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Pesticides in the Diets of Infants and Children 5 Food and Water Consumption DIETARY EXPOSURE OF CHILDREN to pesticides can be estimated by combining data on levels of pesticide residues in foods with data on food consumption patterns for infants and children. Risks to health can be assessed by combining estimates of dietary exposure with information on the toxic potential of pesticides. Various data bases are available for use in these calculations. In this chapter, the committee reviews the dietary surveys conducted to assess patterns of food consumption by the U.S. population, including infants and children. It examines the methods used in these surveys and evaluates their relative strengths and weaknesses. The committee then describes the age-related differences in food consumption patterns demonstrated by survey data and discusses food consumption estimates. The committee also notes various factors and limitations that must be considered in determining the basis for estimating exposure to pesticides residues in food and assessing the risk to infants and children. FOOD CONSUMPTION SURVEYS Small-scale studies on food intake and nutrition were first conducted toward the end of the nineteenth century, when processing techniques were leading to rapid changes in the food supply. The variety of foods available to consumers again increased when in-home refrigerators and freezers became generally available, more sophisticated preservation techniques were introduced, and manufactured foods found their way into the retail market. By 1960 approximately 60% of the food items on supermarket shelves had come into existence during the preceding 15 years, that is, since the end of World War II (Hampe and Wittenberg, 1964).
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Pesticides in the Diets of Infants and Children It therefore became of great interest to researchers to determine what the people of this country were actually eating. In 1909 the U.S. Department of Agriculture (USDA) began to identify changes in the foods available to the civilian public by determining the disappearance of foods into the wholesale and retail markets. This is still done annually by subtracting data on exports, year-end inventories, nonfood uses, and military procurement from data on total production, imports, and beginning-of-the-year inventories. Overestimates result from this method, however, because losses that occur during processing, marketing, and home use are not taken into account. Thus, the resultant information is sometimes called availability or use of foods or nutrients (Stamler, 1979). The USDA estimates national per capita use of foods or food groups by dividing the total available food by the total U.S. population. These data provide information on overall trends in available foods, but they do not indicate how use varies among population subgroups or individuals. Since 1935 the USDA's Human Nutrition Information Service (HNIS) has conducted a series of Nationwide Food Consumption Surveys (NFCS). The first four (1935, 1942, 1948 [urban only], and 1955) surveyed household food use over a 7-day period. No record was made of waste or difference in use among household members. Surveys conducted in 1965–1966, 1977–1978, and 1987–1988 included information on the kinds and amounts of foods eaten by individuals in the household in addition to household food use. For the reasons given later in this chapter, the 1977–1978 survey served as the major source of consumption data used by the committee in the present study. The USDA has conducted a planned series of surveys since 1985 solely concerned with individual food intake (USDA, 1985, 1986a,b, 1987a,b,c, 1988). The results of the most recent surveys have not yet been published. In these surveys, called Continuing Surveys of Food intakes of Individuals (CSFII), data are collected on three separates samples: women 19 to 50 years old and their children 1 to 5 years old (the core group); a sample of low-income women and their children; and in 1985 only, men 19 to 50 years old. In the 1989, 1990, and 1991 surveys, data were collected on all individuals. The National Center for Health Statistics (NCHS), a division of the Department of Health and Human Services, has conducted the National Health and Nutrition Examination Surveys (NHANES) since 1971. The purpose of these surveys is to monitor the overall nutritional status of the population of the United States through comprehensive health and medical histories, dietary interviews, physical examinations, and laboratory measurements. The committee opted not to use the results from these surveys, however, because the number of observations within the age and demographic categories of interest were inadequate for the purposes of the present study.
