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. Author manuscript; available in PMC: 2015 Dec 16.
Published in final edited form as: Int J Emerg Ment Health. 2011;13(4):279–289.

Cancer Incidence Among Police Officers in a U.S. Northeast Region: 1976–2006

Ja K Gu 1,✉, Luenda E Charles 2, Cecil M Burchfiel 3, Michael E Andrew 4, John M Violanti 5
PMCID: PMC4681507  NIHMSID: NIHMS743228  PMID: 22900461

Abstract

Police officers are exposed to occupational hazards which may put them at increased risk of cancer. We examined the incidence of cancer in a cohort of 2,234 white-male police officers in Buffalo, New York. The study population was followed for 31 years (1976–2006). The incidence of cancer, ascertained using a population-based tumor registry, was compared with 9 US regions using the Surveillance Epidemiology and End Results (SEER) program data. Four hundred and six officers (18.2%) developed cancer between 1976 and 2006. The risk of overall cancer among police officers was found to be similar to the general white-male population (Standardized Incidence Ratio [SIR] = 0.94, 95%, Confidence Interval [CI] = 0.85–1.03). An elevated risk of Hodgkin ‘s lymphoma was observed relative to the general population (SIR = 3.34, 95%, CI= 1.22–7.26). The risk of brain cancer, although only slightly elevated relative to the general population (SIR = 1.61, 95%, CI = 0.73–3.05), was significantly increased with 30 years or more of service (SIR = 2.92, 95%, CI = 1.07–6.36). Incidence ratios were significantly lower than expected for skin and bladder cancer. Police officers were at increased risk of Hodgkin’s lymphoma overall and of brain cancer after 30 years of service.

Keywords: Incidence, cancer, law enforcement officers, epidemiology, employment, occupational health

Research studies have demonstrated an increased risk of mortality for several cancers among police. Excess mortality has been found for cancers of the colon, bladder, kidney, trachea, lung, digestive organs, and for melanoma and non-Hodgkin’s lymphoma (Forastiere et al., 1994; Violanti, Vena, & Petralia, 1998; Rosenstock, Demers, Heyer, & Barnhart, 1990). This increased risk of cancer mortality may be due to their occupational exposures. Police officers are routinely exposed to radiation from radar guns (Lotz, Rinsky, & Edwards, 1995; Breckenkamp, Berg, & Blettner, 2003; Finkelstein, 1998; Davis & Mostofi, 1993; Cherry, 2001; Van Netten, Brands, Hoption Cann, Spinelli, & Sheps, 2003), air pollution (Burgaz, Demircigil, Karahalil, & Karakaya, 2002; Carere, Andreoli, & Galati, 2002; Lepardi et al., 2003), ultraviolent-radiation (Ramirez, Federman, & Kirsner, 2005), and are sometimes exposed to chemical hazards (Thrasher, Von Derau, & Burgess, 2009; Pilidis, Karakitsios, Kassomenos, Kazos, & Stalikas, 2009). Other occupational exposures which may increase officers’ risk for cancer include psychological stress (Andrew et al., 2008) and shift work (Gordon, Cleary, Parker, & Czeisler, 1986). The International Agency for Research on Cancer (IARC) has concluded that shift work is a carcinogen (IARC, 2010). Lifestyle factors which may increase the risk for cancer include obesity (Ramey, Downing, & Franke, 2009), decreased physical activity (Richmond, Wodak, Kehoe, & Heather, 1998), sleep deprivation and poor sleep quality (Stevens et al., 2011; Burch et al., 2007), smoking (Sasco, Secretan, & Straif, 2004), and consumption of alcohol (Boffetta & Hashibe, 2006).

The majority of studies of police officers and cancer have been based on mortality. To our knowledge, only a few studies have been published on cancer incidence in police officers. An excess risk of prostate cancer was observed among fire fighters and police officers in Washington State during 1944–1979 (Demers et al., 1992). Another study conducted in Washington State reported increased incidence of testicular cancer (Davis and Mostofi, 1993). Two Canadians studies reported an increased incidence of testicular, skin, and other cancers among police officers (Finkelstein, 1998; Van Netten et al., 2003). Lope and colleagues (2005) reported increased risk for thyroid cancer among Swedish police officers, and a case-cohort study conducted in the Netherlands reported a substantial (67%) increase in prostate cancer risk for each decade of police work (Zeegers, Friesema, Goldbohm, & Van den Brandt, 2004). Therefore, the goal of this paper is to examine the incidence of cancer for police officers in a US northeast metropolitan city and compare this with the U.S. population, using Surveillance Epidemiology and End Results (SEER) data obtained from the National Cancer Institute.

