# Military / radiation "acceptable risk" numbers — the AEC link, and what number they actually used

*Research note, 2026-06-13, chasing the AEC/military connection to the "acceptable risk" lineage (operator query:
"military mentions of acceptable cancer risk — what number? 10⁻⁶?"). **Grade (updated 2026-06-13):** the NBS-59
committee composition is **[CONFIRMED-primary]** (held, H29), and **§2–§3 are now [CONFIRMED-primary] too** — the
NCRP negligible-risk chapter and the FDA↔radiation juxtaposition are read from the **held *De Minimis Risk*
volume (Whipple ed., 1987; register H34)**. Only the ICRP-26 occupational ~10⁻⁴/yr gloss remains lightly
[secondary] pending a close read of `ANIB_1_3.pdf`. Register **H33** (synthesis); primary in **H29 + H34**.*

## The headline answer
**The radiation/AEC world did *not* originate "1 in a million," and when it later set a "negligible/de minimis"
cancer-risk number it used 10⁻⁷ per year (≈10⁻⁵ lifetime), not 10⁻⁶.** The "1 in a million" (10⁻⁶ lifetime) is a
**chemical/FDA** number (Mantel-Bryan 10⁻⁸ → FDA 10⁻⁶) that later spread to EPA and even to the Army's
chemical-hazard guides. The military connection to the lineage is **conceptual and institutional** (radiation
protection invented "acceptable nonzero risk," co-authored by the armed services + AEC) rather than a shared
number.

## 1. The committee was military/nuclear — but used *dose limits*, not a risk probability (1954) — [P]
From the held primary **NBS Handbook 59 / NCRP-17 (register H29)**: the radiation-protection committee was
enlarged "**upon the advent of atomic energy**" (Dec 1946) and its roster lists **U.S. Air Force (Maj. S. E.
Lifton), U.S. Army (Brig. Gen. J. P. Cooney), U.S. Atomic Energy Commission (K. Z. Morgan & J. C. Bugher), U.S.
Navy (Rear Adm. C. F. Behrens)** (ll. 125–128). But in 1954 the standard is a **dose** (0.3 r/week) and
"acceptable risk" is defined by **comparison**, not a probability: "make the risk **essentially the same as is
present in ordinary occupations**" (ll. 1372–73). **No 10⁻⁶.** [CONFIRMED-primary]

## 2. When radiation protection did adopt a risk *number* (1970s–80s) — NOW [CONFIRMED-primary] (held, H34)
*Flipped from [secondary] to primary 2026-06-13: the NCRP chapter is now held — **Charles Meinhold, "The NCRP
Considerations on Levels of Negligible Risk," ch. 11 of* De Minimis Risk *(Whipple ed., Plenum 1987), register
H34** (`papers/lateral/whipple1987_de-minimis-risk_vol2_plenum.txt`).*
- **The radiation "de minimis" number, verbatim:** "a **fatality risk of about 10⁻⁵ per year is close to the
  level below which there is little concern**—i.e., an activity is regarded as reasonably safe… a risk level two
  orders of magnitude lower, i.e., **10⁻⁷ per year, would appear to be trivial and negligible**" (ll. 5011–14);
  and the formal recommendation: "**annual risk commitment increments of 10⁻⁷ or less, or total lifetime risks
  between 10⁻⁵ and 10⁻⁶ or less, are regarded as reasonably negligible**" (ll. 5031–33). The two paired limits:
  "a dose equivalent limit of **100 mrem per year (1 mSv/yr) based on an acceptable annual risk of 10⁻⁵**, and a
  **negligible risk level of 1 mrem per year (10 µSv/yr) based on a negligible annual risk of 10⁻⁷**" (ll. 5039–42).
- **Chosen from a range, like FDA's 10⁻⁶:** the NRC's 10 CFR Part 20 de minimis cutoff — "**Following consideration
  of lower and higher numbers, a value of 0.001 rem (0.01 mSv) per year was selected**" (ll. 5580–83).
- **Same comparison basis as 1954:** "Smallness of risk **in relation to accustomed risks**… the comparison of
  estimated radiogenic risks with other risks involved in a variety of activities of living" (ll. 5009–11).
- **ICRP occupational** acceptable risk (ICRP 26, 1977, held — `ANIB_1_3.pdf`): pegged by comparison to safe
  industries, ~10⁻⁴/yr.
- So the radiation negligible-risk figure is **10⁻⁷/yr (1 mrem/yr) ≈ 10⁻⁵–10⁻⁶ lifetime**, acceptable **10⁻⁵/yr**
  — a cousin of the chemical 10⁻⁶ *lifetime*, in different units, **not the same number**.

