Developmental effects of exposures to environmental factors: the Polish Mother and Child Cohort Study

Maternal suboptimal selenium intake and low-level lead exposure affect offspring's microglial immune profile and its reactivity to a subsequent inflammatory hit

Micronutrients such as selenium (Se) are essentials since prenatal life to support brain and cognitive development. Se deficiency, which affects up to 1 billion people worldwide, can interact with common adverse environmental challenges including (Pb), exacerbating their toxic effects. Exploiting our recently validated rat model of maternal Se restriction and developmental low Pb exposure, our aims were to investigate: (i) the early consequences of suboptimal Se intake and low-Pb exposure on neuroinflammation in neonates' whole brains; (ii) the potential priming effect of suboptimal Se and low-Pb exposure on offspring's glial reactivity to a further inflammatory hit. To these aims female rats were fed with suboptimal (0.04 mg/kg; Subopt) and optimal (0.15 mg/kg; Opt) Se dietary levels throughout pregnancy and lactation and exposed or not to environmentally relevant Pb dose in drinking water (12.5 µg/mL) since 4 weeks pre-mating. We found an overall higher basal expression of inflammatory markers in neonatal brains, as well as in purified microglia and organotypic hippocampal slice cultures, from the Subopt Se offspring. Subopt/Pb cultures were highly activated than Subopt cultures and showed a higher susceptibility to the inflammatory challenge lipopolysaccharide than cultures from the Opt groups. We demonstrate that even a mild Se deficiency and low-Pb exposure during brain development can influence the neuroinflammatory tone of microglia, exacerbate the toxic effects of Pb and prime microglial reactivity to subsequent inflammatory stimuli. These neuroinflammatory changes may be responsible, at least in part, for adverse neurodevelopmental outcomes.

Associations between Prenatal and Postnatal Exposure to Cannabis with Cognition and Behavior at Age 5 Years: The Healthy Start Study

BACKGROUND

Prenatal exposure to cannabis may influence childhood cognition and behavior, but the epidemiologic evidence is mixed. Even less is known about the potential impact of secondhand exposure to cannabis during early childhood.

OBJECTIVE

This study sought to assess whether prenatal and/or postnatal exposure to cannabis was associated with childhood cognition and behavior.

STUDY DESIGN

This sub-study included a convenience sample of 81 mother-child pairs from a Colorado-based cohort. Seven common cannabinoids (including delta 9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD)) and their metabolites were measured in maternal urine collected mid-gestation and child urine collected at age 5 years. Prenatal and postnatal exposure to cannabis was dichotomized as exposed (detection of any cannabinoid) and not exposed. Generalized linear models examined the associations between prenatal or postnatal exposure to cannabis with the NIH Toolbox and Child Behavior Checklist T-scores at age 5 years.

RESULTS

In this study, 7% (n = 6) of the children had prenatal exposure to cannabis and 12% (n = 10) had postnatal exposure to cannabis, with two children experiencing this exposure at both time points. The most common cannabinoid detected in pregnancy was Δ9-THC, whereas the most common cannabinoid detected in childhood was CBD. Postnatal exposure to cannabis was associated with more aggressive behavior (β: 3.2; 95% CI: 0.5, 5.9), attention deficit/hyperactivity problems (β: 8.0; 95% CI: 2.2, 13.7), and oppositional/defiant behaviors (β: 3.2; 95% CI: 0.2, 6.3), as well as less cognitive flexibility (β: -15.6; 95% CI: -30.0, -1.2) and weaker receptive language (β: -9.7; 95% CI: -19.2, -0.3). By contrast, prenatal exposure to cannabis was associated with fewer internalizing behaviors (mean difference: -10.2; 95% CI: -20.3, -0.2) and fewer somatic complaints (mean difference: -5.2, 95% CI: -9.8, -0.6).

CONCLUSIONS

Our study suggests that postnatal exposure to cannabis is associated with more behavioral and cognitive problems among 5-year-old children, independent of prenatal and postnatal exposure to tobacco. The potential risks of cannabis use (including smoking and vaping) during pregnancy and around young children should be more widely communicated to parents.

Impact of polycyclic aromatic hydrocarbon exposure on cognitive function and neurodegeneration in humans: A systematic review and meta-analysis

Introduction

This article documents an emerging body of evidence concerning the neurological effect of polycyclic aromatic hydrocarbon (PAH) exposure with regard to cognitive function and increased risk of neurodegeneration.

Methods

Two electronic databases, PubMed and Web of Science, were systematically searched.

Results

The 37/428 studies selected included outcomes measuring cognitive function, neurobehavioral symptoms of impaired cognition, and pathologies associated with neurodegeneration from pre-natal (21/37 studies), childhood (14/37 studies), and adult (8/37 studies) PAH exposure. Sufficient evidence was found surrounding pre-natal exposure negatively impacting child intelligence, mental development, average overall development, verbal IQ, and memory; externalizing, internalizing, anxious, and depressed behaviors; and behavioral development and child attentiveness. Evidence concerning exposure during childhood and as an adult was scarce and highly heterogeneous; however, the presence of neurodegenerative biomarkers and increased concentrations of cryptic "self" antigens in serum and cerebrospinal fluid samples suggest a higher risk of neurodegenerative disease. Associations with lowered cognitive ability and impaired attentiveness were found in children and memory disturbances, specifically auditory memory, verbal learning, and general memory in adults.

