Vizcaino: HPV, Carcinogen Exposure, and Rebutting the Firefighter Cancer Presumption

Decision at a Glance

Edward Vizcaino v. City of Sacramento, No. ADJ14177811 (Cal. Workers' Comp. Appeals Bd. Dec. 31, 2025), is an Opinion and Decision After Reconsideration issued by a three-commissioner WCAB panel. It is a panel decision, not an en banc decision. The Board unanimously affirmed a workers' compensation administrative law judge's finding that a municipal fire captain sustained a compensable industrial injury in the form of throat cancer, and that the City of Sacramento failed to rebut the Labor Code section 3212.1 cancer presumption. The official opinion is available from the California Department of Industrial Relations.

Current statutory note: Effective January 1, 2026, Labor Code section 3212.1 was amended by SB 230 (Stats. 2025, Ch. 404) to add subdivision (a)(4), extending presumption coverage prospectively to active firefighting members serving FAA Part 139-regulated commercial airports for injuries occurring on or after that date. That amendment does not affect the covered municipal-firefighter classification at issue in Vizcaino or the rebuttal standards the Board applied.

Facts and Procedural Chronology

Edward Vizcaino was employed as a fire captain by the City of Sacramento from August 10, 2005 through December 22, 2020. His duties involved suppressing residential and commercial fires, exposing him to aqueous film-forming foam and combustion products including diesel exhaust fumes. Vizcaino, slip op. at 2.

In August 2020, Vizcaino first noticed swelling on the left side of his neck. In December 2020, he received a formal throat cancer diagnosis, presenting as three masses on the left side of his neck. He reported that no one had told him he had HPV. Vizcaino, slip op. at 2.

On June 10, 2021, qualified medical evaluator Massoud Mahmoudi, D.O., Ph.D., examined Vizcaino and issued a report diagnosing carcinoma of the left tonsil. Vizcaino, slip op. at 2. In a supplemental report of July 1, 2021, Dr. Mahmoudi noted the applicant's history of diesel and fume exposure and a positive HPV diagnosis by history. Vizcaino, slip op. at 2. In a further supplemental report of August 16, 2021, Dr. Mahmoudi linked the oropharyngeal cancer with HPV and stated that he was not aware of a relationship between diesel and combustion matters and tonsillar cancer. Vizcaino, slip op. at 2. Another supplemental report described the relationship as unknown. Vizcaino, slip op. at 2. In a January 10, 2022 supplemental report, Dr. Mahmoudi wrote that he had not found any medical studies demonstrating that exposure to diesel and combustion matters is not reasonably linked to tonsillar cancer. Vizcaino, slip op. at 3.

Dr. Mahmoudi was cross-examined by deposition on November 22, 2021. He identified the primary cancer site as the left tonsil and base of the tongue. He was not aware of medical journal articles or empirical studies associating occupational exposures with non-HPV oropharyngeal cancer. He acknowledged that diesel exhaust is an IARC-recognized carcinogen that causes lung cancer, but testified that no medical evidence supported it causing oropharyngeal cancer. He stated that the relationship between diesel exhaust and throat cancer is possible but unknown, and on the available data there is no relationship. He conceded, however, that carcinogenic acceleration was possible. He testified that HPV was a major cause — but not the sole cause — of Vizcaino's cancer. Vizcaino, slip op. at 3.

Note on internal dating: The Board's opinion contains a minor internal date inconsistency in the exhibit citations for Dr. Mahmoudi's supplemental reports. This analysis follows the dates as printed in the opinion without reproducing characterizations that appear chronologically impossible.

On September 29, 2022, the WCJ issued Findings of Fact and Order finding that Vizcaino sustained an industrial throat cancer injury and that the City failed to rebut the section 3212.1(d) presumption. The City filed a Petition for Reconsideration. The Board previously granted reconsideration to study the issues further, and thereafter issued this Opinion and Decision After Reconsideration. A panel member was replaced following the original grant of reconsideration. Vizcaino, slip op. at 1.

