Association between exposure to alkylbenzenes and cardiovascular disease among National Health and Nutrition Examination Survey (NHANES) participants.

Numerous studies have demonstrated that air pollution is associated with an increased risk of mortality and morbidity due to cardiovascular disease (CVD). Alkylbenzenes are ubiquitous in outdoor and indoor air environments. Yet few studies have evaluated the potential links between exposures to alkylbenzenes and CVD independent of tobacco smoking. In this study, we used the 1999-2004 National Health and Nutrition Examination Survey (NHANES) to examine the relationship between alkylbenzenes (toluene, styrene, ethylbenzene, and the xylenes) and CVD prevalence. All five alkylbenzenes suggested linear trends. Subjects in higher exposure categories of blood alkylbenzenes had higher prevalence of CVD, as compared to subjects in the reference group, of below the limit of detection (LOD) and less than the 50th percentile in the case of toluene and styrene. For the remainder of the alkylbenzes, similar statistically significant associations were observed. Further studies are needed to explore associations between these highly prevalent pollutants and CVD.

The effects of birthweight and breastfeeding on asthma among children aged 1-5 years.

AIM: Asthma is a major cause of morbidity and mortality among children and has steadily increased in prevalence. The combined effect of birthweight and breastfeeding on childhood asthma remains unclear. METHODS: In this study, we analysed a nationally representative sample of children aged 1-5 years from the National Health and Nutrition Examination Survey 1999-2002. Logistic regression was performed to examine the hypothesis whether birthweight and breastfeeding are independently associated with the prevalence of asthma after accounting for the complex sampling design. In addition, we sought to describe the relationship between birthweight and childhood asthma and to assess the potentially combined effect between birthweight and breastfeeding on asthma among children aged 1-5 years after considering the possible effects of social and environmental factors. RESULTS: We found that birthweight (measured continuously) was inversely and linearly associated with the prevalence of childhood asthma (odds ratio (OR) = 0.80 per 1 kg increase in birthweight, 95% confidence interval (CI): 0.65-0.98). Using a categorical variable, low birthweight (LBW) was positively associated with childhood asthma (OR = 1.28, 95% CI: 0.81-2.68). Furthermore, we detected an interaction between birthweight and breastfeeding on childhood asthma. Breastfeeding had a strong protective effect on asthma among children with high birthweight (OR = 0.14, 95% CI: 0.04-0.43) while it had no significant effect on asthma among children with normal birthweight or LBW. CONCLUSIONS: The mechanisms underlying these relationships remain uncertain and warrant further explanation.

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

The role of children's 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 children's hands were rinsed in isopropyl alcohol. Thus, only the chlorpyrifos that accumulated on and remained on the child's hands during the videotaping were removed for analysis after the videotaping session. The rinsate was analyzed for chlorpyrifos. The children's 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 children's use of house space during the videotaping sessions.

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

Children's 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 children's 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 R(2)=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 R(2)=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 R(2)=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.

Seasonal pesticide use in a rural community on the US/Mexico border.

An environmental measurement and correlation study of infant and toddler exposure to pesticides was carried out in a colonia south of the city of Laredo, Texas. As part of the study, homes were visited during the late spring or summer, and during the winter of 2000-2001. At each visit, families reported on their use of pesticides in and around the home and floor wipe samples were collected and analyzed for 14 organophosphate and triazine pesticides. Selection of homes was based on the presence of infants and toddlers. A total of 27 homes participated in both seasonal visits. The interval between visits was 6 +/- 1.4 months. Univariate and multivariate nonparametric analyses were carried out using SPSS statistical software. Pesticide use within the home was more often reported than outside use and showed seasonal variation in use patterns. Indoor use was primarily associated with ants and cockroaches, and secondarily with rodents. The primary room treated was the kitchen, and the primary structures treated were the floors, lower walls, and dish cupboards. Seasonal variations were not found in the use of pesticides used outside the home and outdoor use was primarily associated with ant control. Based on parent reports, most pesticides used in the homes were pyrethroids. Several of the pesticides measured in floor wipe samples, Azinphos methyl, Fonofos, and Simazine, also showed seasonal variations. However, these pesticides are used in agriculture and were not associated with reported house and yard use patterns.

