Toxicologist (dose-response)
Expert class library · Mass tort and product liability · Either side
Evaluates whether a chemical can cause the claimed harm at the dose the plaintiff actually received, rather than at some dose in general. Draws on exposure reconstruction, animal and human studies, and mechanism evidence, and courts treat a reliable dose-response assessment as the hallmark of the discipline.
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Questions this testimony turns on
- What dose or cumulative exposure did the plaintiff actually receive, and how was it reconstructed?
- At what dose has the substance been shown to cause the claimed disease in humans?
- Can regulatory exposure limits or risk values be used to show that the plaintiff's exposure was harmful?
- Do animal or mechanism studies support extrapolation to the plaintiff's exposure level?
- Does the scientific literature show a dose-response relationship between the substance and the disease?
Methods
- Dose-response assessment
- Exposure reconstruction
- Animal study extrapolation
- Mechanism of action analysis
How the testimony is attacked
- No reliable dose-response assessment for the plaintiff. Defendants argue the expert never estimated the dose at which the substance causes harm and compared it to the plaintiff's exposure. In Williams v. Mosaic Fertilizer the Eleventh Circuit affirmed exclusion on that ground, while noting precise numbers are not required.
- Reliance on protective regulatory standards. Opponents argue that air quality standards and EPA risk values build in safety margins and do not predict who will get sick. The Eleventh Circuit agreed that facial reliance on such standards cannot substitute for a predictive dose-response analysis.
- Unreliable exposure inputs. Defendants attack the concentration data used to compute dose. In Hall v. ConocoPhillips the court excluded a dose calculation that used peak one-hour modeled concentrations chosen by another witness rather than data suited to cumulative exposure.
- Ignoring studies that show no dose-response. Defendants argue the expert discounted the largest study showing no dose-response relationship. In Hardeman v. Monsanto the Ninth Circuit held the experts had a reasonable basis to give that study less weight and affirmed admission.
- Failure to account for alternative causes and background risk. Opponents argue the expert did not rule out other causes or account for the baseline rate of the disease. The Mosaic court cited both failures alongside the dose-response problem in affirming exclusion.
- Quantitative versus qualitative exposure. Courts differ on whether the expert must quantify the dose. In Jenkins v. BP the Eleventh Circuit required identification of a harmful exposure level, while in Freeman v. Fon's Pest Management the Louisiana Supreme Court held a qualitative exposure assessment could suffice.
What the public record shows
Courts have filed at least 50 opinions since 2015 that discuss this class of testimony and cite Daubert or Rule 702, as of October 4, 2026. 6 rulings that show how courts handle this class of testimony:
| Outcome | Case | Court | Year | Why |
|---|---|---|---|---|
| Excluded | Jenkins v. BP Exploration & Production Inc.No. 23-11535 | 11th Cir. | 2024 | The Eleventh Circuit affirmed excluding general causation experts in Deepwater Horizon cleanup cases because neither identified the level of exposure to crude oil, dispersants or their chemicals at which they become harmful, found a statistically significant association, or meaningfully applied the Bradford Hill factors. |
| Admitted | Hardeman v. Monsanto Co.997 F.3d 941 | 9th Cir. | 2021 | The Ninth Circuit affirmed admission of the plaintiff's causation experts, holding they had a reasonable basis to discount a large cohort study showing no dose-response and could rely on case-control studies to show a dose-response relationship. |
| Admitted | Burton v. American Cyanamid362 F. Supp. 3d 588 | E.D. Wis. | 2019 | In childhood lead paint cases, the court admitted a defense toxicologist's use of the EPA's IEUBK exposure model to show that sources other than paint could account for the plaintiffs' blood lead levels, holding that challenges to his data and assumptions went to weight, while excluding a lead-hazard specialist's opinions on toxicity as outside his field. |
| Excluded | Williams v. Mosaic Fertilizer, LLC889 F.3d 1239 | 11th Cir. | 2018 | The Eleventh Circuit affirmed exclusion of the plaintiff's causation expert because he relied on protective regulatory standards instead of a predictive dose-response assessment specific to the plaintiff and did not rule out other causes. |
| Exclusion reversed | Freeman v. Fon's Pest Management, Inc.235 So. 3d 1087 | La. | 2018 | The Louisiana Supreme Court reversed the exclusion of three toxicologists and an industrial hygienist in a termiticide exposure case, holding that the objections went to their conclusions rather than their methods, that Daubert does not require a quantitative dose reconstruction where a qualitative exposure assessment is used, and that conflicts among experts go to credibility. |
| Excluded | Hall v. ConocoPhillips248 F. Supp. 3d 1177 | W.D. Okla. | 2017 | The court excluded the plaintiff's benzene dose calculation because it rested on peak short-term modeled concentrations unsuited to cumulative exposure, and without a reliable dose the plaintiff could not establish specific causation. |
Each case links to the free opinion text on CourtListener.
In federal court: amended Rule 702
In federal court, since December 1, 2023, Rule 702 says expressly that the party offering an expert must show the court it is more likely than not that the testimony meets each requirement: that it rests on sufficient facts or data, uses reliable methods, and reflects a reliable application of those methods to the case. Questions about the basis of an opinion are no longer automatically matters of weight for the jury. For how the circuits have applied the amendment, see the Rule 702 tracker, which follows each court of appeals; for what that means for preparing or attacking this class of expert, see the guide on amended Rule 702.
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Updated October 4, 2026. How this page is built: rulings are found by searching court opinions on CourtListener. The summaries are written by AI working from the full text of each opinion, and every citation and link is checked automatically. Outcomes are labelled by what the court did with the expert’s testimony. No individual expert is named. This page summarises public decisions for orientation and is not legal advice; read the opinion before relying on any ruling. Spotted an error? Tell us.