While it is true that the purpose of creosote on the ties is to retard decomposition, the presence of decomposer organisms does not indicate that the toxins have been fully eliminated, just that decomposition of the woody tissues has begun. If a qualified person is re-mediating a toxic site with fungi, for instance, the presence of the fungi on the toxic area does not signify that it is now safe to grow organic (non-toxic) fruits, vegetables, and herbs; it merely indicates that the process has potentially begun toward that end. The only way of telling if there are no toxins present, is with appropriate tests of the material and the surrounding soils. Making such assumptions could lead to serious health problems, from my understanding.
Another good way of telling if the creosote is still present is if the wood isn't decomposing in a situation where it otherwise would. Decomposers won't touch the stuff if it's toxic.
From what I understand, modern creosote is a petrochemical product (made from coal tar and oil tar) which dramatically increases the toxicity of something that was already bad (wood creosote is also toxic, and by the time the railways were built the superior coal product was generally used rather than the inferior wood based product). When a person paints a fence with oil or stain, some of the oils penetrate, and some is on the surface. The stuff on the surface needs to be renewed occasionally as the sun will draw some of it out and other weathering agents (oxygen, wind, rain, critters) will break the substance down or wash it away. Despite it seeming inert to our dulled senses, there are still toxins (and likely some smell) present in the inner layers of wood. Only proper testing would tell, but I doubt that creosote wood looses it's toxicity fully by just losing it's surface color. Some of it definitely wears off in time and biology always seems to have a way of making use of it in the end despite our desire to make things last. I just wouldn't ever recommend that anybody ever use railway ties, or as they are known in other places: sleepers. They are just not worth the risk.
Not sure if the old ties were treated the same way or if they are just so old that the treatment has worn off, but some of them no longer smell and are dry and grey.
Dustin Rhodes wrote:
Robert, what is the railway replacing these toxic ties with when they are damaged?? Is there another material/product, or does the railway just continue on with it as a "necessary evil"?