Table 4.

Cohort studies of formaldehyde exposures and nasopharyngeal cancer

Authors (Years), Country	Cohort description Type of analysis (cohort size)	Exposure assessment	Results SMR or RR (95% CI)
Hauptmann et al.(2004), USA [19]	The cohort with 10 plants of manufacture of or using formaldehyde by the National Cancer Institute from 1966 to 1994; Standardized mortality (25,619 workers; 22,493 men, 3126 women) and Relative risks	Duration; quantitative estimates of cumulative, average and highest peak exposure	8 death, SMR 2.10 (1.05–4.21) Peak exposure (ppm) ≥4.0 RR 1.83 (p-trend < 0.001) Cumulative exposure (ppm-year) 1.5–< 5.5 RR 1.19, ≥5.5 RR 4.14 (p-trend = 0.025)
Freeman et al. (2013), USA [20]	Update of Hauptmann et al.(2004), 1966–2004	Duration; quantitative estimates of cumulative, average and highest peak exposure	9 death, SMR 1.84 (0.84–3.49); Peak Exposure (ppm) ≥4.0 RR 7.66 (0.94–62.34) (p-trend = 0.005)
Marsh et al. (2005), USA [21]	Computed SMRs and RRs for each of 10 study plants and by plant group (Plant 1 (n = 4261) vs. Plants 2–10 (n = 21,358)). 1966–1994	Duration; quantitative estimates of cumulative, average and highest peak exposure	Plant 1 6 deaths, SMR 10.32 (3.79–22.47) plant 2–10 2 deaths, SMR 0.65 (0.08–2.33)
Coggon et al. (2003), UK [23]	Chemical factories that used or produced Formaldehyde; Standardized mortality (14,014 men); 1941–2000	Level of exposure (background, low, moderate, high); among highly exposed, time period and duration of exposure	One death from nasopharyngeal cancer (2.0 expected)
Coggon et al. (2014), UK [24]	Update of Coggon et al., (2003). (14,008 men); 1941–2012	Level of exposure (background, low, moderate, high); among highly exposed, time period and duration of exposure	One death from nasopharyngeal cancer (1.7 expected)
Pinkerton et al. (2004), USA [25]	Garment industry; Standardized mortality (11,039 workers; 2015 men, 9024 women)	Duration, time since first exposure, year of first exposure	No death from nasopharyngeal cancer (0.96 expected)
Meyers et al. (2013), USA [26]	Garment industry; Standardized mortality (11,039 workers; 2015 men, 9024 women)	Duration, time since first exposure, year of first exposure	No death from nasopharyngeal cancer (0.96 expected)
Siew et al. (2012), Finland [27]	All Finnish men born between 1906 and 1945 and employed during 1970, Finnish Cancer Registry for cases of cancers of nasopharynx (n = 149) (n = 30,317). 1971–1995.	Estimation of exposure by Finnish Job Exposure Matrix	Any exposure to formaldehyde RR 0.87 (0.34–2.20) Any exposure to wood dust RR 0.66 (0.30–1.45)
Pira et al. (2012), Italia [28]	Workers of a laminated plastic factory in Piedmont, northern Italy. 2750 subjects (2227 men and 523 women) between 1947 and 2011, for at least 180 days. SMRs	None	No nasopharyngeal cancer was confirmed.

SMR, Standardized mortality ratio; RR, Relative risk