Discussion

Although evidence is not yet conclusive and further research is needed, the studies included supported the hypothesis that PAH exposure negatively impacts cognitive function and increases the risk of neurodegeneration in humans, and recommends considering the introduction of a variable "rural vs. urban" as covariate for adjusting analyses, where the neurological functions affected (as result of our review) are outcome variables.

REPRO_PL-Polish Mother and Child Cohort-Exposure, Health Status, and Neurobehavioral Assessments in Adolescents-Design and Cohort Update

Early life is a crucial window of opportunity to improve health across the life course. The prospective cohort study design is the most adequate to evaluate the longitudinal effects of exposure, the notification of changes in the exposure level and evaluation of the simultaneous impact of various exposures, as well as the assessment of several health effects and trajectories throughout childhood and adolescence. This paper provides an overview of the Polish Mother and Child cohort (REPRO_PL), with particular emphasis on Phase IV of this study. REPRO_PL is conducted in central Europe, where such longitudinal studies are less frequently implemented. In this population-based prospective cohort, which was established in 2007, three phases covering pregnancy (I), early childhood (II), and early school age (III) periods have already been completed. Phase IV gives a uniform opportunity to follow-up children during adolescence in order to evaluate if the consequences of prenatal and early postnatal exposures still persist at the age of 14. Moreover, we will be able to investigate the associations between simultaneous exposures to a broad spectrum of environmental factors, adolescents' health and neurobehavioral outcomes, and their trajectories within life, which is a novel framework of high scientific, public health and clinical priority.

In-utero exposure to indoor air pollution or tobacco smoke and cognitive development in a South African birth cohort study

BACKGROUND AND AIMS

There is increasing evidence indicating that air pollution exposure is associated with neuronal damage. Since pregnancy is a critical window of vulnerability, air pollution exposure during this period could have adverse effects on neurodevelopment. This study aims 1) to analyze associations of prenatal exposure to indoor air pollution (particulate matter with diameters ≤10 μm, PM10) and tobacco smoke with neurodevelopment and 2) to determine whether these associations are mediated by deviations of epigenetic gestational age from chronological gestational age (ΔGA).

METHODS

Data of 734 children from the South African Drakenstein Child Health Study were analyzed. Prenatal PM10 exposure was measured using devices placed in the families' homes. Maternal smoking during pregnancy was determined by maternal urine cotinine measures. The Bayley Scales of Infant and Toddler Development III (BSID-III) was used to measure cognition, language and motor development and adaptive behavior at two years of age. Linear regression models adjusted for maternal age, gestational age, sex of child, ancestry, birth weight/length, and socioeconomic status were used to explore associations between air pollutants and BSID-III scores. A mediation analysis was conducted to analyze if these associations were mediated by ΔGA using DNA methylation measurements from cord blood.

RESULTS

An increase of one interquartile range in natural-log transformed PM10 (lnPM10; 1.58 μg/m3) was significantly associated with lower composite scores in cognition, language, and adaptive behavior sub-scores (composite score β-estimate [95%-confidence interval]: -0.950 [-1.821, -0.120]). Maternal smoking was significantly associated with lower adaptive behavior scores (-3.386 [-5.632, -1.139]). Associations were not significantly mediated by ΔGA (e.g., for PM10 and cognition, proportion mediated [p-value]: 4% [0.52]).

CONCLUSION

We found an association of prenatal exposure to indoor air pollution (PM10) and tobacco smoke on neurodevelopment at two years of age, particularly cognition, language, and adaptive behavior. Further research is needed to understand underlying biological mediators.

Prenatal exposure to neurotoxic metals and micronutrients and neurodevelopmental outcomes in early school age children from Poland