## 3. The convergence — the radiation and chemical "de minimis" met in one 1987 book — NOW held [P] (H34)
The chemical Threshold-of-Regulation work and the radiation negligible-risk work are **published side by side** in
one volume, **now held & verified**: *De Minimis Risk* (C. Whipple, ed., Plenum, 1987; DOI
10.1007/978-1-4684-5293-8; **register H34**) — ch. 8 = **Flamm, Lake, Lorentzen, Rulis, Schwartz & Troxell**,
"Carcinogenic Potencies and Establishment of a Threshold of Regulation for Food Contact Substances" (the chemical
10⁻⁶ machinery, via a "probability distribution of the potencies of known carcinogens" — the 1987 precursor to
Rulis 1992, H13, and the 1995 ToR rule); ch. 11 = the NCRP negligible-risk chapter above; ch. 6 = **Travis &
Richter, "On Defining a De Minimis Risk Level for Carcinogens."** The volume **explicitly juxtaposes the two
numbers** — e.g. "**The FDA interprets its 10⁻⁶ criterion cautiously**" (l. 2030) beside the UK NRPB radiation
target, noting the per-unit gap: the NRPB "**risk target (10⁻⁶ per year rather than 10⁻⁶ per lifetime) was
modified by a factor (of 100)**" (ll. 1284–86). The two round-number-threshold traditions self-consciously joined
under the banner *de minimis* in 1987 — chemical 10⁻⁶/lifetime, radiation 10⁻⁷/year.

## 4. What number the *military* uses — NOW [CONFIRMED-primary] (held, H36): the soldier gets 10⁻⁴
**NRC, *Review of the Army's Technical Guides on Assessing and Managing Chemical Hazards to Deployed Personnel*
(NAP 10974, 2004; now held, register H36; `papers/lateral/10974.pdf` → `/tmp/army.txt`).** The headline number:
- **The U.S. Army's acceptable cancer risk for deployed personnel is 1 × 10⁻⁴ (1 in 10,000)** — "the acceptable
  risk of excess cancer resulting from exposures to chemical carcinogens is **1 × 10⁻⁴ regardless of route**…
  averaged over a lifetime from a **1-year deployment**." Rationale (Army RD-230): "(1) it is the **upper bound
  of the range of cancer risk found acceptable to EPA (1 × 10⁻⁴ to 1 × 10⁻⁶)** and (2) it is an order of
  magnitude less than the… risk… supported for workers by OSHA." And explicitly: "**The selection of an
  acceptable risk level is a policy decision… how much risk the military should accept.**" (Army.txt ll.
  3749–88) → **the deployed soldier is allotted ~100× the acceptable cancer risk of a food-additive consumer
  (10⁻⁴ vs 10⁻⁶) — by stated policy choice, because the benefit (military necessity) is large.**
- **It names the radiation-biology no-threshold origin:** "On the basis of observations from **radiation biology**
  and theories of carcinogenesis, the concept that **nonthreshold effects**… was adopted for regulatory
  purposes… no exposures to carcinogens can be judged risk-free, however small." (ll. 3789–96) — the Army
  manual confirming the very lineage this dossier traces.
- **It independently recounts the FDA 10⁻⁸→10⁻⁶ story, citing the same FR primaries (H32):** "In 1973, FDA
  employed… the **Mantel-Bryan methodology**… The acceptable risk level **proposed at the time was 1 × 10⁻⁸**
  (Mantel & Bryan 1961; **FDA 38 Fed. Reg. 19226 [1973]**; Rodricks et al. 1987)," "firmly entrenched by 1979
  (**FDA 44 Fed. Reg. 17070 [1979]**)." (ll. 7755–88) — a military hazard-guide review citing the exact
  documents we hold (H32) and Rodricks (H1).

