Natalie C G Freeman

Quantitative analysis of children's microactivity patterns: The Minnesota Children's Pesticide Exposure Study.

The National Human Exposure Assessment Survey (NHEXAS)/Minnesota Childrens Pesticide Exposure Study (MNCPES) was a population-based study designed to characterize childrens exposure to residential pesticides and to evaluate the contribution of residential and childrens activities to childrens exposure. Families of 168 children were surveyed for residential use of pesticides and childrens activities. From these homes, families of 102 children between the ages of 3 and 13 years participated in a week-long intensive exposure study. Of the 102 children, 19 children were videotaped for four consecutive hours in their normal daily activities. The survey responses indicated that the youngest children were more likely to exhibit behaviors that would foster exposure to environmental contaminants. Comparison of questionnaire responses indicated that the videotaped subsample was representative of the exposure study population. The microactivities of the videotaped children that might contribute to their exposure via ingestion or dermal routes were quantified. Hand-to-mouth and object-to-mouth activities were observed most frequently among the youngest children. The youngest children were also most likely to be barefoot both indoors and outside. Gender differences were found in mouthing behavior and the proportion of observed time spent outdoors.

Nondietary ingestion of pesticides by children in an agricultural community on the US/Mexico border: preliminary results.

An environmental measurement and correlation study of nondietary ingestion of pesticides was carried out in a colonia in south Texas. The purpose of the study was to evaluate young childrens exposure to environmental levels of organophosphate (OP) pesticides in the household. Samples were collected to measure levels of OP pesticides in housedust and on childrens hands. These, in turn, were compared to levels of OP pesticide metabolites in urine. A total of 52 children, 25 boys and 27 girls, participated in the spring and summer of 2000. The children were 7–53 months of age at the time of recruitment. Univariate and multivariate regression analyses were carried out using SAS statistical software. Seventy-six percent of housedust samples and 50% of hand rinse samples contained OP pesticides. All urine samples had at least one metabolite and over 95% had at least two metabolites above the limit of detection (LOD). Total OP loadings in the housedust ranged from nondetectable (nd) to 78.03 nmol/100 cm2 (mean=0.15 nmol/100 cm2; median=0.07 nmol/100 cm2); total OP loadings on the childrens hands ranged from nd to 13.40 nmol/100 cm2 (mean=1.21 nmol/100 cm2; median=1.41 nmol/100 cm2), and creatinine corrected urinary levels (nmol/mol creatinine) of total OP metabolites ranged from 3.2 to 257 nmol/mol creatinine (mean=42.6; median 27.4 nmol/mol creatinine). Urinary metabolites were inversely associated with the age of the child (in months) with the parameter estimate (pe)=−2.11, P=0.0070, and 95% confidence interval −3.60 to −0.61. The multivariate analysis observed a weak association between concentrations of OP pesticides in housedust, loadings in housedust, and concentration on hands, hand surface area, and urinary levels of OP metabolites. However, hand loadings of OP pesticides were more strongly associated (r2=0.28; P=0.0156) with urinary levels of OP metabolites (pe=6.39; 95% CI 0.98–11.80). This studys preliminary findings suggest that surface loadings of pesticides, on hands, are more highly correlated with urinary bioassays and, therefore, may be more useful for estimation of exposure in epidemiologic studies than levels of pesticides in housedust.

Quantification of children's hand and mouthing activities through a videotaping methodology

A videotaping methodology has been developed for use in quantifying the types and frequencies of childrens hand and mouthing activities that could lead to exposure to environmental pollutants via dermal and ingestion pathways. Twenty children in day care, ages 3–6 years and 10 children in residences, ages 2–5 years, were videotaped during their waking hours for 1 day. Parents of each child completed questionnaires for the purpose of evaluating the accuracy of parental reports of hand-to-mouth rates. Videotapes were translated as quantifiable activities by two trained observers whose reporting reliability was checked throughout the investigation. Results determined that reliability of the videotaping method was very good, even over a year post-training. From videotape data, the average hand-to-mouth frequency rate was determined to be 9.5 contacts/h. These values are considerably higher than the current default value of 1.56 contacts/h under consideration by the EPA.

Children's mouthing and food-handling behavior in an agricultural community on the US/Mexico border

