Service Area


People are exposed to chemicals in all aspects of daily living, including in their environment, workplace, and homes.  Gradient’s expertise in epidemiology allows us to design, conduct, and evaluate in-depth analyses that determine whether exposures are linked to disease risks.  We also consider toxicology, mode-of-action, clinical, and exposure data, and use advanced statistical and spatial analyses to conduct robust, multi-perspective risk assessments.  In addition, Gradient scientists can effectively communicate the results of our analyses to a wide range of audiences, including stakeholders, regulatory and legislative bodies, and the public.

Example Publications:

Prueitt, RL; Li, W; Edwards, L; Zhou, J; Goodman, JE. 2021. “Systematic review of the association between long-term exposure to fine particulate matter and mortality.Int. J. Environ. Health Res.

Boomhower, SR; Long, CM; Li, W; Manidis, TD; Bhatia, A; Goodman, JE. 2021. “A review and analysis of personal and ambient PM2.5 measurements: Implications for epidemiology studies.Inhal. Toxicol. 204(Pt B):112019.

Goodman, JE; Loftus, CT; Zu, K. 2017. “2,4-Dichlorophenoxyacetic acid and non-Hodgkin’s lymphoma: Results from the Agricultural Health Study and an updated meta-analysis.Ann. Epidemiol.

Bailey, LA; Kerper, LE; Goodman, JE. 2017. “Derivation of an occupational exposure level for manganese in welding fumes.Neurotoxicology.

Sample Projects

Evaluation of a Potential Cancer Cluster

In response to citizens’ concerns, Gradient investigated the incidence rate of several cancers in residents living near a municipal landfill to determine whether it was elevated relative to rates in the general population.  We described the findings to city officials and residents at public meetings.

Cross-Sectional Study of Chlorinated Solvents

Gradient modeled chlorinated solvents exposure from drinking water and showering.  We used questionnaire data on disease status and other population characteristics to assess the association between exposures and disease rates in a community living near a Superfund site.

Meta-Analysis of Nitrogen Dioxide and Respiratory Effects

Gradient conducted a meta-analysis and meta-regression of data on airway hyper responsiveness from clinical studies of asthmatic volunteers exposed to nitrogen dioxide (NO2) while exercising or at rest.

Dose-Response Analysis of Blood Lead and Neurocognitive Impairment

Gradient analyzed the statistical basis for a dose-response relationship between blood lead and neurocognitive impairment.  We evaluated the extent to which the relationship could be ascribed to the statistical elements of the modeling or was indicative of the underlying relationship between the two parameters.

Weight-of-Evidence Analysis of Ozone and Cardiovascular Effects

Gradient conducted a weight-of-evidence evaluation of the association between ozone exposure and cardiovascular effects.  We developed and applied a methodological framework to review epidemiology, toxicity, and mechanistic literature to determine whether there was sufficient evidence of a causal association.

Our Team