Biomarkers in paediatric research and practice

Associations among prenatal and postnatal arsenic, lead, and cadmium exposures and motor development in 3-year-old children: a longitudinal birth cohort study in Taiwan

Prenatal and postnatal exposures to heavy metals have been suggested to interfere with neurodevelopment, but the neurotoxicity of lead (Pb), arsenic (As), and cadmium (Cd) is still unclear. In this study, we aimed to assess the associations between the levels of As, Cd, and Pb and children's neurodevelopment. A total of 299 mother-infant pairs were recruited in this study and their meconium were collected. After three years, 53 children underwent the Bayley Scales of Infant and Toddler Development (Bayley-III) examinations and provided hair and fingernail specimens. The levels of As, Cd, and Pb in the meconium, hair, and fingernail were measured by inductively coupled plasma mass spectrometry; the median levels were the following: meconium, 42.7, 5.57, and 25.6 ng/g, respectively; hair, 0.19, 0.05, and 3.61 μg/g, respectively; and fingernail, 0.29, 0.04, and 0.84 μg/g, respectively. After adjusting for potential confounding factors, we found that the log-transformed levels of As in the hair samples was negatively associated with gross motor development (β =  - 0.032; 95% confidence interval: - 0.061 to - 0.004). We conclude that postnatal exposure to As is a crucial period for gross motor development in children, while the effects of Cd and Pb on neurodevelopment are less clear.

The Health Impacts of Hazardous Chemical Exposures among Child Labourers in Low- and Middle-Income Countries

Of 218 million working children worldwide, many are suspected to be exposed to hazardous chemicals. This review aims to synthesize reported evidence over the last two decades on chemical exposure and adverse health consequences in children labourers in low- and middle-income Countries (LMIC). Included studies investigated health outcomes related to chemical exposures among child labourers aged 5-18 in LMIC. Twenty-three papers were selected for review, focusing on pesticides (n = 5), solvents (n = 3), metals (n = 13) and persistent organic pollutants (POPs) (n = 2). Adverse health effects identified among child labourers included abnormal biomarkers, for example elevated blood and urine chemical concentrations, neurobehavioural deficits and neurological symptoms, mental health issues, oxidative stress and DNA damage, poor growth, asthma, and hypothyroidism. Workplace exposure to chemicals has pernicious health effects on child labourers. Large research gaps exist, in particular for long-term health impacts through chronic conditions and diseases with long latencies. A sizeable disease burden in later life is likely to be directly attributable to chemicals exposures. We urge national and international agencies concerned with child labour and occupational health, to prioritize research and interventions aiming to reduce noxious chemical exposures in workplaces where children are likely to be present.

Association between neighbourhood green space and biological markers in school-aged children. Findings from the Generation XXI birth cohort

BACKGROUND

There is considerable literature on the psychological and behavioural benefits of green space. However, less is known about its health-promoting effects, as expressed on biological markers. Additionally, incorporating biomarkers into pediatric research may help elucidate the links between exposures to environmental stressors and lifelong health.

OBJECTIVE

To measure the association between geographical accessibility to green spaces and allostatic load (AL), a measure of biological multi-system dysregulation.

METHODS

We used data from 3108 7-year old children enrolled in Generation XXI, a population-based birth cohort from the Porto Metropolitan Area (Portugal). We computed an AL index based on seven biomarkers representing four regulatory systems: immune/inflammatory system (high sensitivity C-reactive protein); metabolic system (high density lipoprotein; total cholesterol; glycated hemoglobin; waist-hip ratio) and cardiovascular system (systolic and diastolic blood pressure). Accessibility to green spaces was calculated using a Geographic Information System and crude and adjusted associations were estimated using mixed-effects regression models.

RESULTS

Among the 3108 children (51.7% male; mean age 87.3 months), the mean AL index was 0.00 (standard deviation 2.94). Adjusted models showed that having a green space within 400 m and 800 m from the child's school was inversely associated with AL (400 m: beta -0.29 95% CI -0.54 to -0.02; 800 m: -0.29 95% CI -0.51 to -0.07). Also, there was a 12% (0%; 23%) increase in the AL index for every 1 km increase in distance to the nearest green space. No significant associations with AL were observed with residential accessibility to green space or with the presence of a garden at home.

