Shipping Container Housing: Are the Floors Toxic?
by Lloyd Alter, Toronto 
on 04.26.07
When we wrote about the LOT-EK building of containers for New York City we received a comment from Marino Kulas of Conforce International, noting that "over 10 million tropical hardwood trees are cut down every year in order to make container floors. These are trees that take 40-60+ years to mature.Having said this, wood is also a less then perfect raw material due to its inherent natural characteristics when it comes to this application." (Conforce makes a wood-free substitute for floors)
My dad was in the container business, and I once asked him if I could have some container flooring material for use as kitchen counters. He laughed and said that container floors are treated with serious insecticides and fungicides to keep alien bugs out of Australia. As container housing becomes such a popular trend, I have wondered if the floors were still treated and asked Marino Kulas, the President of Conforce, if this was still the case; he confirmed that it is. (recent Australian requirements in big PDF here)
According to "Studies on the sorption of organochlorine insecticides by flour stored on or near treated laminated timber or plywood as used in freight containers", Wood preservatives containing a number of organochlorine insecticides, including aldrin, dieldrin, chlordane and lindane, have been approved in Australia for treating timber used as structural components in cargo containers"
All containers are treated for Australian standards because it is impossible to separate them out of the pool for a single country. The study quoted above (of which we can only read the abstract) determined that there was transfer of the insecticides to the products sitting on the floors.
"The highest insecticide residue levels were found in flour samples stored on newly treated laminated sawn timber. Physical pick-up of insecticide from the surface of the floor was considered to be the major source of contamination. Sorption of insecticides from the atmosphere of the container was the most likely source of contamination in samples stored on or near treated plywood."
So for all of those architects working with old shipping containers, check if those floors are toxic. And given the amount of hardwood being chopped to make new containers that are shipped one way from China, perhaps we need a deposit system for these as well so that they go back and get reused instead of stacking up over here. ::Conforce
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If this is an unsolvable problem, there are other uses for containters. Yank out the flooring and use the metal part of the containers to build artificial reefs!
This is an unfortunate side affect of recycling many products. We are often inheriting other peoples problems when we recycle. For example, I've been seeing recycled rail ties used in design lately. But they contain dangerous preservatives.
Excellent, informative post.
Could anyone answer why the floors aren't metal like the rest of the container?
LA: The point loads of a forklift are high and metal thick enough to survive it without bending and denting would be much heavier than the wood. The walls are strong because they are corrugated but you cannot do that to a floor.
This is a completely un-necessary exposure. Aldrin, dieldrin, chlordane heptachlor and the like have been either completely banned or very highly restricted in their registered uses the US since about 1987. See this fact sheet for details.http://www.epa.gov/safewater/contaminants/dw_contamfs/chlordan.html
Possibly some of the containers in use were made before 1987? Or, perhaps the patents on these insecticides are expired (Velsicol was the original maker of several of them) and some offshore outfit that only cares about low cost is still making these. Regardless, there are most definitely better ways to keep out hitchhiking insects, to preserve wood, and reduce migration of treating agents into container-stored products.
A recycled HDPE floor pan would be an easy start for exposure reduction on existing models. For new containers, steel flooring with an abrasion or dent resistant resistant HDPE skid base might work. This is not rocket science: just basic design changes would be needed. The question is, where are they being manufactured? Is this like the melamine contamination of food protein supplements, where no one cares until a health crisis looms?
It sounds like the wood is being used because it can be flat(to make a good floor) and still be strong, and light enough, for the application. HDPE is not as light/strong as wood.
Also, these containers would make terrible artificial reefs. They have too much surface area and too little weight to avoid being swept around by waves/tides/currents. Also, the don't provide enough small surface complexity to allow little critters to hide from big ones.
Loyd - good reporting here.
But could you please respond to my earlier q's regarding the LOT-EK NYC building - I'm in doubt as to whether those containers are recycled, yes or no? If not, then this issue shouldn't be of any greater concern to them than proper phonics, ha!
And if not recycled and not continually transported, why bother with the confines of existing container shape and size(or why bother at all). Like all matters discussed on these pages, there is a lot more at play here than appears obvious.
Would they be harmful if encapsulated? I would think that any use for housing would involve either covering them with another material or with a sealer. It seems the danger would be if they were sanded causing the dust and chemicals to become airborne. If someone else has more knowledge on this, please respond as to why this would not be a satisfactory solution or what would be.
This subject was of great interest to me so I have spent several hours researching it. I may be wrong, but it appears this is misinformation.
First of all the Austrailian document referenced is out of date, those were the standards issued in September 2003 and the current ones are at http://www.daffa.gov.au/__data/assets/word_doc/113037/cargo.doc dated 15 November 2006. However, I searched the ones from 1 September 2003 and I couldn't find any of those chemicals listed anywhere there either.
Is it possible that some of those chemicals have been used in the manufactuer and treatment of containers? I assume it is but I don't believe it is a practice dictated by the Australians--if it is one at all.
There is no question that container floors are treated to prevent infestations of critters that the rest of the world doesn't want and I wouldn't want want to be ingesting those chemicals whether they are considered safe or not. But unless you are sanding the floors and making those potential chemicals airborne, how are you at risk? Container floors are going to be covered or sealed in all housing applications.
This subject was of great interest to me so I have spent several hours researching it. I may be wrong, but it appears this is misinformation.
First of all the Austrailian document referenced is out of date, those were the standards issued in September 2003 and the current ones are at http://www.daffa.gov.au/__data/assets/word_doc/113037/cargo.doc dated 15 November 2006. However, I searched the ones from 1 September 2003 and I couldn't find any of those chemicals listed anywhere there either.
Is it possible that some of those chemicals have been used in the manufactuer and treatment of containers? I assume it is but I don't believe it is a practice dictated by the Australians--if it is one at all.
There is no question that container floors are treated to prevent infestations of critters that the rest of the world doesn't want and I wouldn't want want to be ingesting those chemicals whether they are considered safe or not. But unless you are sanding the floors and making those potential chemicals airborne, how are you at risk? Container floors are going to be covered or sealed in all housing applications.
Marino Kulos, mentioned in the article, is the founder of Conforce International and the developer of a new product called "eko-flor". This product is made of composite materials and has been accepted by the container industry. It does not use apitong wood, or any other wood for that matter, so the need for insecticides are negated. It also is very strong and lasts a lot longer. This could become an industry standard. You can see it at www.conforce1.com
It could be worthwhile investigating the characteristics of food grade containers. Many food exporters would not tolerate contamination of the level discussed here, particularly for organic products. Note that not all food containers are refrigerated!
My company has developed an eco friendly flooring for shipping containers using the pulp of senile coconut palms that otherwise are burned on the plantations.
The process we use brings about a strong substitute for traditional hardwood plywood that goes into existing containers.
We are trialling now and hope to be into the global market later this year..2009.
No longer does the shipping industry need to harvest our hardwood forests.