Environmental, dietary, demographic, and activity variables associated with biomarkers of exposure for benzene and lead

Integrating Environment and Aging Research: Opportunities for Synergy and Acceleration

Despite significant overlaps in mission, the fields of environmental health sciences and aging biology are just beginning to intersect. It is increasingly clear that genetics alone does not predict an individual’s neurological aging and sensitivity to disease. Accordingly, aging neuroscience is a growing area of mutual interest within environmental health sciences. The impetus for this review came from a workshop hosted by the National Academies of Sciences, Engineering, and Medicine in June of 2020, which focused on integrating the science of aging and environmental health research. It is critical to bridge disciplines with multidisciplinary collaborations across toxicology, comparative biology, epidemiology to understand the impacts of environmental toxicant exposures and age-related outcomes. This scoping review aims to highlight overlaps and gaps in existing knowledge and identify essential research initiatives. It begins with an overview of aging biology and biomarkers, followed by examples of synergy with environmental health sciences. New areas for synergistic research and policy development are also discussed. Technological advances including next-generation sequencing and other-omics tools now offer new opportunities, including exposomic research, to integrate aging biomarkers into environmental health assessments and bridge disciplinary gaps. This is necessary to advance a more complete mechanistic understanding of how life-time exposures to toxicants and other physical and social stressors alter biological aging. New cumulative risk frameworks in environmental health sciences acknowledge that exposures and other external stressors can accumulate across the life course and the advancement of new biomarkers of exposure and response grounded in aging biology can support increased understanding of population vulnerability. Identifying the role of environmental stressors, broadly defined, on aging biology and neuroscience can similarly advance opportunities for intervention and translational research. Several areas of growing research interest include expanding exposomics and use of multi-omics, the microbiome as a mediator of environmental stressors, toxicant mixtures and neurobiology, and the role of structural and historical marginalization and racism in shaping persistent disparities in population aging and outcomes. Integrated foundational and translational aging biology research in environmental health sciences is needed to improve policy, reduce disparities, and enhance the quality of life for older individuals.

Occupational lead toxicity in battery workers

OBJECTIVE

To estimate blood lead level (BLL) and to assess the features of lead toxicity among lead acid battery (LAB) industrial workers.

METHODS

This prospective study was carried out in the medical centre of PCSIR Laboratories, Karachi from March 2012 - March 2013. Fifty LAB industry workers, males and females between 17-65 years were included in the study. They were divided into group 1 with 40 workers- directly related and group 2 with 10 workers -indirectly related, (administration staff members) to LAB manufacture. Detailed history, complete physical examination and BLL estimation by flameless atomic absorption spectrophotometer was done.

RESULTS

Total 34 patients in group 1 and 3 patients in group 2 had elevated BLL. Comparison of group 1 and 2 revealed anemia (40v/s4), bone pain (38v/s7), abdominal pain (38 v/s 2), nausea (32v/s6), head ache & irritability (24v/s6), weakness & lethargy (21v/s6), tremors (13v/s0) insomnia (5v/s4), lead line (4v/s 0) and blood pressure above 140/90 mm of Hg (12v/s0) respectively.

CONCLUSION

High blood lead level and features attributable to lead toxicity were prevalent among LAB industry workers of Karachi.

The public health exposome: a population-based, exposure science approach to health disparities research

The lack of progress in reducing health disparities suggests that new approaches are needed if we are to achieve meaningful, equitable, and lasting reductions. Current scientific paradigms do not adequately capture the complexity of the relationships between environment, personal health and population level disparities. The public health exposome is presented as a universal exposure tracking framework for integrating complex relationships between exogenous and endogenous exposures across the lifespan from conception to death. It uses a social-ecological framework that builds on the exposome paradigm for conceptualizing how exogenous exposures "get under the skin". The public health exposome approach has led our team to develop a taxonomy and bioinformatics infrastructure to integrate health outcomes data with thousands of sources of exogenous exposure, organized in four broad domains: natural, built, social, and policy environments. With the input of a transdisciplinary team, we have borrowed and applied the methods, tools and terms from various disciplines to measure the effects of environmental exposures on personal and population health outcomes and disparities, many of which may not manifest until many years later. As is customary with a paradigm shift, this approach has far reaching implications for research methods and design, analytics, community engagement strategies, and research training.

