P-627 Abstract: Soil ingestion may contribute to a large extent to the exposure to soil-borne pollutants, especially for children because of their strong mouthing behavior. Likewise, adults involved in activities that entail soil contact, such as gardening or burying, may ingest considerable amounts of soil. Soil ingestion can be estimated when soil hand loading, hand surface, frequency of hand-mouth contacts and the amount of adhering soil that is taken up during hand-mouth contact are known. Estimates exist for all these parameters in literature, but they are prone to a large amount of uncertainty. For the current calculations we based ourselves on field measurement data of soil hand loading for children indoors and outdoors, and adults involved in various activities, including gardening, rugby playing and construction works (Holmes et al., Env. Res. 80, 148–157, 1999). Age matched hand surfaces were derived from US-EPA. Assumptions with regard to mouthing behavior in young children (1–6 years) decreased with age, had a age-related most likely value (triangular distribution), and were based on video data published by AuYeung et al. (abstract book 13th Annual Conference of the International Society of Exposure Assessment, Stresa, Italy, 2003, p. 428). For adults a frequency between 0 and 3 was assumed (uniform distribution). Because no theory is available to estimate the amount of adhering soil that is taken up during hand-mouth contact, a uniform distribution between 10 and 60% for children and 0 and 30% for adults was adopted. Based on the above mentioned assumptions, probability density functions were assigned to the different parameters and Monte Carlo simulations were ran (5000 iterations). In this fashion estimates were obtained that ranged for children between (2,89 ± 7,69) mg/h (mean ± 95th percentile) and (14,49 ± 26,14) mg/h for an indoor and outdoor scenario, respectively. One subset of children that were studied and played both indoor and outdoor had a mean ingestion rate of 91,33 mg/h. For adults the hourly ingestion rates were (3,56 ± 7,39), (2,85 ± 6,59) and (6,91 ± 21,74) mg/h for gardeners, archaeologists and construction workers, respectively. Although the estimates for some subsets of outdoor children seemed rather high, in general, no major deviations were found when these data are compared to ingestion rates obtained from tracer studies. In addition, estimates of hourly ingestion rates allow the risk assessor to predict exposure to soil-borne pollutants for a given activity, and environment and duration, more accurately.