High Exposure to Perfluoroalkyl Substances and Antibody Responses to SARS-CoV-2 mRNA Vaccine-an Observational Study in Adults from Ronneby, Sweden.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are widely used, environmentally ubiquitous, and stable chemicals that have been associated with lower vaccine-induced antibody responses in children; however, data on adults are limited. The drinking water from one of the two waterworks in Ronneby, Sweden, was heavily contaminated for decades with PFAS from firefighting foams, primarily perfluorohexane sulfonic acid and perfluorooctanesulfonic acid (PFOS). Vaccination against SARS-CoV-2 offered a unique opportunity to investigate antibody responses to primary vaccination in adults who had been exposed to PFAS. OBJECTIVES: Our objective was to evaluate associations between PFAS, across a wide range of exposure levels, and antibody responses in adults 5 wk and 6 months after a two-dose vaccination regime against SARS-CoV-2. METHODS: Adults age 20-60 y from Ronneby (n=309, median PFOS serum level 47 ng/mL, fifth to 95th percentile 4-213 ng/mL) and a group with background exposure (n=47, median PFOS serum level 4 ng/mL) received two doses of the Spikevax (Moderna) mRNA vaccine. The levels of seven PFAS were measured in serum before vaccination. Serum immunoglobulin G antibodies against the SARS-CoV-2 spike antigen (S-Abs) were measured before vaccination and at 5 wk (n=350) and 6 months (n=329) after the second vaccine dose. Linear regression analyses were fitted against current, historical, and prenatal exposure to PFAS, adjusting for sex, age, and smoking, excluding individuals with previous SARS-CoV-2-infection. RESULTS: PFAS exposure, regardless of how it was estimated, was not negatively associated with antibody levels 5 wk [current PFOS: -0.5% S-Abs/PFOS interquartile range (IQR); 95% confidence interval (CI): -8, 7] or 6 months (current PFOS: 3% S-Abs/PFOS IQR; 95% CI: -6, 12) after COVID-19 vaccination. DISCUSSION: Following a strict study protocol, rigorous study design, and few dropouts, we found no indication that PFAS exposure negatively affected antibody responses to COVID-19 mRNA vaccination for up to 6 months after vaccination. https://doi.org/10.1289/EHP11847.

Fetal exposure to maternal stress and male reproductive function in a cohort of young adults.

OBJECTIVE: To study associations between maternal stress during pregnancy and reproductive function in young men. DESIGN: A cohort study nested in a population-based birth cohort. SETTING: Not applicable. PATIENTS: Young men (n = 1,052; response rate, 19%) participated in the Fetal Programming of Semen Quality cohort from 2017 to 2019. They were recruited from pregnancies in the Danish National Birth Cohort (1996-2001). The men completed an online questionnaire, clinical examination, and collection of blood and semen samples. EXPOSURES: Information on maternal life and emotional stresses was available from a telephone interview covering the interval from the beginning of pregnancy to approximately gestational week 30. MAIN OUTCOME MEASURE(S): We applied negative binomial, linear, and logistic regression to examine associations between life and emotional stress scores (range, 0-18) and reproductive function. The primary outcomes were measures of semen quality, and the secondary outcomes included reproductive hormone levels and testicular volume. RESULT(S): Overall, we observed no negative associations between maternal life or emotional stress and male reproductive function. Maternal emotional stress was associated with higher total sperm count (16% difference; 95% confidence interval [CI], 1-33), serum estradiol (11% difference; 95% CI, 2-21), and calculated free testosterone (ß = 17.8; 95% CI, 1.26-34.3). The results were robust to inverse probability weighting introduced to account for selection. CONCLUSION(S): Although our findings may appear reassuring, further efforts to validate the measures of stress during pregnancy and improve our understanding of the full spectrum of fetal stress exposures and consequences for health later in life are needed.

Use of Personal Care Products and Semen Quality: A Cross-Sectional Study in Young Danish Men.

Personal care products (PCPs) may contain multiple chemicals capable of harming male reproductive function. The aim of this study was, therefore, to assess aggregated PCP exposure and potential associations with measures of semen quality in young men. Participants (n = 1058, age 18-21) were sampled among young men from the Danish National Birth Cohort (DNBC). Upon recruitment in 2017-2019, each man answered an online questionnaire and provided a semen sample. Exposure to 12 common types of PCPs was derived from the questionnaire, and the extent of use and co-use was analyzed. We applied a negative binomial regression model to estimate percentage differences in semen parameters between low, medium and high PCP exposure groups. All participants were exposed to at least one PCP more than once a week, resulting in a mean number (SD) of 5.3 (2.0) PCPs currently used. Most participants (92%) were also exposed to fragranced products on a weekly basis. Little association was observed between aggregated exposure to PCPs and sperm concentration, total sperm count, semen volume, sperm motility and morphology. Despite prevalent use of multiple PCPs, we found little indication of adverse effects of aggregated overall or fragranced PCP exposure on semen quality.