Relationship between passive smoking exposure and urinary heavy metals and lung functions in preschool children

Environmental tobacco smoke (ETS) exposure is a risk factor for asthma in school-age children, but there is limited data of ETS exposure on respiratory health in preschool children. This study investigated the relationship between ETS, lead (Pb), and cadmium (Cd) exposures and asthma symptoms and spirometric indices in Chinese preschoolers. Preschool children from 30 nurseries and kindergartens performed spirometry with incentives of animation programs, and their urinary cotinine, Pb and Cd concentrations were measured by immunoassay and inductively coupled plasma-mass spectrometry, respectively. Two thousand seven hundred sixty-three preschoolers participated, and 1,505 and 893 provided valid spirometric data and urine samples, respectively. Current domestic smoking was reported in 37.5% of children, but only 95 (10.6%) had high urinary cotinine-to-creatinine ratio (≥30 ng/mg). Pb was measurable in 3.9% of samples, whereas 406 (45.5%) children had high Cd. Reported ETS exposure was not associated with any spirometric index, whereas cotinine-to-creatinine ratio was inversely associated with forced expiratory volume in 0.5-sec (β = -0.093, P = 0.003), forced expiratory flow between 25% and 75% of expiration (β = -0.138, P = 0.002) and peak expiratory flow (β = -0.106, P = 0.002). Cd exposure was not associated with reported respiratory symptom or spirometric indices. This community study shows that ETS exposure defined by urinary cotinine is a strong risk factor for lung function impairment measured by spirometry in Chinese preschool children. Urinary cotinine is more reliable than questionnaire for assessing ETS exposure in young children. Although high urinary Cd is common in Hong Kong preschoolers, such biomarker is not associated with any clinical or spirometric outcome.

Is the air pollution health research community prepared to support a multipollutant air quality management framework?

Ambient air pollution is always encountered as a complex mixture, but past regulatory and research strategies largely focused on single pollutants, pollutant classes, and sources one-at-a-time. There is a trend toward managing air quality in a progressively "multipollutant" manner, with the idealized goal of controlling as many air contaminants as possible in an integrated manner to achieve the greatest total reduction of adverse health and environmental impacts. This commentary considers the current ability of the environmental air pollution exposure and health research communities to provide evidence to inform the development of multipollutant air quality management strategies and assess their effectiveness. The commentary is not a literature review, but a summary of key issues and information gaps, strategies for filling the gaps, and realistic expectations for progress that could be made during the next decade. The greatest need is for researchers and sponsors to address air quality health impacts from a truly multipollutant perspective, and the most limiting current information gap is knowledge of personal exposures of different subpopulations, considering activities and microenvironments. Emphasis is needed on clarifying the roles of a broader range of pollutants and their combinations in a more forward-looking manner; that is not driven by current regulatory structures. Although advances in research tools and outcome data will enhance progress, the greater need is to direct existing capabilities toward strategies aimed at placing into proper context the contributions of multiple pollutants and their combinations to the health burdens, and the relative contributions of pollutants and other factors influencing the same outcomes. The authors conclude that the research community has very limited ability to advise multipollutant air quality management and assess its effectiveness at this time, but that considerable progress can be made in a decade, even at current funding levels, if resources and incentives are shifted appropriately.

Exposure science: a view of the past and milestones for the future

BACKGROUND

The study of human exposure to environmental toxicants has evolved as a scientific field over the past 30 years.

OBJECTIVES

This review provides a historical perspective on the growth of exposure science as a field, with some emphasis on the results from initial observational studies in obtaining information needed for generating hypotheses on significant human contact with environmental agents, testing the performance of models, and reducing exposures to protect public health.

DISCUSSION

Advances in activity pattern and behavioral research that established a suite of variables needed to accurately define contact and factors that influence contact are also discussed. The identification and characterization of these factors have played a pivotal role in the growth of the field and in developing exposure reduction strategies. Answers to two key questions on the relevance and fundamental value of exposure science to the fields of environmental health and risk management are presented as a path forward: a) What does one do with such exposure information? b) What roles does exposure science play in situations beyond observational analyses and interpretation?

