Environmental Causal Analysis

One of the most complex challenges our clients face is understanding the cause of alleged or observed environmental changes and identifying management approaches to minimize or avoid such changes. Every environmental system has a variety of stressors. Natural stressors can include temperature extremes, rainfall amounts, invasive species, and harmful algal blooms. Stressors related to human activities can include land development, chemical spills, resource management practices, and wastewater releases, among many others. These stressors can occur on different time and spatial scales within the same system, and teasing apart the cause of environmental change from a 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 evaluate the likelihood of multiple candidate causes contributing to an observed or hypothesized change in a resource. Our approach builds a weight of evidence for each individual candidate cause and is founded in the U.S. Environmental Protection Agency’s Causal Analysis/Diagnosis Decision Information System (CADDIS). Whether evaluating the cause of stress to nursery trees, determining if 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 weight of evidence
  • Identifies data gaps necessary to fully characterize the problem
  • Illustrates causal relationships not otherwise apparent
  • Prevents lapses of logic (e.g., correlation vs. causation)
  • Facilitates communication with a diverse audience (e.g., general public, lawyers, regulators, non-scientists).

Exponent’s environmental causal analysis approach leverages the extensive expertise of our sciences 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 can be examined. Exponent scientists apply causal analysis approaches to determine sources of contamination in allocation cases, evaluate the cause(s) of biological impairments in water bodies (e.g., 303d listings, total maximum daily loads (TMDL), legacy chemicals), guide and support natural resource damage assessments (NRDA), 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
  • Toxicological evaluation
  • Data mining to strengthen and expand the available empirical dataset
  • Data fitness evaluation
  • Data analytics
  • Bayesian probability analysis
  • Spatial analysis and remote sensing
  • Identify data gaps and develop recommendations for additional data collection
  • Design, manage and implement 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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