## 4a. The occupational basis (ICRP-26, 1977; held, H35) and the AEC fallout standards (I-131 volume; H37)
- **ICRP Publication 26 (1977; `ANIB_1_3.pdf`):** the worker dose limit is pegged to the fatal-accident rate of
  "**safe industries**" — "a level of risk representative of a **safe occupation**… comparisons with other safe
  industries" (icrp26.txt ll. 1148–58), i.e. an occupational acceptable risk ~10⁻⁴/yr. The 1954 occupational-
  *comparison* basis (Handbook 59), now made a *number*.
- **NAS, *Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests* (catalog 6283; held, H37):**
  ch. "**Applicable Radiation Exposure Standards and Guides: Past and Present**" documents the AEC-era "**maximum
  permissible concentration / maximum permissible dose**" regime (back to NBS Handbook 52, 1953) applied during
  atmospheric weapons testing — "**the Atomic Energy Commission declared**…"; the **AEC Division of Biology and
  Medicine, Fallout Studies Branch**. The literal weapons-program application of the "permissible dose" device.

### Synthesis — the round number flexes with *whose body* bears the risk
| Who | Number | Source |
|---|---|---|
| **Astronaut** | **~10⁻² / flight** (1 in 100) | NASA post-Columbia (H39–H41) |
| Deployed soldier | **10⁻⁴ / lifetime (per 1-yr deployment)** | U.S. Army RD-230 (H36) |
| Radiation worker / "safe industry" | **~10⁻⁴ / year** | ICRP-26 (H35) |
| Environmental public (EPA range) | **10⁻⁴ – 10⁻⁶ / lifetime** | EPA |
| Food-additive consumer | **10⁻⁶ / lifetime** | FDA (Hutt/SOM; H25, H32) |
| Radiation public ("negligible") | **10⁻⁷ / year** (1 mrem/yr) | NCRP (H34 ch. 11) |
*Same device — "acceptable risk" — calibrated across **~six orders of magnitude** (astronaut 10⁻² → radiation
public 10⁻⁷) by exposure context, population size, volition, and perceived benefit. The astronaut, soldier, and
worker are allotted the *most* risk (high benefit, volunteered); the food additive's trifling benefit buys the
consumer one of the *strictest* numbers. None is a safety threshold; each is a chosen, benefit-weighted round
number. (Space-flight panel: `sources/Spaceflight-risk_Feynman-PateCornell-NYT_excerpt.md`.)*

## Why it matters
- **Answers the operator's question precisely:** the military *does* use acceptable-cancer-risk numbers (the
  10⁻⁴–10⁻⁶ range), but it **borrowed 10⁻⁶ from the chemical/FDA side**; radiation's own "negligible" figure is
  **10⁻⁷/yr (≈10⁻⁵ lifetime)**. "1 in a million" is not a radiation/AEC number.
- **Locates the military DNA correctly:** it's on the **acceptable-risk (number) branch** — radiation protection,
  reorganized for the bomb, invented "acceptable nonzero risk in place of safe dose" — not on the **de minimis
  (legal-doctrine) branch**, which is civilian-commercial (Frawley → SPI → the courts).
- **A clean essay line:** the device that lets a carcinogen into the food supply and the device that told a
  soldier how much fallout was tolerable are the *same idea* — "acceptable risk" — and in 1987 they shared a book
  cover. They were never quite the same *number*: the chemical world rounded to 10⁻⁶ lifetime, the radiation
  world to 10⁻⁷ per year.

## Acquisition status (2026-06-13)
- ✅ **NIRL = 10⁻⁷/yr verbatim — ACQUIRED:** ch. 11 of *De Minimis Risk* (Whipple, 1987), now held (**H34**) —
  supersedes the need for NCRP Report 91.
- ✅ **NAP 10974** (2004) Army acceptable-risk review — **held** (`papers/lateral/10974.pdf`; recounts the FDA
  10⁻⁸→10⁻⁶ history; close-read pending).
- ✅ **ICRP Publication 26** (1977) — **held** (`papers/lateral/ANIB_1_3.pdf`, 87 pp.; occupational ~10⁻⁴/yr;
  close-read pending).
- ✅ **NAS I-131 Nevada-bomb-test volume** (catalog 6283) — **held** (`papers/lateral/Bookshelf_NBK100842.pdf`;
  contains "Applicable Radiation Exposure Standards: Past and Present" — AEC-era dose standards).