Recycling organic resources to land: risk assessment for organic chemicals
Taylor, M.J., Newell-Price, J.P. and Chambers, B.J., ADAS, UK
(free)
The recycling of organic resources to land is the best practicable environmental option in most circumstances, completing natural nutrient and carbon cycles. However, organic resources, as well as conferring benefits to the receiving soil, must not cause harm to either the receiving land or the wider environment (i.e. soil, water and air quality, or human health). The risks posed by nutrient enrichment have been well documented and researched, and ongoing work is assessing the long-term risks associated with heavy metal loading rates. As a result, legislation governing the recycling of organic resources to land is aimed at limiting the impact of nutrients and heavy metal loadings.
In contrast to nutrients and heavy metals, there are no guideline or limit values controlling Organic Compound Contaminant (OCC) loading rates to land. However, the 3rd draft revision of the EU Sludge Directive (April 2000) contained proposed standards for Polychlorinated Biphenyls (PCBs), Polycyclic Aromatic Hydrocarbons (PAHs), Di(2-ethylhexyl)phthalate (DEHP), Dioxins and Furans etc. As a result, it is likely that OCCs will receive further attention and that limit values may be put in place, which organic resources will have to meet, in order for them to be considered ‘suitable’ for recycling to land.
The most robust way to establish if the levels of OCCs in organic resources are potentially damaging to either the environment or human health, is through Risk Assessment, using the EU “Technical Guidance Document on Risk Assessment in Support of Commission Directive 93/67/EEC on Risk Assessment for New Notified Substances”. This paper will demonstrate how the generic EU Risk Assessment methodology can be used to assess the risks posed by OCCs (as well as nutrients and heavy metals) to the environment and human health, as a result of the recycling of organic resources to land.
