Environmental Causal Analysis

One of the most complex challenges our clients face is understanding the causes of alleged or observed environmental changes and identifying management approaches to minimize or avoid such changes. Every environmental system has a variety of stressors, both natural and anthropogenic. Natural stressors can include temperature fluctuations, hydrologic changes, invasive species, and harmful algal blooms. Stressors related to human activities can include land development and land-use activities, chemical spills, wastewater discharges, and resource management practices, among many others. These stressors can occur on different time and spatial scales within the same system, and teasing apart the causes of environmental changes from a complex web of potential stressors can be challenging.

To meet this challenge, Exponent scientists rely on environmental causal analysis—a logical, transparent, and objective step-wise approach to evaluating the likelihood of multiple candidate causes contributing to an observed or hypothesized change in a resource. Based on the U.S. Environmental Protection Agency’s Causal Analysis/Diagnosis Decision Information System (CADDIS), our approach weighs the available evidence for each individual candidate cause.
Whether evaluating the cause of stress to nursery trees, determining whether a historical release of a chemical continues to impact an environment, or evaluating the contribution of a chemical release to an observed stress, environmental causal analysis:

  • Results in a clear and defensible weighing of evidence
  • Identifies data gaps necessary to fully characterize the problem
  • Illustrates causal relationships not otherwise apparent
  • Prevents lapses of logic (e.g., correlation equals causation)
  • Facilitates communication with a diverse stakeholder audience (e.g., general public, lawyers, regulators, non-scientists).

Exponent’s environmental causal analysis approach leverages our extensive scientific expertise to collect data, evaluate lines of evidence, and examine all potential pathways for exposure and injury. Our work is guided by a comprehensive conceptual model from which the lines of evidence are illustrated, data needs identified, and the strength of causation examined. Exponent scientists apply causal analysis approaches to determine sources of contamination in allocation cases, evaluate the causes of biological impairments in water bodies (e.g., 303d listings, total maximum daily loads [TMDL], legacy chemicals), guide and support natural resource damage assessments (NRDAs), assess the potential toxicant in effluent discharges as part of toxicity reduction evaluations (TREs), and increase the efficacy of remedial or restoration measures, among many other applications.


Our services include the following:

  • Conceptual model development to incorporate all potential stressors
  • Forensic chemistry and chemical fingerprinting
  • Historical evaluation of ecological changes from natural and anthropogenic stressors
  • Toxicological and risk evaluation
  • Toxicity reduction evaluation (TRE) and toxicity identification evaluation (TIE)
  • Data mining and scraping of publicly available data to strengthen and expand the available empirical dataset
  • Data fitness evaluation
  • Data analytics
  • Bayesian probability analysis
  • Trends analysis
  • Spatial analysis and remote sensing
  • Data gap identification and recommendations for additional data collection
  • Design, management, and implementation of independent and cooperative field sampling campaigns to fill data gaps
  • Communications support with stakeholders
  • Litigation support.

In addition to providing consulting support, our scientists and engineers serve as expert testifying witnesses.



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