Exposure to Radiation During Work Shifts and Working at Night Act as Occupational Stressors Alter Redox and Inflammatory Markers

Association between nocturnal light exposure and melatonin in humans: a meta-analysis

BACKGROUND

Night shift workers are more susceptible to circadian rhythm disturbances due to their prolonged exposure to nighttime light. This exposure during abnormal periods causes inappropriate suppression of melatonin synthesis and secretion in the pineal gland, thereby disrupting circadian rhythms. While it is believed that nocturnal light exposure is involved in suppressing melatonin secretion, research findings in this area have been inconsistent.

METHODS

Thirteen publications retrieved from PubMed and Web of Science databases were included to compare the differences between night shift workers and controls using aggregated mean differences (MD) and 95% confidence intervals (CI).

RESULTS

After a comprehensive review, 13 publications were included and data on urinary melatonin metabolite 6-sulfameoxymelatonin(aMT6s) were collected for meta-analysis. The results showed that the morning urinary aMT6s levels were significantly lower in the exposed group than in the non-exposed group (MD = -3.69, 95%CI = (-5.41, -1.98), P < 0.0001), with no significant heterogeneity among the original studies (I2 = 42%, P = 0.13). In addition, night shift workers had significantly lower mean levels of 24-h urinary aMT6s than day shift workers (MD = -3.38, 95%CI = (-4.27, -2.49), P < 0.00001, I2 = 0). Nocturnal light was correlated with nocturnal urine aMT6s secretion and inhibited nocturnal aMT6s secretion (MD = -11.68, 95%CI = (-15.70, -7.67), P < 0.00001, I2 = 0). Additionally, nocturnal light inhibited the secretion of melatonin in the blood, with no significant heterogeneity between studies (MD = -11.37, 95%CI = (-15.41, -7.33), P < 0.00001, I2 = 0).

CONCLUSION

The findings of this study indicate that exposure to nocturnal light among night shift workers leads to inhibition of melatonin secretion.

Redox and metabolic reprogramming in breast cancer and cancer-associated adipose tissue

Redox and metabolic processes are tightly coupled in both physiological and pathological conditions. In cancer, their integration occurs at multiple levels and is characterized by synchronized reprogramming both in the tumor tissue and its specific but heterogeneous microenvironment. In breast cancer, the principal microenvironment is the cancer-associated adipose tissue (CAAT). Understanding how the redox-metabolic reprogramming becomes coordinated in human breast cancer is imperative both for cancer prevention and for the establishment of new therapeutic approaches. This review aims to provide an overview of the current knowledge of the redox profiles and regulation of intermediary metabolism in breast cancer while considering the tumor and CAAT of breast cancer as a unique Warburg's pseudo-organ. As cancer is now recognized as a systemic metabolic disease, we have paid particular attention to the cell-specific redox-metabolic reprogramming and the roles of estrogen receptors and circadian rhythms, as well as their crosstalk in the development, growth, progression, and prognosis of breast cancer.

Influence of Neighborhood Social and Natural Environment on Prostate Tumor Histology in a Cohort of Male Health Professionals

Adverse neighborhood social and natural (green space) environments may contribute to the etiology of prostate cancer (CaP), but mechanisms are unclear. We examined associations between neighborhood environment and prostate intratumoral inflammation in 967 men diagnosed with CaP with available tissue samples from 1986-2009 in the Health Professionals Follow-up Study. Exposures were linked to work or residential addresses in 1988. We estimated indices of neighborhood socioeconomic status (nSES) and segregation (Index of Concentration at the Extremes (ICE)) using US Census tract-level data. Surrounding greenness was estimated using seasonal averaged Normalized Difference Vegetation Index (NDVI) data. Surgical tissue underwent pathological review for acute and chronic inflammation, corpora amylacea, and focal atrophic lesions. Adjusted odds ratios (aORs) for inflammation (ordinal) and focal atrophy (binary) were estimated using logistic regression. No associations were observed for acute or chronic inflammation. Each interquartile-range increase in NDVI within 1,230 m of the participant's work or home address (aOR = 0.74, 95% confidence interval (CI): 0.59, 0.93), in ICE-income (aOR = 0.79, 95% CI: 0.61, 1.04), and in ICE-race/income (aOR = 0.79, 95% CI: 0.63, 0.99) was associated with lower odds of postatrophic hyperplasia. Interquartile-range increases in nSES (aOR = 0.76, 95% CI: 0.57, 1.02) and ICE-race/income (aOR = 0.73, 95% CI: 0.54, 0.99) were associated with lower odds of tumor corpora amylacea. Histopathological inflammatory features of prostate tumors may be influenced by neighborhood.

