Reactive HyperemiaBIOBRAND3NCT05753254
Effect on Markers of Cardiovascular, Reproductive and Cancer Risk From Firefighting Training
A study testing Firefighting training exercises with no fire, Firefighting training exercises under wood fire and Firefighting training exercises under gas fire in people with Reactive Hyperemia and Micro RNA, run by National Research Centre for the Working Environment, Denmark at 2 sites in Denmark.
Trial summary
Epidemiological studies based on Danish registries have observed that Danish male firefighters have more cardiovascular disease, infertility diagnose and a trend to increased risk of cancer than other Danish employed males. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Reactive Hyperemia, Micro RNA, Heart Rate Variability
- What is being tested?
- Firefighting training exercises with no fire, Firefighting training exercises under wood fire and Firefighting training exercises under gas fire
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 35 participants
- Where
- 2 sitesDenmark
- Study dates
- 10 Mar 2023to 5 Jul 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- legally competent,
- conscript subjects following a Rescue Specialist Educational course
Who cannot join
- current smoking status,
- pregnancy,
- on prescribed medication,
- body mass index (BMI) bellow 19 or over 30,
- alcohol or drug abuse.
Trial locations and contacts
2 sites in 1 country.
Denmark2 sites
The National Research Centre for the Working Environment
Copenhagen, 2100
Maria Helena Guerra Andersen
København Ø, 4700
About this study
Official title: Effect on Markers of Cardiovascular, Reproductive and Cancer Risk From Firefighting Activities - a Study Under Different Training Methods
Epidemiological studies based on Danish registries have observed that Danish male firefighters have more cardiovascular disease, infertility diagnose and a trend to increased risk of cancer than other Danish employed males. Firefighting activities include a combination of stressors such as strenuous work under heat, smoke and soot known to be able to affect cardiovascular and reproductive health, with smoke and soot also being known to increase the risk of cancer.
The training facilities of real-fire extinguishing exercises in Denmark operate using wood or natural gas fire, which will have differential gradients of smoke, soot and possibly heat. The investigators will use different training conditions to create gradients of the different stressors and investigate health effects thereof. With this approach, the investigators expect to be able to evaluate the individual contribution of the different stressors in markers of cardiovascular, cancer and reproductive health risk. The project will include approx. 35 young conscript participants on a firefighting course, followed in four sessions, three firefighting training sessions under different fire conditions (no fire, wood fire and gas fire) and one control scenario.
Read the detailed description
The study methodology is based on a crossover design on firefighting training under different conditions, with characterization of exposure and assessment of cardiovascular, cancer and reproductive effect biomarkers. The study will be performed in cooperation with the Danish Emergency Management Agency.
The study will have one baseline session, while conscripts are in a classroom, and three sessions of firefighting-related exercises under different fire conditions, used currently in firefighting training programs in Denmark. The three firefighting training sessions will be controlled for equivalent work exercise using full protective gear and under different ambient conditions of firefighting training:
- Firefighting equivalent work (no fire), with exercises performed in a clean environment, without fire (no ambient temperature, soot or smoke). This type of exercise precedes or complements the training under real fire conditions.
- Firefighting under wood fire (wood fire), with exposure to ambient heat, smoke and soot. This is the most common training scenario used by Danish Emergency Management Agency training centres.
- Firefighting under gas fire (gas fire), with exposure to ambient heat, and expectably less smoke and soot than with wood fire. These conditions are used in some Danish training centres, with logistical advantages (ease of turning or putting out the fire and managing the fire fuel) and unknown effect relating to exposure prevention (smoke and soot).
The order of the firefighting sessions will be as randomized as possible, and according to a selection of three sequence order options (no-wood-gas; wood-gas-no and gas-wood-no). Each campaign (corresponding to each rescue course) would desirably have one of these session sequences. It is not possible to blind the participants to the different scenarios, neither the field staff, but all the samples will be blinded for the subsequent laboratory analysis. The training sessions will have 1-3 weeks in between (accordingly with programmatic educational course schemes).
- Conditions
- Reactive Hyperemia, Micro RNA, Heart Rate Variability, DNA Strand Breaks, Oxidative Stress, Heat Stress
- Being tested
- Firefighting training exercises with no fire, Firefighting training exercises under wood fire, Firefighting training exercises under gas fire
- Keywords
- Comet assay, 8-oxodG, PAH CALUX, hydroxyl-PAHs and nitro-PAH metabolites, microRNA, AhR activation, scrotal temperature, core body temperature, urine, serum, blood, follicle-stimulating hormone, inhibin B, EndoPAT
- Medical subject headings
- Hyperemia, Heat Stress Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Firefighting training exercises with no fireOther
The participants will be performing firefighting equivalent work in a clean environment, without fire (no ambient temperature, soot or smoke).
Firefighting training exercises under wood fireOther
The participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models), under wood fire conditions.