Turning the tide: reducing mortality among Danish merchant seafarers.

OBJECTIVES: While life at sea traditionally has presented a variety of potential hazards, rigorous measures have been taken in the past decades to ensure the safety and health of all aboard merchant ships. The aim of this study was to examine overall and cause-specific mortality among Danish seafarers in light of these changes. METHODS: A cohort of 44 555 male (75%) and female (25%) seafarers employed on Danish ships during 1986-1999 was established through records from the Danish Seafarer Registry. Subsequently, information on vital status and causes of death was linked to members of the cohort from the Danish Civil Registration System and the Danish Register of Causes of Death using unique personal identification numbers. Standardized mortality ratios (SMRs) were calculated for the seafarers using rates from a sample of the Danish employed population. RESULTS: Among seafarers with first employment prior to 1992, the overall mortality was high, with increases observed for many individual causes of death (overall SMR 1.78, 95% CI 1.72 to 1.83 for male seafarers; SMR 1.61, 95% CI 1.48 to 1.75 for female seafarers). Mortality among seafarers employed in the following period was reduced, with only a slight remaining excess of deaths. This excess in mortality was evident primarily among non-officers on board tankers and smaller ships. CONCLUSIONS: During recent decades, mortality among seafarers has changed, replacing the traditional image of a high-risk profession with almost normalised figures compared with the general working population. Marked imbalances in mortality according to job and ship categories have persisted though.

Cancer incidence among seafarers and fishermen in the Nordic countries.

Objectives Maritime workers may be exposed to several occupational hazards at sea. The aim of this study was to assess cancer incidence among seafarers and fishermen in the Nordic countries and identify patterns in morbidity in the context of existing studies in this field. Methods A cohort of 81 740 male seafarers and 66 926 male fishermen was established from census data on 15 million citizens in the five Nordic countries. Using personal identity codes, information on vital status and cancer was linked to members of the cohort from the national population and cancer registries for the follow-up period 1961-2005. Standardized incidence ratios (SIR) were calculated applying national cancer incidence rates for each country and pooling results. Results The overall incidence of cancer was increased among the male seafarers [SIR 1.22, 95% confidence interval (CI) 1.19-1.23]. Significant excesses were observed for multiple cancer sites among the seafarers, while results for the fishermen were mixed. Lip cancer incidence was increased among both maritime populations. For mesothelioma (SIR 2.17, 95% CI 1.83-2.56 seafarers) and non-melanoma skin cancer (SIR 1.23, 95% CI 1.14-1.32 seafarers), incidence was increased among the seafarers. Conclusion In our cohort, seafaring was associated with a higher overall incidence of cancer compared to the general population. While the majority of cancers could not be linked to specific occupational factors, increases in mesothelioma, lip and non-melanoma-skin cancer indicate previous exposure to asbestos, ultraviolet radiation and potentially also chemicals with dermal carcinogenic properties at sea.

Full employment history of Danish firefighters potentially involving additional exposures, 1964-2015.

BACKGROUND: This study aimed to demonstrate the possibility of using data on full employment history to describe occupational patterns of Danish firefighters that may indicate additional hazards encountered by these workers. METHODS: An established cohort of Danish full-time and part-time/volunteer firefighters was used in the study (N = 9952) as well as occupational history covering the period 1964-2015, which was retrieved from a nationwide pension fund with compulsory membership. The most frequently held employments other than firefighting, together with temporal patterns of these employments, were explored in descriptive analyses. RESULTS: Besides working in the firefighter service, both full-time and part-time/volunteer firefighters had frequently been employed in the military and the police (55% and 38%) and more than 10% of both types of firefighters in a number of blue-collar jobs, including construction-related jobs (eg, masonry, joining, carpentry, insulation, and installation), laundry and dry cleaning, the auto industry, and rubber and plastic production. Part-time/volunteer firefighters had more frequently been employed in the machine industry, fabricated metal production, the wood and furniture industry, and farming. Both types of firefighters were initially employed in other jobs before their employment in firefighting. CONCLUSION: The cohort of Danish firefighters had frequently been working in other professions potentially exposing them to additional hazardous exposures, and occupational patterns varied by type of firefighter employment. Accounting for full employment history is, for that reason, considered essential when exploring associations between specific professions and health outcomes.

Risk of asthma and chronic obstructive pulmonary disease in a large historical cohort of Danish firefighters.