Precise Legal Questions

1. Whether the applicant established the statutory predicates under Labor Code section 3212.1 to invoke the firefighter cancer presumption.
2. Whether the City rebutted the presumption under section 3212.1(d) by presenting (a) an HPV diagnosis characterized as a major but not sole cause, and (b) a medical evaluator's opinion that no literature links diesel exhaust to tonsillar cancer.

Statutory Framework

Labor Code section 3212.1, as operative prior to the January 1, 2026 amendment, provides in subdivision (b) that the term injury includes cancer that develops or manifests during covered service if the member demonstrates exposure to a known IARC-defined carcinogen. Subdivision (d) establishes that the cancer shall be presumed to arise out of and in the course of employment. The presumption is disputable and may be controverted only by evidence that the primary cancer site has been established and that the carcinogen to which the member demonstrated exposure is not reasonably linked to the disabling cancer. The post-employment extension runs up to 120 months, at three months per full year of requisite service. Vizcaino, slip op. at 3.

Argument and Reasoning: Step by Step

Step 1 — Applicant's prima facie showing

The Board confirmed that Vizcaino satisfied all three predicates identified in the en banc decision the Board cited as Faust v. City of San Diego, 68 Cal.Comp.Cases 1822 (Appeals Board en banc 2003): (1) active firefighting service in a covered municipal fire department; (2) actual exposure during that employment to diesel exhaust, an IARC-recognized known carcinogen, through suppression of residential and commercial fires; and (3) development and manifestation of cancer — with symptoms first appearing in August 2020 and formal diagnosis in December 2020 — within the statutory time period. Vizcaino, slip op. at 4–5. Minimal actual exposure satisfies the threshold; the applicant need not prove at this stage that the exposure proximately caused the cancer. Once these elements are established, the presumption attaches and the burden shifts to the employer.

Step 2 — Employer's dual rebuttal burden under section 3212.1(d)

To rebut the presumption, the City had to establish both: (1) the primary site of the cancer; and (2) by competent medical or scientific evidence, that the carcinogen to which Vizcaino demonstrated exposure is not reasonably linked to the disabling cancer. The Board applied the standard from Faust as endorsed by the Court of Appeal in City of Long Beach v. Workers' Comp. Appeals Bd. (Garcia), 126 Cal.App.4th 298 (2005): an employer satisfies this burden by showing the identified link is so lacking that it cannot logically be inferred — remote, hypothetical, or statistically improbable links do not survive, but the employer must prove the no-reasonable-link proposition affirmatively, not merely show that no one has yet demonstrated a link. Vizcaino, slip op. at 5–6.

Step 3 — Primary site: first element met

Dr. Mahmoudi's testimony identifying the left tonsil and base of the tongue as the primary cancer site satisfied the first rebuttal element. The Board confirmed this. Vizcaino, slip op. at 5.

Step 4 — No-reasonable-link showing: second element not met

The Board held that Dr. Mahmoudi's opinion on the second element rested on an insufficient foundation. His conclusion — that no reasonable link exists between diesel exhaust and tonsillar cancer — was grounded in his inability to find medical literature establishing such a connection, not in affirmative scientific reasoning demonstrating that the connection does not exist. The Board relied on the rule, drawn from Garcia and applied consistently in the Board's own decisions, that evidence showing no link has been demonstrated is not adequate to rebut the presumption. The employer must show by medical probability that a reasonable link does not exist. An evaluator's statement that the relationship is unknown or that supporting studies are absent is not that affirmative showing. Vizcaino, slip op. at 6–7. The Board further cited prior writ-denied decisions — including County of Ventura v. Workers' Comp. Appeals Bd. (Bastian), 75 Cal.Comp.Cases 513 and City of Compton v. Workers' Comp. Appeals Bd. (Branscomb), 76 Cal.Comp.Cases 991 — for the same proposition, as reflected in the Board's opinion at pages 6–7.

