Consumption data intake estimates

Pharmacokinetics has played a crucial and somewhat unusual role in the assessment of health risks from methylmercury. Some of the epidemiology studies of this fish contaminant involved the measurement of mercury levels in the hair of pregnant women, and subsequent measurements of health outcomes in their offspring (Chapter 4). Various sets of pharmacokinetic data allowed estimation of the level of methylmercury intake through fish consumption (its only source) that gave rise to the measured levels in hair. In this way it was possible to identify the dose-response relationship in terms of intake, not hair level. Once the dose-response relationship was established in this way, the EPA was able to follow its usual procedure for establishing an RfD (which is 0.1 ag/(kg b.w. day)). 

Exposure dose = estimated chemical intake from local marine fish and shellfish consumption data extracted from EPD s consultancy study A Study of Toxic Substances Pollution in Hong Kong, Agreement No. CE 22/99 . 

Two types of epidemiological relationships have been found in two different populations. Both relationships were inverse to selenium bioavailability and paralleled the results from animal studies. In one type of study, selenium bioavailability has been inversely related to human cancer mortality in American cities and states (14-15). Schrauzer et.al. correlated the age-adjusted mortality from cancer at 17 major body sites with the apparent dietary selenium intakes estimated from food consumption data in 27 countries (16). Significant inverse correlations were observed for cancers of the large intestine, rectum, prostate, breast, ovary, lung, and leukemia. In addition, weaker inverse associations were found for cancers of the pancreas, skin, and bladder. 

The intake estimates are based on dietary intake data collected in the Danish nationwide food consumption survey of 2000-2002 [3]. The food consumption data were sampled throughout the 3 year period in order to account for possible seasonal variations in dietary habits. The representative sample of Danes included... 

TABLE 9.5. Estimated Intakes by Infants (4-6 Years) of Cd, Hg, and Pb Using Age-Specific Consumption Data from the Danish Dietary Survey for the 2000-2002 Period... 

For a 4-6-year-old child however, the mean and 95th percentile of Pb intakes estimated on the basis of age-specific consumption data from the 2000-2002 dietary survey (Table 9.5) correspond to 13 and 20 percent of the PTWI value, respectively. 

The trace element intake per kg of body weight by children, however, is even higher than that for adults. For this reason it is important to continue the study of the dietary habits of children, including children 2-4 years old. Such consumption data will allow for an important future estimation of the intake of those trace elements that pose a particular risk to young children, that is, Hg and Pb. 

When calculating chronic dietary exposure, the deterministic models use point values for both food consumption and residue concentration, thereby yielding a point estimate of dietary exposure. In the US, the initial chronic dietary exposure estimate is the Theoretical Maximum Residue Contribution (TMRC) and is analogous to the Theoretical Maximum Daily Intake (TMDI) used to estimate chronic dietary exposure in the EU. Both the TMRC and the TMDI are relatively conservative estimates of dietary expostire. The TMRC is calculated as the product of the mean consumption value and the US pesticide tolerance [6]. In the EU, the TMDI is calculated as the product of the mean consumption value and the Maximum Residue Limit (MRL) [7]. The objective of both calculations is essentially identical to calculate an estimate of the central tendency of the dietary exposure. Both calculated values use the central tendency dietary exposure estimate as the estimate of chronic (long-term) dietary exposure and calculate it using mean consumption data and the maximum residue permitted on the commodity. 

The methodology is different in the UK, where the TMDI is calculated as an estimate of high-end dietary intake, using the 97.5 percentile consumption data for the two most highly consumed commodities and mean consumption estimates for the remaining commodities [8], as shown in the following equation ... 

At this time, acute dietary exposure in the EU is typically estimated by calculating National Estimates of Short Term Intakes (NESTIs) at the national level or International Estimates of Short Term Intakes (lESTIs) at the international level. Practically, however, the only readily available data for calculating estimates of short-term exposures are those from the UK. In practice, NESTIs calculated with the UK food consumption data are used to represent potential acute dietary exposures across the EU. As will be shown in the following paragraphs, the NESTI calculation provides a point estimate of acute dietary exposure. 

Food frequency questioimaires determine the frequency with which certain foodstuffs are consumed over a given period. Thus it is necessary to predefine the foodstuffs of interest and these may be targeted to a nutrient(s) or food(s) of specific interest. They are rarely conducted for specific contaminants arising from the packaging of the foodstuffs consumed. It is possible (Parmar et al. 1997) to combine the food frequency quesfioimaire with portion sizes (MAFF for example) in order to obtain an estimate of food intake, particularly where consumption data are limited. 

Dietary nuclide intakes are estimated by several methods (WHO, 1983), e.g., selective studies of individual foods, market basket studies, model dish studies and duplicate portion studies. The first procedure involves the estimation of mean dietary nuclide intakes by collecting staple foods, which are consumed by the subject, and then chemically analyzing them. In market basket studies, individual or composite foods obtained from food stores in the area are analyzed. Data on the food consumption rates of the average person then take on an especially important role. Model dish studies involve the preparation of typical dishes based on both food and dish consumption data and analysis of each dish. Duplicate portion studies offer the greatest degree of reality compared to the other methods. At a minimum, all meals consumed by an individual during one day are chemically analyzed. After the accident in the Ukraine, data on the dietary intakes of Cs, °Sr and transuranium have come from analyses of staple individual foodstuffs. Total diet studies for Ukrainians are scarce. 

Dietary exposure assessments per capita are described in Table 9. Average daily estimates of intakes of chlorite and chlorate ranged from 0.2 to 0.7 pg/kg bw and from 0.1 to 0.6 pg/kg bw, respectively. The use of food balance sheets may give an overestimate of average exposure, but underestimate intake for individuals with high intakes of food additives. For this reason, further assessments were conducted, based on individual food consumption data. 

Table 8. Summary of the consumption data from 13 GEMS/Food Consumption Cluster Diets used for estimates of international dietary intake ofAFBi and AFT... 

Domestic disappearance data are only approximations of food intake because no allowances are made for waste past the wholesale level for this reason such data yield information only on "apparent" food consumption. Food consumption data from the 1970-1972 Nutrition Canada Survey (Health and Welfare Canada, 1975) provided an estimate of the actual fat intake by different physiological groups of Canadians (Table II). Fat intake ranged from 31 g per day by infants to 154 g per day by males in the 20-39 year age group. The fat intake for the population can be estimated by calculating a mean that is weighted by the proportions of the population in each... 

The estimated daily intake of a substance in the context of the entire diet is of paramount importance in assessing the safety of any food ingredient. In the case of infant formulas, this determination should be straightforward as long as formulas are the sole source of nutrition. When solid food is introduced, a more detailed analysis must be conducted based on dietary records and panel data if the substance naturally occurs in the diet. For example, a careful record (diary) of all food consumed for a period of a few weeks should be kept and then analyzed for the substance in question. Another approach is to analyze available consumption data for foods containing the substance and calculating an estimated level of intake. These values are then combined with the estimated intake from the formula, appropriate safety factors are applied, and a safety determination is conducted. 

Source Pietinen, P (1982) Estimating sodium intake from food consumption data. Ann Nutr Metab, 26 90-99 Gregoy J, Foster K, Tyler H, Wiseman M. The Dietary and Nutritional Survey of British Aduits. HMSO (London, 1990). Sanchez-Castillo et at. (1996) Salt intake and blood pressure in rural and metropolitan Mexico. Archives of Medical Research 27 559-566. 

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