Chrono-modulated effects of external stressors on oxidative stress and damage in humans: A scoping review on night shift work

BACKGROUND

Oxidative stress and tissue damage (OSD) play a pivotal role as an early-stage process in chronic disease pathogenesis. However, there has been little research to better understand the temporal (χρόνος[chronos]) dimensions of OSD process associated with environmental (non-genetic, including behaviors/lifestyle) and/or occupational stressors, like night shift work. OSD processes have recently attracted attention in relation to time-resolved external stressor trajectories in personalized medicine (prevention) initiatives, as they seem to interact with circadian clock systems towards the improved delineation of the early stages of (chronic) disease process.

OBJECTIVES

This work critically reviewed human studies targeting the temporal dynamics of OSD and circadian clock system's activity in response to environmental/occupational stressors; the case of night shift work was examined.

METHODS

Being a key stressor influencing OSD processes and circadian rhythm, night shift work was evaluated as part of a scoping review of research in OSD, including inflammatory and metabolic processes to determine the extent of OSD research undertaken in human populations, methodologies, tools and biomarkers used and the extent that the temporal dimensions of exposure and biological effect(s) were accounted for. Online databases were searched for papers published from 2000 onwards, resulting in the selection of 53 original publications.

RESULTS AND DISCUSSION

The majority of studies (n = 41) took place in occupational settings, while the rest were conducted in the general population or patient groups. Most occupational studies targeted outcomes of oxidative stress/damage (n = 19), followed by the combination of OSD with inflammatory response (n = 10), and studies focused on metabolic outcomes (n = 12). Only a minor fraction of the studies measured biomarkers related to circadian rhythm, such as, melatonin, its metabolite, or cortisol. Night shift work was associated with select biomarkers of OSD and inflammation, albeit with mixed results. Although much progress in delineating the biological mechanisms of OSD process has been made, an equally thorough investigation on the temporal trajectory of OSD processes as triggered by environmental/occupational stressors in human studies has yet to fully evolve.

Nightshift work can induce oxidative DNA damage: a pilot study

BACKGROUND

Regular sleep is very important for human health; however, the short-term and long-term effects of nightshift with sleep deprivation and disturbance on human metabolism, such as oxidative stress, have not been effectively evaluated based on a realistic cohort. We conducted the first long-term follow-up cohort study to evaluate the effect of nightshift work on DNA damage.

METHODS

We recruited 16 healthy volunteers (aged 33 ± 5 years) working night shifts at the Department of Laboratory Medicine at a local hospital. Their matched serum and urine samples were collected at four time points: before, during (twice), and after the nightshift period. The levels of 8-oxo-7,8-dihydroguanosine (8-oxoG) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), two important nucleic-acid damage markers, were accurately determined based on a robust self-established LC‒MS/MS method. The Mann-Whitney U or Kruskal-Wallis test was used for comparisons, and Pearson's or Spearman's correlation analysis was used to calculate the correlation coefficients.

RESULTS

The levels of serum 8-oxodG, estimated glomerular filtration rate-corrected serum 8-oxodG, and the serum-to-urine 8-oxodG ratio significantly increased during the nightshift period. These levels were significantly higher than pre-nightshift work level even after 1 month of discontinuation, but no such significant change was found for 8-oxoG. Moreover, 8-oxoG and 8-oxodG levels were significantly positively associated with many routine biomarkers, such as total bilirubin and urea levels, and significantly negatively associated with serum lipids, such as total cholesterol levels.

CONCLUSION

The results of our cohort study suggested that working night shifts may increase oxidative DNA damage even after a month of discontinuing nightshift work. Further studies with large-scale cohorts, different nightshift modes, and longer follow-up times are needed to clarify the short- and long-term effects of night shifts on DNA damage and find effective solutions to combat the negative effects.

Construction of an evaluation system for medical staff's occupational protection ability based on knowledge, attitude, and practice theory, and a cross-sectional survey of current conditions

INTRODUCTION

Medical personnel should be in close proximity and high frequency of contact with patients, and be exposed to physical, biological and chemical risk factors for a long time. The incidence of various occupational exposures is high. however, there is still a lack of the medical staff Occupational Protection Core Competence Evaluation Index system with high reliability and validity.

AIM

Based on the theory of knowledge, attitude, and practice, the evaluation system of occupational protection ability of medical personnel was established, and the current situation of occupational protection ability of medical personnel at different levels was investigated, so as to take targeted training and intervention measures to improve the occupational protection ability of medical personnel and reduce the incidence of occupational exposure.

