Abt Associates has helped the Environmental Protection Agency (EPA), the Agency for Toxic Substances and Disease Registry (ATSDR), and other clients develop methods for—and implement—systematic reviews. We are well-versed in using the tools and methods required to conduct a transparent and defensible product.
Abt’s deep understanding of the systematic literature review process is based on our hands-on experience screening studies, extracting data, conducting bias assessments, and summarizing results for multiple clients. We understand there are standardized methods, tools, and approaches that are utilized in order to ensure transparency in not only the literature review process but also in hazard characterization.
Our Health and Environment team has developed many different literature review products, ranging from full systematic reviews and meta-analyses to quick-turnaround summaries, reference lists, and annotated bibliographies. We work with clients to identify and tailor the format most appropriate for each particular work effort.
To conduct successful literature and document reviews, our team draws on Abt’s internal capabilities, which include digital subscriptions to a wide range of information sources and peer-reviewed journals; capable staff who can systematically sort through hundreds or thousands of potential references explicitly documenting the inclusion or exclusion of the potential references by a predetermined criteria; subject matter experts who can summarize literature coherently; and experienced technical writers, editors, graphic specialists, and web designers who can effectively communicate findings through print or online reports. We tailor our literature searches and document search methods to the particular needs of the project, and adhere to a structured approach to ensure that the end product is unbiased and high quality. We understand the need for a predetermined methodology, appropriate documentation, the integration of evidence, and unbiased presentation of findings.
Abt currently holds more than $15 million in contracts related to systematic review. Further, we are familiar with EPA’s approach to conducting systematic reviews under the amended Toxic Substance Control Act and potential updates to this process, and we appreciate the immense amount of work required to complete these reviews.
Abt is experienced in using tools for systematic reviews, including:
Health Assessment Workspace Collaborative (HAWC),
Through our work, we have familiarity and have used defined methods while conducting reviews, such as:
the Navigation Guide
the National Toxicology Program’s Office of Health Assessment and Translation’s (OHAT) handbook, and
the National Academy of Science recommendations based on reviews of EPA methods and guidance documents.
To support the development of methods for conducting systematic literature reviews for high-priority chemicals under the amended Toxic Substance Control Act, Abt Associates (under subcontract to Versar Inc.) developed data quality criteria to evaluate the exposure data presented in environmental epidemiological studies. To develop these criteria, an evaluation of EPA’s General Assessment Factors (the biomonitoring, environmental epidemiology, and short-lived chemicals instrument), and the OHAT’s risk of bias (RoB) tool were necessary. Abt utilized these tools to inform the development of evaluation metrics by which to assess the exposure assessment methods used in environmental epidemiological studies. Once the criteria were agreed upon with EPA, we tested them with several studies and provided input to EPA on the lessons learned from conducting the test evaluations.
Abt is supporting ATSDR in all facets of developing toxicological profiles for contaminants found at national priority list sites, including for some priority list chemicals such as 1,2 dichloroethane. This work includes defining search strings, searching various databases for toxicity information, and synthesizing the literature in a comprehensive report. We have implemented systematic reviews for several of the chemicals, for which we have then developed profiles. To implement the reviews, we begin by uploading our search results into DistillerSR and use our custom-made forms to conduct title, abstract, and full text screening. For studies that are included after full text review, data extraction is done, also in Abt-made DistillerSR forms. For select endpoints, risk of bias and confidence assessments are conducted using the RoB tool and ATSDR’s guidelines on confidence assessment. The data evaluations are then integrated into conclusions on the hazard. Through our partnership with ATSDR, we have screened tens of thousands of articles, defined inclusion and exclusion criteria, and created standardized processes and forms that can be tuned to other projects that use systematic review to evaluate chemical hazard.