CONCLUSIONS

The discussion identifies the need for more focused use of observational studies of exposure for epidemiologic analyses. Further, the introduction and use of new tools and approaches for hypothesis testing that can improve the use of exposure science in prevention research for risk management is needed to affect the source-to-effect continuum. A major restructuring of the field is not required to achieve innovation. However, additional resources for training and education are required to ensure that the potential for exposure science to play a central role in reducing and preventing excess risk within environmental/occupational health is achieved.

Neurotoxic effects and biomarkers of lead exposure: a review

Lead, a systemic toxicant affecting virtually every organ system, primarily affects the central nervous system, particularly the developing brain. Consequently, children are at a greater risk than adults of suffering from the neurotoxic effects of lead. To date, no safe lead-exposure threshold has been identified. The ability of lead to pass through the blood-brain barrier is due in large part to its ability to substitute for calcium ions. Within the brain, lead-induced damage in the prefrontal cerebral cortex, hippocampus, and cerebellum can lead to a variety of neurologic disorders. At the molecular level, lead interferes with the regulatory action of calcium on cell functions and disrupts many intracellular biological activities. Experimental studies have also shown that lead exposure may have genotoxic effects, especially in the brain, bone marrow, liver, and lung cells. Knowledge of the neurotoxicology of lead has advanced in recent decades due to new information on its toxic mechanisms and cellular specificity. This paper presents an overview, updated to January 2009, of the neurotoxic effects of lead with regard to children, adults, and experimental animals at both cellular and molecular levels, and discusses the biomarkers of lead exposure that are useful for risk assessment in the field of environmental health.

Biologically based modeling of multimedia, multipathway, multiroute population exposures to arsenic

This article presents an integrated, biologically based, source-to-dose assessment framework for modeling multimedia/multipathway/multiroute exposures to arsenic. Case studies demonstrating this framework are presented for three US counties (Hunderton County, NJ; Pima County, AZ; and Franklin County, OH), representing substantially different conditions of exposure. The approach taken utilizes the Modeling ENvironment for TOtal Risk studies (MENTOR) in an implementation that incorporates and extends the approach pioneered by Stochastic Human Exposure and Dose Simulation (SHEDS), in conjunction with a number of available databases, including NATA, NHEXAS, CSFII, and CHAD, and extends modeling techniques that have been developed in recent years. Model results indicate that, in most cases, the food intake pathway is the dominant contributor to total exposure and dose to arsenic. Model predictions are evaluated qualitatively by comparing distributions of predicted total arsenic amounts in urine with those derived using biomarker measurements from the NHEXAS--Region V study: the population distributions of urinary total arsenic levels calculated through MENTOR and from the NHEXAS measurements are in general qualitative agreement. Observed differences are due to various factors, such as interindividual variation in arsenic metabolism in humans, that are not fully accounted for in the current model implementation but can be incorporated in the future, in the open framework of MENTOR. The present study demonstrates that integrated source-to-dose modeling for arsenic can not only provide estimates of the relative contributions of multipathway exposure routes to the total exposure estimates, but can also estimate internal target tissue doses for speciated organic and inorganic arsenic, which can eventually be used to improve evaluation of health risks associated with exposures to arsenic from multiple sources, routes, and pathways.

From a theoretical framework of human exposure and dose assessment to computational system implementation: the Modeling ENvironment for TOtal Risk Studies (MENTOR)

Georgopoulos and Lioy (1994) presented a theoretical framework for exposure analysis, incorporating multiple levels of empirical and mechanistic information while characterizing/reducing uncertainties. The present review summarizes efforts towards implementing that framework, through the development of a mechanistic source-to-dose Modeling ENvironment for TOtal Risks studies (MENTOR), a computational toolbox that provides various modeling and data analysis tools to facilitate assessment of cumulative and aggregate (multipathway) exposures to contaminant mixtures. MENTOR adopts a "Person Oriented Modeling" (POM) approach that can be applied to either specific individuals or to populations/subpopulations of interest; the latter is accomplished by defining samples of "virtual" individuals that statistically reproduce the physiological, demographic, etc., attributes of the populations studied. MENTOR implementations currently incorporate and expand USEPA's SHEDS (Stochastic Human Exposure and Dose Simulation) approach and consider multiple exposure routes (inhalation, food, drinking water intake; non-dietary ingestion; dermal absorption). Typically, simulations involve: (1) characterizing background levels of contaminants by combining model predictions and measurement studies; (2) characterizing multimedia levels and temporal profiles of contaminants in various residential and occupational microenvironments; (3) selecting sample populations that statistically reproduce essential demographics (age, gender, race, occupation, education) of relevant population units (e.g., census tracts); (4) developing activity event sequences for each member of the sample by matching attributes to entries of USEPA's Consolidated Human Activity Database (CHAD); (5) calculating intake rates for the sample population members, reflecting physiological attributes and activities pursued; (6) combining intake rates from multiple routes to assess exposures; (7) estimating target tissue doses with physiologically based dosimetry/toxicokinetic modeling.

