Intervale temporarily suspends sale of compost

The Chittenden Solid Waste District is temporarily suspending sales of compost products from its subsidiary, Intervale Compost Products (ICP), located on Intervale Road in Burlington. Low levels of a substance known as benzo(a)pyrene (BaP) have been found in the compost. While this substance is pervasive throughout the Burlington area, there are no State or Federal standards for its presence in compost. Sales have been suspended as a precautionary measure while the State and CSWD determine whether or not there is cause for concern. Intervale Compost Products is still accepting compostable material during regular business hours.One of a family of compounds known as polycyclic aromatic hydrocarbons (PAH), BaP is a carcinogen and has been traced to none other than the leaves and yard trimmings brought to the Intervale and to CSWD Drop-Off Centers by residents and businesses in the area. PAHs are formed during the incomplete combustion of gas, diesel fuel, coal, oil, wood, and other organic substances, including tobacco and grilled foods. As airborne compounds, PAHs cling to the waxy surface of leaves, and are "inhaled" by leaves as well, building up within them over time. Those leaves fall to the ground and are brought to a central location. The organisms that break those leaves down into compost inadvertently add to the problem because they prefer to consume the organic parts and leave most of the PAHs. This further concentrates them. PAHs do eventually break down in active soil.BaP is present at varying levels in compost and topsoil throughout Vermont and the U.S. CSWD is consulting with Will Brinton, of Woods End Laboratories in Mount Vernon, Maine, who will look into whether the levels of PAHs found in Intervale compost products constitutes a risk to human health. Brinton, a national expert on compost analysis, has tested compost around the U.S. and found that all samples contained detectable levels of PAHs."While I personally believe that the compost products are safe and pose no significant risk to the public, we are temporarily suspending sales of all ICP products until we can better understand the situation," stated CSWD General Manager Tom Moreau. "Understanding the impact on human health requires the development of risk assessment scenarios that have not yet been done in regard to the presence of PAHs in compost.""The challenge is to determine what is a truly acceptable risk," noted Moreau. "Right now, different states have widely varying guidelines. ICP is serving as the canary in the coal mine to signal that we need to focus our attention on better understanding where we need to be on this." It appears that the adjacent states of Massachusetts and New York have acceptable levels far higher than Vermont's for PAHs and BaP for soil remediation projects. The ICP compost can easily meet those guidelines. The issue came to light when a private contractor, who tested ICP topsoil and compost for possible use in remediation projects, found levels of arsenic and BaP that exceeded state guidelines. These results were made available to CSWD in early December 2008.CSWD immediately ran tests that confirmed the presence of PAHs. CSWD is awaiting the results of further tests and is working with the State of Vermont as well as looking into how other states and provinces are regulating these compounds in soils or composts.
Source: CSWD Newsletter