Abt helped OSHA conduct a systematic review to determine the effect of infection control measures on transmission of diseases (e.g., influenza, meningitis) among healthcare workers and patients in healthcare settings. First, we formulated population, intervention, comparison, and outcome (PICO) statements to help guide the searches. To reflect the two populations of interest, we conducted a tiered search approach: in tier 1 we focused on healthcare workers and in tier 2 we focused on patients. We developed inclusion and exclusion criteria relating to each population studied, outcomes measured, the setting of transmission, the intervention used, the time period of publication, and the language of publication. We then created search terms based on the available and relevant Medical Subject Heading (MeSH) terms in the PubMed database. Each study identified underwent title and abstract screening by two independent reviewers. Data was extracted from these studies to inform a report supporting proposed OSHA regulations on infection control measures.
Abt conducted a literature review of the immunosuppressive effects of per- and polyfluoroalkyl substances (PFAS) and assessed National Health and Nutrition Examination Survey (NHANES) data to identify whether available data may address key gaps in the literature. Working with Abt’s in-house librarian, search strings were developed to identify literature that evaluated 15 PFAS chemicals and potential impacts on the immune system. Using HAWC, Abt conducted title, abstract, and full text screening of approximately 2,000 toxicological and epidemiological articles. For articles that were included after full text review, data was extracted in Abt-developed spreadsheets. The Abt team then synthesized the studies on potential immunologic impacts associated with PFAS exposure in the form of evidence tables and three separate reports: a summary of toxicological evidence, a summary of epidemiological evidence, and a synthesis of data to outline data gaps.
Dr. Lynch has over 20 years of experience and specializes in human health risk assessment. She has served as project manager on systematic reviews involving a variety of environmental contaminants. Lynch is particularly particularly interested in benefits estimation which requires synthesizing and translating the findings from toxicological and epidemiological literature to estimates that are useful for benefits analysis. This involves adapting and running probabilistic models to estimate risks and using EPA’s Benchmark Dose Modeling Software. Lynch has a MPH and D.Sc. in environmental health from Boston University School of Public Health.
Dr. Rekha Balachandran is a toxicologist with extensive training in bench research, particularly in studying toxicological effects in in vivo and in vitro models to understand human health risks. At Abt, she implements systematic reviews, including for ATSDR’s ToxProfiles, where she develops narrow inclusion criteria allowing many databases to be searched while minimizing the capture of non-relevant literature. She has applied OHAT’s methods to conduct risk-of-bias assessments, and provides support to the literature review screening, data extraction, draft development, and MRL derivation in the ToxProfiles. Balachandran has her Ph.D. in Toxicology and Chronobiology from the University of Illinois at Urbana Champaign.
Dr. Wilson is an internationally known expert in research synthesis and meta-analysis. This includes designing, conducting, and disseminating rigorous research studies and systematic reviews. From 2010 to 2017, she was an editor at Campbell Systematic Reviews, where she provided assistance to grantees on systematic review design and facilitated trainings on this topic. Dr. Wilson was awarded the 2020 Society for Prevention Research’s Nan Tobler Award for Review of the Prevention Science Literature. Wilson has a Ph.D. in policy development and program evaluation from Vanderbilt University.
Dr. Klein is an expert in biostatistical and econometric modeling methods, with experience conducting benefits and human health risk assessments. His training in machine learning methods, including natural language processing, has led to innovative solutions for literature searches. Klein serves as lead author on three ATSDR ToxProfiles. He was the technical lead in developing a maximum contaminant level goal for perchlorate in drinking water, and led the assessment of health benefits for its proposed regulation by EPA. Klein has a Ph.D. in occupational health services research and policy from the University of Minnesota School of Public Health.
Ms. Antezana is an environmental health expert with training in data visualization and analysis, and has served as lead author for three ATSDR ToxProfiles. Antezana has also developed methods to ensure evidence is synthesized and integrated consistently—and presented clearly—across a review. Previous contributions include a review of copper for the revised Lead and Copper Rule, and systematic reviews on available data on PFAS and the state of the science regarding its effects on immune outcomes. Antezana has a master’s in public health from Boston University School of Public Health.
Abt Associates uses data and bold thinking to improve the quality of people’s lives worldwide. From increasing crop yields and combatting infectious disease, to ensuring safe drinking water and promoting access to affordable housing—and more—we partner with clients and communities to tackle their most complex challenges.