Childrens mouthing and food-handling activities were measured during a study of nondietary ingestion of pesticides in a south Texas community. Mouthing data on 52 children, ranging in age from 7 to 53 months, were collected using questionnaires and videotaping. Data on childrens play and hand-washing habits were also collected. Children were grouped into four age categories: infants (7–12 months), 1-year-olds (13–24 months), 2-year-olds (25–36 months) and preschoolers (37–53 months). The frequency and type of events prompting hand washing did not vary by age category except for hand washing after using the bathroom; this increased with increasing age category. Reported contact with grass and dirt also increased with increasing age category. The median hourly hand-to-mouth frequency for the four age groups ranged from 9.9 to 19.4, with 2-year-olds having the lowest frequency and preschoolers having the highest. The median hourly object to mouth frequency ranged from 5.5 to 18.1 across the four age categories; the frequency decreased as age increased (adjusted R2=0.179; P=0.003). The median hourly hand-to-food frequency for the four age groups ranged from 10.0 to 16.1, with the highest frequency being observed in the 1-year-olds. Hand-to-mouth frequency was associated with food contact frequency, particularly for children over 12 months of age (adjusted R2=0.291; P=0.002). The frequency and duration of hand-to-mouth, object-to-mouth and food-handling behaviors were all greater indoors than outdoors. Infants were more likely to remain indoors than children in other age groups. The time children spent playing on the floor decreased with increasing age (adjusted R2=0.096; P=0.031). Parental assessment was correlated with hand-to-mouth activity but not with object-to-mouth activity. The highest combined (hand and object) mouthing rates were observed among infants, suggesting that this age group has the greatest potential for exposure to environmental toxins.

Household exposure factors, asthma, and school absenteeism in a predominantly Hispanic community

The Passaic Asthma Reduction Effort (PARÉ) used an asthma symptom and household exposure factor questionnaire to screen 4634 elementary school children over a 4-year period in Passaic, New Jersey. During the first year, an additional 240 preschool children were also screened. Overall, 16% of the school children were reported by their parents to have been diagnosed with asthma. In all, 30% of responding families claimed to have at least one family member diagnosed with asthma and this was five times more likely if the target child had asthma. Exposures consistently associated with childhood asthma diagnosis included environmental tobacco smoke (ETS), presence of dampness/mold, roaches, and furry pets in the home. Diagnosis of asthma was primarily associated with all six symptoms used in the PARÉ questionnaire, and secondarily with environmental factors. Puerto Rican and black children had the highest asthma prevalence (26% and 33%), while Mexican children had the lowest (7%). Use of medications and school absenteeism among asthmatic children were associated with wheeze and night cough, but not with any specific environmental exposure. Increased school absenteeism by children undiagnosed with asthma was associated with ETS and dampness/mold in the home. Differences in asthma diagnosis and absenteeism in response to environmental factors were found across ethnic subgroups. Getting asthmatic children on medical management protocols and providing families with education about environmental risk reduction should aid in reducing morbidity in this ethnically complex population. Such coordinated efforts offer the promise of reducing school absenteeism.

Design strategy for assessing multi-pathway exposure for children: the Minnesota Children's Pesticide Exposure Study (MNCPES).

Although children are exposed to a variety of environmental hazards, including pesticides, there is a scarcity of information available to estimate exposures realistically. This article reports on one of the first attempts to measure multi-pathway pesticide exposures in a population-based sample of urban and non-urban children. A design strategy was developed to assess multi-pathway pesticide exposures in children using personal exposure measurements in combination with complimentary measurements of biological markers of exposure, concentrations in relevant environmental media, and time spent in important microenvironments and participating in exposure-related activities. Sample collection and analysis emphasized measurement of three insecticides (i.e., chlorpyrifos, diazinon, and malathion) and one herbicide (i.e., atrazine). These compounds were selected because of their frequent use, presence in multiple environmental media, expected population exposures, and related hazard/toxicity. The study was conducted during the summer of 1997 in Minnesota and involved a stratified sample of households with children ages 3–12 years. Participants resided in either (a) the cities of Minneapolis and St. Paul (urban households), or (b) Rice and Goodhue Counties just south of the metropolitan area (non-urban households). Results from a residential inventory documenting storage and use of products containing the target pesticides were used to preferentially select households where children were likely to have higher exposures. The study successfully obtained pesticide exposure data for 102 children, including measurements of personal exposures (air, hand rinse, duplicate diet), environmental concentrations (residential indoor/outdoor air, drinking water, residential surfaces, soil), activity patterns (obtained by questionnaire, diary, videotaping), and internal dose (metabolites in urine).

Contributions of children's activities to pesticide hand loadings following residential pesticide application

The role of childrens activities in leading to pesticide exposure was evaluated by comparing pesticide loadings on the hands of children with the activities of the same children observed over a 4-h period. In all, 10 children ranging in age from 24 to 55 months were videotaped on the second day following a routine professional crack and crevice chlorpyrifos application in their homes. Before and following the video session, the childrens hands were rinsed in isopropyl alcohol. Thus, only the chlorpyrifos that accumulated on and remained on the childs hands during the videotaping were removed for analysis after the videotaping session. The rinsate was analyzed for chlorpyrifos. The childrens behaviors were quantified using virtual tracking device and the frequency and duration of behaviors, the hourly rate of behaviors, and the locations in which behaviors occurred were compared to hand loadings of pesticides. Pesticide hand loadings obtained following the videotaping sessions were associated with pesticide levels on surfaces and toys, but not with air levels. Pesticide loadings obtained following the videotaping sessions were also associated with frequencies, durations, and hourly rates of contact with bottles, and object-to-mouth behaviors, as well as contact duration with upholstered/textured surfaces. The hand loadings were also associated with the number of locations where the children exhibited object-to-mouth behavior and with childrens use of house space during the videotaping sessions.