Employing dynamical and chemical processes for contaminant mixtures outdoors to the indoor environment: the implications for total human exposure analysis and prevention

There are many physical and chemical processes that affect the accumulation of outdoor pollutants. In recent years some of the information and concepts previously ascribed to outdoor pollution has been found to be useful in examining indoor dynamic and chemical processes. Further, becau se of the confining nature of the indoor environment, processes such as the "grasshopper effect" can lead to sustained higher levels of semivolatile chemicals indoors and affect multiroute (inhalation, dermal, incidental dietary, and nondietary ingestion) exposures. Such processes can also lead to a complex mixture of both semivolatile and volatile compounds in indoor air and on surfaces or within objects. This article specifically examines the above in combination with another indoor issue, indoor chemistry, and places the results into a context that can be used to evaluate (1) multipollutant cumulative or aggregate exposures and risks indoors, (2) exposure reduction strategies that can create healthy indoor environments. It is not a review of the entire field of the indoor environment or indoor air or the indoor environment, which has been covered in numerous volumes and reports. The complexities of the scientific issues are discussed by also placing them into our traditional approaches outdoor and indoor to pollution management, to indicate the difficulty in establishing the exposures that require mitigation or prevention. Further, some emerging issues are discussed as well as how to specifically address long-term single or multiroute exposures to semivolatile compounds within the "Total Indoor Environment."

Environmental tobacco smoke (ETS) exposure in children with asthma-relation between lead and cadmium, and cotinine concentrations in urine

Exposure to heavy metals from environmental tobacco smoke (ETS) was investigated in 23 children with asthma (8.4+/-3.7 yr). ETS exposure was assessed by an inquiry data-based exposure index, the urinary concentration of cotinine (U-cotinine; a major nicotine metabolite) and the house dust (fine and coarse fractions) concentrations of nicotine at home. The corresponding concentrations of the heavy metals cadmium and lead in dust and urine (U-Cd; U-Pb) were determined in the same samples. There were strong associations between the ETS exposure index and U-cotinine (r(s)=0.62; P<0.002) and nicotine in house dust (r(s)=0.77; P<0.001). There was a strong positive correlation between lead and cadmium concentrations in both fine (r(s)=0.86; P<0.001) and coarse dust (r(s)=0.57; P=0.02). Although, there was a tendency for a relation between nicotine and lead concentrations in fine dust (r(s)=0.52; P=0.06), no other significant associations were found between house dust metals and nicotine concentrations. U-Cd correlated well with U-cotinine (r(s)=0.50; P=0.02). Further, U-Pb were associated with U-cotinine, however not statistically significant (r(s)=0.41; P=0.06). A probable explanation is a direct inhalation of side-stream smoke containing heavy metals and/ or an increased pulmonary uptake, due to a small airways disease in children with asthma.

ADVANCES IN RISK ASSESSMENT AND COMMUNICATION

Risk analysis continues to evolve. There is increasing depth and breadth to each component of the four-step risk-assessment paradigm of hazard identification, dose-response analysis, exposure assessment, and risk characterization. Basic conceptual approaches to understanding how people perceive risk are being tested against a growing body of empirical observations, many involving stakeholders. Emerging ideas such as the precautionary principle have provided challenges that have led to a rethinking of the role of risk assessment in environmental health. Newer problems, such as intergenerational issues posed by long-lasting radiation pollution, environmental justice, and the assessment and communication of risks related to terrorism, have spurred innovative approaches to risk analysis.