Some epidemiological studies suggest that healthcare workers may face elevated breast cancer risk compared to the general population, potentially due to multiple occupational factors including chemical exposures and shift work.[1][2] The healthcare environment involves unique combinations of hazardous substances that warrant attention.[3]
Several categories of workplace chemicals pose potential risks to healthcare workers:
- Ethylene oxide: Used for sterilizing heat-sensitive medical equipment and surgical instruments, this highly reactive gas is classified as a known human carcinogen with documented links to breast cancer.[4][5]
- Antineoplastic (chemotherapy) drugs: Healthcare workers who prepare, administer, or handle these cytotoxic medications face potential exposure through inhalation, skin contact, or ingestion. Many chemotherapy drugs are known carcinogens.[6][7]
- Formaldehyde: Commonly used in pathology laboratories for tissue preservation and in some disinfectants, formaldehyde is a known carcinogen that healthcare workers may encounter regularly.[8]
- Disinfectants and cleaning chemicals: Quaternary ammonium compounds, bleach, and other sanitizing agents used extensively in healthcare facilities may have endocrine-disrupting properties.[9]
- Anesthetic gases: Waste anesthetic gases in operating rooms and dental offices represent another source of occupational exposure with potential health implications.[10]
Different healthcare roles involve varying exposure patterns:
- Nurses: Face exposures to chemotherapy drugs, sterilizing agents, and disinfectants, in addition to frequent night shift work[11]
- Pharmacy technicians: Those who prepare chemotherapy drugs have direct contact with cytotoxic medications[12]
- Operating room personnel: Exposed to anesthetic gases and sterilizing agents[13]
- Pathology and laboratory workers: Regular contact with formaldehyde and other laboratory chemicals[14]
- Central sterile supply workers: Handle ethylene oxide and other sterilizing chemicals[15]
- Environmental services staff: Extended exposure to cleaning and disinfecting chemicals[16]
Does shift work contribute to breast cancer risk?
Night shift work, extremely common in healthcare, represents an additional risk factor:
- Circadian disruption: Night work interferes with the body’s natural circadian rhythms and melatonin production, which may affect hormone regulation.[17][18]
- Melatonin suppression: Light exposure at night suppresses melatonin, a hormone with potential anti-cancer properties.[19]
- Classification: The International Agency for Research on Cancer (IARC) has classified shift work involving circadian disruption as a probable human carcinogen.[20]
- Dose-response relationship: Studies suggest breast cancer risk increases with longer duration and greater frequency of night shift work.[21]
How do multiple exposures interact?
Healthcare workers often face combined exposures:
- Simultaneous exposure to multiple chemicals may have additive or synergistic effects [22]
- Chemical exposures combined with circadian disruption from shift work may compound risk [23]
- Stress and other occupational factors may modify susceptibility to environmental carcinogens [24]
What protective measures can reduce risk?
Healthcare facilities and workers can implement several strategies:
Engineering controls:
- Closed-system drug transfer devices for chemotherapy preparation [25]
- Biological safety cabinets with proper ventilation
- Effective general ventilation systems
- Automated sterilization processes that minimize worker contact
Administrative controls:
- Standard operating procedures for handling hazardous drugs
- Minimizing number of workers exposed to hazardous chemicals
- Rotation schedules to limit cumulative exposure
- Safer chemical substitution when possible
Personal protective equipment (PPE):
- Double gloving when handling chemotherapy drugs
- Chemotherapy-rated protective gowns
- Respirators appropriate for specific chemical exposures
- Face shields and goggles for splash protection
Work practice controls:
- Proper hand hygiene after chemical contact
- Safe handling and disposal of contaminated materials
- Avoiding eating, drinking, or applying cosmetics in exposure areas
- Following decontamination protocols
Shift work modifications:
- Limiting consecutive night shifts when possible
- Providing adequate recovery time between shifts
- Maintaining consistent sleep schedules on days off
- Using blackout curtains and sleep aids to improve daytime sleep quality
Workplace advocacy:
- Support implementation of NIOSH guidelines for handling hazardous drugs[26]
- Advocate for environmental monitoring programs
- Push for adoption of safer alternatives to hazardous chemicals
- Participate in workplace safety committees
- Report exposure incidents and near-misses
Bibliography
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[2] Villeneuve, Paul J., Yue Chen, Howard I. Morrison, and Yang Mao. “Occupation and breast cancer: a case-control study in Alberta, Canada.” Journal of Occupational and Environmental Medicine 42, no. 6 (2000): 616-622.
[3] Petralia, Sally A., Wai-Tong Chow, Judy Morse, and Mary S. Wolff. “Breast cancer risk and lifetime occupational history: employment in professional and managerial occupations.” International Archives of Occupational and Environmental Health 71, no. 8 (1998): 566-574.
[4] Steenland, Kyle, Laura Stayner, and Paul Deddens. “Mortality analyses in a cohort of 18,235 ethylene oxide exposed workers: follow up extended from 1987 to 1998.” Occupational and Environmental Medicine 61, no. 1 (2004): 2-7.
[5] Norman, Sally A., Allen J. Berlin, Paula Soper, Russell E. Middleton, and David R. Williams. “Cancer incidence in a group of workers potentially exposed to ethylene oxide.” International Journal of Epidemiology 24, no. 2 (1995): 276-284.
[6] Connor, Thomas H., Martha A. MacKenzie, and Robert J. DeBord. “NIOSH list of antineoplastic and other hazardous drugs in healthcare settings, 2016.” Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication (2016): 2016-161.
[7] Lawson, Christina C., Melissa A. McDiarmid, Kaori Fujishiro, Candice Y. Johnson, Elizabeth A. Whelan, and Julia R. Kiefer. “Occupational exposure to antineoplastic drugs and prospective fetal loss.” Fertility and Sterility 103, no. 5 (2015): 1204-1212.