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Pesticides in the Diets of Infants and Children The only national study of average intakes of pesticides, toxic substances, radionuclides, and industrial chemicals is the Total Diet Study conducted by the Food and Drug Administration (FDA). Four times a year, foods considered to be representative of the average U.S. diet are purchased from grocery stores across the United States and individually analyzed in FDA laboratories for the constituents mentioned above. Until April 1982 the food items used in the Total Diet Study were based on data from the 1965–1966 NFCS. Since then, they have been based on data from the 1977–1978 NFCS and second NHANES, which was conducted during 1976–1980. (The Total Diet Study is discussed further in Chapter 6, which focuses on pesticide residues in food.) Infants, defined as less than 1 year of age, represent a separate and extremely critical population group with respect to purposes of this study. The number and classification of foods consumed by infants are almost exclusively processed and manufactured by a limited number of companies. Dietary intake studies have been conducted by Gerber Products Company and Ross Laboratories to evaluate intake for these populations, and those dietary studies were used by the committee. SURVEY METHODOLOGY Three basic types of methods are used to gather data in food consumption surveys (Burk and Pao, 1976; Dwyer, 1988): retrospective, prospective, and a combination of retrospective and prospective. Retrospective methods include the 24-hour (or 1-day) food recall and the food frequency questionnaire. Prospective methods require the used of food records or diaries—the weighed food record and the estimated food record (sometimes called the household measure food record). In combination surveys, investigators use both prospective and retrospective methods, e.g., the recall and weighed food record. (For a comprehensive overview, see Dwyer, 1988.) Retrospective Methods The 24-Hour (or 1-Day) Recall Method In surveys conducted with this method, interviewers ask subjects to recall the quantities of particular foods and beverages consumed on the previous day or during the preceding 24 hours. More precise estimates of portions are obtained when the respondents are provided with measurement guides such as food models, abstract shapes, and tableware (DHHS, 1983); measuring cups, spoons, and rulers (USDA, 1987); and pictures (Frank et al., 1977; Posner et al., 1982). Madden et al. (1976) found no significant differences between mean intake data obtained from the 24-hour recall and actual observed intake
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Pesticides in the Diets of Infants and Children over that period. They noted, however, that the data were not representative of an individual intake averaged over different days. Recalls of food consumption over a period longer than 24 hours produce more representative data on general intake patterns, but are less precise than the 24-hour recall because they depend to a greater extent on memory (Block et al., 1986). In general, the validity of the recall method and the extent of bias depend on a variety of factors related to collection methods (Backstrom and Hursh-Cesar, 1981). In face-to-face interviews it is easier to elicit a response. Such interviews are more efficient when there are several family members or a long questionnaire; however, they are expensive primarily because of travel costs. In contrast, telephone interviews are relatively inexpensive, quick, easy to monitor, unlimited geographically, and can ensure a greater degree of anonymity ( Wilson and Rothschild, 1987). Telephones may be used in combination with, or as a follow up to, other interview techniques. They do have several disadvantages, however: subjects can easily terminate an interview prematurely, long or complicated questionnaires are difficult to administer, and many low-income families lack telephones. In all cases, selection and training of the interviewers are critical to the success of the survey. The single, short (15- to 30-minute) guided interview produces higher response rates than all other methods. Moreover, accuracy is enhanced in several ways: the recall period is short and precise, measurement aids may be used to increase the accuracy of consumption estimates, and the quantities reported can be easily converted to nutrient equivalents. Mail interviews are inexpensive, and they may be used in combination with other interview methods (Posner et al., 1982). Furthermore, interviewer bias is avoided. Negative aspects include low response rates, exclusion of illiterate persons, and lack of control over who responds and how they respond. Food Frequency Questionnaires In its simplest form, the food frequency questionnaire consists of a checklist of foods or food groups and a set of categories indicating daily, weekly, or monthly frequency of food consumption during a specified period—weeks, months, or a year. The checklists may contain as few as 20 items or more than 100. The questionnaire can be administered in person, over the telephone, or by mail, with the attendant advantages and disadvantages described above (Willett et al., 1985). Subjects may use a visual aid to estimate portion sizes (Chu et al.,1984). When the quantities have been estimated, the nutrient content of the foods consumed may in turn be estimated. The food frequency questionnaire is a quick, inexpensive, and simple