Firefighting training exercises under gas fireOther
The participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models), under gas fire conditions.
| Study group | Role | What they receive |
|---|---|---|
| Baseline session | No intervention | Baseline measurements will be performed in the same schedule as measurements in the three other arms. In the baseline session, participants are in classroom before starting any firefighting exercise |
| Firefighting exercises without fire | Experimental | Firefighting equivalent work, with exercises performed in a clean environment, without fire (no ambient temperature, soot or smoke). This type of exercise usually precedes or complements the training under real fire conditions. Receives: Other: Firefighting training exercises with no fire |
| Firefighting under wood fire | Experimental | Firefighting under wood fire, with exposure to ambient heat, smoke and soot. This is the most common training scenario used in the training centres. The participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models Receives: Other: Firefighting training exercises under wood fire |
| Firefighting under gas fire | Experimental | Firefighting under gas fire, with exposure to ambient heat, and expectably less smoke and soot than with wood fire. These conditions are used in some Danish training centres, with logistical advantages (ease of turning or putting out the fire and managing the fire fuel) and unknown effect relating to exposure prevention (smoke and soot). The participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models Receives: Other: Firefighting training exercises under gas fire |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in reactive hyperemia index - afternoon
Reactive hyperemia index (RHI) measured with the device EndoPAT 2000. A reactive hyperemia is induced by a blood cuff on the upper arm and the peripheral vasodilation response is assessed in the small digital vessels of a fingertip with a portable device connected to a computer, with RHI determined by an algorithm from the device, with lower index values corresponding to a worsen situation.
Measured: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Change in reactive hyperemia index - morning
Reactive hyperemia index (RHI) measured with the device EndoPAT 2000. A reactive hyperemia is induced by a blood cuff on the upper arm and the peripheral vasodilation response is assessed in the small digital vessels of a fingertip with a portable device connected to a computer, with RHI determined by an algorithm from the device, with lower index values corresponding to a worsen situation.
Measured: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Change in Heart Rate Variability pNN50 at rest - afternoon
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. pNN50 is the proportion of successive NN intervals differing by more than 50 milliseconds divided by the total number of N intervals (given in percentage).
Measured: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Change in Heart Rate Variability pNN50 at rest - morning
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. pNN50 is the proportion of successive NN intervals differing by more than 50 milliseconds divided by the total number of N intervals (given in percentage).
Measured: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Change in Heart Rate Variability RMSSD at rest - afternoon
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. RMSSD is the square root of the mean squared differences of successive NN intervals (given in milliseconds)
Measured: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Change in Heart Rate Variability RMSSD at rest - morning
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. RMSSD is the square root of the mean squared differences of successive NN intervals (given in milliseconds)
Measured: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Change in Heart Rate Variability ratio LF/HF at rest - afternoon
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. Ratio of low frequency and high frequency bands
Measured: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Change in Heart Rate Variability ratio LF/HF at rest - morning
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. Ratio of low frequency and high frequency bands
Measured: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Changes in levels of 8-oxodG excretion in first morning urine
Oxidized nucleobase 8-oxodG will be measured in urine samples by High-performance liquid chromatography (HPLC) as marker of oxidative stress, together with creatinine, for adjusting for urine concentration. Data will be reported as nanomol 8-oxodG per millimol creatinine.
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in levels of DNA strand breaks in peripheral blood mononuclear cells
DNA strand breaks will be measured by comet assay, and reported as number of lesions per 10^6 base pairs, transformed from percentage of DNA in tail using the calibration curve from the well-establish relationship between ionizing radiation dose and yield of strand breaks in DNA.
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in core temperature
Core body temperature will be assessed by an ingestible pill thermometer with data recorded and reported as time series during the period in transit.
Measured: Baseline day, during the day of firefighting without fire, during the day of firefighting under wood fire and during the day of firefighting under gas fire.
Changes in scrotal temperature
Scrotal temperature will be assessed by skin sensor placed in the scrotum of male participants and reported as scrotal skin temperature time series.
Measured: Baseline day, during the day of firefighting without fire, during the day of firefighting under wood fire and during the day of firefighting under gas fire.
Changes in scrotal thermoregulation
Core body temperature will be assessed by an ingestible pill thermometer and scrotal temperature will be assessed by skin sensor placed in the scrotum of male participants, to assess the thermoregulation of the scrotum during firefighting exercises. Time series of core body temperature and scrotal skin temperature will be analysed for eventual thermoregulation disruption.
Measured: Baseline day, during the day of firefighting without fire, during the day of firefighting under wood fire and during the day of firefighting under gas fire.
Changes in levels of circulating micro RNA
Circulating micro RNA candidates will be measured by RNA extraction from serum samples, reverse transcribed into complementary DNA (cDNA) and analysed with quantitative polymerase chain reaction (qPCR).