METHODS

Based on the knowledge, attitude, and practice theory, the index system of occupational protection core competence of medical personnel was initially constructed by literature retrieval, expert consultation, group discussion, semi-structured interview and other qualitative and quantitative methods, and the reliability and validity of the index system was tested by Delphi expert consultation method. By convenient cluster sampling method, from March to September 2021, the current status of occupational protection core competence of medical personnel was investigated among medical staff from one Class III Grade A hospital and two medical schools in Jinan City, Shandong Province, China.

RESULTS

The evaluation system for medical staff's occupational protection ability included 3 first-level indexes, 11 second-level indexes, and 109 third-level indexes. A total of 684 valid questionnaires were collected from Grade III, Class A hospital medical staff and two medical school students in clinical practice in Shandong, China. Kruskal Walls test showed that there were significant differences in the overall distribution of occupational protection knowledge, attitude, and practice among registered nurses, nursing students, registered physicians, and physician students (H = 70.252, P < 0.001; H = 76.507, P < 0.001; H = 80.782, P < 0.001); there were statistical significance in the knowledge/ attitude/ practice of nursing and physician students at different levels (H = 33.733, P < 0.001; H = 29.158, P < 0.001; H = 28.740, P < 0.001).

CONCLUSION

The results of the evaluation system for the medical staff's occupational protection ability are reliable and can provide a reference for training the medical staff's occupational protection ability. Managers should strengthen the training of theoretical knowledge of occupational protection ability of medical staff.

Assessment of thyroid gland hormones and ultrasonographic abnormalities in medical staff occupationally exposed to ionizing radiation

BACKGROUND

Ionizing radiation (IR) is high-energy radiation that has the potential to displace electrons from atoms and break chemical bonds. It has the ability to introduce mutations, DNA strand breakage, and cell death. Being a radiosensitive organ, exposure of the thyroid gland to IR can lead to significant changes in its function.

AIM OF THE WORK

Was to measure the levels of thyroid hormones panel and ultrasonography abnormalities in medical staff occupationally exposed to IR.

SUBJECTS AND METHODS

A total of 120 subjects were divided into three main groups: Group I: radiation-exposed workers occupationally exposed to radioiodine (131I) (n = 40), Group II: radiation-exposed workers occupationally exposed to X-ray (n = 40), and Group III: non-exposed healthy professionals matched in age and sex with the previous groups (n = 40). Thyroid hormones panel including free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), anti-thyroperoxidase antibodies (anti-TPO), and thyroglobulin (Tg) were measured. Thyroid ultrasonography was performed. Oxidative stress markers such as malondialdehyde (MDA), hydrogen peroxide (H2O2), and total antioxidant capacity (TAC) were measured.

RESULTS

Group I had significantly higher fT3 levels than the control group. fT3 levels were considerably higher, while TSH was substantially lower in group II participants than in the control group. Tg was markedly lower in radiation-exposed workers. However, anti-TPO levels in radiation-exposed workers were significantly higher than in the control group. MDA and H₂O₂ were substantially higher; TAC was significantly lower in radiation-exposed workers compared to the control group. According to ultrasonographic examination, thyroid volume and the percentage of thyroid nodules in all radiation workers were significantly higher than in the control group.

CONCLUSION

Despite low exposure doses, occupational exposure to IR affects the thyroid hormones and links with a higher likelihood of developing thyroid immune diseases.

The association between circadian rhythm of cortisol and shift work regularity among midwives-A multicenter study in Southeast China

Objective

This article aims to explore the association between the trends of cortisol rhythm and the regularity of shift work among midwives.

Methods

Midwives from six Southeast Chinese hospitals were recruited through cluster sampling in a multi-center cross-sectional study. Urine samples were collected half an hour after waking up, at 11:00, 19:00, and 23:00 on two consecutive days in a longitudinal cohort. The urinary cortisol was assayed by the chemiluminescence method.

Results

A total of 86 midwives were included in this study, contributing 688 cortisol samples. The midwives displayed a circadian rhythm in cortisol secretion, with zeniths in the morning and nadirs in the evening. The trend of the first day was repeated on the second day. Although the total working hours per week of the two groups, namely the regular shift group (N = 43) and the irregular shift group (N = 43), were the same, significant main effects of groups (F = 62.569, p < 0.001), time (F = 45.304, p < 0.001), and group-by-time interaction (F = 226.695, p < 0.001) were indicated through linear mixed models. The main effect of day was not statistically significant, with F = 0.105 and p = 0.746. The fluctuation range of cortisol curve in the group with irregular schedules was slightly lower than that in the group with regular schedules.

