Methods: Impact Model

Impact Model Methodology

This page details the methodology, assumptions, and limitations of the Impact Model financial calculator.

Purpose

The Impact Model estimates the financial impact of investing in early interventions for diseases with established links to environmental pollution. In this model, "cures" refers broadly to biological interventions that prevent, halt, or reverse exposure-related disease before it becomes chronic or irreversible. By quantifying both the upfront costs of developing these interventions and the downstream savings from eliminating disease burden, we can evaluate whether pollution-linked disease represents a viable target for large-scale health investment.

Approach

We begin with eight disease conditions that are disproportionately linked to environmental exposures. These conditions were selected based on disease burden, strength of environmental evidence, and plausibility of early biological intervention. For each condition, we estimate the proportion of disease burden likely attributable to pollutant exposure, with particular attention to populations that experience cumulative and inequitable risk.

We then model multiple scenarios in which early biological interventions are developed to reduce or prevent exposure-related disease prior to onset. For each scenario, we project R&D and implementation costs over time alongside savings from avoided healthcare expenditures.

To address accountability, we also explore scenarios in which polluters contribute to the costs of these interventions if liability is established after a defined attribution period. This includes estimating the proportion of estimated cure investments that could be recouped under different timelines and responsibility assumptions.

Methods

For each disease, we estimate the environmentally-attributable disease burden: the proportion of cases where environmental exposures are believed to play a contributing role. These estimates combine multiple exposure categories: ambient air pollution (PM2.5), heavy metals (lead, cadmium), occupational exposures, and industrial chemicals (PFAS, EDCs).

Where available, we draw on Global Burden of Disease estimates. For exposures not covered by GBD (e.g., endocrine disruptors, PFAS), we synthesize estimates from peer-reviewed epidemiological studies. These combined estimates carry greater uncertainty than single-exposure attributions.

Financial Calculations

The model tracks three financial flows over 20 years:

Investment in Cures (Red)

The cumulative cost of developing and deploying early interventions. Calculated as people treated multiplied by the estimated intervention cost for each disease.

Avoided Healthcare Costs (Green)

The cumulative savings from preventing chronic disease. Each year, people who received early intervention no longer incur ongoing healthcare costs. This compounds as more people are treated.

Recovered from Polluters (Teal)

The portion of intervention costs recoverable from polluters through liability mechanisms. This ramps up over the "Attribution Timeline" as legal and scientific frameworks mature.

Example: If $10B is invested in interventions, Polluter Liability is 75%, and we're 5 years into a 10-year attribution timeline, the recoverable amount is $10B × 0.75 × 0.5 = $3.75B.

How Polluter Liability Works

The model assumes that as interventions are developed and deployed, a portion of the cost can be recovered from entities responsible for the pollution that caused the disease. This mechanism has three components:

• Polluter Liability % (default 75%) — The share of intervention costs that could theoretically be attributed to polluters. This reflects that not all environmental disease has an identifiable responsible party, and legal recovery is never 100%.
• Attribution Timeline (default 10 years) — The time required for scientific consensus and legal frameworks to mature enough to enable cost recovery. During year 1 after an intervention launches, attribution is minimal; by year 10, it reaches full potential.
• Attribution Progress — A linear ramp from 0% to 100% over the Attribution Timeline. In year 5 of a 10-year timeline, 50% of the Polluter Liability can be recovered.

Model Parameters

Assumptions & Limitations

Intervention Cost Methodology

The "Cure Cost" in this model represents the per-patient treatment cost to deliver a curative or disease-modifying intervention. This is distinct from R&D costs, which are amortized across all patients through drug pricing. When pharmaceutical companies set prices for gene therapies and biologics, they factor in development costs, manufacturing, and profit margins—so the per-patient price implicitly includes R&D cost recovery.

How Intervention Costs Are Calculated

For example, if 500,000 people receive a cardiovascular intervention at $85,000 per patient, the yearly investment is $42.5 billion. This accumulates over the 20-year model period as more patients receive treatment.

Types of Interventions

The model assumes one-time curative interventions that eliminate or prevent disease, after which patients no longer incur ongoing healthcare costs for that condition. In practice, interventions fall into several categories:

• One-time gene therapies — Single administration that corrects underlying biology (e.g., GDNF gene therapy for Parkinson's, cardiovascular gene therapies in development)
• Cell therapies — Transplantation of functional cells (e.g., islet cell therapy for diabetes, stem cell approaches)
• Limited-duration biologics — Treatment courses with defined endpoints (e.g., anti-amyloid therapies for Alzheimer's averaging ~3.6 years)
• Ongoing biologics (as proxy) — For diseases without curative options yet, we use current biologic pricing as estimates for future interventions

Intervention Cost Estimates by Disease

Important Caveats

• R&D costs are implicit: Drug prices include manufacturer R&D cost recovery. The model does not separately track the ~$1-3 billion typically required to develop a new therapy.
• Prices will change: Gene therapy costs are expected to decrease as manufacturing scales. Conversely, novel therapies may initially be priced higher.
• Not all therapies are curative: Some listed therapies (e.g., asthma biologics) are ongoing treatments, not one-time cures. The model uses these as proxies for future curative interventions.
• Monitoring costs excluded: Additional costs for required monitoring (e.g., brain scans for Alzheimer's therapies, lab work) are not fully captured.

Data Sources

• Prevalence: Global Burden of Disease 2023
• Environmental Attribution: GBD 2023 risk factors, supplemented by peer-reviewed epidemiological literature
• Healthcare Costs: Disease-specific foundations (AHA, ADA, Parkinson's Foundation, etc.) and CDC data
• Intervention Costs: Based on current gene therapy and biologics market pricing (2024-2025), including FDA-approved therapies and clinical trial estimates

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