CONCLUSION

We found a cross-sectional negative association between accessibility to green space near schools and AL in children, suggesting that the provision of green space may contribute to improvements in population health beginning early in life.

Prenatal Tobacco Exposure Modulated the Association of Genetic variants with Diagnosed ADHD and its symptom domain in children: A Community Based Case-Control Study

The purpose of our study was to test the hypothesis that prenatal tobacco smoking exposure (PSE) could modulate the association of genetic variants with ADHD. A community based case-control study was conducted among Chinese children and 168 ADHD patients and 233 controls were recruited by using combination diagnosis of DSM-IV, SNAP-IV and semi-structured clinical interview. Logistic regression analysis was performed to estimate the effect of prenatal tobacco smoking exposure and genotype frequencies on ADHD susceptibility individually by adjustment for potential confounders. Multiplicative and additive interaction analysis were performed to evaluate the interactions between risk genes and PSE with regard to ADHD. Prenatal tobacco smoke exposure was a significant risk factor of ADHD even after adjusted for other potential confounders. ADRA2A rs553668, DRD2 rs1124491 and SLC6A4 rs6354 were identified to be associated with ADHD. A significant multiplicative and additive gene-environment interactions were observed between the PSE and the ADRA2A rs553668 in relation to ADHD and ADHD-ODD. The risk of the genetic variants in ADHD was increased significantly if the child had prenatal tobacco exposure. The genetic risk for ADHD could be influenced by the presence of environmental risks. The environmental and the genetic risks are not distinct to each other. More gene-environment interaction studies were needed to reveal the etiology of ADHD.

Toxicological importance of human biomonitoring of metallic and metalloid elements in different biological samples

Human biomonitoring has become an important tool for the assessment of internal doses of metallic and metalloid elements. These elements are of great significance because of their toxic properties and wide distribution in environmental compartments. Although blood and urine are the most used and accepted matrices for human biomonitoring, other non-conventional samples (saliva, placenta, meconium, hair, nails, teeth, breast milk) may have practical advantages and would provide additional information on health risk. Nevertheless, the analysis of these compounds in biological matrices other than blood and urine has not yet been accepted as a useful tool for biomonitoring. The validation of analytical procedures is absolutely necessary for a proper implementation of non-conventional samples in biomonitoring programs. However, the lack of reliable and useful analytical methodologies to assess exposure to metallic elements, and the potential interference of external contamination and variation in biological features of non-conventional samples are important limitations for setting health-based reference values. The influence of potential confounding factors on metallic concentration should always be considered. More research is needed to ascertain whether or not non-conventional matrices offer definitive advantages over the traditional samples and to broaden the available database for establishing worldwide accepted reference values in non-exposed populations.

The impact of toxins on the developing brain

The impact of toxins on the developing brain is usually subtle for an individual child, but the damage can be substantial at the population level. Numerous challenges must be addressed to definitively test the impact of toxins on brain development in children: We must quantify exposure using a biologic marker or pollutant; account for an ever-expanding set of potential confounders; identify critical windows of vulnerability; and repeatedly examine the association of biologic markers of toxins with intellectual abilities, behaviors, and brain function in distinct cohorts. Despite these challenges, numerous toxins have been implicated in the development of intellectual deficits and mental disorders in children. Yet, too little has been done to protect children from these ubiquitous but insidious toxins. The objective of this review is to provide an overview on the population impact of toxins on the developing brain and describe implications for public health.