OBJECTIVE: Firefighters are exposed to numerous respiratory hazards, but large studies on the risk of pulmonary disease are scarce. The objective of this study was to examine incidence of asthma and chronic obstructive pulmonary disease (COPD) in a nationwide cohort of Danish firefighters. METHODS: We used individual historical employment records on 11 968 Danish male firefighters primarily supplied by trade unions and fire agencies. Furthermore, we used the Supplementary Pension Fund Register to form an occupational reference group consisting of military employees. Information on respiratory incidence was retrieved from the nationwide Danish National Patient Registry. Age and calendar time standardised incidence ratio (SIR) and Poisson regression analyses (incidence rate ratio) were used for estimation of risks, including 95% CIs. RESULTS: Compared with military employees, the overall age and calendar-time adjusted risk for asthma was significantly increased among full-time firefighters (SIR=1.58, 95% CI 1.32 to 1.88), but not among part-time/volunteer firefighters. Full-time firefighters' risk for asthma did not vary by duration of employment. No consistent evidence of an increased risk for chronic obstructive pulmonary disease was detected. CONCLUSION: Danish firefighters have an increased risk of asthma, but the causes, whether occupational or not, remain to be established.

Cancer incidence among merchant seafarers: an extended follow-up of a Danish cohort.

OBJECTIVES: While maritime safety generally has improved dramatically over the last century, modern seafarers are still faced with numerous occupational hazards potentially affecting their risk of chronic diseases such as cancer. The aim of this study is to offer updated information on the incidence of specific cancers among both male and female seafarers. METHODS: Using records from the Danish Seafarer Registry, all seafarers employed on Danish ships during 1986-1999 were identified, resulting in a cohort of 33 084 men and 11 209 women. Information on vital status and cancer was linked to each member of the cohort from the Danish Civil Registration System and the Danish Cancer Registry using the unique Danish personal identification number. SIRs were estimated for specific cancers using national rates. RESULTS: The overall incidence of cancer was increased for both male and female seafarers (SIR 1.19, 95% CI 1.15 to 1.23, and SIR 1.14, 95% CI 1.07 to 1.22) compared with the general population. This excess was primarily driven by increases in gastrointestinal, respiratory and genitourinary cancers. In addition, male seafarers working in areas with asbestos exposure showed significantly increased risk of mesothelioma. Finally, the male seafarers had an increased risk of lip cancer. CONCLUSIONS: The majority of cancers among seafarers continue to be lifestyle-related. However, occupational exposure to asbestos and ultraviolet radiation seems to affect the cancer pattern among the male seafarers as well.

Incidence of cardiovascular disease in a historical cohort of Danish firefighters.

OBJECTIVES: Firefighters are exposed to multiple cardiovascular hazards, but few epidemiological studies have addressed their cardiovascular morbidity. The objective of this study was therefore to examine the incidence of cardiovascular diseases (CVD) in Danish firefighters. METHODS: We used individual historical employment records on 11.691 male Danish firefighters supplied by trade unions and fire agencies. The Supplementary Pension Fund Register was used to establish two occupational reference groups (a random sample from the male employed population and military employees). Information on CVD incidence was retrieved from the nationwide Danish National Patient Registry. SIRs and Poisson regression analyses (incidence rate ratio) were used for estimation of risks, including 95% CIs. RESULTS: In comparison with the population sample, the age-adjusted and calendar time-adjusted SIR for all CVDs combined was increased in firefighters (SIR=1.10, 95% CI 1.05 to 1.15). The risk was also elevated for the most frequent outcomes, including angina pectoris (SIR=1.16, 95% CI 1.08 to 1.24), acute myocardial infarction (SIR=1.16, 95% CI 1.06 to 1.26), chronic ischaemic heart disease (SIR=1.15, 95% CI 1.06 to 1.24) and atrial fibrillation/flutter (SIR=1.25, 95% CI 1.14 to 1.36). This analysis showed the most elevated SIRs for CVD in full-time firefighters compared with part-time/volunteer firefighters. Both types of firefighters employed <15 years had an increased risk of CVD. Similar risk patterns appeared in comparisons with the military. Internal analysis supported external findings. CONCLUSION: The risk of overall CVD, including the most frequent subtypes was modestly increased in Danish firefighters and was most elevated in full-time firefighters compared with other male employees.

Long-term follow-up for cancer incidence in a cohort of Danish firefighters.

OBJECTIVES: To examine cancer incidence among Danish firefighters using several employment-related exposure subgroups. METHODS: A historical cohort of 9061 male Danish firefighters was established from collected personnel and membership records from employers and trade unions. Using the unique Danish personal identification number, information on additional previous employment, cancer and vital status was linked to members of the cohort from the Supplementary Pension Fund Register, the Danish Cancer Registry and the Danish Civil Registration System. SIRs were calculated for specific cancer types using rates for the general population, a sample of the working population and military employees, respectively. RESULTS: Compared with the selected reference groups, the overall observed incidence of cancer among the firefighters was at level with the expected (SIR 1.02, 95% CI 0.96 to 1.09 vs the general population). The SIR for colon cancer was consistently significantly reduced, while the slight excess seen for melanoma of the skin, prostate and testicular cancer compared with the general population was not reproduced using the military as reference. CONCLUSIONS: Previous associations with melanoma of the skin, prostate and testicular cancer are supported by our main results. However, the increase in incidence of these cancers is not reproduced using the military as reference. Similarities in cancer profile for the firefighters and the military point to shared risk factors in either lifestyle or work environment.