Exposure to environmental factors, such as neurotoxic metals and micronutrients, during critical periods of development can contribute to long-term consequences in offspring's health, including neurodevelopmental outcomes. The aim of this study was to evaluate the association between simultaneous prenatal exposure to metals [lead (Pb), cadmium (Cd), mercury (Hg)] and micronutrients [selenium (Se), zinc (Zn), copper (Cu)] and neurodevelopmental outcomes in school-age children from the Polish Mother and Child Cohort (REPRO_PL). Metals and micronutrients concentrations were measured in cord blood (Pb, Cd, Se, Zn, Cu) and in maternal hair (Hg) collected during the 3rd trimester of pregnancy. Behavioral and emotional problems, as well as children's cognitive and psychomotor development, were assessed in 436 school-age children using the Strengths and Difficulties Questionnaire (SDQ, filled in by the mothers) and the Polish adaptation of the Intelligence and Development Scales (IDS, administered by trained psychologists). Multivariate regression models were applied after imputation of missing values, using two approaches: (i) a joint analysis taking into account all metals and micronutrients simultaneously, and (ii) an ExWAS study (single-exposure model). In the SDQ, Hyperactivity/Inattention problems and Total difficulties were associated with higher Hg concentrations in maternal hair (0.18, 95% CI: 0.05; 0.3; and 0.14, 95% CI: 0.01; 0.3, respectively), whereas Emotional symptoms were inversely associated with Se and Zn levels in cord blood (-0.13, 95% CI: -0.3; 0.004; and -0.10, 95% CI: -0.2; 0.02, respectively). In the IDS, cord blood Pb levels were found to be negatively associated with Fluid and Crystallized IQ (-0.12, 95% CI: -0.3; 0.02; and -0.14, 95% CI: -0.3; 0.007, respectively) as well as Mathematical skills (-0.15, 95% CI: -0.3; 0.01). The current research has been able to simultaneously assess the exposure to various interacting chemicals during the prenatal period. We demonstrate that prenatal co-exposures to Pb, Hg, Zn and Se have long-term influences on the neuropsychological outcome of school-age children.

Prenatal Mercury Exposure and Neurodevelopment up to the Age of 5 Years: A Systematic Review

Neurodevelopmental delays can interfere with children’s engagement with the world and further development, and may have negative consequences into adulthood. Mercury is highly toxic and may negatively influence neurodevelopment because it can freely cross the placenta and accumulate in the fetal brain. We searched four publication databases (Embase, PsycINFO, PubMed/MEDLINE, Scopus) for studies examining the relationship between early life mercury exposure and scores on neurodevelopmental performance measures in children aged 0 to 5 years old. Study quality was assessed using the National Institutes of Health (NIH) Quality Assessment Tool. Thirty-two prospective studies were included in the review. Neurodevelopmental performance was measured using 23 different scales, most commonly the Bayley Scales of Infant and Toddler Development (BSID). In most cases, the evidence for an association between mercury and neurodevelopment was weak. There did not appear to be exceptions for particular childhood ages, outcome scales, or mercury levels. The small number of results to the contrary were more likely to be studies which did not meet our high-quality criteria, and could be a consequence of multiple testing, selection bias, or incomplete confounder adjustment. Based on current evidence, dietary mercury exposure during pregnancy is unlikely to be a risk factor for low neurodevelopmental functioning in early childhood.

Association between tobacco and/or alcohol consumption during pregnancy and infant development: BRISA Cohort

Fetuses exposed to alcohol and/or tobacco are at risk for perinatal adversities. However, little is currently known about the association of the separate or concomitant use of alcohol and tobacco with infant motor and cognitive development. Thus, the objective of the present study was to investigate the association between maternal consumption of alcohol and/or tobacco during pregnancy and the motor and cognitive development of children starting from the second year of life. The study included 1006 children of a cohort started during the prenatal period (22-25 weeks of pregnancy), evaluated at birth and reevaluated during the second year of life in 2011/2013. The children were divided into four groups according to the alcohol and/or tobacco consumption reported by their mothers at childbirth: no consumption (NC), separate alcohol consumption (AC), separate tobacco consumption (TC), and concomitant use of both (ACTC). The Bayley Scale of Infant and Toddler Development Third Edition screening tool was used for the assessment of motor and cognitive development. Adjusted Poisson regression models were used to determine the association between groups and delayed development. The results indicated that only the ACTC group showed a higher risk of motor delay, specifically regarding fine motor skills, compared to the NC group (RR=2.81; 95%CI: 1.65; 4.77). Separate alcohol or tobacco consumption was not associated with delayed gross motor or cognitive development. However, the concomitant use of the two substances increased the risk of delayed acquisition of fine motor skills.

Maternal health behaviors during pregnancy in rural Northwestern China

Background

Maternal health during pregnancy is a key input in fetal health and child development. This study aims to systematically describe the health behaviors of pregnant women in rural China and identify which subgroups of women are more likely to engage in unhealthy behaviors during pregnancy.

Methods

We surveyed 1088 pregnant women in rural northwestern China on exposure to unhealthy substances, nutritional behaviors, the timing and frequency of antenatal care, and demographic characteristics.

Results

Pregnant women were active in seeking antenatal care and had low rates of alcohol consumption (5.1%), exposure to toxins (4.8%), and exposure to radiation (2.9%). However, tobacco exposure was widespread (40.3%), as was low dietary diversity (61.8%), unhealthy weight gain (59.7%), unhealthy pre-pregnancy BMI (29.7%), and no folic acid intake (17.1%). Maternal education is closely linked to better health behaviors, whereas experience with a previous pregnancy is not.

Conclusions

Tobacco exposure and unhealthy nutritional behaviors are common among pregnant women in rural northwestern China. The findings indicate that in the absence of professional health information, relying on experience of previous pregnancies alone may not help rural women avoid unhealthy maternal behaviors. Maternal health education campaigns targeting nutrition and tobacco exposure during pregnancy may improve maternal, fetal, and child health in rural China.