Conclusion

Our results may indicate that cortisol was more inhibited in midwives with irregular shift patterns than those with regular shift patterns. It is necessary to further study the relationship between cortisol rhythm and patterns of midwives' shifts in future so as to lay a foundation for hospital managers to develop a more reasonable scheduling system for midwives with the further purpose to minimize their occupational fatigue and ensure the safety of mothers and infants.

Assessment of risks for breast cancer in a flight attendant exposed to night shift work and cosmic ionizing radiation: a case report

Background

Some epidemiological studies have estimated exposure among flight attendants with and without breast cancer. However, it is difficult to find a quantitative evaluation of occupational exposure factors related to cancer development individually in the case of breast cancer in flight attendants. That is, most, if not all, epidemiological studies of breast cancer in flight attendants with quantitative exposure estimates have estimated exposure in the absence of individual flight history data.

Case presentation

A 41-year-old woman visited the hospital due to a left breast mass after a regular check-up. Breast cancer was suspected on ultrasonography. Following core biopsy, she underwent various imaging modalities. She was diagnosed invasive ductal carcinoma of no special type (estrogen receptor positive in 90%, progesterone receptor positive in 3%, human epidermal growth factor receptor 2/neu equivocal) with histologic grade 3 and nuclear grade 3 in the left breast. Neoadjuvant chemotherapy was administered to reduce the tumor size before surgery. However, due to serious chemotherapy side effects, the patient opted for alternative and integrative therapies. She joined the airline in January, 1996. Out of all flights, international flights and night flights accounted for 94.9% and 26.2, respectively. Night flights were conducted at least four times per month. Moreover, based on the virtual computer program CARI-6M, the estimated dose of cosmic radiation exposure was 78.81 mSv. There were no other personal triggers or family history of breast cancer.

Conclusions

This case report shows that the potentially causal relationship between occupational harmful factors and the incidence of breast cancer may become more pronounced when night shift workers who work continuously are exposed to cosmic ionizing radiation. Therefore, close attention and efforts are needed to adjust night shift work schedules and regulate cosmic ionizing radiation exposure.

Women's health and night shift work: Potential targets for future strategies in breast cancer (Review)

Breast cancer is the leading cause of cancer-associated amongst women worldwide. Several studies have shown that individual, environmental and occupational factors can serve an important role in the onset of breast cancer; although the majority of studies have demonstrated this association, and several studies have investigated the biological pathways, it is impossible to describe with certainty the causal relationship that involve circadian rhythm disruption and melatonin dysregulation with the oncogenic processes. Over the years, due to the introduction of more effective screening tools, an increase in the incidence of breast cancer as well as a decrease in the age at diagnosis has been witnessed. Subsequently, an increasing number of individuals have obtained care at a younger age, which has meant that after surgery and chemotherapy, these workers have had to return to work. In light of these paradigmatic changes, the aim of the present review was to identify potential targets for future organisational strategies that should be adopted in the workplace by occupational physicians, both for prevention and for the return-to-work process of working women who have suffered from breast cancer.

Night Work and Breast Cancer Risk in Nurses: Multifactorial Risk Analysis

Night work has been highlighted by the International Agency for Research on Cancer (IARC) as a likely carcinogenic factor for humans, associated with breast cancer and professions that require continuity of work. Knowing the impact that short and long-term night work has on the nurses' collective seems a priority, therefore, this study aims to analyse the relationship between night work and the development of breast cancer risk factors in nurses. For this, a cross-sectional study through an online questionnaire on breast cancer risk variables and working life was designed. The study was conducted in Spain and the sample consisted of 966 nurses, of whom 502 were healthy participants and 56 were breast cancer patients. These two groups were compared in the analyses. A descriptive analysis was performed, and the relationship was tested using χ2 independence test and OR calculation. The CHAID (Chi Square Automatic Interaction Detection) data mining method allowed for the creation of a segmentation tree for the main risk variables. The most significant risk variables related to working life have been the number of years worked, nights worked throughout life, and years working more than 3 nights per month. Exceeding 16 years of work has been significant for women and men. When the time worked is less than 16 years, the number of cases increases if there is a family history of cancer and if there have been more than 500 nights of work. High-intensity night work seems more harmful at an early age. The accumulation of years and nights worked increase the risk of breast cancer when factors such as sleep disturbance, physical stress, or family responsibilities come together.