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Pesticides in the Diets of Infants and Children method for obtaining information on food intake from large numbers of subjects (Sampson, 1985), and its administration does not require highly trained personnel. Epidemiologist have found the questionnaire useful in studying the relationship between diet and disease risk. Attempts have been made to validate the accuracy of consumption frequency estimates by comparing them to food records (Chu et al., 1984; Willett et al., 1985; Freudenheim et al., 1987). The limitations of this method outweigh its strengths. Its accuracy may be compromised by the long recall period, estimates of past intake may be biased by current intake, and respondent burden is heavy if the checklist is long and complex. Moreover, the questionnaire may not be appropriate for people who consume unusual diets or for children. In the future, a combination of methods may be used to overcome these limitations. Prospective Methods Food Records or Diaries These usually self-administered reports of current food intake can cover periods ranging from 1 day to as long as 1 year (Basiotis et al., 1987). Subjects or their surrogates, e.g., parents, record the portions of all foods and beverages ingested immediately after each eating occasion. The foods are either weighed (the weighed food record) (Acheson et al., 1980; Anderson and Blendis, 1981; Marr and Heady, 1986) or measured with a cup, ruler, or other aid (the estimated food or household measure record) (McGee et al., 1982; Acosta et al., 1983; Elahi et al., 1983). Foods eaten away from home must be estimated. The latter method is used most often, but the weighed food record is widely regarded as the most accurate procedure and is often used to validate other methods. Both methods require trained personnel to demonstrate proper weighing, or measuring, and recording techniques. Written instructions are also provided (Sempos et al., 1984). Reliance on memory is minimal, the recall period is precise, interviewer bias is avoided, omissions of foods and beverages consumed tend to be minimal, and the accuracy of portion estimates is enhanced by the weighing and measuring techniques. However, respondents must be literate and willing to accept the heavy burden of participation—factors that can bias the sample. In long-term surveys, boredom or fatigue may lead to a decline in accurate reporting. Combined Retrospective and Prospective Methods A combination of recall and records methods is sometimes used to obtain multiple-day intake data for individuals in a large survey or study
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Pesticides in the Diets of Infants and Children (Schnakenberg et al., 1981; USDA, 1983). Because the limitations of one method offset the limitations of the other, a greater accuracy of mean intake estimates can be expected. Examples of combinations include 1-day recall and 2-day record (Patterson, 1971; USDA, 1983), 3-day recall and 4-day record (Futrell et al., 1971), and 1-day recall and 14- to 17-day record (Schnakenberg et al., 1981). Diet histories may also involve a combination of methods (Dwyer, 1988). Methods Used in USDA Surveys Although the USDA has sought similar information in its various dietary intake surveys, it has changed the methods used in an attempt to obtain better measures of average intake. The agency has advanced from a 1-day recall only insuring (1965–1966 Household Food Consumption Survey) to a 3-day combination (1-day recall and 2-day record) during all four seasons in the 1977–1978 and 1987–1988 NFCS. The 3 days of intake data for more than 30,000 people, obtained by using this combination method, produced a better measure of an individual's average intake than did the 1-day measure used in 1965. In the 1985 and 1986 CSFII, 6 nonconsecutive days of intake data were collected by trained interviewers who administered the 1-day recall method every 2 months over the course of the year. The first interview was conducted in person; the remaining five were accomplished over the telephone. Mothers provided the recall information for their children. This system proved costly, and the drop-out rates over the course of the year were high (Table 5-1). The substantial decrease in participation (approximately 50%) can be attributed to either the 145 respondents (10% of the sample) who moved to another geographical region or to such socioeconomic characteristics as being younger, having a low income, being in poor health, being on a special diet, having one or more children, being a suburban dweller, or working. As a result of the drawbacks in the 1985 and 1986 CSFII, the combination of 1-day recall and 2-day record used in the 1977–1978 NFCS was reinstituted in the 1987–1988 NFCS and the 1989 and subsequent CSFII to obtain 3 consecutive days of dietary intake data. In both the NFCS and later CSFII, dietary information was collected on all individuals—not just the sex-age groups surveyed in the 1985 and 1986 CSFII. SURVEY DESIGN To determine the validity of a survey sample, it is necessary to consider a variety of factors such as the survey design, sample weighting, and comparison of resulting data to standards. The committee began by examining
