Every one of these numbers was built for a purpose, and none of those purposes was deciding whether a particular person was harmed.
Start a conversation with our AI Research Concierge, already scoped to regulatory standards as evidence. Pick a starting point, or describe your situation directly.
Regulatory values are attractive in litigation because they are numerical, official, and easy to compare against a measurement. They are also systematically misused. A maximum contaminant level balances health protection against treatment feasibility and cost for public water systems. A screening level is a conservative trigger for further investigation. A reference dose is an estimate of daily exposure likely to be without appreciable risk over a lifetime, derived by applying substantial uncertainty factors below an observed effect level. None is a threshold above which harm occurs. Understanding what each value represents — how it was derived, what it balances, and what margins are built into it — determines what it can properly be offered to prove, and this is one of the more reliable places to find an opposing expert overreaching.
Different purposes, different derivations, different evidentiary weight.
Enforceable drinking water limits balancing health goals against treatment feasibility and cost — not health thresholds.
Non-enforceable levels set without regard to feasibility, closer to a pure health objective and often below the enforceable limit.
Conservative values triggering further evaluation. Designed to over-identify, so exceedance means investigate, not harm.
Estimates of exposure likely without appreciable risk, derived with deliberate uncertainty factors below observed effect levels.
Set for healthy adult workers over working hours — a poor reference point for continuous community exposure.
Statements that a substance can cause an effect under some conditions, not that it did so at a given dose.
How these values are properly handled.
Misuse of a regulatory value is a discrete, well-understood ground of attack that can reach an entire opinion.
PFAS is the live example. EPA proposed on 18 May 2026 to retain the PFOA and PFOS limits while extending compliance to 2031, and to rescind the determinations for PFHxS, PFNA, GenX and the Hazard Index mixture; comments closed 20 July 2026 with nothing final. An opinion citing a limit as settled needs to say which limit, as of when — and check whether the state standard now governs instead.
Several things, none of which is that a claimant was harmed. It can establish that a substance was present above a level the regulator selected for a stated purpose. It can support notice — that a party knew or should have known of a condition requiring action. It can establish a permit violation or a response obligation. It can be relevant to the standard of care. What it cannot do is substitute for the dose-response analysis connecting exposure to effect in the individual, and experts who use it that way are describing the value as something it is not.
It substantially limits certain uses and not others. A standard promulgated after the exposure ended cannot establish that a party breached a requirement that did not exist, and its use for standard-of-care arguments is correspondingly weak — though what was knowable at the time, from the contemporaneous literature rather than from the later standard, remains fair ground. Current values may still be relevant to whether present conditions warrant response. Conflating a modern standard with historical obligations is a common and readily identified error.
Directly, because it is increasingly the operative situation. Where the federal position is contracting and states are setting their own, the applicable requirement may be the state one, and states differ substantially from one another. An analysis should identify which standard actually governs the site and the period, note where others differ, and explain the basis for the one relied on. Silently selecting the most favourable value from among several available is exactly the kind of choice that surfaces badly under cross-examination.
It carries different weight rather than more. A health-based goal is set without regard to treatment feasibility or cost, so it is closer to a pure statement of health protectiveness — which makes it arguably more probative on health questions and less probative on compliance, since it is not enforceable. Where a goal is set at zero, as it is for some carcinogens, exceedance conveys very little about magnitude of risk. As with every value here, what matters is explaining what it represents rather than deploying the number alone.
Describe the value and how it is being offered. We will scope it and connect you with the right expert.