Recent regulatory drivers in many countries around the world are aimed at removing, or at least reducing, the disposal of waste materials to landfill. The recycling of suitable waste materials based on application to land for nutrient value or in construction, can potentially offer a sustainable alternative to landfill.

Nevertheless, this recycling of waste materials may also present potential environmental and human health risks due to the chemicals present. The development of scenarios of use for these materials enables chemical exposures to be estimated and verified through the use of field measurements. Predicted No Effect Concentrations (PNECs) in sediments, waters and soils can be developed to provide an assessment of potential risks, from direct toxicity or secondary poisoning.

Furthermore, risks to humans need to be assessed to ensure adequate protection during application of the materials and to assess dietary exposure for chemicals in materials applied to agricultural land that may be taken up by plants or be transferred to meat, dairy produce and eggs. Modelling of intake by sensitive groups such as infants is undertaken to ensure than exposure is below standard safe levels such as TDIs (tolerable daily intakes).

Examples of project areas:

• Use of solid waste in development and construction, e.g. use of ash and aggregate in road construction
• Chemical prioritisation and screening risk assessment of application of sewage sludges, composts and green wastes to land
• Assessment of potential risks from the use of waste waters as irrigation waters on broadscale agriculture.
• Assessment of potential environmental risks of specific organic materials from food processing, incineration and industrial processes to land.