Spatial biomonitoring of persistent organic pollutants in Iran: a study using locally produced butter

Abstract

Butter is a readily collected, integrative and inexpensive sampling matrix for the spatial mapping of persistent organic pollutants (POPs) at the national or regional scale. As air-plant-animal transfers generally supply the POPs reaching butter lipid, this study used butter for an initial evaluation of the occurrence, levels and distribution of POPs (selected organochlorine pesticides and PCBs) in Iran, a country for which very little information on usage, emissions and environmental burdens of these compounds exists. Fifty samples from rural and urban areas, in the north, west and central regions of the country were collected from local farms in spring 2007. Concentrations of p,p′-DDT and p,p′-DDE varied widely by a factor of ∼1000 and ∼370 (8450 pg g⁻¹lipid and 46 800 pg g⁻¹lipid on average). The highest levels, found mainly in urban areas in the centre of the country, were amongst the highest reported in the world. PCB concentrations (4320 pg g⁻¹lipid on average) varied by a factor of ∼160 and were highest close to urban centres and lowest in the rural northwest. Although Iran is not known for widespread PCB usage in the past, concentrations were higher than a ‘global average’ reported in a butter survey in 2001. This simple sampling approach could be adopted in other regions where cows graze, as part of an initial screening to help meet obligations under the Stockholm Convention.