Following the cleaning of the bottles, a waste sludge is produced that Coca-Cola have been disposing of on the land of local farmers, claiming it was a useful fertilizer. Following a BBC Radio 4 program, samples of the sludge were analyzed by scientists at Exeter University in the south-west of England and found to contain toxic chemicals including lead and cadmium - both of which can be harmful to humans - and further suggested that there was little or no benefit of the sludge as a fertilizer. Recent tests by the local state laboratories find that the levels of toxic chemicals are within safety levels but that it should not be used as a fertilizer.