Ok before I start I must say I do not speak with authority on this subject but somebody on my blog has asked the question. So here goes;
Toxic / hazardous waste comes in many shapes and sizes but generally speaking it is a substance that is poisonous and harmful to peoples health.
For many years and even today you will always have a by product produced from various sources such as industry / hospitals / agriculture or even in some cases domestic.
If you look on Wikipedia a frightening view is of a picture showing a valley in Kentucy USA which contains thousands of barrels containing harmful waste.
In life we are exposed to products which are also harmful such as paint, white spirit, engine oils, pesticides and contaminated items such as syringes when working in a clinical environment or clearing general waste. As individuals most people know how to deal with these items safely.
Working with toxic / hazardous waste is highly regulated any clearance company would be foolish to think it is ok to carry this type of waste and not dispose of it correctly.
Profit can be made but the expense to cover all eventualities such as insurance and correct transportation usually means it is only big companies that take on this role of disposal. Toxic or hazardous waste is usually kept in containment silos or incinerated and with some contained within a landfill site.
Be aware penalties are harsh for those that transgress in this area - fines and prison are possibilities for those who dont do things properly. Final note as a small clearance company I would not entertain carrying toxic waste knowingly.
Remember the most common one is Asbestos - widely produced in open caste mines throughout the world in the 30's 40's 50's it still has long reaching implications to carry it illegally. Many things were made of asbestos so keep an eye out for shed/garage roofs, pipework, fences, roof tiles and insulation.
If in doubt leave it out as the old saying goes.