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Pesticides in the Diets of Infants and Children TABLE 5-1 Unweighted Counts of Individuals for the 1985 and 1986 CSFII Number of Subjects in Surveya Year Income Category Subjects First Day All 6 Days 1985 All Incomes Children 489 161 Women 1,459 692 Men 658 NAb 1985 Low Incomes Children 1,190(714)c 221 Women 2,081(1,322)c 547 1986 All Incomes Children 509 219 Women 1,451 751 1986 Low Incomes Children 762 307 Women 1,320 595 a The numbers in these columns are not additive since the represent different study groups. b Men were sampled for only 1 day. c More responses than expected were received for day 1, and they included a large number of low-income households. To reduce the number of low-income households to the targeted number of 1,200 for interviewing on days 2-5, systematic subsamples were drawn for both women and children. The numbers in parentheses refer to those subsamples. SOURCE: USDA, 1988. the design of the CSFII and the NFCS. The 1985 and 1986 CSFII and the 1977–1978 and 1987–1988 NFCS were designed to provide a multistage, stratified, probability sample that was representative of the 48 conterminous states. A multistage sample is drawn by selecting random groups in stages. At each stage, groups of individuals are selected from increasingly smaller segments of the population. The term stratified indicates that the population is divided into mutually exclusive subsets, or strata, before the sample is drawn. Taken together, these subsets represent the total population that is being examined. However, the sampling plan is applied separately within each stratum. Because the strata are defined by geographic location, the sampling within each stratum is called an area sample. In a probability sample, every group has a known probability of selection. Thus, every element in the population must be enumerated before the sample is drawn to facilitate determination of the likelihood of selecting any group of individuals into the sample. These probabilities may or may not be equal for all groups. The use of uniform criteria for each group helps minimize the extent of enumeration required to determine selection probabilities. Each group sampled, therefore, has a known probability of selection. Although this method is fairly complex, it provides data that
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Pesticides in the Diets of Infants and Children TABLE 5-2 Distribution of Strata within the Conterminous United States as Defined by the Bureau of Census Geographic Divisions Number of Strata Region Census Division Central City Suburban Nonmetropolitan Northeast New England 1 1 1 Middle Atlantic 3 5 1 Midwest East North Central 3 6 2 West North Central 1 1 2 South South Atlantic 2 5 3 East South Central 1 1 2 West South Central 2 3 2 West Mountain 1 1 1 Pacific 3 5 1 Total 17 28 15 SOURCE: Adapted from the U.S. Department of Agriculture, 1985. are statistically projectable, with known sampling error, to the entire conterminous United States. Nonprobability samples, where groups are not enumerated, are generally easier to obtain but do not provide data that are statistically projectable to the general population. The 48 states were grouped into the nine census geographic divisions, which in turn were divided into three classifications: central city, suburban, and nonmetropolitan (Table 5-2). From these 27 superstrata, 60 strata (17 central city, 28 suburban, and 15 metropolitan) were obtained. Both the CSFII and the NFCS surveys consisted of four stages. During the first stage, the probability proportion to size (PPS) technique was used to select two primary sampling units (PSUs) from each of the 60 strata in both the CSFII and NFCS. These 120 PSUs included counties, cities, or parts of cities, and were relatively homogenous with regard to demographic characteristic. In designing food surveys, care must be taken to ensure that the sample of consumers is representative of the general population. Even a scientifically designed probability sample may not be representative due to nonresponse and other practical problems. This could lead to bias in the estimates of mean intake, especially if there is a systematic component to the nonresponse. An accepted method for adjusting the estimates of intake would be to weight the data in such a way that they more closely reflect the general population. Fuller (1991) discusses using regression estimation for adjusting intake when appropriate auxiliary information exists. Fuller et al. (1991) adjusted intake for sociodemographic factors for the 1987–1988 NFCS and found a significant difference between the resulting mean intake as compared with mean intake calculated without such weighting.
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Pesticides in the Diets of Infants and Children Nusser et al. (1991) considered characterizing usual daily intake distributions as opposed to mean daily intake. Usual intake is useful in providing information about nutritional deficiencies occurring over a long period. They show that use of the distribution of mean intake as an estimate of the distribution of usual intake can lead to erroneous inferences regarding nutritional status. In particular, the variance of mean intakes contains intra individual variability and is thus greater than the variance of usual intakes. Other parameters of the two distributions may differ as well. SAMPLE WEIGHTS Although the CSFII and NFCS samples were designed to be self-weighting, adjustments to the samples were required because not all eligible households participated, not all eligible individuals in eligible households were interviewed, and not all interviews yielded complete dietary information. Weighting factors were developed for each individual participating in the survey and were applied to data from completed intake records to adjust for these sources of nonresponse. Other weighting considerations included economic homogeneity, geographic heterogeneity, and age. SAMPLE SIZE Sample size is an important determinant of sample variation and statistical precision. Decisions regarding sample sizes therefore depend on the level of precision desired for the data needed to estimate a population parameter of interest. The size of the sample required an established goal of precision for an estimate can be determined through calculations that depend on the coefficient of variation (CV) and an assumed probability distribution for the data. The coefficient is the standard error of an estimate expressed as a fraction of the sample mean. As the CV of an estimate increases, its accuracy decreases. In general, NFCS and CSFII intake estimates with CVs exceeding 50% are not published. Estimates with CVs of 15% to 50% are published by USDA with caveats regarding their accuracy. COMPARISONS OF INTAKE DATA WITH STANDARDS Intake data are often compared with a widely accepted value such as the Recommended Dietary Allowances (RDAs). The RDAs are intended to meet ''the known nutrient needs of practically all healthy persons" in the United States (NRC, 1989); however, since nutrient needs vary among people, margins of safety are built into the RDAs for many nutrients. For
