "aromatic" due to its sweet smell). It has six carbon atoms and six hydrogen atoms in a ring. It is a flammable liquid used to make many chemicals that, in turn, go into common consumer products like plastics, rubber, nylon, dyes, detergents, drugs, synthetic fibres, and pesticides. It is used as a solvent in paints, varnishes and lacquer thinners. Due to its versatility, benzene is shipped in very large quantities as a pure chemical as well as in mixtures.
How it is shipped?
Benzene boils at 80ºC, so it is typically carried at unpressurised at room temperature in tank ships and tank barges.
Why should we care ?
Benzene is very common. It is also very dangerous.
For example :
Shipping concerns
Benzene vapour may be released during normal cargo venting and transfer operations and during tank cleaning. As it is heavier than air, the vapour can accumulate on the deck, possibly in concentrations high enough to be damaging or even fatal.
Health concerns
How much benzene is "bad"? The official exposure level to avoid is more than 0.5ppm (parts per million). That amount can be in the air you breathe every day at work (for up to a 30- year career) and not get sick.
It is a little hard to understand a number like 0.5ppm. Think of it like this: you travel over 4,800km on land across Australia from Cairns, Queensland to Perth, Western Australia or in America from New York to Los Angeles. Of this distance, 0.5ppm is about 2.3 metres. That is a very small fraction, which is the point.
A little benzene can do a lot of harm. That said, you can tolerate more during a one-time accidental exposure, the level that is immediately dangerous to life and health is 500ppm.
Benzene is a dangerous chemical, but years ago people did not know this. At one time it was a standard practice for workers to wash grease and oil off their hands with benzene. And because no one really knew how bad it was, current regulations were not in effect, and marine inspectors commonly entered cargo tanks that had held benzene without respirators.
Dealing simply and seriously with the matter
Simply speaking, benzene is a chemical with a license to kill.
Benzene safety depends on all involved: the safety rules can be inconvenient; however it is essential. Many marine workers have died from leukaemia and other diseases linked to benzene exposure.
Prevention methods:
Said Lamey Tawfik
