Is it safe to grow veggies in Styrofoam boxes?

I know that many gardeners around Australia and possibly elsewhere in the world, grow vegetables in Styrofoam boxes especially if they are renting or don't have a lot of space to put in larger gardens. We recently saw a couple of episodes on the ABC's Gardening Australia where the boxes were made into self-watering containers. As it is very dry here in SE Queensland at the moment and we are always on the look-out for any gardening methods that will save us water, we bought some broccoli boxes from a local greengrocer to give it a try.

We were quite interested to see on  Gardening Australia recently that a young couple living in rental accommodation were growing heaps of vegetables in Styrofoam broccoli boxes. The programme was called A Small Kingdom. In an episode later on in the year, Jerry Coleby-Williams showed viewers how to make a self-watering container also using a broccoli box.

My husband, being a tad deaf, thought that Jerry said you could use either gravel or Styrofoam (he really said pearlite) in the base of the Styrofoam box so had a scout around the back yard for old Styrofoam boxes and I was given the job of breaking them into pieces to put in the base. However, I got tired of doing that so finished off filling the water reservoir section with some of the leftover cypress chips from our watersaver garden.

A hose had already been placed in the bottom of the box to deliver water as needed once the box had been set up.

A drainage hole was cut into the side and then water was added to the base and filled until it reached the drainage hole.

As this was purely an experiment with different materials, the gardening CEO decided to then cover the base with weedmat whereas Jerry used shadecloth to hold the soil. Then the homemade potting mix was added. I had some beetroot seedlings which really needed to be planted out and, although they probably aren't the best plants to use in this system which is ideal for leafy vegetables,we wanted to see how they would cope with the extreme heat during the forecast heatwave.

So just before the heat hit I planted a few beetroot seedlings last Thursday the 2nd January...




and they survived the record breaking heat during Saturday when it nearly reached 40 degrees here. I took this photo yesterday, 7th January, and they still looked quite healthy.

The CEO decided then that he would make another large watersaver garden as someone had offered him the base and that he would use Styrofoam pieces in the water reservoir which would make it cheaper than buying more cypress woodchips so he has been collecting more Styrofoam. I told him that Jerry had said Pearlite on the show not Styrofoam so he said to check it out so I clarified that issue after watching the Gardening Australia programme again.

While still on the computer, I thought I would do some searches to see what other people used in their water reservoir if they were using the same type of boxes and suddenly I remembered that it is always a 'no no' to drink hot drinks out of Styrofoam cups so started searching about whether it was actually safe to grow food in this product at all.

Firstly, I read on the ABC message board that it was probably safe to use it.  Then a search on the safety of Styrofoam came up with a search result which linked to the US breast cancer website which was a bit unsettling to say the least although there was some good information about plastics as well.

This website was a bit confusing as it sounded like it was okay to use it for growing plants but then someone in the comments section says it is definitely not safe to use when growing vegetables. Then the CrossRoads website says this:

 Styrene is classified as a possible human carcinogen by the EPA and by the International Agency for Research on Cancer (IARC). 
 

I would rather err on the side of caution but was wondering if anyone reading this has looked into the safety of growing food in Styrofoam boxes. I know you can't believe everything you read on the internet but I wouldn't even know where to go to find out the real facts.

Can any of my readers enlighten me or am I just being paranoid? :-)

16/4/14 If you would like to read more about this issue there is an updated post here.