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in urinary potency of AhR activation
The aryl hydrocarbon receptor (AhR) activation will be assessed in vitro using urine samples on the PAH CALUX (Chemical Activated LUciferase gene eXpression bioassay) reporter assay. The smoke and soot exposures are complex mixtures of compounds with potential toxic effect. Routine measurements of PAHs are usually quantified for a target list of 16 common soot elements and even less chemical species for urinary metabolites, but many other compounds are present in both soot and metabolites mixtures. The toxicity of PAHs is primarily caused through the binding to AhR, and induction of AhR related genes and subsequent toxic pathways. The outcome will be measured in the form of benzo[a]pyrene equivalence.
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in potency of AhR activation from skin deposits
The aryl hydrocarbon receptor (AhR) activation will be assessed in vitro using wipe samples on the PAH CALUX (Chemical Activated LUciferase gene eXpression bioassay) reporter assay. The smoke and soot exposures are complex mixtures of compounds with potential toxic effect. Routine measurements of PAHs are usually quantified for a target list of 16 common soot elements, but many other compounds are present in soot mixtures. The toxicity of PAHs is primarily caused through the binding to AhR, and induction of AhR related genes and subsequent toxic pathways. The outcome will be measured in the form of benzo[a]pyrene equivalence.
Measured: Baseline, before firefighting without fire, immediately after firefighting without fire, before firefighting under wood fire, immediately after firefighting under wood fire, before firefighting under gas fire, immediately after firefighting under gas
Secondary outcomes (10)
Changes in levels of follicle-stimulating hormone in serum
Follicle-stimulating hormone (FSH) will be measured in serum samples
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in levels of serum inhibin B
Inhibin B hormone will be measured in serum samples
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in urinary levels of PAH metabolites excretion
The internal dose of polycyclic aromatic hydrocarbons (PAHs), that would have the contribution from different exposure routes, will be assessed in first morning urine samples and measured for 7 isomer hydroxyl-PAH compounds and 5 nitro-PAH compounds, measured by high-performance liquid chromatography (HPLC)
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in levels of PAHs in skin wipes from the neck
Skin wipes will be sampled to determine the PAH composition of deposited soot on the neck area. The wipes will be analysed for the 16 US Environmental Protection Agency priority list of PAH compounds by HPLC.
Measured: Baseline, before firefighting without fire, immediately after firefighting without fire, before firefighting under wood fire, immediately after firefighting under wood fire, before firefighting under gas fire, immediately after firefighting under gas
Changes in FEV1 spirometric measurements
Lung function will be measured by spirometry using the Spirometer device EasyOne Air. Forced Expiratory Volume at 1 second (FEV1).
Measured: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in FVC spirometric measurements
Lung function will be measured by spirometry using the Spirometer device EasyOne Air. Forced Vital capacity (FVC).
Measured: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in PEF spirometric measurements
Lung function will be measured by spirometry using the Spirometer device EasyOne Air. Peak Expiratory Flow (PEF).
Measured: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in FEV1/FVC ratio from spirometric measurements
Lung function will be measured by spirometry using the Spirometer device EasyOne Air. Forced Expiratory Volume at 1 second (FEV1) and Forced Vital Capacity (FVC) ratio is calculated from device output.
Measured: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in blood troponin levels
Cardiac troponin levels using ELISA immunoassays will be assessed in serum samples.
Measured: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in work load measured by muscle activity
Muscle activity will be assessed to control for body workload through electromyography (EMG) using the portable device Nexus10. Bipolar surface EMG electrodes are applied to the skin over the muscles in 3 relevant body regions (shoulder, leg and back). The signals are collected with a data logger and reported as work load during a working day.
Measured: Baseline day, firefighting without fire day, firefighting under wood fire day and firefighting under gas fire day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Mar 2023
- Study start10 Mar 2023
- Primary completion5 Jul 2024
- Study completion5 Jul 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (18)Papers the sponsor has linked to this study.
- Other trials for Reactive HyperemiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participants will perform firefighting full day exercises under 3 different conditions (without fire, under wood fire and under gas fire), sessions which will occur with weeks in between, and biological markers will be assessed and compared in relation to a baseline session, where the participants are having theoretical classes.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 35 participants (actual)
Sponsor and investigators
- Lead sponsor
- National Research Centre for the Working Environment, Denmark
- Sponsor type
- Other government
- Collaborators
- University of Copenhagen, University Hospital Bispebjerg and Frederiksberg, Copenhagen University Hospital, Rigshospitalet
- Responsible party
- Principal investigator, Maria Helena Guerra Andersen, National Research Centre for the Working Environment, Denmark
- Investigators
- Maria Helena G Andersen, PhD, Principal investigator, The National Research Centre for the Working Environment (NRCWE)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05753254
- Sponsor's protocol ID
- 72403
- Other IDs
- FFIKA WP4.3, AMFF 16-2022-03, H-21068847
- Acronym
- BIOBRAND3
- Status last verified
- Jul 2025
- First submitted
- 2 Feb 2023
- Last updated
- 6 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Supportive information and fully anonymized information will be shared and whenever possible (in supplementary material) published along with the results, but following European Union General Data Protection Regulation (GDPR) and Danish rules, no non or pseudo anonymized data might be shared.