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Pesticides in the Diets of Infants and Children this reason, analysts have selected a fixed cutoff point, such as two-thirds or three-fourths of the RDA, as a point of comparison. One committee convened by the Food and Nutrition Board (FNB) of the National Research Council suggested that distributions of requirements or tolerances would be more appropriate for this purpose (NRC, 1986). This FNB committee recommended that a probability approach be used to estimate the prevalence of inadequate intake, i.e., the probability that a specific intake is inadequate to meet an individual's requirement (NRC, 1986). VALIDATION OF FOOD CONSUMPTION DATA Food consumption data must be validated before they are used to calculate risk, in part because the integrity of formulated and combined foods is compromised when those foods are broken down into their constituents. The method of calculation used by the EPA to estimate risk converts consumption data directly into food components, thereby eliminating the need to follow all the separate validation steps. (See "Quantification of Consumption Data," below, for a further discussion of the EPA method.) Substantial uncertainty is inherent in food consumption data because of a variety of factors. Principal among these are recording errors and biases. It is therefore difficult to extrapolate results to the general U.S. population. Of the different protocols that have been used in dietary surveys, none is uniformly better than all others. Even the most extensive dietary sampling schemes may be subject to biases or practical limitations. Because of this, a variety of survey methods have evolved to address different objectives, each with its own strengths and weaknesses. Two primary objectives of food consumption surveys are to assess the mean intake of a group of individuals or the mean intake of a particular individual. Because food consumption varies markedly both within individuals and between individuals (Beaton et al., 1979; Beaton et al., 1983; Todd et al., 1983), methods that are appropriate for one objective may not be appropriate for the other. The validity of the results relative to the study objectives is of central importance (Block, 1982). Validation of data on food consumption is a difficult task. Ideally, all types and quantities of food consumed by the survey respondents would be recorded in a complete and accurate fashion; this record of actual consumption could then be used as a reference value against which to compare estimates of consumption based on different survey protocols. Kim et al. (1984) studied a method whereby individuals are asked to set aside a duplicate portion of the food they ate for future
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Pesticides in the Diets of Infants and Children analysis. The investigators found that the process of setting aside the extra food actually led to smaller quantities consumed than in the usual pattern of intake. To avoid biases associated with self-reported food consumption data, an inconspicuous observer could maintain a diary of foods consumed—a technique used by Madden et al. (1976), Gersovitz et al. (1978), and Krantzler et al. (1982). However, these studies were carried out in controlled environments such as dormitories, dining halls, or other congregate meal sites, thus making it difficult to extrapolate conclusions to the general population. Because of the difficulties in measuring actual intake, validation to a large extent tended to focus on the comparison of results obtained from different survey methods (Block, 1982). For example, relatively new survey methods such as questionnaires have been compared with established methods such as multiple-day records (Jain et al., 1980; Axelson and Csernus, 1983; Willett et al., 1985; Byers et al., 1987; Krall and Dwyer, 1987; Pietinen et al., 1988). Methods are also sometimes compared to determine which one will produce the most reliable estimates of intake of specific nutrients such as vitamin A (Young et al., 1952; Russell-Briefel et al., 1985; Sorenson et al., 1985). THE STRENGTHS AND WEAKNESSES OF THE FOOD CONSUMPTION DATA BASES IN ESTIMATING PESTICIDE EXPOSURE OF CHILDREN The 1977-1978 NFCS data have the following major limitations. Over the years since that survey was conducted, average overall dietary patterns may have changed in response to advanced food technology, advertising, taste, and health consciousness, among other variables. The sample of nursing infants was small (n = 106). The 3-day survey period reflects too brief a consumption period, even though it was conducted over all four seasons. Water consumption was not considered. Despite these substantive limitations, the NFCS has provided the only comprehensive data currently available for comparisons of food consumption by all age classes in our population, which is the primary reason the committee chose the 1977–1978 NFCS as the basis for this report. Because the EPA also relies on the same food intake data, the committee's findings can easily be compared with the risks estimated by that agency. The committee compensated for the limited sample size for nursing infants by reviewing survey data reported by Purvis and Bartholmey (1988).