MATERIALS AND METHODS

Study Population

A list of Buffalo police officers (N = 3,391) who worked at least 5 years as officers in the city of Buffalo between 1950 and 2005 was sent to the New York State Cancer Registry (NYSCR) where it was linked with NYSCR data. The period of investigation for cancer incidence was from January 1, 1976 to December 31, 2006. NYSCR provided cancer case, date of diagnosis, site, tumor’s histology, and a recode value that converts site and histology to specific types of cancer. The target population included all white male officers who worked at least 5 years as a city employee of Buffalo between 1950 and 2005. Exclusions included female officers (n = 298) and non-white officers (n = 205) because of relatively small numbers of individuals, officers who died before January 1, 1976 (n = 610) when the follow-up for the cancer incidence analysis started, and those who did not have birth date and hire date information (n = 44), leaving a total of 2,234 officers in the study population.

Person-Years at Risk

The cumulated person-years for each officer began the first day of the study (January 1, 1976) or the date when 5 years of employment was achieved, and ended on the date of cancer diagnosis, date of death, date of loss to follow-up, or the end of the study period (December 31, 2006), whichever occurred first. The person-years at cancer risk contributed by each officer were classified into 14 age groups (22–24, 25–29, 30–34, 35–39, … …, 80–84, 85+) and 7 calendar year groups (1976–79, 1980–84, 1985–89, 1990–94, 1995–99, 2000–04, 2005–06).

Age-and calendar year-specific cancer incidence rates for US population

SEER 9 registries from the National Cancer Institute is a surveillance data set available since 1973 and is provided by the National Cancer Institute (2009). One of the main goals of SEER was to collect complete and accurate data on all cancers diagnosed among residents of the geographic area covered by SEER cancer registries. The data set includes information on demographics and cancer diagnosis from nine US regions: Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, San Francisco-Oakland, Seattle-Puget Sound, and Utah. SEER 9 registries cover 9.2% of the US population based on the year 2000.

Statistical Analysis

Expected numbers of cancer cases were calculated based on 5-year age- and calendar year- specific incidence rates multiplied by the cohort’s person-years in each specific stratum. The Standardized Incident Rate (SIR) for a specific type of cancer was obtained by dividing the total number of observed cases by the corresponding total expected number. The statistical significance of the difference between observed and expected numbers was determined by the Mantel-Haenszel chi-square test with 1 degree of freedom, and the 95% confidence intervals (CIs) were calculated for the SIR point estimates (Rothman & Boice, 1979).

RESULTS

A total of 2,234 white male officers were enrolled in this study; 1,214 (54.3%) were still alive at the end of follow-up, December 31, 2006 (Table 1). Table 1 shows the distribution of several characteristics such as vital status and occupational factors. Four hundred and six officers (18.2%) developed cancer between 1976 and 2006. Eighty-two percent of officers had been hired before the age of 30, and 76% were in service for 20 or more years. Approximately 66% of those first diagnosed with cancer were diagnosed between the ages of 55 and 74 years, and the mean age of diagnosis was 65.7 years. Multiple malignancies were observed in 46 officers during the period. Our analyses were based on the first occurrence.

Table 1.