Publications
Andersen MHG, Saber AT, Pedersen PB, Loft S, Hansen AM, Koponen IK, Pedersen JE, Ebbehoj N, Norskov EC, Clausen PA, Garde AH, Vogel U, Moller P. Cardiovascular health effects following exposure of human volunteers during fire extinction exercises. Environ Health. 2017 Sep 6;16(1):96. doi: 10.1186/s12940-017-0303-8.
PubMed 28877717Andersen MHG, Saber AT, Clausen PA, Pedersen JE, Lohr M, Kermanizadeh A, Loft S, Ebbehoj N, Hansen AM, Pedersen PB, Koponen IK, Norskov EC, Moller P, Vogel U. Association between polycyclic aromatic hydrocarbon exposure and peripheral blood mononuclear cell DNA damage in human volunteers during fire extinction exercises. Mutagenesis. 2018 Feb 24;33(1):105-115. doi: 10.1093/mutage/gex021.
PubMed 29045708Andersen MHG, Saber AT, Pedersen JE, Pedersen PB, Clausen PA, Lohr M, Kermanizadeh A, Loft S, Ebbehoj NE, Hansen AM, Kalevi Koponen I, Norskov EC, Vogel U, Moller P. Assessment of polycyclic aromatic hydrocarbon exposure, lung function, systemic inflammation, and genotoxicity in peripheral blood mononuclear cells from firefighters before and after a work shift. Environ Mol Mutagen. 2018 Jul;59(6):539-548. doi: 10.1002/em.22193. Epub 2018 May 15.
PubMed 29761929Andersen MHG, Saber AT, Frederiksen M, Clausen PA, Sejbaek CS, Hemmingsen CH, Ebbehoj NE, Catalan J, Aimonen K, Koivisto J, Loft S, Moller P, Vogel U. Occupational exposure and markers of genetic damage, systemic inflammation and lung function: a Danish cross-sectional study among air force personnel. Sci Rep. 2021 Sep 9;11(1):17998. doi: 10.1038/s41598-021-97382-5.
PubMed 34504215Beitel SC, Flahr LM, Hoppe-Jones C, Burgess JL, Littau SR, Gulotta J, Moore P, Wallentine D, Snyder SA. Assessment of the toxicity of firefighter exposures using the PAH CALUX bioassay. Environ Int. 2020 Feb;135:105207. doi: 10.1016/j.envint.2019.105207. Epub 2019 Dec 4.
PubMed 31812113Henriksen T, Weimann A, Larsen EL, Poulsen HE. Quantification of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-guanosine concentrations in urine and plasma for estimating 24-h urinary output. Free Radic Biol Med. 2021 Aug 20;172:350-357. doi: 10.1016/j.freeradbiomed.2021.06.014. Epub 2021 Jun 22.
PubMed 34166769Hjollund NH, Storgaard L, Ernst E, Bonde JP, Olsen J. Impact of diurnal scrotal temperature on semen quality. Reprod Toxicol. 2002 May-Jun;16(3):215-21. doi: 10.1016/s0890-6238(02)00025-4.
PubMed 12128094Jung A, Schuppe HC. Influence of genital heat stress on semen quality in humans. Andrologia. 2007 Dec;39(6):203-15. doi: 10.1111/j.1439-0272.2007.00794.x.
PubMed 18076419Kales SN, Soteriades ES, Christophi CA, Christiani DC. Emergency duties and deaths from heart disease among firefighters in the United States. N Engl J Med. 2007 Mar 22;356(12):1207-15. doi: 10.1056/NEJMoa060357.
PubMed 17377158Keir JLA, Akhtar US, Matschke DMJ, Kirkham TL, Chan HM, Ayotte P, White PA, Blais JM. Elevated Exposures to Polycyclic Aromatic Hydrocarbons and Other Organic Mutagens in Ottawa Firefighters Participating in Emergency, On-Shift Fire Suppression. Environ Sci Technol. 2017 Nov 7;51(21):12745-12755. doi: 10.1021/acs.est.7b02850. Epub 2017 Oct 18.
PubMed 29043785Kumar K, Trzybulska D, Tsatsanis C, Giwercman A, Almstrup K. Identification of circulating small non-coding RNAs in relation to male subfertility and reproductive hormones. Mol Cell Endocrinol. 2019 Jul 15;492:110443. doi: 10.1016/j.mce.2019.05.002. Epub 2019 May 8.