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Pesticides in the Diets of Infants and Children Orr-Ewing, 1986; Butte et al., 1992). For a more detailed review of these data, see Nutrition During Lactation (NRC, 1991). Because the volume of human milk consumption varies widely, the estimates of supplementary food consumption shown in Table 5-6 are conservative, i.e., they are higher than the amounts likely to be consumed by these infants. The 1988 National Maternal and Infant Health Survey contained a number of questions that promise to shed more light on infant food consumption during the first 6 months of life. Unfortunately, the analysis could not be made available to the committee in time for inclusion in this report. As demonstrated by the preceding discussion and accompanying tables, use of available intake data to assess dietary exposures of nursing infants is complex. Human milk is the major food and source of essential nutrients consumed by these infants during their first year of life, but a vast range of variables must be considered: the age at which supplementary foods are introduced, the selection of foods given to them, and the volume of human milk consumed. Factors greatly affecting the feeding patterns of this group include economic status, ethnic background, region, and the age, marital status, educational level, parity, and employment of the mother. Infant formula is the sole source of food for nonnursing infants for the first 3 months of life. Milk or milk-based food remains the predominant source of energy and nutrients for all infants throughout their first year of life. Averaged over the first 12 months, nonfat and fat milk solids provide 44.2% and 10.4%, respectively, of their diet. These figures were derived from DRES conversion of formula into its component parts: fat and nonfat milk solids, milk sugar, coconut oil, and soybean oil. Coconut oil represents only 1.4% of the average diet of nonnursing infants, but the consumption is almost 50 times greater than that of the national average (Table 5-6). The diet of infants is gradually supplemented with specially prepared, predominantly processed foods produced by a small number of manufacturers. When presented as RACs, fruit and fruit juice constitute the highest proportion of the early supplemental foods, accounting for an estimated 16.1% of the diet, averaged over the first year of life. These are led by apple juice (4.4% as RAC) and fresh apples (3.2% as RAC). Caloric consumption by infants per unit of body weight is higher than that for adults—approximately 2.5 times higher for the very young infant (NRC, 1989). Therefore, comparison of the consumption data for infants and adults on the basis of grams per kilogram of body weight results in an elevated value for infants. The diets of infants and children are less diverse than those of the general population. The 1977–1978 NFCS reports intakes of
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Pesticides in the Diets of Infants and Children 375 foods (reported as RACs), for the entire sample of more than 30,000 people. In contrast, 148 RACs were reported for the 457 nonnursing infants sampled, indicating a relative lack of diversity in the diets of this subgroup. It is therefore important to monitor both the percentage of total diet and the multiple of the national average consumption for each food and for each age group to identify areas relative to dietary exposure to pesticides. Several factors must be considered when evaluating the consumption data on infants. For example, caution must be exercised not to overestimate introduced foods to avoid estimates of intake that greatly exceed the consumption capacity of the infant. Furthermore, changes resulting from various processing techniques, especially fractionation (e.g., for soybean oil), must not be overlooked. Other influences include many of those noted earlier for nursing infants, e.g., region, socioeconomic status, and other variables. Milk also predominates in the diet of 1- to 6-year-ld children, as shown by the values for nonfat and fat milk solids (30.4% and 13.4%, respectively). Orange juice, fresh apples, apple juice, and bananas together constitute 11.1% of their diet. The data also show that the diets of this group have become more diverse to include wheat, beef, sugar, eggs, and chicken, and more varieties of vegetables are consumed. The number of foods eaten above the U.S. average, and the multiples of their excess, have declined. This is most likely attributable not only to the rapid increase in dietary diversity after the age of 1 year, but also to a diminishing effect of the body weight conversion factor as average childhood weights approach average adult weights. The diets of children from 7 to 12 years old have attained a greater level of diversity and show changes in proportion. Wheat flour, beef, and potatoes have reached higher percentages of the diet, whereas the intake levels of some foods (e.g., milk constituents and orange juice) have declined slightly. Many of the foods that constitute the greatest percentages of the diet are the same as those for 1to 6-year-old children, although there are differences in the rankings of the percentages of the total diet of those age groups. As shown by the multiples of the U.S. average consumption, the intakes by 7- to 12-year-old children are approaching those of the overall population. Among teenagers from 13 to 19 years old, wheat flour, beef, potatoes, and eggs continue their ascendance in dietary predominance over fruits and vegetables with the exceptions of orange juice, apples, and tomatoes. Orange juice ranks fifth among the foods that constitute the highest percentages of the diet consumed by this age group. The multiples of the U.S. average consumption have declined, and for 10 food items, are below the national average.