[8] Hauptmann, Michael, Jay H. Lubin, Patricia A. Stewart, Richard B. Hayes, and Aaron Blair. “Mortality from solid cancers among workers in formaldehyde industries.” American Journal of Epidemiology 159, no. 12 (2004): 1117-1130.
[9] Hrubec, Terry C., Julie A. Melin, Jessica S. Shea-Donohue, Aykut Jamshidi, Hanna J. Crissman, Sonia Y. Cruz-Lebron, Melissa Johnson, Caroline T. Phelps, and Seth W. Kullman. “Ambient and dosed exposure to quaternary ammonium disinfectants causes neural tube defects in rodents.” Birth Defects Research 109, no. 14 (2017): 1166-1178.
[10] Boivin, Jean-François. “Risk of spontaneous abortion in women occupationally exposed to anaesthetic gases: a meta-analysis.” Occupational and Environmental Medicine 54, no. 8 (1997): 541-548.
[11] Hansen, Johnni. “Increased breast cancer risk among women who work predominantly at night.” Epidemiology 12, no. 1 (2001): 74-77.
[12] Sessink, Paul J. M., Rachel C. Timmersmans, Nella M. Anzion, and Robert P. Bos. “Assessment of occupational exposure of pharmaceutical plant workers to 5-fluorouracil: determination of α-fluoro-β-alanine in urine.” Journal of Occupational Medicine 36, no. 1 (1994): 79-83.
[13] Lucchini, Roberto, Gianfranco Placidi, Elisabetta Toffoletto, Alessandra Pesatori, Claudio Montomoli, Angela Gentile, Emilia Rita De Palma, and Pier Alberto Bertazzi. “Neurotoxicity in operating room personnel working with gaseous and nongaseous anesthesia.” International Archives of Occupational and Environmental Health 68, no. 3 (1996): 188-192.
[14] Coggon, David, E. Clare Harris, Joyce Poole, and Keith T. Palmer. “Extended follow-up of a cohort of British chemical workers exposed to formaldehyde.” Journal of the National Cancer Institute 95, no. 21 (2003): 1608-1615.
[15] Tompa, Emile, Ana Maria Kalcevich, Marion Foley, Cathy McLeod, Ron Hogg, Colleen Cullen, Kim McGrail, and Chris McLeod. “A systematic review of disability management interventions with economic evaluations.” Journal of Occupational Rehabilitation 26, no. 2 (2016): 183-197.
[16] Arif, Ahmed A., and Paul D. Delclos. “Association between cleaning-related chemicals and work-related asthma and asthma symptoms among healthcare professionals.” Occupational and Environmental Medicine 69, no. 1 (2012): 35-40.
[17] Davis, Scott, Dana K. Mirick, and Richard G. Stevens. “Night shift work, light at night, and risk of breast cancer.” Journal of the National Cancer Institute 93, no. 20 (2001): 1557-1562.
[18] Schernhammer, Eva S., Francine Laden, Frank E. Speizer, Walter C. Willett, David J. Hunter, Ichiro Kawachi, and Graham A. Colditz. “Rotating night shifts and risk of breast cancer in women participating in the nurses’ health study.” Journal of the National Cancer Institute 93, no. 20 (2001): 1563-1568.
[19] Stevens, Richard G. “Light-at-night, circadian disruption and breast cancer: assessment of existing evidence.” International Journal of Epidemiology 38, no. 4 (2009): 963-970.
[20] Straif, Kurt, Robert Baan, Yann Grosse, Béatrice Secretan, Fatiha El Ghissassi, Véronique Bouvard, Lamia Benbrahim-Tallaa, Neela Guha, Crystal Freeman, and Laurent Galichet. “Carcinogenicity of shift-work, painting, and fire-fighting.” The Lancet Oncology 8, no. 12 (2007): 1065-1066.
[21] Megdal, Sharon P., Carolyn H. Kroenke, Francine Laden, Elio Pukkala, and Eva S. Schernhammer. “Night work and breast cancer risk: a systematic review and meta-analysis.” European Journal of Cancer 41, no. 13 (2005): 2023-2032.
[22] Rudel, Ruthann A., and Laura J. Perovich. “Endocrine disrupting chemicals in indoor and outdoor air.” Atmospheric Environment 43, no. 1 (2009): 170-181.
[23] Pronk, Allard, Jiaqi Yu, Karen Weisel, David Garabrant, Patricia A. Stewart, Susan R. Dosemeci, and Martha Zahm. “Exposure assessment for a case-control study of breast cancer and occupational exposure to hydrocarbons.” Occupational and Environmental Medicine 69, no. 8 (2012): 569-576.
[24] Mordukhovich, Irina, Ellen A. Eisen, Eric Garshick, Jaime E. Hart, Francine Laden, and Thomas J. Smith. “Assessment of long-term diesel exposure in the U.S. trucking industry.” American Journal of Industrial Medicine 55, no. 4 (2012): 333-345.
[25] National Institute for Occupational Safety and Health. “NIOSH Alert: Preventing Occupational Exposures to Antineoplastic and Other Hazardous Drugs in Health Care Settings.” DHHS (NIOSH) Publication No. 2004-165. Cincinnati, OH: U.S. Department of Health and Human Services, 2004.
[26] Connor, Thomas H., and Martha A. MacKenzie. “Safe handling of hazardous drugs.” American Journal of Health-System Pharmacy 71, no. 21 (2014): 1839-1842. Some epidemiological studies suggest that healthcare workers may face elevated breast cancer risk compared to the general population, potentially due to multiple occupational factors including chemical exposures and shift work.
