Estimated Daily Doses (EDDs) of PAH by Exposure Pathway Using the modeled and literature-derived food concentrations, the estimated daily dose (EDD) in g/kg body weight of contaminant impinging on children, according to year class (age 2 to 5), sex (girls or boys) and site (as per households above), was calculated using standard equations from Health Canada (1995) and food intake rates from a study of children 2-5 years old in South Africa (Labadorios 2000). Separation by sex was done to account for differences in body weights, activities and dietary patterns. Since previous studies have shown that substantial amounts of purchased foods in Kampala are locally grown, that is, they are products of urban agriculture, the dietary assessments for the children did not differentiate between home-grown or purchased items (CIAT 2004; Maxwell 1995; SIUPA 20031 ). The EDDs for each food class were calculated as the product of intake rates and food PAH concentrations, normalized for weight in kilograms.
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SIUPA was renamed Urban Harvest in 2003 ESTIMATING CHILDREN’S EXPOSURE TO ORGANIC CHEMICAL CONTAMINANTS
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Food concentrations Types of foods considered were based on a nutritional intake study of children 2-5 years old in South Africa (Labadorios 2000), grouped according to the categories of the Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities by the U.S. EPA (1998). For raw food concentrations, vegetation such as matoke (banana), cassava, parsley, millet and cocoyams were assumed to accumulate contaminants through atmospheric deposition of particle-phase and gas-phase contaminants and root uptake (U.S. EPA 1998). Each mechanism has different importance for different classes of vegetation, foods, contaminants and environments. The vegetation classes used in the MUM-FAMrisk model include: belowground vegetation (root vegetables), aboveground vegetation, cereals and grains, forage and silage, fruits and juices, nuts and seeds and vegetable oils and fats (Jones-Otazo 2004). The vegetation in each class was further categorized as either protected or exposed. It was categorized as protected if the edible portion is not exposed to the atmosphere. For example, millet was classified as protected vegetation as the grain is enclosed in a husk and thus not exposed to atmosphere. Millet PAH concentrations were modeled using soil concentrations derived from samples taken from households based on the assumption that the only mechanism of contaminant accumulation is through root uptake. Vegetation was classified as exposed when the edible portion of the plant is open to atmospheric deposition (Jones-Otazo 2004). Exposed vegetation concentrations were modeled using air and soil concentrations based on the assumption that contaminant accumulation occurs both by atmospheric deposition and root uptake. Based on these, modeled food tissue concentrations (wet weight) were calculated for each vegetation class. Ranges for modeled data concentrations of all three PAH for all food items were between 0.0-33 ng/g wet weight. This is slightly less than those found in other studies, e.g. 1-120 ng/ g wet weight in Wennrich et al. (2002), which could be due to the higher rates of photodegradation of PAH in Ugandan soils. PAH concentrations in other food classes such as beef, fish and dairy were taken from the literature.