A recent study lists Styrene as a possible carcinogen. This is important news since one of Eco Brooklyn’s green roof medium providers, Gaia Soil, has polystyrene as one of its main ingredients. Our concern is that we are installing green roofs in New York with materials that may cause cancer.

Years ago when Eco Brooklyn first started using Gaia Soil in our NY green roof installations I discussed the issue of using polystyrene at length with Paul and he dispelled my concerns. But plastic is plastic and so I wanted to revisit the issue. So I contacted Gaia Soil director Paul Mankiewicz to get his thoughts.

Here is his answer:

well, these people have been saying this a while, and it never seems to hold up to any real research.

without being one-sided, let me say that I see no way styrofoam could cause cancer since it it a polymer, that is, many molecules joined together, so there is no known way that it can impact a specific biochemical pathway to cause a change in cell division behavior, what cancer is based on.

the argument could be made that styrene, the molecule polystyrene is made of, causes cancer.
Since styrene is a basis component of wood, you would have to look at a large number of kinds of potential contacts to see where the styrene might be coming from, since wood is also on our floors, etc.

I have no great love of polystyrene, styrofoam, but everything I have looked at indicates that it is all too plentiful, and considered to be safe to be in contact with food and drink.

When I have seen actual numbers for free styrene from styrofoam, I recall it being in the parts per trillion, – as one researcher put it years back, much much less than the free styrene you get from shuffling your feet on a wooden floor.

and while I don’t cook with it and expect I never will, styrene is a certified food additive, as in the attached PDF Document.
Styrene is also quite amenable to microbial attack, and so is metabolized/broken down by the bacteria in soils.

many thanks for this though, always best to keep checking

The attached PDF Document Paul mentions lists a lot of useful info. The main points are:

  • We produce and throw away MANY THOUSANDS of pounds of Polystyrene a year, which is saying a lot since the stuff is so damn light.
  • Styrene administered to animals has shown conclusive negative health effects. For humans the results are less conclusive.
  • The amounts given to animals were much much greater than anything a green roof could possibly produce.

From what I gather Paul’s conclusion is:

  • We need to deal with Polystyrene waste.
  • It performs several useful functions in green roof medium.
  • It does not pose a significant health risk beyond say wood dust.

As a side note, carpenters do have a higher rate of lung cancer than the normal population, but not as high as drivers exposed to diesel fumes….cancer is everywhere. Just google it for an endless stream of cancer related information.

My conclusion to the Styrofoam in green roof medium is still undecided. I would use Gaia Soil again. I think it is a useful reuse of what is otherwise garbage on its way to some land fill (somewhere else where other people have to deal with it and I can forget about it and pretend it is not my problem).

I do think the levels are low enough to not be an issue. I suspect the NY smog is probably more of an issue to my lungs.

I think the bigger issue is the consumption of Styrene in the first place. I know for a fact that the polystyrene plastic cups in my cupboard are letting off more VOC’s than the already off-gassed polystyrene on my green roof. I did a smell test and the results were obvious.

I inherited the cups from a school picnic and I’m not quite sure what to do with them. Do I throw them out unused? Do I use them? I’ll probably throw them out unused as toxic garbage.

We all need to stop buying polystyrene. Builders need to stop using it in housing, boats and the many other uses it has. If we stop consuming it then they will stop making it. And we will have less polystyrene trash to deal with.