Modelling consumer exposures to nutrients and additives in animal products.

Current guidelines for assessing human exposures to nutrients and other substances used in animal feed are based on methods used for veterinary pharmaceuticals. These methods assume high-level daily consumption of animal products and do not take account of differences between species or between consuming humans. A more detailed dietary modelling approach is described, which takes these factors into account as well as high-level consumption by different age groups. The proposed approach is evaluated in three case studies, iodine, selenium and astaxanthin, which have previously undergone thorough evaluation by EU authorities. When applied in a tiered approach, the proposed model provides results that are consistent with previous assessments and with results obtained using other modelling techniques. The results indicate that the method has the potential to provide a conservative, reliable and flexible alternative to existing approaches to intake estimation.

The usage, occurrence and dietary intakes of white mineral oils and waxes in Europe.

Dietary exposures to mineral hydrocarbons were estimated from information about patterns of usage, concentrations in foods and quantities of foods consumed. An industry survey showed that the largest usage of food-grade white mineral oils was in plastics manufacture although the majority are used in non-food applications. The largest volumes of wax usage were in packaging. Conservative estimates indicated that daily intakes of white mineral oils ranged from 0.39 to 0.91 mg/kg bw/day for adults and from 0.75 to 1.77 mg/kg bw/day for children (mean and 97.5th percentiles). Total wax intakes ranged from 0.08 to 0.19 mg/kg bw/day for adults and 0.23 to 0.64 mg/kg bw/day for pre-school children. When usage factors were applied, estimates of chronic intakes of white oils were reduced to 0.09-0.20 mg/kg bw/day for adults and to 0.17-0.39 mg/kg bw/day for children. Total wax intakes were reduced to 0.01-0.02 mg/kg bw/day for adults and to 0.02-0.06 mg/kg bw/day for children. For white mineral oils the principal source of exposure for most consumers was imported de-dusted grain. The principal source of potential wax exposure was from glazing agents on confectionery. There was no evidence of intakes exceeding SCF ADIs for microcrystalline waxes or certain white mineral oils and levels of exposure were similar to those of naturally-occurring mineral hydrocarbons in foods.

Estimating acute dietary intakes of chemicals.

In some cases a single dose above an acceptable daily intake could elicit an adverse effect. In other cases a cumulative dose over several days may be necessary before an effect is expressed. Estimates of acute intake must relate to what is known about the toxicokinetics of the substance, in relation to the toxicological studies associated with the relevant end point. This is because estimates of intake can vary considerably over even a few days in some circumstances. Acute reference doses should therefore be qualified by an exposure interval. Default values can introduce considerable conservatism into intake estimates. Techniques for estimating acute intakes are very varied. They can range in complexity from conservative screening methods to sophisticated techniques designed to simulate real situations. Monte Carlo models allow for the distributions of chemical concentrations and food consumption patterns to be taken into account. For acute dietary risk assessments very high upper percentile cutoffs are sometimes applied, even as high as 99.9%. However, assumptions applied in such methods can lead to misleading results. Great care must also be used when interpreting such statistics because uncertainty and inaccuracy in the data increase considerably in the upper "tail" of the distribution.

Evaluation of the budget method for screening food additive intakes.

The Budget Method, originally developed for determining food additive use limits, has been proposed as a tool for screening food additive intakes to establish monitoring priorities. Theoretical Maximum Daily Intake (TMDI) estimates derived using the Budget Method rely on assumptions regarding physiological requirements for energy and liquid and on the energy density of food rather than on food consumption survey data. This report summarizes work performed to determine the validity of Budget Method assumptions and to assess the potential for error in assigning monitoring priority based on Budget Method results. Budget Method assumptions regarding energy and liquid intake were compared with data from UK, German and US nationwide food consumption surveys. It was found that the Budget Method assumptions of energy intake and liquid intake are higher than mean intakes reported in surveys. The Budget Method assumption regarding energy density of foods also was found to be a slight overestimate. Budget Method TMDIs for case study additives were in each case larger than survey-based 95th percentile per capita additive intake estimates. Based on these results, the Budget Method appears to be a suitably conservative screen for establishing additive monitoring priorities based on potential lifetime average intakes.

Carcinogens in food: priorities for regulatory action.

A pragmatic possible approach to the prioritization of chemical carcinogens occurring as food contaminants is described, based on the carcinogenic risk to the population. This should be of value in ensuring that resources for assessment and management of carcinogens in food are directed to the most important areas with regard to carcinogenic risk to the population. Key components of this approach are an assessment of the carcinogenic hazard to humans combined with estimations of intakes per person and of the proportion of the population exposed. These are used to derive an index referred to as the Population Carcinogenic Index. Concerning the hazard assessment expert judgement is used to place the chemical in one of five categories. The highest category is for chemical carcinogens that are believed to act by a genotoxic mechanism. It is recognised that such compounds may vary enormously with respect to their potency and various approaches to ranking carcinogens on the basis of potency are reviewed. The approach adopted is to subdivide the genotoxic carcinogens category into high, medium and low potency based on the TD50 value. Methods of estimating intakes and exposed populations are considered and an approach which groups these into broad categories is developed. The hazard and exposure assessments are then combined to derive the Population Carcinogenicity Index.

In vivo tibia lead measurements as an index of cumulative exposure in occupationally exposed subjects.

In vivo tibia lead measurements of 20 non-occupationally exposed and 190 occupationally exposed people drawn from three factories were made using a non-invasive x ray fluorescence technique in which characteristic x rays from lead are excited by gamma rays from a cadmium-109 source. The maximum skin dose to a small region of the shin was 0.45 mSv. The relation between tibia lead and blood lead was weak in workers from one factory (r = 0.11, p greater than 0.6) and among the non-occupationally exposed subjects (r = 0.07, p greater than 0.7); however, a stronger relation was observed in the other two factories (r = 0.45, p less than 0.0001 and r = 0.53, p less than 0.0001). Correlation coefficients between tibia lead and duration of employment were consistently higher at all three factories respectively (r = 0.86, p less than 0.0001; r = 0.61, p less than 0.0001; r = 0.80, p less than 0.0001). A strong relation was observed between tibia lead and a simple, time integrated, blood lead index among workers from the two factories from which blood lead histories were available. The regression equation from two groups of workers (n = 88, 79) did not significantly differ despite different exposure conditions. The correlation coefficient for the combined data set (n = 167) was 0.84 (p less than 0.0001). This shows clearly that tibia lead, measured in vivo by x-ray fluorescence, provides a good indicator of long term exposure to lead as assessed by a cumulative blood lead index.