The Environment Agency (EA) is investigating the dumping of 23 barrels of polymer resin.
Erewash and Broxtowe borough councils removed the drums and stored them at their depots despite not knowing the contents and possible dangers involved.
The EA has now confirmed that the substance in the metal containers dumped at Trent Lock in Derbyshire and Cossal in Nottinghamshire is not harmful to public health.
It has been identified as a polymer resin, which is often used in wood adhesives, surface coatings and to strengthen paper tissues.
EA environment officer Paul Reeves said: “This type of substance is not seen to be harmful to human health, and we have carried out checks in the local areas and watercourses to see if we need to take any further action to remedy environmental effects.
“Waste crime is a scourge that we have to crack down on. It can affect any neighbourhood, anywhere, and individuals or businesses that allow somebody else to dispose of their waste must take their share of the responsibility.
“We were lucky this time as the incident was reported quickly and drums made safe, meaning that any danger they posed was minimised.
“Businesses, councils and householders must make sure they know where their waste is being taken so it doesn’t end up in the hands of illegal operators.”
Meanwhile, the Environmental Services Association and the Chartered Institution of Wastes Management have launched a waste crime and duty of care awareness campaign.
The first phase of the ’Right Waste, Right Place’ project, funded by the EA, will be targeted at small and medium-sized firms.