PubMed 31077744Morup N, Rajpert-De Meyts E, Juul A, Daugaard G, Almstrup K. Evaluation of Circulating miRNA Biomarkers of Testicular Germ Cell Tumors during Therapy and Follow-up-A Copenhagen Experience. Cancers (Basel). 2020 Mar 23;12(3):759. doi: 10.3390/cancers12030759.
PubMed 32210101Pedersen JE, Ugelvig Petersen K, Ebbehoj NE, Bonde JP, Hansen J. Incidence of cardiovascular disease in a historical cohort of Danish firefighters. Occup Environ Med. 2018 May;75(5):337-343. doi: 10.1136/oemed-2017-104734. Epub 2018 Jan 26.
PubMed 29374097Petersen KU, Hansen J, Ebbehoej NE, Bonde JP. Infertility in a Cohort of Male Danish Firefighters: A Register-Based Study. Am J Epidemiol. 2019 Feb 1;188(2):339-346. doi: 10.1093/aje/kwy235.
PubMed 30452532Kirstine Ugelvig Petersen K, Pedersen JE, Bonde JP, Ebbehoej NE, Hansen J. Long-term follow-up for cancer incidence in a cohort of Danish firefighters. Occup Environ Med. 2018 Apr;75(4):263-269. doi: 10.1136/oemed-2017-104660. Epub 2017 Oct 21.
PubMed 29055884
Study at a glance
From the registry record, last updated by the sponsor on 6 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect on Markers of Cardiovascular, Reproductive and Cancer Risk From Firefighting Activities - a Study Under Different Training Methods
- ClinicalTrials.gov ID
- NCT05753254
- Acronym / sponsor ID
- BIOBRAND3 / 72403
- Conditions
- Reactive Hyperemia, Micro RNA, Heart Rate Variability, DNA Strand Breaks, Oxidative Stress, Heat Stress
- Keywords
- Comet assay, 8-oxodG, PAH CALUX, hydroxyl-PAHs and nitro-PAH metabolites, microRNA, AhR activation, scrotal temperature, core body temperature
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 35 participants (actual)
- Lead sponsor
- National Research Centre for the Working Environment, DenmarkOther government
- Collaborators
- University of Copenhagen, University Hospital Bispebjerg and Frederiksberg, Copenhagen University Hospital, Rigshospitalet
- Study start
- 10 Mar 2023 (actual)
- Primary completion
- 5 Jul 2024 (actual)
- Study completion
- 5 Jul 2024 (actual)
- First posted
- 3 Mar 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Epidemiological studies based on Danish registries have observed that Danish male firefighters have more cardiovascular disease, infertility diagnose and a trend to increased risk of cancer than other Danish employed males. Firefighting activities include a combination of stressors such as strenuous work under heat, smoke and soot known to be able to affect cardiovascular and reproductive health, with smoke and soot also being known to increase the risk of cancer.
The training facilities of real-fire extinguishing exercises in Denmark operate using wood or natural gas fire, which will have differential gradients of smoke, soot and possibly heat. The investigators will use different training conditions to create gradients of the different stressors and investigate health effects thereof. With this approach, the investigators expect to be able to evaluate the individual contribution of the different stressors in markers of cardiovascular, cancer and reproductive health risk. The project will include approx. 35 young conscript participants on a firefighting course, followed in four sessions, three firefighting training sessions under different fire conditions (no fire, wood fire and gas fire) and one control scenario.
Detailed description
The study methodology is based on a crossover design on firefighting training under different conditions, with characterization of exposure and assessment of cardiovascular, cancer and reproductive effect biomarkers. The study will be performed in cooperation with the Danish Emergency Management Agency.
The study will have one baseline session, while conscripts are in a classroom, and three sessions of firefighting-related exercises under different fire conditions, used currently in firefighting training programs in Denmark. The three firefighting training sessions will be controlled for equivalent work exercise using full protective gear and under different ambient conditions of firefighting training:
- Firefighting equivalent work (no fire), with exercises performed in a clean environment, without fire (no ambient temperature, soot or smoke). This type of exercise precedes or complements the training under real fire conditions.
- Firefighting under wood fire (wood fire), with exposure to ambient heat, smoke and soot. This is the most common training scenario used by Danish Emergency Management Agency training centres.
- Firefighting under gas fire (gas fire), with exposure to ambient heat, and expectably less smoke and soot than with wood fire. These conditions are used in some Danish training centres, with logistical advantages (ease of turning or putting out the fire and managing the fire fuel) and unknown effect relating to exposure prevention (smoke and soot).
The order of the firefighting sessions will be as randomized as possible, and according to a selection of three sequence order options (no-wood-gas; wood-gas-no and gas-wood-no). Each campaign (corresponding to each rescue course) would desirably have one of these session sequences. It is not possible to blind the participants to the different scenarios, neither the field staff, but all the samples will be blinded for the subsequent laboratory analysis. The training sessions will have 1-3 weeks in between (accordingly with programmatic educational course schemes).
