Children's Daily Exposure Research Articles

Association of screen exposure/sedentary behavior and precocious puberty/early puberty.

In recent years, with the development of society, children's daily exposure to screen time has gradually increased. Screen exposure and sedentary behavior have brought a host of harms to children's lives. The aim of this study was to explore the effects of screen exposure and sedentary behavior on precocious puberty and early development. This is a cross-sectional study in the school-based population. A total of 3,560 children were recruited from Qufu City, Shandong province using multistage stratified cluster random sampling. All study subjects had a physical examination by professional pediatricians in October 2019, and were investigated with health questionnaires. Precocious puberty is defined as development of secondary sexual signs in boys before 9 years or in girls before 8 years. Screen time was calculated as the average of screen time on weekdays and weekend days, and sedentary time was calculated as the average of sedentary time on weekdays and weekend days. After adjusting for potential confounders, logistic regression was used to examine the association between screen exposure and sedentary behavior and early puberty and precocious puberty. Sedentary time was a risk factor for precocious puberty and early development (OR = 1.428, 95% CI = 1.087-1.876) in girls without adjustment. No significant association was found between screen exposure and early puberty and early development both in girls and boys. Excessive sedentary behavior was associated with an increased risk of early puberty, especially in girls, while there was no significant association between screen exposure and early puberty and early development. In addition, further longitudinal investigations are needed to determine the causal relationship between screen exposure, sedentary behavior and precocious puberty.

Source Apportionment of Children Daily Exposure to Particulate Matter

Source Apportionment of Children Daily Exposure to Particulate Matter

Assessment of children's exposure to carbonaceous matter and to PM major and trace elements

Particulate matter (PM) pollution is one of the major environmental concerns due to its harmful effects on human health. As children are particularly vulnerable to particle exposure, this study integrates the concentration of PM chemical compounds measured in the micro-environments (MEs) where children spend most of their time to assess the daily exposure and inhaled dose. PM samples were analysed for organic and elemental carbon and for major and trace elements. Results showed that the MEs that contribute most to the children's daily exposure (80%) and inhaled dose (65%) were homes and schools. Results indicated that the high contribution of particulate organic matter (POM) indoors indicate high contributions of indoor sources to the organic fraction of the particles. The highest concentrations of PM chemical compounds and the highest Indoor/Outdoor ratios were measured in schools, where the contribution of mineral elements stands out due to the resuspension of dust caused by the students and to the chalk used in blackboards. The contribution of the outdoor particles to inhaled dose (24%) was higher than to the exposure (12%), due to the highest inhalation rates associated with the activities performed outdoor. This study indicates the importance of indoor air quality for the children's exposure and health.

Anti-androgenic compounds in breast milk and cryptorchidism among Norwegian boys in the HUMIS birth cohort

The prevalence of cryptorchidism has increased over the past decades, yet its origins remain poorly understood. Testis descent is dependent on androgens and likely affected by endocrine disrupting compounds (EDCs), targeting the androgen receptor (AR). We investigated the association between anti-androgenic activity, not derived from natural hormones, in maternal breast milk and impaired testis descent among boys. We performed a case-control study based on 199 breast milk samples from 94 mothers of cryptorchid boys and 105 random non-cryptorchid boys participating in the Norwegian HUMIS (Human Milk Study) cohort. For each participant, apolar, and polar fractions were extracted, and combined to reconstitute a mixture. Anti-androgenic activity was measured in all three fractions using the human cell-based in vitro anti-AR CALUX® assay and expressed in μg of flutamide equivalent, a well-known antiandrogen. Results from fraction analyses were compared among boys with cryptorchidism and controls using multiple logistic regression, controlling for appropriate confounders identified using a directed acyclic graph. Children's daily exposure to anti-androgenic EDCs through breastfeeding was estimated to 78 μg flutamide eq./kg of body weigh/day. The activity was higher in the polar fraction (1.48 ± 1.37 μg flutamide eq./g of milk) mainly representing non-persistent chemicals, in contrast to other fractions. However, the activity in the polar extracts was decreased when in mixtures with the apolar fraction, indicating synergistic interactions. No significant difference in the activity was observed according to cryptorchid status for polar, apolar or mixed breast milk fractions. The study showed anti-androgenic activity in nearly all human milk samples, and at levels higher than the advisory threshold. However, no significant association was observed between cryptorchidism and antiandrogenic activity measured in either polar, apolar, or mixture fractions derived from breast milk.

Semivolatile organic compounds in French schools: Partitioning between the gas phase, airborne particles and settled dust.