Characteristics of Buffalo police officers by cancer status

Cancer
(N=406)		 No Cancer
(N=1,828)		 All
(N=2,234)
Characteristic N (%) N (%) N (%)
Vital status
  Alive 140 (43.5) 1,074 (58.8) 1,214 (54.3)
  Deceased 266 (65.5) 644 (35.2) 910 (40.7)
  Loss to follow-up 0 (0.0) 110 (6.0) 110 (4.9)
Age hired as police officer
  <=24 131 (32.3) 706 (38.6) 837 (37.5)
  25–29 189 (46.6) 815 (44.6) 1,004 (44.9)
  30–34 75 (18.5) 243 (13.3) 318 (14.2)
  35+ 11 (2.7) 64 (3.5) 75 (3.4)
Calendar year of hire
  <1950 145 (35.7) 463 (25.3) 608 (27.2)
  1950–1959 136 (33.5) 322 (17.6) 458 (20.5)
  1960–1969 98 (24.1) 427 (23.4) 525 (23.5)
  1970–1979 18 (4.4) 163 (8.9) 181 (8.1)
  1980–1989 8 (2.0) 266 (14.6) 274 (12.3)
  1990–1999 1 (0.3) 169 (9.3) 170 (7.6)
  2000–2005 0 (0.0) 18 (1.0) 18 (0.8)
Length of police service
  5–9 12 (3.0) 152 (8.3) 164 (7.3)
  10–19 48 (11.8) 328 (17.9) 376 (16.8)
  20–29 155 (38.2) 708 (38.7) 863 (38.6)
  30–39 174 (42.9) 569 (31.1) 743 (33.3)
  40+ 17 (4.2) 71 (3.9) 88 (3.9)
Person-years by age group
  25–34 11 (0.2) 104 (0.3) 115 (0.3)
  35–44 135 (2.0) 2,248 (6.3) 2,248 (5.6)
  45–54 502 (7.5) 5,600 (15.7) 6,101 (14.4)
  55–64 2,027 (30.3) 9,330 (26.1) 11,164 (26.8)
  65–74 2,391 (35.7) 8,773 (24.6) 10,792 (26.3)
  75–84 1,344 (20.1) 6,898 (19.3) 8,243 (19.4)
  85+ 289 (4.3) 2,746 (7.7) 3,035 (7.2)
  Total 6,698 (100.0) 35,699 (100.0) 42,398 (100.0)
Age at cancer diagnosis
  <=54 60 (14.8)
  55–74 269 (66.2)
  75+ 77 (19.0)
Mean (SD) Mean (SD) Mean (SD)
Years of Police Service 28.1 (8.1) 25.2 (9.4) 25.7 (9.2)
Age at cancer diagnosis 65.7 (10.8) N/A N/A
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The age- and calendar year- adjusted SIRs and 95% CIs for officers are presented in Table 2. The overall number of observed cancer incident cases for white male officers was similar to the number expected (SIR = 0.94, 95% CI = 0.85–1.03) based on the US white male population. Of the 18 lymphomas observed, a third (n = 6) were Hodgkin’s lymphomas; the other two thirds (n = 12) were non-Hodgkin’s lymphomas. The incidence of Hodgkin’s lymphoma was significantly greater than that which would be expected for the white male population (SIR =3.34, 95% CI = 1.22–7.26). Slightly increased incidence ratios were observed for kidney (SIR = 1.56, 95% CI = 0.94–2.43), brain (SIR = 1.61, 95% CI = 0.73–3.05), and thyroid cancer (SIR = 1.99, 95% CI =0.64–4.64), although none of the excesses were statistically significant. In contrast, incidence ratios were significantly decreased for skin (SIR = 0.54, 95% CI = 0.26–0.98) and bladder cancer (SIR = 0.64, 95% CI = 0.39–0.99). No excess risk was found for cancer of the digestive system (SIR = 1.01, 95% CI = 0.81–1.24) and respiratory system (SIR = 0.97, 95% CI = 0.77–1.20). Among digestive system cancers, esophagus (SIR =1.39, 95% CI = 0.60–2.73), stomach (SIR = 1.28, 95% CI = 0.66–2.24), and rectal cancer (SIR = 1.22, 95% CI = 0.67–2.05) were slightly elevated yet not statistically significant, while colon (SIR = 0.80, 95% CI =0.53–1.14), liver (SIR = 0.82, 95% CI = 0.16–2.39), and pancreatic cancer (SIR = 0.87, 95% CI = 0.40–1.66) were slightly decreased.

Table 2.

Cancer incidence in Buffalo police officers, 1976–2006.