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Pesticides in the Diets of Infants and Children There is a dramatic drop in nonfat milk solids for adults 20 years old and older (from 28.6% of the total diet of teenagers to 18.2% for adults). All the foods comprising more than 1% of the diet of teenagers appear again for adults along with lettuce, fin fish, and fat pork. All food items listed except lettuce are consumed in amounts less than the national average, showing the greater diversity of the adult diet. ISSUES RELATED TO THE EVALUATION OF FOOD MONITORING DATA Differences in Consumption Among Age Groups As demonstrated by the NFCS data (Tables 5-5, 5-6 and 5-7), infant and early childhood consumption patterns differ greatly from those of adults and the population as a whole. The most dominant factor that emerges from interpretive evaluation of intake data remains as milk in some form. The proportion of the balance of the diet represented by fruits, by liquids, especially fruit juices and by vegetables is much higher for infants than for older children or adults. For several fruit juices, this relationship is maintained even when commodity intake is not adjusted by body weight. Thus, use of the U.S. average intake as a basis for estimating pesticide exposures of infants and children may result in underestimates of pesticide residues in their diet. As noted earlier in this chapter, water intake is considerably higher for infants than for other age categories. The sources of this high intake include foods such as concentrated juices, cereals, and infant formula that are mixed with water prior to consumption. Therefore, water must be a major consideration in estimating of the risk from dietary exposure to pesticides for infants and children. The Gerber data show several changes in the diet over the first year of life that have potentially important implications for the exposure of infants to pesticides (Johnson et al., 1981). There is a gradual substitution of cow's milk and apple juice for human milk and infant formula. Soybean oil and coconut oil consumption decreases, reflecting the declining intake of infant formula. Intakes of fruits and vegetables increase steadily, and the diet in general begins to diversify. Because of the young ages of the study population, the 90th percentile of the Gerber sample often shows consumption of such foods as peaches, pears, carrots, and oats for only a few individuals. As the percentage of eaters increases as the children grow older, the 90th percentile commonly exceeds the mean of eaters only and would therefore provide a higher degree of protection if used as the basis of risk projections and tolerance setting.
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Pesticides in the Diets of Infants and Children Differences in Consumption within Age Groups Variations in consumption patterns within age groups may be considerable. Consider, for example, the great differences among the diets of vegetarians, certain ethnic and religious groups, individuals with medically restricted diets, and populations in different regions of the country. It is quite probable that subgroups within the various age categories consume both average daily and daily high levels of food considerably above the NFCS values, but an analysis of these variations is not possible with current survey data. For chronic risk assessment, EPA has traditionally relied on mean consumption estimates for large groups such as the entire U.S. population or children between the ages of 1 and 6 years or 7 and 12 years. The 90th percentile has been avoided, because no individual consumes the 90th percentile of all foods regulated by the FDA and USDA. Some individuals may, however, consistently consume a few foods at the 90th percentile for their age group. Obviously, these clusters would vary among individuals and eventually resolve to the mean for the age group. To determine the significance of this observation, the committee identified the 25 foods most consumed by 170 1-year-old children in the 1985–1986 CSFII. Results from DRES calculations based on CSFII results illustrate that mean intake data clearly do not reflect the actual intakes of some foods by some subjects and therefore that their use can lead to underestimates of pesticide exposure. For example, 88 of the children (52%) consumed 6 to 10 foods over the mean, and only 5 (2.9%) consumed no foods over the mean. The many foods over the mean. The many foods consumed at levels lower than the mean constituted a minor portion of the diet. These considerations regarding consumption are used as the basis for the committee's discussions in the remaining chapters of this report. CONCLUSIONS AND RECOMMENDATIONS The committee reached its conclusions and recommendations for this chapter after an extensive review of information available on food and water consumption. All major sources of data on food consumption by infants and children compiled by government agencies and the food industry were considered and evaluated. Information on water intake was derived from an extensive evaluation of food survey information conducted for the National Cancer Institute. The committee weighed the strengths and the limitations of each source of information in order to identify the most acceptable data to be used in conjunction with pesticide residue information to determine exposure, as discussed in Chapters 6 and 7.