Adapting the Ages and Stages Questionnaire to Identify and Quantify Development Among Children With Evidence of Zika Infection

This article describes novel methods of applying the Ages and Stages Questionnaire-3rd edition (ASQ-3) to assess and quantify developmental delay among children following the 2015-2016 Zika virus outbreak in Brazil. Many of the children with Zika virus infection were expected to have severe developmental delay. However, administering the ASQ-3 to caregivers of these children according to standard protocol would have screened for the overall presence of delay but not the severity of delay. We adopted an amended protocol for administration of the ASQ-3 to quantify the developmental functioning of children severely affected by Zika virus infection in this investigation. Protocols for administering the ASQ-3 among this population were drafted in consultation with developmental measurement experts and are presented here. Specific developmental estimates are discussed, including developmental age equivalents, developmental quotients, and developmental quotient z scores. The calculations of these estimates are presented with examples in the context of the 2015-2016 Zika virus outbreak and associated microcephaly among prenatally infected children from 2 states in northeastern Brazil. Potential applications of these methods for estimating developmental ability among similar pediatric populations are discussed.

Prenatal Exposure to Tobacco and Offspring Neurocognitive Development in the Healthy Start Study

OBJECTIVE

To explore the associations between prenatal exposure to tobacco and neurocognitive development, in the absence of prematurity or low birth weight.

STUDY DESIGN

We followed mother-child pairs within Healthy Start through 6 years of age. Children were born at ≥37 weeks of gestation with a birth weight of ≥2500 g. Parents completed the Third Edition Ages and Stages Questionnaire (n = 246) and children completed a subset of the National Institutes of Health Toolbox Cognition Battery (n = 200). The Ages and Stages Questionnaire domains were dichotomized as fail/monitor and pass. Maternal urinary cotinine was measured at approximately 27 weeks of gestation. Separate logistic regression models estimated associations between prenatal exposure to tobacco (cotinine below vs above the limit of detection) and the Ages and Stages Questionnaire domains. Separate linear regression models estimated associations between prenatal exposure to tobacco and fully corrected T-scores for inhibitory control, cognitive flexibility, and receptive language, as assessed by the National Institutes of Health Toolbox. A priori covariates included sex, maternal age, maternal education, daily caloric intake during pregnancy, race/ethnicity, household income, maternal psychiatric disorders, and, in secondary models, postnatal exposure to tobacco.

RESULTS

Compared with unexposed offspring, exposed offspring were more likely to receive a fail/monitor score for fine motor skills (OR, 3.9; 95% CI, 1.5-10.3) and decreased inhibitory control (B: -3.0; 95% CI, -6.1 to -0.7). After adjusting for postnatal exposure, only the association with fine motor skills persisted.

CONCLUSIONS

Prenatal and postnatal exposures to tobacco may influence neurocognitive development, in the absence of preterm delivery or low birth weight. Increased developmental screening may be warranted for exposed children.

Pregnancy exposome and child psychomotor development in three European birth cohorts

Characterization of the exposome, the totality of all environmental factors that one is exposed to from conception onwards, has been recommended to better evaluate the role of environmental influences on developmental programming and life-course vulnerability to major chronic diseases. In the framework of the Health and Environment-wide Associations based on Large population Surveys (HEALS) project we considered the pregnancy exposome exploiting two databases (PHIME and REPRO_PL) that include birth cohorts from three EU countries (Croatia, Slovenia and Poland). The databases contained information on several chemical exposures, socio-demographic, lifestyle and health related factors from conception to child birth, and neuropsychological scores assessed by the Bayley Scales of Infant and Toddler Development in the first two years of life. Our main goal was to assess consistency of environmental influences on neurodevelopment, if any, across European countries differing for geographical, socio-demographic characteristics and levels of chemical exposures to metals such as lead (Pb), mercury (Hg), cadmium (Cd) and trace elements, including micronutrients such as zinc (Zn) and selenium (Se). To this aim, we first selected variables common to the different databases, then applied univariate and multivariate regression analyses to identify factors linked to neurodevelopment, and finally performed meta-analysis to detect potential heterogeneity among cohorts and pooled estimates. Significant differences in exposure levels among the three sub-cohorts were observed as for Hg and Se; exposure levels under study were relatively low and within the range described in existing EU biomonitoring studies. The univariate analyses did not show any common pattern of association as only in the Polish cohort chemical exposure had an impact on neuropsychological outcome. In the meta-analysis, some consistent trends were evident, relative to the adverse influence of Pb on children's language and cognition and the positive influence of Se on language abilities. The effects of the neurotoxic metal Hg positively influenced the motor scores in the Polish cohorts, while it decreased the motor scores in the Slovenia and Croatian sub-cohorts. The only socio-demographic factor consistently associated to the outcome among cohorts was child's sex, with females performing better than males on cognitive and language scores. These findings point to the need of harmonizing existing cohorts or creating prospective study designs that facilitate comparisons in the exposome over time, places and kind of environmental exposures.

Prenatal Exposure to Environmental Tobacco Smoke and Early Development of Children in Rural Guizhou Province, China

BACKGROUND

There is a substantial body of evidence supporting the association between maternal active smoking during pregnancy and child development, but the association between prenatal exposure to environmental tobacco smoke (ETS) and early child development has not been well documented. This cross-sectional study examines the association between prenatal exposure to ETS and the development of children in their first two years of life.

METHODS

We interviewed the primary caregivers of 446 children under two years old in rural Guizhou Province, China. Based on self-reported assessments about whether the mother was exposed to ETS during pregnancy, we divided the children into the ETS-exposed group or the non-exposed group. Sociodemographic information was collected through a questionnaire. The cognitive, language, motor, and socioemotional abilities of children were assessed using the Bayley Scales of Infant Development III (BSID-III). A multivariate linear regression model adjusting for confounding variables was used to estimate the association of interest.

RESULTS

About 60% of mothers experienced ETS exposure during pregnancy. Cognitive and language scores were lower among children in the ETS-exposed group. When adjusting for characteristics of the child, the mother, the household, and village fixed effects, prenatal exposure to ETS was associated with lower cognition scores (-3.41; 95% confidence interval (CI): -6.39 to -0.42; p = 0.03) and language scores (-3.01; 95% CI: -5.39 to -0.09; p = 0.04). Frequency of prenatal exposure to ETS was also negatively associated with language development (-0.48; 95% CI: -0.87 to -0.09; p = 0.02) before children reached two years old.

CONCLUSIONS

Prenatal exposure to ETS is negatively associated with the cognitive and language development of rural young children within their first two years of life. The government should take action to raise public awareness about the negative effects of tobacco use, with an emphasis on the protection of pregnant women and their children, in order to carry through comprehensive smoke-free laws in rural areas, while also increasing tobacco taxation.

Biomarkers of Exposure to Secondhand and Thirdhand Tobacco Smoke: Recent Advances and Future Perspectives

Smoking is the leading preventable disease worldwide and passive smoking is estimated to be the cause of about 1.0% of worldwide mortality. The determination of tobacco smoke biomarkers in human biological matrices is key to assess the health effects related to the exposure to environmental tobacco smoke. The biomonitoring of cotinine, the main nicotine metabolite, in human biofluids-including urine, serum or saliva-has been extensively used to assess this exposure. However, the simultaneous determination of cotinine together with other tobacco biomarkers and the selection of alternative biological matrices, such as hair, skin or exhaled breath, would enable a better characterization of the kind and extent of tobacco exposure. This review aims to perform a critical analysis of the up-to-date literature focused on the simultaneous determination of multiple tobacco smoke biomarkers studied in different biological matrices, due to the exposure to secondhand smoke (SHS) and thirdhand smoke (THS). Target biomarkers included both tobacco-specific biomarkers-nicotine and tobacco specific nitrosamine biomarkers-and tobacco-related biomarkers, such as those from polycyclic aromatic hydrocarbons, volatile organic compounds, metals and carbon monoxide. To conclude, we discuss the suitability of determining multiple biomarkers through several relevant examples of SHS and THS exposure.

Multiple low-level exposures: Hg interactions with co-occurring neurotoxic substances in early life

All chemical forms of Hg can affect neurodevelopment; however, low levels of organic Hg (methylmercury-MeHg and ethylmercury-EtHg in Thimerosal-containing vaccines, hereafter 'TCV') exposures during early life (pregnancy and lactation) co-occur with other environmental neurotoxic substances. These neurotoxicants may act in parallel, synergistically, or antagonistically to Hg. Nevertheless, the risks of neurotoxicity associated with multiple neuro-toxicants depend on type, time, combinations of exposure, and environmental and/or genetic-associated factors. Neurological developmental disorders, delays in cognition and behavioral outcomes associated with multiple exposures (which include Hg) may show transient or lasting outcomes depending on constitutional and/or environmental factors that can interact to neutralize, aggravate or attenuate these effects; often these studies are challenging to interpret. During pregnancy and lactation, fish-MeHg exposure is frequently confounded with the opposing effects of neuroactive nutrients (in fish) that lead to positive, negative, or no effects on neurobehavioral tests. In infancy, exposures to acute binary mixtures (TCV- EtHg and Al-adjuvants in infant immunizations) are associated with increased risks of tics and other developmental disorders. Despite the certitude that promulgates single environmental neurotoxicants, empirical comparisons of combined exposures indicate that Hg-related outcome is uneven. Hg in combination with other neurotoxic mixtures may elevate risks of neurotoxicity, but these risks arise in circumstances that are not yet predictable. Therefore, to achieve the goals of the Minamata treaty and to safeguard the health of children, low levels of mercury exposure (in any chemical form) needs to be further reduced whether the source is environmental (air- and food-borne) or iatrogenic (pediatric TCVs).

Sex-Dependent Impact of Low-Level Lead Exposure during Prenatal Period on Child Psychomotor Functions

The impact of exposure to lead on child neurodevelopment has been well established. However, sex differences in vulnerability are still not fully explained. We aimed at evaluating the effect of a low-level lead exposure, as measured between 20 to 24 weeks of pregnancy and in cord blood, on developmental scores up to 24 months of age in 402 children from the Polish Mother and Child Cohort (REPRO_PL). Additionally, sex-dependent susceptibility to lead at this very early stage of psychomotor development was assessed. The blood lead levels were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). In order to estimate the children’s neurodevelopment, the Bayley Scales of Infant and Toddler Development was applied. The geometric mean (GM) for blood lead level during 20–24 weeks of pregnancy was 0.99 ± 0.15 µg/dL and, in the cord blood, it was 0.96 ± 0.16 µg/dL. There was no statistically significant impact of lead exposure during prenatal period on the girls’ psychomotor abilities. Among the boys, we observed lower scores for cognitive functions, along with increasing cord blood lead levels (β = −2.07; p = 0.04), whereas the results for the language and motor abilities were not statistically significant (p > 0.05). Our findings show that fetal exposure to very low lead levels might affect early cognitive domain, with boys being more susceptible than girls. Education on health, higher public awareness, as well as intervention programs, along with relevant regulations, are still needed to reduce risks for the vulnerable population subgroups.

Prenatal exposure to environmental pollutants and child development trajectories through 7 years

BACKGROUND

Prenatal exposure to environmental pollutants such as mold, lead, pesticides, tobacco, and air pollutants has been suggested to impair cognitive development. Evidence is needed from longitudinal studies to understand their joint impact on child development across time.

OBJECTIVE

To study associations between exposure to indoor environmental pollutants or outdoor air pollution during pregnancy and offspring cognitive development trajectories through 7 years.

METHODS

We included 718 Mexican mother-child pairs. Prenatal exposure to indoor environmental pollutants (mold, ventilation, pesticides, tobacco smoke, and use of vidiartred clay pots) was self-reported by the mothers and integrated into an index, or objectively measured in the case of outdoor air pollutants (nitrogen oxides, benzene, toluene, and xylene). Child global cognitive development was measured at 12, 18, 60, or 84 months. Using Latent Class Growth Analysis, we identified three developmental trajectories (positive = 108, average = 362, low = 248). We used multinomial logistic models to test associations between environmental pollutant score (EPS) or outdoor air pollutants, and cognitive development trajectories.

RESULTS

After adjustment for sociodemographic covariates, EPS was associated with the average (OR = 1.26 95%CI = 1.01, 1.55) and low (OR = 1.41 95%CI = 1.11, 1.79) trajectories compared to positive; where a unit increase in EPS means an additional prenatal exposure to a pollutant. There was no association between outdoor air pollutants and cognitive development trajectories.

CONCLUSION

Children of women who reported higher exposure to indoor environmental pollutants during pregnancy were more likely to follow worse developmental trajectories through 7 years. These results support the development and testing of interventions to reduce exposure to environmental pollutants during pregnancy and early childhood as a potential strategy to improve long-term cognitive development.

Environmental Tobacco Smoke Exposure during Pregnancy and Child Neurodevelopment

The developing fetus is especially vulnerable to environmental toxicants, including tobacco constituents. The aim of this study was to assess the impact of environmental tobacco smoke (ETS) exposure during pregnancy on child neurodevelopment within the first two years of life. The study population consisted of 461 non-smoking pregnant women (saliva cotinine level <10 ng/mL). Maternal passive smoking was assessed based on the cotinine level in saliva analyzed by the use of high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-ESI + MS/MS) and by questionnaire data. The cotinine cut-off value for passive smoking was established at 1.5 ng/mL (sensitivity 63%, specificity 71%). Psychomotor development was assessed in children at the age of one- and two-years using the Bayley Scales of Infant and Toddler Development. Approximately 30% of the women were exposed to ETS during pregnancy. The multivariate linear regression model indicated that ETS exposure in the 1st and the 2nd trimesters of pregnancy were associated with decreasing child language functions at the age of one (β = −3.0, p = 0.03, and β = −4.1, p = 0.008, respectively), and two years (β = −3.8, p = 0.05, and β = −6.3, p = 0.005, respectively). A negative association was found for cotinine level ≥1.5 ng/mL in the 2nd trimester of pregnancy and child cognition at the age of 2 (β = −4.6, p = 0.05), as well as cotinine levels ≥1.5 ng/mL in all trimesters of pregnancy and child motor abilities at two years of age (β = −3.9, p = 0.06, β = −5.3, p = 0.02, and β = −4.2, p = 0.05, for the 1st, the 2nd, and the 3rd trimester of pregnancy, respectively; for the 1st trimester the effect was of borderline statistical significance). This study confirmed that ETS exposure during pregnancy can have a negative impact on child psychomotor development within the first two years of life and underscore the importance of public health interventions aiming at reducing this exposure.

Maternal stress during pregnancy and neurodevelopmental outcomes of children during the first 2 years of life

AIM

A growing body of literature documents associations between maternal stress in pregnancy and child development, but findings across studies are often inconsistent. The aim of this study was to estimate the association between exposure to different kinds of prenatal stress and child psychomotor development.

METHODS

The study population consisted of 372 mother-child pairs from Polish Mother and Child Cohort. The analysis was restricted to the women who worked at least 1 month during pregnancy period. Maternal psychological stress during pregnancy was assessed based on: the Subjective Work Characteristics Questionnaire, Perceived Stress Scale and Social Readjustment Rating Scale. The level of satisfaction with family functioning and support was evaluated by APGAR Family Scale. Child psychomotor development was assessed at the 12th and 24th months of age by Bayley Scales of Infant and Toddler Development.

RESULTS

Negative impact on child cognitive development at the age of two was observed for the Perceived Stress Scale (β = -0.8; P = 0.01) and the Social Readjustment Rating Scale (β = -0.4; P = 0.03) after adjusting for the variety of confounders. Occupational stress, as well as satisfaction with family functioning, was not significantly associated with child psychomotor development (P > 0.05).

CONCLUSIONS

The study supports the findings that prenatal exposure to maternal stress is significantly associated with decreased child cognitive functions. In order to further understand and quantify the effects of prenatal stress on child neurodevelopment further studies are needed. This will be important for developing interventions that provide more assistance to pregnant women, including emotional support or help to manage psychological stress.

Current progress on understanding the impact of mercury on human health

Mercury pollution and its impacts on human health is of global concern. The authors of this paper were members of the Plenary Panel on Human Health in the 12th International Conference on Mercury as a Global Pollutant held in Korea in June 2015. The Panel was asked by the conference organizers to address two questions: what is the current understanding of the impacts of mercury exposure on human health and what information is needed to evaluate the effectiveness of the Minamata Convention in lowering exposure and preventing adverse effects. The authors conducted a critical review of the literature published since January 2012 and discussed the current state-of-knowledge in the following areas: environmental exposure and/or risk assessment; kinetics and biomonitoring; effects on children development; effects on adult general populations; effects on artisanal and small-scale gold miners (ASGM); effects on dental workers; risk of ethylmercury in thimerosal-containing vaccines; interactions with nutrients; genetic determinants and; risk communication and management. Knowledge gaps in each area were identified and recommendations for future research were made. The Panel concluded that more knowledge synthesis efforts are needed to translate the research results into management tools for health professionals and policy makers.

Selenium status during pregnancy and child psychomotor development-Polish Mother and Child Cohort study

BACKGROUND

The studies on the impact of selenium (Se) levels in different pregnancy periods on child psychomotor functions are limited. The aim of this study was to evaluate the impact of prenatal Se on child neurodevelopment.

METHODS

The study population consisted of 410 mother-child pairs from Polish Mother and Child Cohort. Se levels were measured in each trimester of pregnancy, at delivery, and in cord blood by graphite furnace atomic absorption spectrometry. Psychomotor development was assessed in children at the age of 1 and 2 y using the Bayley Scales of Infant and Toddler Development.

RESULTS

Plasma Se levels decreased through pregnancy (from 48.3 ± 10.6 µg/l in the first trimester to 38.4 ± 11.8 µg/l at delivery; P < 0.05). A statistically significant positive association between Se levels in the first trimester of pregnancy and motor development (β = 0.2, P = 0.002) at 1 y of age, and language development (β = 0.2, P = 0.03) at 2 y of age was observed. The positive effect of Se levels on cognitive score at 2 y of age was of borderline significance (β = 0.2, P = 0.05).

CONCLUSION

Prenatal selenium status was associated with child psychomotor abilities within the first years of life. Further epidemiological and preclinical studies are needed to confirm the association and elucidate the underlying mechanisms of these effects.

The extent of mercury (Hg) exposure among Saudi mothers and their respective infants

A total of 1016 healthy Saudi mothers and their respective infants (aged 3-12 months) were recruited from 57 Primary Health Care Centers (PHCCs) in Riyadh, Saudi Arabia, to evaluate the extent of mercury (Hg) exposure and predict its sources in the healthy Saudi population. Total Hg levels were measured in maternal urine, breast milk, blood, and hair and in the infants' urine and hair. Only 1.9% of the mothers had urinary Hg (UHg)>10 μg/l, the limit for asymptomatic adults recommended by the World Health Organization, but the median (0.99 μg/l) was higher than in other countries. Also, 49.3% of the mothers had UHg>1 μg/l, the German reference value for adults. Median infant UHg was 0.729 μg/l, and 77 and 93 % of the infants had levels higher than 0.4 and 0.1 μg/l, the reference values of the Centers for Disease Control and Prevention and for Germany, respectively. The median Hg level in breast milk was 0.884 μg/l. Even though 43.2% of the milk samples were above the background level for Hg in human milk (1 μg/l), our results were lower than those reported from other countries. Median maternal total Hg in blood was 0.637 μg/l, and only 0.4 and 6.9% of samples were higher than the Hg reference levels of 5.8 μg/l of the Environmental Protection Agency (EPA) and of 2 μg/l for Germany, respectively. Total Hg levels in hair (HHg) varied widely among mothers and infants, but only 3.9% of the mothers and 2.8% of the infants had HHg>1 μg/g (the EPA reference level). Median HHg values were 0.117 μg/g dry weight in mothers and 0.1 μg/g dry weight in infants; both were lower than in other countries. The Hg levels in mothers and their respective infants were relatively low, but our results were consistent with other studies indicating that dental amalgam fillings and fish consumption were the main predictors of maternal Hg exposure. Among the several biomarkers of Hg exposure, Hg levels in maternal hair and urine were the strongest predictors of infant exposure. The lack of an association between Hg in breast milk and Hg in infant urine and hair suggested that the infants were exposed to Hg predominately during pregnancy rather than during breastfeeding. We expect that our data can serve as a baseline for further biomonitoring and follow-up studies, particularly of the long-term impact of Hg on childhood neurodevelopment.

Maternal lifestyle during pregnancy and child psychomotor development - Polish Mother and Child Cohort study

BACKGROUND

Nowadays special attention is paid to prenatal exposures to maternal lifestyle factors and their impact on a child development.

AIM

The objective of this study was to evaluate the impact of modifiable maternal lifestyle factors on child neurodevelopment based on the Polish Mother and Child Cohort study.

MATERIAL AND METHODS

The current analysis included 538 mother-child pairs. The following factors related to maternal lifestyle were considered: smoking and environmental tobacco smoke (ETS) exposure (based on the cotinine level in maternal saliva measured using LC-ESI+MS/MS method), alcohol consumption and leisure-time physical activity (LTPA) in pregnancy, pre-pregnancy BMI, and folic acid supplementations before and during pregnancy based on questionnaire data. Psychomotor development was assessed in children at the ages of one and two by the Bayley Scales of Infant and Toddler Development.

RESULTS

Significant association was observed between prenatal exposure to tobacco constituents and a decreased child motor development in assessments performed at both ages (β=-0.8, p=0.01; β=-1.4, p<0.001). Maternal pre-pregnancy underweight was associated with decreased language abilities at 12 months of age (β=-5.2, p=0.01) and cognitive and motor development at 24 months of age, for which the associations were of borderline significance (p=0.06). The recommended level of LTPA during pregnancy was beneficial for child language development at two years of age (β=4.8, p=0.02). For alcohol and folic acid consumption there were no significant associations with any of the analyzed domains of child neurodevelopment.

CONCLUSIONS

Children prenatally exposed to tobacco compounds and those of underweight mothers had a decreased psychomotor development. The recommended level of LTPA during pregnancy had positive impact on child development. These results underscore the importance of policies and public health interventions promoting healthy lifestyle among women in reproductive age and during pregnancy.

Phthalate exposure and child development: the Polish Mother and Child Cohort Study

BACKGROUND

Widespread phthalate exposure has prompted investigations concerning their potential adverse health effects.

AIM

The objective of this study was to evaluate the impact of pre and early postnatal phthalate exposure on child psychomotor development based on the data from the prospective Polish Mother and Child Cohort Study (REPRO PL).

STUDY DESIGN, SUBJECTS AND OUTCOME MEASURES

Phthalate exposure was determined by measuring 11 phthalate metabolites (MEP, MiBP, MnBP, 3OH-MnBP, MBzP, MEHP, 5OH-MEHP, 5oxo-MEHP, OH-MiNP, oxo-MiNP, and MnOP) in the urine collected from mothers during the third trimester of pregnancy (prenatal exposure) and from their children at the 24th month of age (postnatal exposure). The analysis was performed by the HPLC-MS/MS method. Psychomotor development was assessed in children at the age of 2years by the Bayley Scales of Infant and Toddler Development.

RESULTS

Child motor development was inversely associated with natural log concentrations (μg/g creatinine) of 3OH-MnBP (β= -2.3; 95% CI -4.0 to -0.6), 5OH-MEHP (β= -1.2; 95% CI -2.2 to -0.3), 5oxo-MEHP (β= -1.8; 95% CI -3.3 to -0.2) and sum of DEHP metabolites (β= -2.2; 95% CI -3.6 to -0.8), DnBP metabolites (β= -1.9; 95% CI -3.4 to -0.4), and high molecular weight phthalates (β= -2.5; 95% CI -4.1 to -0.9) in the urine collected from mothers during pregnancy after adjustment for a variety of potential confounders. Additional adjustment for postnatal phthalate exposure did not change the results. Postnatal child exposure to phthalates was not associated with any of the measured scores of child psychomotor development.

CONCLUSIONS

The study findings add further support to the possibility that prenatal phthalate exposure may be detrimental to child neurodevelopment and underscore the importance of policies and public health interventions aiming at reduction of such exposure.