Cancer Sites (ICD-O-31) Observed Expected SIR 95% CI
All Cancers 406 432.52 0.94 0.85–1.03
Buccal cavity and pharynx (C000–C148) 10 15.23 0.66 0.31–1.21
Digestive system (C150–C269, C480–C488) 89 88.14 1.01 0.81–1.24
  Esophagus (C150–C159) 8 5.77 1.39 0.60–2.73
  Stomach (C160–C169) 12 9.35 1.28 0.66–2.24
  Colon (C180–C189) 29 36.47 0.80 0.53–1.14
  Rectum (C209) 14 11.44 1.22 0.67–2.05
  Liver (C220) 3 3.66 0.82 0.16–2.39
  Pancreas (C250–C259) 9 10.32 0.87 0.40–1.66
Respiratory system (C320–C399) 83 85.81 0.97 0.77–1.20
  Lung and Bronchus (C340–C349) 69 76.03 0.91 0.71–1.15
Skin (C440–C449) 10 18.68 0.54 0.26–0.98*
Prostate (C619) 104 118.13 0.88 0.72–1.07
Urinary System (C649–C689) 40 44.65 0.90 0.64–1.22
  Bladder (C670–C679) 20 31.22 0.64 0.39–0.99*
  Kidney (C649, C659) 19 12.19 1.56 0.94–2.43
Brain(C710–C719) 9 5.61 1.61 0.73–3.05
Thyroid (C739) 5 2.52 1.99 0.64–4.64
  Lymphoma2 18 18.01 1.00 0.59–1.58
  Hodgkin’s lymphoma2 6 1.80 3.34 1.22–7.26*
Non-Hodgkin’s lymphoma2 12 16.21 0.74 0.38–1.29
Leukemia2 15 12.35 1.21 0.68–2.00
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1

International Classification of Disease for Oncology, 3rd Edition, 2000. Classified using site code.

2

Classified using ICD-O-3 Histology.

*

Statistical significance

Table 3 displays all cancer incidence ratios by characteristics related to employment as a police officer. The younger age groups had slightly higher cancer rates (SIR = 1.15 for ages 22–54, SIR =1.16 for ages 55–64) than the older age groups (SIR = 0.91 for ages 65–74, SIR = 0.67 for ages 75+). Cancer incidence decreased significantly with increasing age at diagnosis (P <0.001). The cancer incidence ratio was higher in years 2000–06 than in the previous years.

Table 3.

Cancer incidence by selected characteristics, 1976–2006.

Characteristic Observed Expected SIR 95% CI
Age at Employment
  <=24 131 124.05 1.06 0.88–1.25
  25–29 189 212.10 0.89 0.77–1.03
  30+ 86 96.37 0.89 0.71–1.10
  P-value for trend 0.312
Employment
  0–19 60 56.33 1.07 0.81–1.37
  20–29 155 273.90 0.89 0.76–1.04
  30+ 191 202.29 0.94 0.82–1.09
  P-value for trend 0.372
Age at Cancer Diagnosis
  22–54 60 52.00 1.15 0.88–1.49
  55–64 127 109.16 1.16 0.97–1.38
  65–74 142 156.39 0.91 0.76–1.07
  75+ 77 114.97 0.67 0.53–0.84*
  P-value for trend <0.001
Calendar Year
  1976–1979 39 43.33 0.90 0.64–1.23
  1980–1984 56 61.83 0.91 0.68–1.18
  1985–1989 65 71.95 0.90 0.70–1.15
  1990–1994 69 81.31 0.85 0.66–1.07
  1995–1999 69 75.27 0.92 0.71–1.16
  2000–2004 75 72.56 1.03 0.81–1.30
  2005–2006 33 26.28 1.26 0.86–1.76
  P-value for trend 0.194
Latency †
  0–29 69 72.81 0.95 0.74–1.20
  30–39 146 142.99 1.02 0.86–1.20
  40+ 191 226.72 0.88 0.76–1.02
  P-value for trend 0.965
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*

Statistical significance

†

Latency: years from onset of work to cancer diagnosis

Cancer incidence by years of police service is presented in Table 4. There were no statistically significant elevated risks for site-specific cancer, except for brain cancer among officers with 30 years or more of service (SIR = 2.92, 95% CI = 1.07–6.36). The risk of Hodgkin’s lymphoma (SIR = 5.23, 95% CI = 1.68–12.19) was increased among officers with less than 30 years of latency (data not shown).