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 4
- Model description
- Participants will perform firefighting full day exercises under 3 different conditions (without fire, under wood fire and under gas fire), sessions which will occur with weeks in between, and biological markers will be assessed and compared in relation to a baseline session, where the participants are having theoretical classes.
| Arm | Type | Receives |
|---|---|---|
| Baseline session | No intervention | –Baseline measurements will be performed in the same schedule as measurements in the three other arms. In the baseline session, participants are in classroom before starting any firefighting exercise |
| Firefighting exercises without fire | Experimental | Other: Firefighting training exercises with no fireFirefighting equivalent work, with exercises performed in a clean environment, without fire (no ambient temperature, soot or smoke). This type of exercise usually precedes or complements the training under real fire conditions. |
| Firefighting under wood fire | Experimental | Other: Firefighting training exercises under wood fireFirefighting under wood fire, with exposure to ambient heat, smoke and soot. This is the most common training scenario used in the training centres. The participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models |
| Firefighting under gas fire | Experimental | Other: Firefighting training exercises under gas fireFirefighting under gas fire, with exposure to ambient heat, and expectably less smoke and soot than with wood fire. These conditions are used in some Danish training centres, with logistical advantages (ease of turning or putting out the fire and managing the fire fuel) and unknown effect relating to exposure prevention (smoke and soot). The participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- legally competent,
- conscript subjects following a Rescue Specialist Educational course
Key exclusion criteria (5 listed)
- current smoking status,
- pregnancy,
- on prescribed medication,
- body mass index (BMI) bellow 19 or over 30,
- alcohol or drug abuse.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Firefighting training exercises with no fireThe participants will be performing firefighting equivalent work in a clean environment, without fire (no ambient temperature, soot or smoke). | Other | Firefighting exercises without fire |
| Firefighting training exercises under wood fireThe participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models), under wood fire conditions. | Other | Firefighting under wood fire |
| Firefighting training exercises under gas fireThe participants will be in teams performing pre-defined tasks (knocking down the fire, moving heavy objects, and searching and rescuing metal stand in models), under gas fire conditions. | Other | Firefighting under gas fire |
Primary outcome
Change in reactive hyperemia index - afternoon
Time frame: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Reactive hyperemia index (RHI) measured with the device EndoPAT 2000. A reactive hyperemia is induced by a blood cuff on the upper arm and the peripheral vasodilation response is assessed in the small digital vessels of a fingertip with a portable device connected to a computer, with RHI determined by an algorithm from the device, with lower index values corresponding to a worsen situation.
Change in reactive hyperemia index - morning
Time frame: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Reactive hyperemia index (RHI) measured with the device EndoPAT 2000. A reactive hyperemia is induced by a blood cuff on the upper arm and the peripheral vasodilation response is assessed in the small digital vessels of a fingertip with a portable device connected to a computer, with RHI determined by an algorithm from the device, with lower index values corresponding to a worsen situation.
Change in Heart Rate Variability pNN50 at rest - afternoon
Time frame: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. pNN50 is the proportion of successive NN intervals differing by more than 50 milliseconds divided by the total number of N intervals (given in percentage).
Change in Heart Rate Variability pNN50 at rest - morning
Time frame: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. pNN50 is the proportion of successive NN intervals differing by more than 50 milliseconds divided by the total number of N intervals (given in percentage).
Change in Heart Rate Variability RMSSD at rest - afternoon
Time frame: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. RMSSD is the square root of the mean squared differences of successive NN intervals (given in milliseconds)
Change in Heart Rate Variability RMSSD at rest - morning
Time frame: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. RMSSD is the square root of the mean squared differences of successive NN intervals (given in milliseconds)
Change in Heart Rate Variability ratio LF/HF at rest - afternoon
Time frame: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. Ratio of low frequency and high frequency bands
Change in Heart Rate Variability ratio LF/HF at rest - morning
Time frame: Baseline morning measurement, morning measurement in subsequent day after firefighting without fire, morning measurement in subsequent day after firefighting under wood fire and morning measurement in subsequent day after firefighting under gas fire
Heart rate variability (HRV) measured with the device EndoPAT 2000. The HRV is calculated using the initial 5.5 complete minutes before the cuff is applied. Ratio of low frequency and high frequency bands
Changes in levels of 8-oxodG excretion in first morning urine
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Oxidized nucleobase 8-oxodG will be measured in urine samples by High-performance liquid chromatography (HPLC) as marker of oxidative stress, together with creatinine, for adjusting for urine concentration. Data will be reported as nanomol 8-oxodG per millimol creatinine.
Changes in levels of DNA strand breaks in peripheral blood mononuclear cells
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
DNA strand breaks will be measured by comet assay, and reported as number of lesions per 10^6 base pairs, transformed from percentage of DNA in tail using the calibration curve from the well-establish relationship between ionizing radiation dose and yield of strand breaks in DNA.