The neurological effects of prenatal and postnatal mercury/methylmercury exposure on three-year-old children in Taiwan

This study attempts to elucidate the relationship between neurological effects and mercury/methylmercury concentrations in various biomarkers, including meconium, hair, fingernail, and toenail. Eight-three mother-infant pairs were recruited between August 2008 and December 2009, and follow-up examinations on these children were completed after three years. The Bayley Scales of Infant and Toddler Development (Bayley-III) for evaluating the cognitive, language, and motor development of three-year-old children were calculated and validated. The geometric mean of the total mercury concentration in meconium was 89.6 ng g(-1). The methylmercury concentrations in hair, fingernail, and toenail samples were 1.96, 0.64, and 0.55 μg g(-1), respectively. Seventy percent of children had hair methylmercury concentrations exceeding the U.S. environmental protection agency (EPA) reference of 1 μg g(-1). A significantly positive correlation was obtained between methylmercury levels in hair, fingernail, and toenail. These methylmercury levels were also significantly positively correlated with the children's fish intake and negatively correlated with a Bayley-III scale score of expressive language. The prenatal mercury exposure, however, did not show significant influence on neurological development. High fish consumption appears to be a critical risk factor for methylmercury levels in children and may cause a lower expressive language score.

Biomarkers of maternal diabetes and its complication in pregnancy

There are specific biomarkers - indicators of normal and abnormal processes - in diabetic pregnancies that predict the degree of diabetic control as well as embryonic and fetal growth and development. They can be detected in maternal blood, amniotic fluid or in the cord plasma of the newborn infant. While the cord plasma levels are of little clinical relevance because they do not allow us to interfere with the outcome of pregnancy, biomarkers in maternal blood or amniotic fluid may help us to better control the outcome of diabetic pregnancies. Important biomarkers in maternal blood are fasting glucose, HbA1c and IGFs. Relevant biomarkers in amniotic fluid are insulin, erythropoietin and markers of bone formation and resorption. Cord plasma biomarkers include IGFs, leptin, adiponectin, resistin, markers of oxidative stress and of hypoxia. Whether these biomarkers can be predictors of long term outcome in infants of diabetic mothers is yet to be determined.

Human exposure to heavy metals in the vicinity of Portuguese solid waste incinerators – Part 3: Biomonitoring of Pb in blood of children under the age of 6 years

As a part of environmental health surveillance programs related to Portuguese solid waste incinerators (SWI), two biomonitoring projects have been established to investigate additional exposure to lead in children under the age of 6 years living in the vicinity of those facilities. The above-mentioned programs, being the only ones in the country that integrate systematic observations on human exposure to heavy metals, have to provide systematic data from Portuguese regions on the extent and pattern of human exposure to heavy metals, namely to lead. The present paper is the third of a series of papers prepared to accomplish that objective in regards to lead exposure as evaluated by measuring lead levels in children under the age of 6 years. Altogether, 250 children from Lisbon and 247 from Madeira Island have already been involved in the investigation. The present study evaluates spatial and temporal trends of lead exposure, based on comparisons of children's blood lead levels, either stratified by living area (exposed and control groups), or by time of exposure (T0, the baseline time, and T1, after approximately 2 years of regular operation of the facilities). The results obtained correspond to a relatively reduced number of individuals. Possibly for this reason, they are not fully conclusive in relation to whether living in the vicinity of SWI represents an additional risk of higher exposure to lead. Time trends of lead exposure as evaluated by blood lead levels in children also do not show any clear pattern. These conclusions and the fact that altogether around 3% of children from the whole group have blood lead levels >or=10 microg/dl warrant further investigation in order to clarify the contribution of incinerator emissions to the levels of lead in children and to identify alternative sources for preventive purposes, taking into consideration the relevance of even low lead exposure from a public health perspective, mainly in relation to children.

Woman, alcohol and environment: Emerging risks for health

Alcohol drinking is one of the most relevant problems in Western Countries but the negative effects of alcohol misuse are often neglected or underestimated with serious consequences for public health. Over the last few years a rapid growth in the number of drinking females and the decrease of their age of first use, have increased the health risk for women and their offspring. Moreover, modern environments facilitate pollutants exposure, further escalating the health risks due to lifestyle habits. This review takes into account the peculiarities of alcohol effects on female health and the risks of teratogenic effects. The possible interaction between alcohol and pollutants exposure is also discussed. The role of biomarkers against alcohol-related damage is presented as an invaluable clinical tool, including early intervention, treatment monitoring and, above all, prevention of prenatal non-reversible damage. Recent alcohol studies show the greater severity of alcohol damage in female subjects and the need of gender-targeted intervention.