The indoor environmental quality in classrooms can largely affect children's daily exposure to indoor chemicals in schools. To date, there has not been a comprehensive study of the concentrations of semivolatile organic compounds (SVOCs) in French schools. Therefore, the French Observatory for Indoor Air Quality (OQAI) performed a field study of SVOCs in 308 nurseries and elementary schools between June 2013 and June 2017. The concentrations of 52 SVOCs, including phthalates, polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), synthetic musks, and pesticides, were measured in air and settled dust (40 SVOCs in both air and dust, 12 in either air or dust). The results showed that phthalates had the highest concentrations among the SVOCs in both the air and dust. Other SVOCs, including tributyl phosphate, fluorene, phenanthrene, gamma-hexachlorocyclohexane (gamma-HCH, lindane), galaxolide, and tonalide, also showed high concentrations in both the air and dust. Theoretical equations were developed to estimate the SVOC partitioning between the air and settled dust from either the octanol/air partition coefficient or the boiling point of the SVOCs. The regression constants of the equations were determined using the data set of the present study for phthalates and PAHs.

Is active travel a breath of fresh air? Examining children's exposure to air pollution during the school commute

The aim of this study was to assess how children's personal exposure to fine particulate matter (PM2.5) during the school commute is influenced by mode of travel and neighborhood environment in a mid-sized Canadian city. A total of 101 commutes to and from school were tracked using a GPS, and personal exposure to PM2.5 along commute routes was assessed by spatially-referencing the monitored exposure levels with time-synchronized GPS data. Students who walked to and from school were exposed to lower PM2.5 concentrations than those in cars or riding the school bus. There was also a significant difference in mean PM2.5 concentrations by the built environment, with children who walked to school in suburban neighborhoods experiencing higher personal concentrations than children in urban neighborhoods. To reduce children's daily exposure to air pollutants, neighborhoods should be designed to maximize the number of children who are able to walk between home and school.

Children's exposure to sized-fractioned particulate matter and black carbon in an urban environment

Fine air particulate matter (PM2.5) is currently one of the major environmental issues influencing people's health. The first step for assessing the health effects of inhaled PM2.5 is based on the evaluation of the human exposure levels. The main objective of this study is to quantify children's daily exposure to sized-fractioned PM2.5 and Black Carbon (BC) in an urban environment. Children from Lisbon metropolitan area carried portable monitoring equipment during three days and recorded the time spent in their activities and respective microenvironments (MEs). The average exposure to PM2.5 (19 μg/m3) was higher than that registered by the nearest fixed urban background station (11 μg/m3), evidencing the importance of assessing the personal daily exposure. The average exposure to PM1, PM0.5 and PM0.25 was 14 μg/m3, 11 μg/m3, and 7.7 μg/m3, respectively. Time-activity pattern records showed that children spent more than 80% of their time indoors, especially at home (55%) and in the classroom (22%), where they received 44% of the daily BC dose. Although commuting only accounted for 5.0% of the daily time, children inhaled 23% of their daily BC dose when travelling in rush hours to school. Time series analysis of the BC concentrations showed an average of 1.3 μg/m3, with high peak levels in underground parking lots (63 μg/m3), during charcoal grills (53 μg/m3), and when candles were burning (6.6 μg/m3). This work highlights the importance of urban planning to reduce children's exposure to traffic emissions, combined with awareness-raising actions for citizens concerning the impact of indoor sources.

Characteristics of elementary school children's daily exposure to black carbon (BC) in Korea

A daily black carbon (BC) exposure assessment of forty 10-12 years-old children was conducted in the Seoul Metropolitan Area from August 2015 to January 2016. Each participant carried a micro-aethalometer to measure BC concentrations for 24 h while their whereabouts and microenvironments (MEs) were recorded via a time-activity diary (TAD) and follow-up interviews. Analysis of variance (ANOVA) was employed to compare average BC levels by potential risk factors including demographic, temporal, residential, and indoor/outdoor/transportation activity variables. The children's average daily exposure was 1.93 μg/m3, with a range of 0.2–85.43 μg/m3 (mean daily individual exposure ranges from 0.54 to 4.80 μg/m3). Even children attending the same elementary school reported BC exposures which differed by approximately 40%, primarily because of individually distinct time-activity patterns and the MEs with which each child interacted. On weekends (Saturdays and Sundays) (1.86 ± 2.50 μg/m3) and holidays (Saturdays, Sundays, and vacation) (1.71 ± 2.48 μg/m3), children were subject to reduced exposures to BC, likely due to decreased surrounding traffic volumes and different time-activity patterns on weekend days compared to on weekdays (from Mondays to Fridays) (1.95 ± 2.44 μg/m3) or school days (weekdays during the school semesters) (2.05 ± 2.43 μg/m3). Commuting in diesel vehicles (often to private academies) or in the subway, cooking, and environmental tobacco smoke were all found to elevate BC exposure. Likewise, proximity to traffic sources and parental indoor smoking contributed to the enhancement of residential BC concentrations. Our findings suggested a need to emplace proactive measures including diesel fleet regulation and smoking cessation campaigns to protect children from high levels of BC exposure.