Changes in core temperature
Time frame: Baseline day, during the day of firefighting without fire, during the day of firefighting under wood fire and during the day of firefighting under gas fire.
Core body temperature will be assessed by an ingestible pill thermometer with data recorded and reported as time series during the period in transit.
Changes in scrotal temperature
Time frame: Baseline day, during the day of firefighting without fire, during the day of firefighting under wood fire and during the day of firefighting under gas fire.
Scrotal temperature will be assessed by skin sensor placed in the scrotum of male participants and reported as scrotal skin temperature time series.
Changes in scrotal thermoregulation
Time frame: Baseline day, during the day of firefighting without fire, during the day of firefighting under wood fire and during the day of firefighting under gas fire.
Core body temperature will be assessed by an ingestible pill thermometer and scrotal temperature will be assessed by skin sensor placed in the scrotum of male participants, to assess the thermoregulation of the scrotum during firefighting exercises. Time series of core body temperature and scrotal skin temperature will be analysed for eventual thermoregulation disruption.
Changes in levels of circulating micro RNA
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Circulating micro RNA candidates will be measured by RNA extraction from serum samples, reverse transcribed into complementary DNA (cDNA) and analysed with quantitative polymerase chain reaction (qPCR).
Changes in urinary potency of AhR activation
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
The aryl hydrocarbon receptor (AhR) activation will be assessed in vitro using urine samples on the PAH CALUX (Chemical Activated LUciferase gene eXpression bioassay) reporter assay. The smoke and soot exposures are complex mixtures of compounds with potential toxic effect. Routine measurements of PAHs are usually quantified for a target list of 16 common soot elements and even less chemical species for urinary metabolites, but many other compounds are present in both soot and metabolites mixtures. The toxicity of PAHs is primarily caused through the binding to AhR, and induction of AhR related genes and subsequent toxic pathways. The outcome will be measured in the form of benzo[a]pyrene equivalence.
Changes in potency of AhR activation from skin deposits
Time frame: Baseline, before firefighting without fire, immediately after firefighting without fire, before firefighting under wood fire, immediately after firefighting under wood fire, before firefighting under gas fire, immediately after firefighting under gas
The aryl hydrocarbon receptor (AhR) activation will be assessed in vitro using wipe samples on the PAH CALUX (Chemical Activated LUciferase gene eXpression bioassay) reporter assay. The smoke and soot exposures are complex mixtures of compounds with potential toxic effect. Routine measurements of PAHs are usually quantified for a target list of 16 common soot elements, but many other compounds are present in soot mixtures. The toxicity of PAHs is primarily caused through the binding to AhR, and induction of AhR related genes and subsequent toxic pathways. The outcome will be measured in the form of benzo[a]pyrene equivalence.
10 secondary outcomes
Changes in levels of follicle-stimulating hormone in serum
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in levels of serum inhibin B
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in urinary levels of PAH metabolites excretion
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in levels of PAHs in skin wipes from the neck
Time frame: Baseline, before firefighting without fire, immediately after firefighting without fire, before firefighting under wood fire, immediately after firefighting under wood fire, before firefighting under gas fire, immediately after firefighting under gas
Changes in FEV1 spirometric measurements
Time frame: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in FVC spirometric measurements
Time frame: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in PEF spirometric measurements
Time frame: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in FEV1/FVC ratio from spirometric measurements
Time frame: Baseline, immediately after firefighting without fire, immediately after firefighting under wood fire and immediately after firefighting under gas fire
Changes in blood troponin levels
Time frame: Baseline, before firefighting without fire, day after firefighting without fire, before firefighting under wood fire, day after firefighting under wood fire, before firefighting under gas fire, day after firefighting under gas fire
Changes in work load measured by muscle activity
Time frame: Baseline day, firefighting without fire day, firefighting under wood fire day and firefighting under gas fire day
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Aug 2025.
- Background: PubMed 28877717Andersen MHG, Saber AT, Pedersen PB, Loft S, Hansen AM, Koponen IK, Pedersen JE, Ebbehoj N, Norskov EC, Clausen PA, Garde AH, Vogel U, Moller P. Cardiovascular health effects following exposure of human volunteers during fire extinction exercises. Environ Health. 2017 Sep 6;16(1):96. doi: 10.1186/s12940-017-0303-8.
- Background: PubMed 29045708Andersen MHG, Saber AT, Clausen PA, Pedersen JE, Lohr M, Kermanizadeh A, Loft S, Ebbehoj N, Hansen AM, Pedersen PB, Koponen IK, Norskov EC, Moller P, Vogel U. Association between polycyclic aromatic hydrocarbon exposure and peripheral blood mononuclear cell DNA damage in human volunteers during fire extinction exercises. Mutagenesis. 2018 Feb 24;33(1):105-115. doi: 10.1093/mutage/gex021.
