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. Author manuscript; available in PMC: 2022 Jan 1.
Published in final edited form as: Environ Int. 2021 Sep 20;158:106877. doi: 10.1016/j.envint.2021.106877

Table 2.

Summary of Cr (VI) Neurological Studies in Humans

Occupation/ Exposure Geographic Region Date(s) of Exposure Number People Studied Measured Cr(VI) Exposure Health Effect(s) Calculated Risk Reference
Cancer Studies
Ferroalloy and Stainless Steel Production France 1 year,
1952–1982		 2,269 N.R. Brain cancer SMR = 3.36 (0.41–12.24 Moulin et al., 1990
Arc Welder Germany 6+ months,
1950–1970		 2,416 N.R. Brain cancer 2.7 (0.2–29.3) RR Becker et al., 1991
“Chromium and compounds” Denver, CO 1976–1983 252 cases
222 controls		 N.R. Brain cancer Father’s OR = 0.8 (0.3–2.8) Feingold et al., 1991
Boiler welder Norway 1942–1981 2,597 N.R. Brain cancer SIR = 102 (49–188) Danielson et al., 1996
Chrome tannery worker Italy 6+ months, 1955–1988 1,244 N.R. Brain cancer SMR = 168 (46–431) Montanaro et al., 1997
Concrete worker Sweden 1971–1986 33,503 N.R. Brain cancer SIR = 107 (88–129) Knuttson et al., 2000
Turner, toolmaker Finland N.R. 413,877 12 μg/g/m3 chromates Brain cancer SIR = 11.9 Wesseling et al., 2002
Occupational All (meta-analysis) N.R. (Meta-analysis) N.R. Brain cancer SMR = 88 (64–118) Cole and Rodu, 2005
Chromium salts Canada N.R. 21,020 cases
5,039 controls		 N.R. Brain cancer Multivariable OR:
Men = 1.40 (0.74–2.63)
Women = 1.06 (0.22–5.12)
Both = 1.35 (0.75–2.41)		 Pan et al., 2005
Cr Plating Japan N.R. 1,193 N.R. Brain cancer SMR = 9.14 (1.81–22.09) Hara et al., 2010
Cement Production Korea 1988–2007
>1 day		 10,740 N.R. Brain cancer 3 cases
SMR = 3.58 (0.74–10.47)		 Koh et al., 2011
Aircraft Manufacturing Worker Burbank, CA >1 year, 1960–1996 77,943 7,458 exposed workers (16.5%) Brain/CNS cancer Chromates SMR = 0.88 (0.54–1.36)
Non-factory SMR = 1.09 (0.90–1.32)		 Lipworth et al., 2011
Jet Fuel Manufacturing Connecticut, USA 1952–2004 210,784 Mean = 0.2 μg/g/m3 Glioblastoma OR: >0–0.065 = 1.00 (0.55–1.68)
0.066–0.093 = 0.93 (0.56–1.50)
0.094+ = 0.81 (0.53–1.22)		 Marsh et al., 2013
Jet Fuel Manufacturing Connecticut, USA 1952–2004 113,439 Mean = 0.24 μg/g/m3 Glioblastoma RR: >0–0.065 = 1.17 (0.79–1.72)
0.066–0.093 = 0.75 (0.54–1.04)
0.094+ = 0.90 (0.67–1.23)
Ferrochromium and stainless steel production Finland 1967–2004 8,146 22–143 μg/g/m3 Brain cancer SIR:
0.93 (0.55–1.47)		 Huvinen and Pukkula, 2013
Welding 7 countries (mostly UK & Germany) N.R. 1,800 cases
5,160 controls		 N.R. Glioma No significant effect detected Parent et al., 2017
Occupational All (meta-analysis) N.R. (Meta-analysis) N.R. Cancer CNS cancer = 1.22 (0.67–2.23)
Brain cancer = 1.04 (0.87–1.24)		 Deng et al., 2019
Metal-on-Metal Hip Replacement Studies
Failed Metal-on-Metal Hip Replacement Japan 2 years 1 221 μg/g/L Polyneuropathy N.R. Ikeda et al., 2010
Failed Metal-on-Metal Hip Replacement United Kingdom 8 ± 1.7 years 25 Blood = 1.42 (1.01–3.86) μg/g/L Benign essential tremor; regional decreased gray matter N.R. Clark et al., 2014
Failed Metal-on-Metal Hip Replacement United Kingdom 4.4 years 10 Blood = 338 nmol/L (144–164) Depression, short term memory deficit, neurocognitive deficit N.R. Green et al., 2017
Failed Non-Metal-on-Metal Hip Replacement Netherlands 6 months, fatal 1 Blood = 48.8 μg/L Asymmetrical hearing loss, visual impairment, unintentional weight loss N.R. Peters et al., 2017
Failed Metal-on-Metal Hip Replacement France <1 year 1 Blood = 65.9 μg/L Rapid cognitive decline, behavioral disorders, lack of memory, brutal hearing and visual loss N.R. Leocoanet et al., 2019
Other Health Endpoints
Chromate factory worker Japan 7+ years post-employment 33 N.R. Impaired olfaction, perforated septum (unrelated to olfaction loss) N.R. Watanabe and Fukuchi, 1981
Chromium Production Worker Baltimore, MD N.R. 2,354 N.R. Cause of death:
Mental & psych disorders;
Nervous system disorder		 SMR:
1.42 (1.00–1.95)
0.53 (0.32–0.83)		 Gibb et al., 2015
Cr Plating Korea 0.9–18.2 years
(avg = 7.9)		 N.R. Cr(III) = 0.059, 0.021, 0.0063, 0.0047 mg/m3
Cr(VI) = 0.013, 0.033, 0.0054, 0.0047 mg/m3 		Impaired olfactory recognition, but detection unaffected N.R. Kitamura et al., 2003
River Pollution N Spain Lifetime 9,434 N.R. Motor Neuron Disease SMR = 1.12 (1.08–1.17)
15.7% incr risk		 Sánchez-Díaz et al, 2018
Environmental Pollution S Spain Lifetime
(age 6–11, avg 7.8)		 393 0.44 (SD±1.32) μg/g/L urine
0.93 (SD±2.45) μg/g creat
0.33 (SD±1.13) μg/g hair		 Impaired neuropsychological development N.R. Caparros-Gonzalez et al., 2019

N.R. = Not reported; SMR = standard mortality ratio; SIR = standard incidence ratio; OR = odds ratio; RR = relative risk