Table 4.

Site-specific cancer standardized incidence ratios by years of police service.

Cancer Sites Years of Service
0–19 20–29 30+
Obs Exp SIR (95%CI) Obs Exp SIR (95%CI) Obs Exp SIR (95%CI)
All Cancers 60 56.33 1.07 (0.81– 1.37) 155 173.90 0.89 (0.76– 1.04) 191 202.29 0.94 (0.82– 1.09)
Buccal cavity and pharynx 2 2.38 0.85 (0.09– 3.03) 4 6.60 0.61 (0.16– 1.55) 4 6.24 0.64 (0.17– 1.64)
Digestive system 12 10.61 1.14 (0.58– 1.98) 31 34.69 0.89 (0.61– 1.27) 46 42.84 1.07 (0.79– 1.43)
  Esophagus 1 0.69 1.46 (0.02– 8.07) 2 2.44 0.82 (0.09– 2.96) 5 2.64 1.90 (0.61– 4.42)
  Stomach 1 1.17 0.86 (0.01– 4.77) 5 3.63 1.38 (0.44– 3.21) 6 4.56 1.32 (0.48– 2.87)
  Colon 4 4.20 0.96 (0.26– 2.44) 7 13.86 0.51 (0.20– 1.04) 18 18.41 0.98 (0.58– 1.55)
  Rectum 4 1.44 2.79 (0.75– 7.11) 5 4.63 1.08 (0.35– 2.52) 5 5.37 0.93 (0.30– 2.17)
  Liver 0 0.45 - 1 1.55 0.64 (0.01– 3.58) 2 1.65 1.21 (0.14– 4.37)
  Pancreas 2 1.23 1.64 (0.18– 5.88) 3 4.13 0.73 (0.15– 2.12) 4 4.96 0.81 (0.22– 2.06)
Respiratory system 9 10.46 0.86 (0.39– 1.63) 31 34.87 0.89 (0.60– 1.26) 43 40.49 1.06 (0.77– 1.43)
  Lung and Bronchus 7 9.11 0.77 (0.31– 1.58) 27 30.73 0.88 (0.58– 1.28) 35 36.20 0.97 (0.67– 1.34)
Skin 1 4.47 0.23 (0.00– 1.24) 3 7.95 0.38 (0.08– 1.10) 6 6.25 0.96 (0.35– 2.09)
Prostate 13 11.27 1.15 (0.61– 1.97) 49 47.17 1.04 (0.77– 1.37) 42 59.68 0.70 (0.51– 0.95)
Urinary System 7 5.52 1.28 (0.51– 2.61) 13 17.98 0.72 (0.38– 1.24) 20 21.15 0.95 (0.58– 1.46)
  Bladder 2 3.63 0.55 (0.06– 1.99) 6 12.23 0.49 (0.18– 1.07) 12 15.36 0.78 (0.40– 1.37)
  Kidney 5 1.75 2.85 (0.92– 6.66) 7 5.29 1.32 (0.53– 2.73) 7 5.15 1.36 (0.54– 2.80)
Brain 2 1.20 1.67 (0.19– 6.03) 1 2.36 0.42 (0.01– 2.36) 6 2.05 2.92 (1.07– 6.36)*
Thyroid 3 0.72 4.16 (0.84–12.17) 0 1.08 - 2 0.72 2.77 (0.31–10.02)
Lymphoma 4 3.48 1.15 (0.31– 2.94) 8 7.41 1.08 (0.46– 2.13) 6 7.11 0.84 (0.31– 1.84)
  Hodgkin’s lymphoma 2 0.67 2.99 (0.34–10.78) 3 0.66 4.57 (0.92–13.36) 1 0.47 2.12 (0.03–11.79)
  Non-Hodgkin’s lymphoma 2 2.81 0.71 (0.08– 2.57) 5 6.76 0.74 (0.24– 1.73) 5 6.64 0.75 (0.24– 1.76)
Leukemia 2 1.75 1.14 (0.13– 4.13) 7 4.84 1.45 (0.58– 2.98) 6 5.75 1.04 (0.38– 2.27)
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*

Statistical significance

DISCUSSION

This study examined overall and site-specific cancer incidence among a cohort of white male police officers in Buffalo, New York. Overall, police officers had slightly lower cancer rates than the general population. Finkelstein (1998) stated in his research of Ontario police officers that the lower rate may be reflective of the “healthy worker effect” and may also be partly attributable to failure to ascertain diagnoses among officers who emigrated from the study.

This study revealed elevated risks in some analyses for brain cancer and Hodgkin’s lymphoma, but not for skin and prostate cancer. Brain cancer was significantly elevated among those with 30 years or more of service. In a study of Ontario police officers, the incidence of melanoma was increased, while the incidence of brain cancer and Hodgkin’s disease were not elevated (Finkelstein, 1998). Violanti and colleagues (1998), in the 1950–1990 Buffalo police cohort mortality study, reported excess mortality for Hodgkin’s disease and slight but not significant elevations in brain cancer and leukemia. Vena and colleagues (2011) extended that study for the Buffalo police cohort through 2005, and found that mortality from brain cancer, Hodgkin’s lymphoma, and leukemia were significantly higher than expected.

Most police officers, except executives and detectives, engage in the widespread use of radio transmissions and radar during the work hours, and could be exposed for long periods of time. Police speed enforcement radar devices generate a continuous wave reference frequency in X-band (10.50 – 10.55 Ghz), K-band (24.05 – 24.250 Ghz), or Kaband (33.4 – 36.0 Ghz) (US. Department of Transportation, 2007) and transmit nonionizing electromagnetic frequency. There is some evidence that emissions from radar may increase testicular cancer (van Netten et al., 2003; Davis & Mostofi, 1993; Lotz et al., 1995), melanoma (Findelstein et al., 1998; Lotz et al., 1995; van Netten et al., 2003), brain cancer (Cherry, 2001; Lotz et al., 1995), lymphatic & hematopoietic system cancer (Szmigielski, 1996), and leukemia (Van Netten et al., 2003; Groves et al., 2002).

Police officers are also likely to be exposed to several kinds of chemicals through cleaning firearms, using fingerprint powder in forensic work, and being exposed to toxic chemicals such as carbon monoxide, lead, benzene, sulfur dioxide, particulate matter, and nitrogen dioxide in highway and street duties, which may lead to an increased risk of these diseases (Violanti et al., 1998; Burgaz et al., 2002; Proietti et al., 2005; Vimercati et al. 2006). Cherry (2001) also evaluated those who were exposed for a long period of time to microwaves from police radar and found a significantly increased risk of astrocytoma. Breckenkamp and colleagues (2003) found excess risk of brain tumors and leukemia in police. It is possible that some of the police officers in our study had served in the Vietnam and Korean wars and may have been exposed to Agent Orange. Agent Orange was contaminated with a toxic dioxin compound, 2,3,7,8-tetrachlorodibenzodioxin (TCDD), and was used as a herbicide and defoliant during the Vietnam war (1961–1971) and in the Korean Demilitarized Zone (DMZ) in the late 1960s and early 1970s (United States, Department of Veterans Affair [US DOVA], 2011a; Kang et al., 1991). Veterans who were exposed to Agent Orange had higher rates of leukemia, Hodgkin’s lymphoma and non-Hodgkin’s lymphoma, and cancers of the brain, lung, throat, and liver (Breslin, Kang, Lee, Burt, & Shepard, 1988; Thomas & Kang, 1990; US DOVA, 2011b).

Police officers may frequently come in contact with persons who might be infected with a virus. Epstein-Barr virus is a common contagious virus and in some cases could result in the development of Hodgkin’s lymphoma, Burkitt’s lymphoma, and nasopharyngeal cancer (CDC, 2006; Schottenfeld & Fraumeni, 2006; Pattle & Farrell, 2006; Veltri, Shah, McClung, Klingberg, & Sprinkle, 1983).

A slightly elevated risk of kidney cancer was found in our study, but it was not statistically significant. Forastiere et al. (1994) and Violanti et al. (1998) also reported some elevation in kidney cancer mortality (SMR = 1.39, 95% CI = 0.56–2.8; SMR = 2.08, 95% CI = 1.00–2.88 respectively) in police officers. The American Cancer Society (2010) includes the following as risk factors for kidney cancer: smoking, obesity, and the chemical exposures (asbestos, cadmium, benzene, solvents, and trichloroethylene) on the job. Police work includes high stress, longer hours of work, and irregular meals due to shift work. Lifestyle factors such as smoking and obesity may be elevated, and the long time spent in traffic may expose them to chemical agents. Some of these exposures may be associated with kidney disease in police.