- Background: PubMed 29761929Andersen MHG, Saber AT, Pedersen JE, Pedersen PB, Clausen PA, Lohr M, Kermanizadeh A, Loft S, Ebbehoj NE, Hansen AM, Kalevi Koponen I, Norskov EC, Vogel U, Moller P. Assessment of polycyclic aromatic hydrocarbon exposure, lung function, systemic inflammation, and genotoxicity in peripheral blood mononuclear cells from firefighters before and after a work shift. Environ Mol Mutagen. 2018 Jul;59(6):539-548. doi: 10.1002/em.22193. Epub 2018 May 15.
- Background: PubMed 34504215Andersen MHG, Saber AT, Frederiksen M, Clausen PA, Sejbaek CS, Hemmingsen CH, Ebbehoj NE, Catalan J, Aimonen K, Koivisto J, Loft S, Moller P, Vogel U. Occupational exposure and markers of genetic damage, systemic inflammation and lung function: a Danish cross-sectional study among air force personnel. Sci Rep. 2021 Sep 9;11(1):17998. doi: 10.1038/s41598-021-97382-5.
- Background: PubMed 31812113Beitel SC, Flahr LM, Hoppe-Jones C, Burgess JL, Littau SR, Gulotta J, Moore P, Wallentine D, Snyder SA. Assessment of the toxicity of firefighter exposures using the PAH CALUX bioassay. Environ Int. 2020 Feb;135:105207. doi: 10.1016/j.envint.2019.105207. Epub 2019 Dec 4.
- Background: PubMed 34166769Henriksen T, Weimann A, Larsen EL, Poulsen HE. Quantification of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-guanosine concentrations in urine and plasma for estimating 24-h urinary output. Free Radic Biol Med. 2021 Aug 20;172:350-357. doi: 10.1016/j.freeradbiomed.2021.06.014. Epub 2021 Jun 22.
- Background: PubMed 12128094Hjollund NH, Storgaard L, Ernst E, Bonde JP, Olsen J. Impact of diurnal scrotal temperature on semen quality. Reprod Toxicol. 2002 May-Jun;16(3):215-21. doi: 10.1016/s0890-6238(02)00025-4.
- Background: PubMed 18076419Jung A, Schuppe HC. Influence of genital heat stress on semen quality in humans. Andrologia. 2007 Dec;39(6):203-15. doi: 10.1111/j.1439-0272.2007.00794.x.
- Background: PubMed 17377158Kales SN, Soteriades ES, Christophi CA, Christiani DC. Emergency duties and deaths from heart disease among firefighters in the United States. N Engl J Med. 2007 Mar 22;356(12):1207-15. doi: 10.1056/NEJMoa060357.
- Background: PubMed 29043785Keir JLA, Akhtar US, Matschke DMJ, Kirkham TL, Chan HM, Ayotte P, White PA, Blais JM. Elevated Exposures to Polycyclic Aromatic Hydrocarbons and Other Organic Mutagens in Ottawa Firefighters Participating in Emergency, On-Shift Fire Suppression. Environ Sci Technol. 2017 Nov 7;51(21):12745-12755. doi: 10.1021/acs.est.7b02850. Epub 2017 Oct 18.
- Background: PubMed 31077744Kumar K, Trzybulska D, Tsatsanis C, Giwercman A, Almstrup K. Identification of circulating small non-coding RNAs in relation to male subfertility and reproductive hormones. Mol Cell Endocrinol. 2019 Jul 15;492:110443. doi: 10.1016/j.mce.2019.05.002. Epub 2019 May 8.
- Background: PubMed 32210101Morup N, Rajpert-De Meyts E, Juul A, Daugaard G, Almstrup K. Evaluation of Circulating miRNA Biomarkers of Testicular Germ Cell Tumors during Therapy and Follow-up-A Copenhagen Experience. Cancers (Basel). 2020 Mar 23;12(3):759. doi: 10.3390/cancers12030759.
- Individual participant dataSharing planned: No. Supportive information and fully anonymized information will be shared and whenever possible (in supplementary material) published along with the results, but following European Union General Data Protection Regulation (GDPR) and Danish rules, no non or pseudo anonymized data might be shared.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Maria Helena G Andersen, PhD principal investigator
The National Research Centre for the Working Environment (NRCWE)
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Firefighting training exercises with no fire, Firefighting training exercises under wood fire and Firefighting training exercises under gas fire in people with Reactive Hyperemia and Micro RNA, run by National Research Centre for the Working Environment, Denmark at 2 sites in Denmark.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 6 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Denmark. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in reactive hyperemia index - afternoon (time frame: Baseline afternoon measurement, afternoon measurement immediately after firefighting without fire, afternoon measurement immediately after firefighting under wood fire and afternoon measurements immediately after firefighting under gas fire). The study lists 16 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05753254, which also lists 18 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Aug 2025.