• Question: is lead poisonous? if yes, then why? :)

    Asked by aammyy to Donna, Jo, Mark, Stuart, timcraggs on 14 Jun 2010 in Categories: .
    • Photo: Mark Lancaster

      Mark Lancaster answered on 13 Jun 2010:

      Yes – it is relatively recently that this came to be known e.g. there were lead additives in paints and in petrol until the 1950s/60s which in hindsight probably lowered life expectancy and the Romans made their water pipes from lead and there is a school of thought that thinks lead poisoning contributed to the fall of the Roman Empire. If you ingest lead then inside your body it will undergo chemical reactions with proteins and will replace the useful zinc, calcium and iron in the protein molecules with lead – the protein molecules then don’t work properly (since their shape has changed by the lead) and then you start to suffer since proteins (this is where I’m out of my knowledge zone – I can blag chemistry but not biology !) control many behind the scenes bodily functions : sperm production, regulation of blood pressure, electrical signalling to the brain – so as soon as these starting going wonky you’re in trouble…

    • Photo: Joanna Buckley

      Joanna Buckley answered on 13 Jun 2010:

      Hurrah, a chemistry question. Nice one, aammyy, keep them coming!

      Yes, lead is poisonous. You wouldn’t want to go around touching things containing lead because lead poisoning causes some pretty nasty symptoms. In order of least-fatal first, the symptoms of lead poisoning are headaches, weakness, vomiting, infertility, kidney failiure, fits, brain damage and death. My parents recently bought my boyfriend a couple of old model buses which are made of white metal. Nowadays, kids toys aren’t made of things which can potentially kill you so we don’t have to worry but we always have to make sure we wash our hands really well when we touch them. (Well I say that but some toys had to be recalled in 2007 because lead paint was used but that was a very rare case).

      Put simply, lead is a poison because it can interact really easily with processes, functions and chemicals in our bodies. We’re made of loads of different metals – calcium, magnesium, phosphorous, potassium, sulphur etc etc and lead can basically replace these very important metals in our bodies. By replacing other metals, it affects the proteins and changes their shape which causes certain genes to turn on and off. This is not good. The proteins known to be affected by lead are at the core of all those nasty symptoms which is why you get those in particular.

      If you are unlucky enough to get lead poisoning you can be treated for it. Chemists have developed big chemical sponges which surround the lead and make it safe. These are called chelating agents. Chelate means claw in greek (or possibly latin, I can’t remember) and these large chemicals clamp onto the lead, like the claws of a crab, and makes them inert or unreactive. You can then excrete them (I hate the word excrete, but it sounds a lot better than the alternative).

      There’s a common misconception that you should never drink water from the hot tap. I worked with someone once who went crazy when he saw me fill the kettle with water from the hot tap. I think this comes from the fact that a very VERY long time ago, water pipes were made from lead and the hot water surging through them dissolved a bit of the lead, making that water toxic. I told him this and he walked away, looking a bit embarrassed.

    • Photo: Donna MacCallum

      Donna MacCallum answered on 14 Jun 2010:

      Lead is a very poisonous metal. In the human body we produce proteins called enzmyes that are responsible for carrying out all the reactions that allow us to produce energy from food to live, to breakdown toxic things in the body and to produce new cells and tissues. Most of these enzmyes contain metal ions that help them to work properly. Lead can actually replace the normal metal ion in these enzymes, preventing them from working properly. Another essential system that is affected by lead is the production and function of haemoglobin (i.e. the red blood cells don’t work properly) – this leads to the poisoned person feeling very tired all the time.

    • Photo: Tim Craggs

      Tim Craggs answered on 14 Jun 2010:

      Lead IS poisonous.

      It is poisonous because it can take the place of (displace) other metals which are essential for the way some biological processes work. So for example, some of the proteins that are known to be affected by lead regulate blood pressure (which can cause development delays in children and high blood pressure in adults), heme production (which can lead to anemia), and sperm production (possibly implicating lead in infertility). Lead displaces calcium in the reactions that transmit electrical impulses in the brain, which is another way of saying it diminishes your ability to think or recall information, or makes you stupid.

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