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Pesticides in the Diets of Infants and Children Information on foods as consumed was broken down into constituents of foods by the same process currently used by government to establish regulatory policy. This conversion process—the Dietary Residue Evaluation System (DRES)—expresses foods in terms of individual raw agricultural commodities (RACs). Potential dietary exposures to pesticides are related to food and water intake. To identify the differences in exposures of infants and children compared with adults, intake data were grouped into various age categories. Consumption of water, human milk, and processed foods were considered separately in order to assess their respective contributions to dietary pesticide exposure for infants and young children. Conclusions Food consumption patterns for infants and children differ markedly from those of adults. Children consume more calories relative to body weight than do adults. Dietary diversity increases with age: infants and young children consume fewer distinct foods than do adults. On a body weight basis, infants and young children consume notably more of certain foods than do adults. Water, as drinking water and as a component of food, is not adequately considered in most consumption surveys. Examination of intake data by age categories clearly illustrates the differences in consumption patterns that must be considered when estimating exposure of infants and children to pesticides; however, current information on food and water intake by age category is insufficient to produce credible exposure estimates. Processed foods are predominant in the diets of younger age groups. Recommendations Knowledge of food consumption is an important consideration in assessing the risk to infants and children from dietary exposures to pesticides. Therefore, more focused, direct, comprehensive, and contemporary dietary information is required for infants and children. Because of the myriad and rapid changes in diet that occur during the developmental stages of life, intake data must be precisely divided into age subdivisions and the sample must be large enough to produce meaningful results. A simple, uniform method needs to be developed for conversion of
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Pesticides in the Diets of Infants and Children a product as consumed to its components in terms of raw agricultural commodities. Those foods most frequently consumed by young children and infants need to be identified and quantified more specifically. Reporting should be specific and discrete foods clearly identified. Water intake and food intake should both receive full consideration in estimating dietary exposure and assessing risk, especially for infants and young children. Because of the changing nature of children's diets during growth, food consumption surveys should include adequate sample sizes of children aged 0 to 12 months, 13 to 24 months, 25 to 36 months, 37 to 48 months, 49 to 60 months, 5 to 10 years, and 11 to 18 years. Intake data and survey methodology need to be standardized to make them more useful in a variety of applications, including estimating exposure and assessing risk. Food consumption surveys should be coordinated among the involved organizations and performed on a continuing basis in order to examine trends of food and water consumption, especially by infants and children. REFERENCES Acheson, K.J., I.T. Campbell, O.G. Edholm, D.S. Miller, and M.J. Stock. 1980. The measurement of food and energy intake in man: An evaluation of some techniques. Am. J. Clin. Nutr. 33:1147–1154. Acosta, P.B., C. Trahms, N.S. Wellman, and M. Williamson. 1983.Phenylalanine intakes of 1- to 6-year-old children with phenylketonuria undergoing therapy. Am. J. Clin. Nutr. 38:694–700. Anderson, G.H., and L.M. Blendis. 1981. Plasma neutral amino acid ratios in normal man and in patients with hepatic encephalopathy: Correlations with self-selected protein and energy consumption. Am. J. Clin. Nutr. 34:377–385. Axelson, J.M., and M.M. Csernus. 1983. Reliability and validity of a food frequency checklist. J. Am. Diet. Assoc. 83:152–155. Backstrom, C.H., and G.D. Hursh-Cesar. 1981. Survey Research, 2nd ed. New York: Macmillan. Basiotis, P.P., S.O. Welsh, F.J. Cronin, J.L. Kelsay, and W. Mertz. 1987. Number of days of food intake records required to estimate individual and group nutrient intakes with defined confidence. J. Nutr. 117:1638–1641. Beaton, G.H., J. Milner, P. Corey, V. McGuire, M. Cousins, E. Stewart, M. de Ramos, D. Hewitt, P.V. Grambsch, N. Kassim, and J.A. Little. 1979. Sources of variance in 24-hour dietary recall data: Implications for nutrition study design and interpretation. Am. J. Clin. Nutr. 32:2546–2549.
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Representative terms from entire chapter: