Environmental Health

Statistical Approaches for Investigating Periods of Susceptibility in Children's Environmental Health Research Abstract Purpose of Review Children's environmental health researchers are increasingly interested in identifying time intervals during which individuals are most susceptible to adverse impacts of environmental exposures. We review recent advances in methods for assessing susceptible periods. Recent Findings We identified three general classes of modeling approaches aimed at identifying susceptible periods in children's environmental health research: multiple informant models, distributed lag models, and Bayesian approaches. Benefits over traditional regression modeling include the ability to formally test period effect differences, to incorporate highly time-resolved exposure data, or to address correlation among exposure periods or exposure mixtures. Summary Several statistical approaches exist for investigating periods of susceptibility. Assessment of susceptible periods would be advanced by additional basic biological research, further development of statistical methods to assess susceptibility to complex exposure mixtures, validation studies evaluating model assumptions, replication studies in different populations, and consideration of susceptible periods from before conception to disease onset.

Biomonitoring and Nonpersistent Chemicals—Understanding and Addressing Variability and Exposure Misclassification Abstract Purpose of Review We offer here a review of intraindividual variability in urinary biomarkers for assessing exposure to nonpersistent chemicals. We provide thoughts on how to better evaluate exposure to nonpersistent chemicals. Recent Findings We summarized reported values of intraclass correlation coefficients and found that most values fall into categories that indicate only poor to good reproducibility. Even within the "good" classification, a large percentage of study participants is likely to be misclassified as to their exposure. Summary There is sufficient information to support the statement that studies using only one spot measurement of a nonpersistent chemical will be unreliable. It is unequivocal that multiple samples have to be collected over a period of toxicological relevance and with consideration of exposure patterns. Sponsors of research and researchers themselves should be vocal about ensuring that sufficient resources are made available to properly characterize exposures when studying nonpersistent chemicals. Otherwise, we will continue to see an ever-growing body of literature yielding inconsistent and/or uninterpretable results.

Understanding and Mitigating the Replication Crisis, for Environmental Epidemiologists Abstract Purpose of Review In recent years, investigators in a variety of fields have reported that most published findings can not be replicated. This review evaluates the factors contributing to lack of reproducibility, implications for environmental epidemiology, and strategies for mitigation. Recent Findings Although publication bias and other types of selective reporting may contribute substantially to irreproducible results, underpowered analyses and low prevalence of true associations likely explain most failures to replicate novel scientific results. Epidemiologists can counter these risks by ensuring that analyses are well-powered or precise, focusing on scientifically justified hypotheses, strictly controlling type I error rates, emphasizing estimation over statistical significance, avoiding practices that introduce bias, or employing bias analysis and triangulation. Avoidance of p values has no effect on reproducibility if confidence intervals excluding the null are emphasized in a similar manner. Summary Increased attention to exposure mixtures and susceptible subpopulations, and wider use of omics technologies, will likely decrease the proportion of investigated associations that are true associations, requiring greater caution in study design, analysis, and interpretation. Though well intentioned, these recent trends in environmental epidemiology will likely decrease reproducibility if no effective actions are taken to mitigate the risk of spurious findings.

Transforming Our Cities: Best Practices Towards Clean Air and Active Transportation Abstract Purpose of Review By 2050, 70% of the global population will live in urban areas, exposing a greater number of people to specific city-related health risks that will only be exacerbated by climate change. Two prominent health risks are poor air quality and physical inactivity. We aim to review the literature and state the best practices for clean air and active transportation in urban areas. Recent Findings Cities have been targeting reductions in air pollution and physical inactivity to improve population health. Oslo, Paris, and Madrid plan on banning cars from their city centers to mitigate climate change, reduce vehicle emissions, and increase walking and cycling. Urban streets are being redesigned to accommodate and integrate various modes of transportation to ensure individuals can become actively mobile and healthy. Investments in pedestrian, cycling, and public transport infrastructure and services can both improve air quality and support active transportation. Emerging technologies like electric and autonomous vehicles are being developed and may reduce air pollution but have limited impact on physical activity. Green spaces too can mitigate air pollution and encourage physical activity. Summary Clean air and active transportation overlap considerably as they are both functions of mobility. The best practices of clean air and active transportation have produced impressive results, which are improved when enacted simultaneously in integrated policy packages. Further research is needed in middle- and low-income countries, using measurements from real-world interventions, tracing air pollution back to the sources responsible, and holistically addressing the entire spectrum of exposures and health outcomes related to transportation.

Mendelian Randomization and the Environmental Epigenetics of Health: a Systematic Review Abstract Purpose of Review Epigenetic modifications are environmentally responsive and may play a mechanistic role in the development of disease. Mendelian randomization uses genetic variation to assess the causal effect of modifiable exposures on health outcomes. We conducted a systematic review of Mendelian randomization studies evaluating the causal role of DNA methylation (DNAm) changes on the development of health states, emphasizing on studies that formally evaluate exposure-DNAm, in addition to DNAm-outcome, causal associations. Recent Findings We identified 15 articles, 4 of them including an environmental determinant of DNAm, including self-reported tobacco smoke exposure, in utero tobacco smoke exposure, measured vitamin B12, and glycemia. Summary Selected articles suggest a causal association of DNAm with some cardiometabolic endpoints. DNAm seemed to partly explain the association of postnatal and prenatal exposure to tobacco smoke and vitamin B12 with inflammation biomarkers, birth weight, and cognitive outcomes, respectively. However, the current evidence is not sufficient to infer causality. Additional Mendelian randomization studies from large epidemiologic samples are needed to support the causal role of environmental factors as determinants of health-related epigenetic modifications.

Planetary Health and Population Health: the Anthropocene Requires Different Thinking and Approaches in Serving Public Health

Planetary Epidemiology: Towards First Principles Abstract Purpose of Review To combine evolutionary principles of competition and co-operation with limits to growth models, generating six principles for a new sub-discipline, called "planetary epidemiology." Suggestions are made for how to quantify four principles. Recent Findings Climate change is one of a suite of threats increasingly being re-discovered by health workers as a major threat to civilization. Although "planetary health" is now in vogue, neither it nor its allied sub-disciplines have, as yet, had significant impact on epidemiology. Few if any theorists have sought to develop principles for Earth system human epidemiology, in its ecological, social, and technological milieu. Summary The principles of planetary epidemiology described here can be used to stimulate applied, quantitative work to explore past, contemporary, and future population health, at scales from local to planetary, in order to promote enduring health. It is also proposed that global well-being will decline this century, without radical reform.

The Holistic Effects of Climate Change on the Culture, Well-Being, and Health of the Saami, the Only Indigenous People in the European Union Abstract Purpose of Review (1) To develop a framework for understanding the holistic effects of climate change on the Saami people; (2) to summarize the scientific evidence about the primary, secondary, and tertiary effects of climate change on Saami culture and Sápmi region; and (3) to identify gaps in the knowledge of the effects of climate change on health and well-being of the Saami. Recent Findings The Saami health is on average similar, or slightly better compared to the health of other populations in the same area. Warming climate has already influenced Saami reindeer culture. Mental health and suicide risk partly linked to changing physical and social environments are major concerns. Summary The lifestyle, diet, and morbidity of the Saami are changing to resemble the majority populations posing threats for the health of the Saami and making them more vulnerable to the adverse effects of climate change. Climate change is a threat for the cultural way of life of Saami. Possibilities for Saami to adapt to climate change are limited.

Adverse Maternal Metabolic Intrauterine Environment and Placental Epigenetics: Implications for Fetal Metabolic Programming Abstract Purpose of Review Herein, we summarize existent epidemiological studies relating adverse maternal metabolic environments of maternal obesity and gestational diabetes and placental DNA methylation. Recent Findings Multiple studies have evaluated associations between intrauterine exposure to gestational diabetes and/or maternal glucose levels and DNA methylation at candidate metabolic genes as well as in epigenome-wide studies. Some of the genomic regions more consistently associated include lipid-related genes (LPL and PPARGC1A), the major histocompatibility complex (MHC), and imprinted genes. Studies solely focused on maternal obesity influences on the placental epigenome are scarce. Summary Understanding the placental mechanisms involved in fetal metabolic programming could lead to discovery of placental biomarkers at birth that predict later-life metabolic risk. Moving forward is important to standardize methods utilized in epigenetics research; consistent methodology can help interpret disparate findings. Larger studies with longitudinal follow-up are needed to address future challenges in fetal programming research.

Pesticides and Child's Health in France Abstract Purpose of Review The use of pesticides is predominant in agriculture, inducing environmental contamination, and has been extended to the domestic sphere. In France, > 500 pesticides were authorized for use in 2009; given their various toxicological properties, there are legitimate concerns about the possible consequences for child health. This review summarizes the recent French studies of good quality dealing with pesticides and child health. Recent Findings Three cohorts (mother–child, retrospective) and two case–control studies have been conducted in the last decade. Using various instruments for exposure assessment including biomarkers, they have suggested alterations of subclinical health parameters at birth, increased risk of otitis at age 2, and increased risk of several types of childhood cancer. However, there were no adverse neurodevelopmental outcomes at 6 years of age following prenatal exposure to pesticides. Summary Both agricultural and domestic pesticides might be involved in such adverse health outcomes. Similar studies are lacking in Europe. Studies on fungicides and child health are scarce.