Chlorpyrifos Accumulation Patterns for Child-Accessible Surfaces and Objects and Urinary Metabolite Excretion by Children for 2 Weeks after Crack-and-Crevice Application

The Children’s Post-Pesticide Application Exposure Study (CPPAES) was conducted to look at the distribution of chlorpyrifos within a home environment for 2 weeks after a routine professional crack-and-crevice application and to determine the amount of the chlorpyrifos that is absorbed by a child living within the home. Ten residential homes with a 2- to 5-year-old child in each were selected for study, and the homes were treated with chlorpyrifos. Pesticide measurements were made from the indoor air, indoor surfaces, and plush toys. In addition, periodic morning urine samples were collected from each of the children throughout the 2-week period. We analyzed the urine samples for 3,5,6-trichloropyridinol, the primary urinary metabolite of chlorpyrifos, and used the results to estimate the children’s absorbed dose. Average chlorpyrifos levels in the indoor air and surfaces were 26 (pretreatment)/120 (posttreatment) ng/m3 and 0.48 (pretreatment)/2.8 (posttreatment) ng/cm2, respectively, reaching peak levels between days 0 and 2; subsequently, concentrations decreased throughout the 2-week period. Chlorpyrifos in/on the plush toys ranged from 7.3 to 1,949 ng/toy postapplication, with concentrations increasing throughout the 2-week period, demonstrating a cumulative adsorption/absorption process indoors. The daily amount of chlorpyrifos estimated to be absorbed by the CPPAES children postapplication ranged from 0.04 to 4.8 μg/kg/day. During the 2 weeks after the crack-and-crevice application, there was no significant increase in the amount of chlorpyrifos absorbed by the CPPAES children.

House dust levels of selected insecticides and a herbicide measured by the EL and LWW samplers and comparisons to hand rinses and urine metabolites

During the Minnesota Childrens Pesticide Exposure Study (MNCPES), comparisons were made between the insecticide/herbicide loadings obtained with two household dust/insecticide or herbicide samplers: the Edwards and Lioy (EL) press sampler (used for dust collection from carpets or other surfaces) and the Lioy, Wainman and Weisel (LWW) surface wipe sampler. The results were compared with hand rinse levels, and urine metabolite levels obtained from 102 children (ages 3–13). All measurements were made during a 1-week sampling period, and information was obtained on household pesticide use and each childs activities. Of the homes, <5% had recent spot uses of a pesticide but none had recent general applications. The analyses focused primarily on atrazine (a herbicide), and malathion, diazinon, and chlorpyrifos (insecticides). Metabolites were measured for atrazine, malathion and chlorpyrifos. The atrazine levels obtained using the EL indicate that this compound was transported into the home by an unquantified transport mechanism (e.g. tracking of soil). Two malathion hand rinse values exceeded >170 ng/cm2, suggesting that since indoor surface levels were low, these children had other sources of exposure. Atrazine, chlorpyrifos and malathion were detectable in >30% of the homes by the EL, LWW or hand rinse. Only chlorpyrifos had detectable levels in ≥50% of the samples for all types, i.e. compound or metabolite, which is consistent with it being a common household pesticide. The median (and maximum) chlorpyrifos levels for the EL surface, EL carpet, LWW surface (two rooms), hand rinse, and urine metabolites were: 0.07 (32.6) ng/cm2; 0.07 (44.5) ng/cm2; 0.34 (3.64) ng/cm2; 0.42 (14.4) ng/cm2; 0.03 (2.14) ng/hand and 6.9 (59.0) µg/g, respectively. A strong correlation was found for chlorpyrifos between the EL surface and carpet samples. Chlorpyrifos levels detected by LWW had a different distribution and concentration range than the EL, indicating that it collected more than the surface dislodgeable insecticide. EL was directly comparable to the hand rinse or urine levels, but only the LWW had a weak correlation with hand rinse levels, suggesting that the children had other sources of chlorpyrifos exposure. Thus, mechanistic exposure studies are needed to more accurately establish exposure–dose relationships in residential settings.

The Relationship of Health Insurance to the Diagnosis and Management of Asthma and Respiratory Problems in Children in a Predominantly Hispanic Urban Community

OBJECTIVES As part of an asthma screening study, we evaluated the relationship of health care insurance coverage to the diagnosis and treatment of elementary school children for asthma and related respiratory problems from 1998 through 2001. METHODS A bilingual questionnaire assessing health care coverage, asthma diagnosis, respiratory symptoms, and use of medications was distributed to parents of 6235 public and private school children in grades 2 through 5 in Passaic, NJ. RESULTS Responses for 4380 children (70%) revealed disparities in health care coverage and asthma diagnosis among racial and ethnic groups. Mexican and Dominican children had significant increases in health care coverage over the 4 years. CONCLUSIONS The percentage of children with health insurance grew from 67% in 1998 to 81% in 2001, and the increase was related to NJ KidCare. Diagnosis of asthma and treatment were related to health care coverage.