Contributing Factors of Foodborne Illness Outbreaks — National Outbreak Reporting System, United States, 2014-2022
Cited in 3 Likelier entries (3 risks, 0 decisions).
Used in 3 entries
For each citing entry, the verbatim excerpt and Likelier's calculation notes (how the source's number was converted to the lifetime-probability framing) are shown below. Click through to read the full claim ledger.
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Among 2,677 foodborne outbreaks 2014-2022, 'allowing foods to remain out of temperature control' during preparation contributed to 9.9-15.2% and during service/display to 8.9-13.6%; 'improper cooling' contributed to 8.8-17.3%
“"Allowing foods to remain out of temperature control during preparation contributed to 15.2% of outbreaks during 2014-2016, 12.2% during 2017-2019, and 9.9% during 2020-2022. Allowing foods to remain out of temperature control during food service or display contributed to 13.6%, 10.4%, and 8.9%, respectively, across the three periods. Improper cooling of food contributed to 9.4%, 8.8%, and 10.9%."”
Calculation notes
CDC NORS is the canonical US surveillance system for outbreak contributing factors. Summing the three temperature-related factors gives an upper envelope of roughly 30-40% of outbreaks, but the categories overlap (an outbreak can be coded with multiple contributing factors), so we deflate to ~20% as the central estimate for the share of US foodborne illness where temperature abuse was meaningfully involved. Applied to Scallan's 48 million illnesses/year: 0.20 × 48e6 ≈ 9.6 million cases/year, or ~1 in 35 of the US population. Over 59 adult-remaining years: 1 - (1 - 0.029)^59 ≈ 0.82.
Independence note: NORS draws on the same state and local public-health reporting pipeline as CDC FoodNet and the Scallan et al. estimates; treat as a methodological sibling rather than a fully independent data source.
Source date: 2025-03-13 · Accessed: 2026-04-16
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Cross-contamination of foods was among the top five contributing factors for bacterial outbreaks at 22.0% (2014-2016) and 20.8% (2017-2019); bare-hand contact by infected food workers declined from 20.5% to 8.9% across the three periods
“"For bacterial outbreaks, cross-contamination of foods was among the top five contributing factors during the first (22.0%) and second periods (20.8%), but not during the third period. [...] The proportion of outbreaks with contamination from an infectious food worker through barehand contact with food decreased (20.5%, 15.2%, and 8.9%, respectively) across the three time periods."”
Calculation notes
CDC NORS is the canonical US surveillance system for outbreak contributing factors. The 20-22% cross-contamination rate among bacterial outbreaks provides the upper anchor for the share of all foodborne illness attributable to cross-contamination. We deflate to ~15% as the central estimate because not all foodborne illness is bacterial, not all is detected via outbreak surveillance, and NORS contributing factors can be coded multiply. Applied to Scallan's 48 million illnesses/year: 0.15 x 48e6 = 7.2 million cases/year, or ~2.18% of the US population per year.
Independence note: NORS draws on the same state and local public-health reporting pipeline as CDC FoodNet and the Scallan et al. estimates; treat as a methodological sibling rather than a fully independent data source.
Source date: 2025-03-13 · Accessed: 2026-04-19
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Among 2,677 foodborne outbreaks 2014-2022, 'inadequate time and temperature during initial cooking/thermal processing' contributed to 12.1%, 9.6%, and 12.1% across the three reporting periods; consistently a top-five contributing factor
“"Inadequate time and temperature control during initial cooking of food was among the top five contributing factors during all three periods (23.8 percent, 20.4 percent, and 20.9 percent, respectively) [broader category]. More specifically, the proportion of outbreaks associated with inadequate time and temperature control during initial cooking/thermal processing of food decreased from the first (12.1 percent) to the second period (9.6 percent), and increased during the third period (12.1 percent)."”
Calculation notes
The NORS MMWR report is the primary source for the 12% central estimate. The broader "inadequate time and temperature during cooking" category runs 20-24%, but this includes holding and display temperatures, which overlap with the food-left-unrefrigerated entry. The narrower "initial cooking/thermal processing" subcategory (9.6-12.1%) isolates the undercooking contribution. Applied to Scallan's 48 million illnesses/year: 0.12 x 48e6 = 5.76 million cases/year, or ~1.75% of the US population annually. Over 59 adult-remaining years: 1 - (1 - 0.0175)^59 = 0.645.
Independence note: NORS is a CDC surveillance system drawing on state/local outbreak reporting. Methodologically linked to FoodNet and Scallan estimates but provides the contributing-factor breakdown those sources lack.
Source date: 2025-03-13 · Accessed: 2026-04-19
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