Asthma and respiratory dysfunction among urban, primarily Hispanic school children.

A screening program identified children with poorly managed asthma or respiratory dysfunction. Children in grades 2-5 in all Passaic, New Jersey, schools were eligible for screening with questionnaires and a biometric test. Those with risk factors or failed biometric screening were referred to primary care providers. Of the 6,579 eligible children, 3,657 (56%) had parental questionnaires returned and 3,834 (58%) were biometrically screened. Over the 4-yr study period, 6-22% of children were previously diagnosed with asthma. Approximately 20% of children demonstrated peak flow measures <75% of predicted values. Predictors of a prior diagnosis of asthma and a medical treatment plan for asthma management were health care coverage and ethnicity. Predictors of peak flow test failure were the presence of roaches and mold in the home, pesticide use, and a family member with asthma.

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.

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

The Passaic Asthma Reduction Effort (PARE) 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 PARE 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.

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 children's exposure to environmental levels of organophosphate (OP) pesticides in the household. Samples were collected to measure levels of OP pesticides in housedust and on children's 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 cm(2) (mean=0.15 nmol/100 cm(2); median=0.07 nmol/100 cm(2)); total OP loadings on the children's hands ranged from nd to 13.40 nmol/100 cm(2) (mean=1.21 nmol/100 cm(2); median=1.41 nmol/100 cm(2)), 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 (r(2)=0.28; P=0.0156) with urinary levels of OP metabolites (pe=6.39; 95% CI 0.98-11.80). This study's 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.

Chapter one: exposure measurements.

Determining human exposure to suspended particulate concentrations requires measurements that quantify different particle properties in microenvironments where people live, work, and play. Particle mass, size, and chemical composition are important exposure variables, and these are typically measured with time-integrated samples on filters that are later submitted to laboratory analyses. This requires substantial sample handling, quality assurance, and data reduction. Newer technologies are being developed that allow in-situ, time-resolved measurements for mass, carbon, sulfate, nitrate, particle size, and other variables. These are large measurement systems that are more suitable for fixed monitoring sites than for personal applications. Human exposure studies need to be designed to accomplish specific objectives rather than to serve too many purposes. Resources need to be divided among study design, field sampling, laboratory analysis, quality assurance, data management, and data analysis phases. Many exposure projects allocated too little to the non-measurement activities.

Methods for collecting time/activity pattern information related to exposure to combustion products.

Focus groups, surveys and questionnaires, diaries and observations can be used to gather information about people's exposure to a wide range of combustion products. Information about locations and durations of exposure, and sources of exposure can be obtained with these instruments. The types of instruments used must be fine tuned to meet the design characteristics of the community in which the study will be conducted.

Dust: a metric for use in residential and building exposure assessment and source characterization.

In this review, we examine house dust and residential soil and their use for identifying sources and the quantifying levels of toxicants for the estimation of exposure. We answer critical questions that focus on the selection of samples or sampling strategies for collection and discuss areas of uncertainty and gaps in knowledge. We discuss the evolution of dust sampling with a special emphasis on work conducted after the publication of the 1992 review by McArthur [Appl Occup Environ Hyg 7(9):599-606 (1992)]. The approaches to sampling dust examined include surface wipe sampling, vacuum sampling, and other sampling approaches, including attic sampling. The metrics of presentation of results for toxicants in dust surface loading (micrograms per square centimeter) or surface concentration (micrograms per gram) are discussed. We evaluate these metrics in terms of how the information can be used in source characterization and in exposure characterization. We discuss the types of companion information on source use and household or personal activity patterns required to assess the significance of the dust exposure. The status and needs for wipe samplers, surface samplers, and vacuum samplers are summarized with some discussion on the strengths and weaknesses of each type of sampler. We also discuss needs for research and development and the current status of standardization. Case studies are provided to illustrate the use of house dust and residential soil in source characterization, forensic analyses, or human exposure assessment.