Modelling risk of aflatoxin in milk

Recently aflatoxin B1 contamination has been reported to occur in maize grown in Italy and this commodity usually represent 50% of the concentrated feed normally used in Italy for lactating cows. As a consequence aflatoxin M1 exceeding statutory limits in milk has been found in many samples of milk consigned at processing plants. Consumption patterns and small body weight expose children to a higher risk of chronic intoxication from aflatoxin in milk, but this could be mitigated by low prevalence of hepatitis B infection. The objective of the present work was to develop a quantitative risk assessment model in which the exposure and risk of aflatoxin chronic intoxication from consumption of milk in Italy are estimated. Aflatoxin levels observed in 2512 bulk milk samples taken from Jannuary 2001 to July 2004 at processing plants at two large milk processing plants located in North of Italy and the weight of the consignments were used to estimate the amount of milk at varying level of aflatoxin that have been processed during the last four years in North of Italy. These data that are relative to 837 farms located in North and Centre of Italy were compared with other of different sources, namely those relative to surveillance/monitoring activity carried out by Istituti Zooprofilattici to confirm that similar picture could be drawn with independent and different sampling plans. An Excel spreadsheet model was built in which input for assessing exposure were represented by distributions based on the surveys of aflatoxin concentration in bulk raw milk and consumption data based on the study of the Italian Institute for Research on Food and Nutrition. Mixing of bulk milk consignments is the only basic process that could affect the concentration of aflatoxin in consumable milk and this was simulated using data relative to storage tank capacity observed in the two milk processing plants These dose-response relationships (carcinogen potency for HBsAg+ and HBsAg- individuals) estimated by JECFA were used to estimate the additional number of hepatocarcinoma cases in the Italian population from consumption of milk. Exposure assessment took into account for the variability/uncertainty in milk consumption. The Risk characterization took into account the relative body weight and the prevalence of Hepatitis carriers in the different population strata (children, adolescents, adults, and the elderly). The estimated mean risk (i.e. additional number of hepatocarcinoma cases per year per million people) ranged between 6.23 * 10-3 in children and 1.23 *10-3 in adults. Mean risk as a consequence of the aflatoxin crisis observed in the fall 2003 has increased in children from 4.33 * 10-3 to 8.89*10-3