Step 5 — HPV as major cause: does not establish sole causation or exclude acceleration

The City argued that HPV's role as the cancer's cause rebutted any industrial link. The Board rejected this because Dr. Mahmoudi's own deposition testimony foreclosed the argument: he testified that HPV was a major cause, not the sole cause, and he conceded that carcinogenic acceleration from workplace exposures was possible. A competing non-industrial cause that neither excludes occupational contribution nor rules out toxic acceleration does not establish that the workplace carcinogen is not reasonably linked to the disabling cancer. Vizcaino, slip op. at 3, 7.

Step 6 — Latency argument: insufficient to exclude industrial causation

The City also argued, relying on a study in evidence as Defense Exhibit B, that the applicable latency period for HPV-related cancer excluded occupational causation. The Board rejected this contention. The Board found that the study did not establish that Vizcaino could not have developed cancer within the relevant latency period even assuming the possibility of carcinogenic acceleration. The Board cited City of Pittsburg v. Workers' Comp. Appeals Bd. (Ligouri), 83 Cal.Comp.Cases 711 (writ denied 2018), cited in the Board's opinion at page 7, for the proposition that a latency-period argument must affirmatively exclude industrial causation on the specific facts — a general latency range does not do so when acceleration remains medically possible.

Step 7 — Adoption of WCJ's Report and Recommendation

The Board adopted and incorporated the WCJ's Report and Recommendation on the Petition for Reconsideration as part of its reasoning, in addition to addressing the issues in its own discussion. Vizcaino, slip op. at 1.

Panel Composition and Disposition

The decision was issued unanimously. Commissioner Katherine Williams Dodd authored the opinion. Commissioners Joseph V. Capurro and José H. Razo each concurred. There were no separate concurring or dissenting writings. Vizcaino, slip op. at 8.

Disposition: The September 29, 2022 Findings of Fact and Order is AFFIRMED in its entirety as the Decision After Reconsideration of the Workers' Compensation Appeals Board. Vizcaino, slip op. at 8.

Practical Significance, Limits, and Current Law

Vizcaino illustrates three concrete limits on the employer's rebuttal case in firefighter cancer proceedings involving competing non-industrial causes.

First, an evaluator's inability to identify peer-reviewed literature linking a workplace carcinogen to a particular cancer site is not the same as an affirmative showing that no reasonable link exists. Employers who rely primarily on a silent literature search have not met the statutory burden, regardless of how credentialed or detailed the medical report is otherwise.

Second, identifying a recognized non-industrial cause — including a viral carcinogen like HPV — does not rebut the presumption unless the employer’s evidence establishes that no reasonable occupational link exists, addressing acceleration where the record raises it. Those concessions mattered alongside the evaluator’s reliance on missing literature and the inadequacy of the latency evidence. The opinion does not turn every statement of a conceivable connection into proof of a reasonable link.

Third, a latency-period argument requires the medical evidence to address the specific facts of the claim, including possible acceleration, and must affirmatively exclude industrial causation rather than posit a general expected timeframe.

What Vizcaino does not decide: It does not establish that diesel exhaust causes tonsillar cancer, that HPV exposure is ever industrial, or that every firefighter throat cancer claim is compensable. The presumption is rebuttable in principle; Vizcaino describes what the rebuttal evidence must affirmatively show, not that rebuttal is impossible.

The January 1, 2026 amendment to Labor Code section 3212.1 added FAA commercial airport firefighters to the covered classifications prospectively. The rebuttal framework analyzed in Vizcaino is drawn from subdivision (d), which is unchanged by that amendment.

For the reader-focused guide to competing-cause evidence and the evidence tasks a firefighter should complete, see HPV-Positive Throat Cancer in a Firefighter: What the Competing-Cause Evidence Must Explain. Our California workers' compensation practice page explains how to contact the firm.