The socioeconomic gradient of secondhand smoke exposure in children: evidence from 26 low-income and middle-income countries

ObjectiveTo provide the first analysis of socioeconomic inequalities in children's daily exposure to indoor smoking in households in 26 low-income and middle-income countries (LMICs).MethodsWe used nationally representative household samples (n=369...

Children's daily exposure to polychlorinated biphenyls from dietary supplements containing fish oils

In children, omega-3 polyunsaturated fatty acids (PUFAs) may elicit a suite of health benefits including enhancement of cognitive development. Subsequently, dietary supplements containing omega-3 PUFAs have become increasingly popular. Often, the largest source of beneficial PUFAs in these supplements is fish oil, which may contain significant levels of contaminants such as polychlorinated biphenyls (PCBs). The objectives of this study were to evaluate congener-specific PCB concentrations in 13 over-the-counter children's dietary supplements containing fish oils/powders and assess potential PCB exposures through ingestion of these products on a daily basis. Every supplement analysed contained PCBs, with a mean concentration of 9 ± 8 ng PCBs/g supplement. When following serving size suggestions, mean daily exposure values ranged from 2.5 to 50.3 ng PCBs/day. Daily exposures for children's supplements were significantly lower than those previously reported for adult supplements and may be explained, in part, by the variability in the amount of fish oil (and PUFA content) in a serving size. Based on this study, factors such as fish oil purification methods (e.g., molecular distillation) and the trophic level of the fish species used to make the fish oil cannot be used as indicators of PCB levels within children's supplements. Fish supplements may decrease or increase daily PCB exposure compared with ingestion of fresh fish. However, eating fish high in omega-3 PUFAs and low in PCBs may reduce PCB exposure compared with daily supplementation with fish oils for some products studied.

Urban gardens: Lead exposure, recontamination mechanisms, and implications for remediation design

Environmental lead contamination is prevalent in urban areas where soil represents a significant sink and pathway of exposure. This study characterizes the speciation of lead that is relevant to local recontamination and to human exposure in the backyard gardens of Roxbury and Dorchester, MA, USA. One hundred forty-one backyard gardens were tested by X-ray fluorescence, and 81% of gardens have lead levels above the US EPA action limit of 400 μg/g. Raised gardening beds are the in situ exposure reduction method used in the communities to promote urban gardening. Raised beds were tested for lead and the results showed that the lead concentration increased from an initial range of 150±40 μg/g to an average of 336 μg/g over 4 years. The percent distribution of lead in the fine grain soil (<100 μm) and the trace metal signature of the raised beds support the conclusion that the mechanism of recontamination is wind-transported particles. Scanning electron microscopy and sequential extraction were used to characterize the speciation of lead, and the trace metal signature of the fine grain soil in both gardens and raised gardening beds is characteristic of lead-based paint. This study demonstrates that raised beds are a limited exposure reduction method and require maintenance to achieve exposure reduction goals. An exposure model was developed based on a suite of parameters that combine relevant values from the literature with site-specific quantification of exposure pathways. This model suggests that consumption of homegrown produce accounts for only 3% of children's daily exposure of lead while ingestion of fine grained soil (<100 μm) accounts for 82% of the daily exposure. This study indicates that urban lead remediation on a yard-by-yard scale requires constant maintenance and that remediation may need to occur on a neighborhood-wide scale.

Sources, Sinks, and Exposure Pathways of Lead in Urban Garden Soil

The chemistry of Pb in urban soil must be understood in order to limit human exposure to Pb in soil and produce and to implement remediation schemes. In inner-city gardens where Pb contamination is prevalent and financial resources are limited, it is critical to identify the variables that control Pb bioavailability. Field-portable X-ray fluorescence was used to measure Pb in 103 urban gardens in Roxbury and Dorchester, MA, and 88% were found to contain Pb above the USEPA reportable limit of 400 mug g(-1). Phosphorus, iron, loss on ignition, and pH data were collected, Pb-bearing phases were identified by X-ray diffraction, and Pb isotopes were measured using inductively coupled plasma mass spectrometry. Four test crops were grown both in situ and in Roxbury soil in a greenhouse, and plant tissue was analyzed for Pb uptake by polarized energy-dispersive X-ray fluorescence. Variation at the neighborhood scale in soil mineralogical and chemical characteristics suggests that the bioavailable fraction of Pb in gardens is site specific. Based on Pb isotope analysis, two historical Pb sources appear to dominate the inventory of Pb in Roxbury gardens: leaded gasoline ((207) Pb/(206) Pb = 0.827) and Pb-based paint ((207)Pb/(206) Pb = 0.867). Nearly 70% of the samples analyzed can be isotopically described by mixing these two end members, with Pb-based paint contributing 40 to 80% of the mass balance. A simplified urban human exposure model suggests that the consumption of produce from urban gardens is equivalent to approximately 10 to 25% of children's daily exposure from tap water. Furthermore, analysis of over 60 samples of plant tissue from the four test species suggests that in these urban gardens unamended phytoremediation is an inadequate tool for decreasing soil Pb.