The present study did not find excess risks for the incidence of colon cancer in white male officers, while excess mortality from colon cancer had been reported in a previous Buffalo Police mortality study 1950–1990 by Violanti and colleagues (1998). Our findings showed that the risk for esophageal cancer was slightly elevated yet not statistically significant. Violanti et al. (1988) and Vena et al. (2011) found that mortality for cancer of the esophagus was significantly elevated among Buffalo police officers. These differences between incidence and mortality may reflect insufficient follow-up for cancer incidence involving cancers with long latency periods.

Our findings for respiratory system cancers and lung cancer were similar to earlier studies that found the risks of these cancers were equal to or less than for the general population (Demers et al. 1992, Finkelstein 1998; Forastiere et al. 1994). Patrol officers are highly exposed to traffic pollution; thus carbon monoxide, benzene, and lead exposure could be relatively frequent (Tomao, Baccolo, Sacchi, De Sio, & Tomei, 2002; Tomei et al., 2001). The chemicals and particles present in vehicle emission may impair pulmonary function (Pal, Robert, Dutta, & Pal, 2010; Proietti et al., 2005) and cause allergic sensitization (Vimercati et al. 2006). In addition, Vineis and Husgafvel-Pursiainen (2005) and Castano-Vinyals and colleagues (2004) reported an association between air pollution and biomarkers of lung carcinogenesis.

In recent years, shiftwork has been shown to be a potential cause of breast cancer (Schernhammer, Kroenke, Laden, & Hankinson, 2006; Davis, Mirick, & Stevens, 2001), colorectal cancer (Schernhammer et al., 2003) and endometrial cancer (Viswanathan, Hankinson, & Schernhammer, 2007) for women, and prostate cancer (Kubo et al., 2006) for men, since it disrupts the circadian rhythm, the body’s biological clock. Most police officers are in rotating shift work. Our findings for male officers do not show excess risk of prostate, colon, and rectal cancer.

Strengths and Limitations

This study is one of the few to investigate cancer risk in police officers. Additionally, it is the first study to compare cancer risk using data from the SEER program of the National Cancer Institute. Since the United States does not have a pool of cancer registries that covers the entire nation, our standard population used to generate expected incidence is only based on 9.2% of US total population.

Additionally, as the number of female officers in traditionally male-dominated occupations increases, future research is needed on cancer risk in females as well as in minority officers such as African-Americans, and Hispanic Americans. This study excluded females and minority groups since the number of cancers occurring in these groups was too small. Thus, generalizability of results may be limited to white male police officers in a mid-sized urban setting.

This study has a retrospective cohort design. Potential confounding factors were limited to the demographic variables available. Other factors which may confound the associations, such as smoking habits, alcohol intake, second jobs, military experience, and environmental exposure, were not available.

CONCLUSION

Compared with the previous mortality studies for Buffalo police by Violanti and colleagues (1998) and Vena and colleagues (2011), the present study found that overall police cancer incidence was not elevated compared with a standard reference population. However, a significantly increased incidence of Hodgkin’s lymphoma was observed among Buffalo police officers. This study also found an excess risk of brain cancer after 30 or more years of police service. A long period of exposure to radar emissions could be one possible explanation for this excess. Future research in police officers could investigate associations of radar exposure and other risk factors with cancer perhaps using a case-control design.

Acknowledgments

This work was supported by the National Institute for Occupational Safety and Health (NIOSH), contract no. 212-2008-M-25404. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Contributor Information

Ja K. Gu, Email: jgu@cdc.gov, Biostatistics and Epidemiology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health.

Luenda E. Charles, Biostatistics and Epidemiology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health

Cecil M. Burchfiel, Biostatistics and Epidemiology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health

Michael E. Andrew, Biostatistics and Epidemiology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health

John M Violanti, Department of Social and Preventive Medicine, School of Public Health and Health Professions, State University of New York at Buffalo.

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