Table 1.

Details of Studies Included in the Systematic Review.

Authors	Type	Sample Characteristics (sample size, demographics)	Study Focus and Design (quantitative/qualitative, study focus, analysis)	Key Findings
Baran et al. (2016)	Peer-reviewed article	N = 58 slaughterhouse workers (SHW) Location: Denmark Demographics: Mage = n/a Ethnicity = n/a Gender = n/a (demographic breakdown is only given for all occupations)	Quantitative design: survey Utilized dirty work theory to examine SHWs psychological well-being. Comparison between SHWs and 44 other professions.	SHWs have lower physical and psychological well-being (low self-esteem, lack of purpose, lack of personal development) compared with other professions, including controls matched on levels of prestige and dirtiness.
Emhan et al. (2012)	Peer-reviewed article	N = 43 SHW Location: Turkey Demographics: Mage = n/a Ethnicity = n/a Gender = all male	Quantitative design: survey Psychological symptom profiles of SHW compared with butchers and office workers.	SHWs had higher levels of distress and psychological issues compared with butchers for somatization, anxiety, anger hostility, and psychoticism. There was no significant difference between them on obsessive-compulsiveness, interpersonal sensitivity, depression, phobic anxiety, paranoia. All measures were significantly higher than office workers.
Fitzgerald et al. (2009)	Peer-reviewed article	N = 581 nonmetropolitan counties Location: United States	Quantitative: crime survey (secondary source) The link between crime rates and slaughterhouse employment	Slaughterhouse employment was associated with an increase in total arrests and reports, rape arrests, sexual offenses. Found no link between crimes against the family or violent crimes (after 1997).
Horton and Lipscomb (2011)	Peer-reviewed article	N = 296 SHW Location: United States Demographics: Mage = 33 Ethnicity = 99% Black Gender = all female	A longitudinal analysis of Lipscomb et al. (2007); tracking the prevalence of depressive symptoms over 5 years.	Depression rates were 46% at baseline interview (103 participants); however, the depression rates decreased over the 5 years (as did the number of participants). Average prevalence of depression was 32% across the 5 years.
Hutz et al. (2013)	Peer-reviewed article	N = 951 SHW Location: South Brazil Demographics: Mage = 32 Ethnicity = n/a Gender = mostly female (63.5%)	Mental illness due to adverse (stressful) working conditions Comparison between SHWs, university workers and students Quantitative.	SHWs had higher levels of vulnerability, psychological “disadjustment,” anxiety, and depression compared with both controls. Within SHW—those involved in cutting processes have much higher rates.
Jacques (2015)	Peer-reviewed article	N = 248 non-Metropolitan counties Location: United States	Quantitative: crime survey (secondary source) The link between crime rates and slaughterhouse employment when controlling for social disorganization variables.	Increase in total arrests (22%), rape (166%), offenses against the family (90%) but nonsignificant results for violent and murder offenses. No indication of whether the workers actually committed the crime though.
Kristensen (1991)	Peer-reviewed article	N = 4407 SHW Location: Denmark Demographics: Mage = Ethnicity = n/a Gender = mostly male (78%)	Quantitative: survey Primary focus was on their physical health but also examined stress symptoms.	Findings demonstrated that half the sample suffered from stress symptoms (common stress, nervousness, mental instability, anxiety, and sleeplessness).
Lander et al. (2016)	Peer-reviewed article	N = 268 SHW Location: United States Demographics: Mage = 39 Ethnicity = majority non-Hispanic Gender = mostly male (64%)	Quantitative: survey Whether depression was a risk for future injury.	13.8% screened positive for depressive symptoms in the last 6 months, compared with 3.4% in general public.
Leibler et al. (2017)	Peer-reviewed article	N = 137 unionized SHW Location: United states Demographics: Mage = 44 Ethnicity = 92% Hispanic Gender = mostly male (55%)	Quantitative: Interviews and survey (Kessler-6) Examine the prevalence of serious psychological distress (SPD; nonspecific anxiety)	SPD was 4.4% in slaughterhouses compared with 3.6% in general population in the last 6 months. 81% reported no distress Those on the kill floor experienced more distress compared with those on the cut floor. Ethnicity was a significant predictor of SPD; Non-Hispanic White workers were six times more likely to report SPD. However, the authors argued that this is a result of being the minority group.
Lipscomb et al. (2007)	Peer-reviewed article	N = 291 SHW Location: United States Demographics: Mage = Ethnicity = 98.5% Black Gender = all female Multiple jobs	Quantitative: surveys Prevalence of depression in female poultry processers compared with locals and examine which factors are associated with depression.	Prevalence of depressive symptoms was 48% compared with 20% of working women. After adjusting for socioeconomic variables, the poultry workers’ depressive symptoms were still 80% higher. Prevalence of severe depression was 550% higher than controls.
McLoughlin (2018)	Peer-reviewed article	N = 16 SHW Location: Ireland Demographics: Mage = n/a Ethnicity = n/a Gender = mostly male (87.5%) Kill floor only	Qualitative: Interviews and participant observation. Emic phenomenological emotionography.	Findings indicated that the hegemonic masculine ideals are the basis of a “good SHW” and thus workers must deny, repress, or diminish any emotions they feel.
Richards et al. (2013)	Peer-reviewed article	N = 26 SHW Location: Australia Demographics: Mage = 36 Ethnicity = n/a Gender = mostly male (54%)	Quantitative: survey Examine the attitudes toward animals and propensity for aggression	SHWs had a substantially higher propensity for aggression compared with farmers, particularly within physical aggression and hostility subscales (similar to incarcerated populations). Female SHWs, in particular, had lower attitudes toward animals and a higher propensity for aggression than males.
Thompson (1983)	Peer-reviewed article	N = 350 SHW Location: United States Demographics: Mage = n/a Ethnicity = 2/3 White Gender = male	Qualitative: 9-week participant observation. To examine how SHWs cope with the strains of their work and maintain a sense of self-worth	SHWs must struggle with the fear of physical danger, monotony (which sometimes causes injury and the dehumanization of becoming part of “the machine.” Suggested that workers cope by sabotaging their own/others’ work, as it allows them to express their individuality.
Victor and Barnard (2016)	Peer-reviewed article	N = 13 SHW Location: South Africa Demographics: Mage = mostly 30–40 Ethnicity = n/a Gender = all male	Qualitative: phenomenological To examine the well-being of SHWs and understand the process of becoming a slaughterer.	Four themes: becoming a slaughterer (experiencing the mental trauma of the first kill and experiencing recurring dreams and nightmares), (mal)adjusting to slaughter work (heightened emotive responses, personality changes), coping with and maintaining the work (presenting psychological defenses, finding strength and meaning, displaying constructive and destructive coping tactics), and living with psychosocial consequences of being a slaughterer (work–life spillover, experiencing social detachment, and isolation).