Increased oxidative stress in shoe industry workers with low-level exposure to a mixture of volatile organic compounds

Participant age and BMI by sex, expressed as median and IQR

	Exposed men (Production unit A) (N=11)	Control men (N=25)	Exposed women (Production unit B) (N=38)	Control women (N=25)
Median age (years)	35 (29–37)	32 (27.5–39.5)	39 (31.75–45.25)	34 (27–40)
Median BMI (kg/m2)	26.90 (25.90–31.00)	24.22 (22.40–26.21)	25.75 (22.70–27.77)	24.00 (22.25–25.90)

Spearman’s non-parametric correlation between oxidative status parameters, employment duration, and trace metal levels in female workersexposed to a mixture of volatile organic compounds in the shoe industry

	Employment years	Fe mg/L)	Mg (mg/L)	Zn (mg/L)	Cu (mg/L)	AOPP (µmol/L)	O2•− (mmol NBT/min/L)	TOS (µmol/L)	PAB (HKU)	SOD (U/L)	PON1 (U/L)	TAS (µmol/L)	SHG (mmol/L)	Total proteins (g/L)	OSI (AU)
AOPP (µmol/L)	−0.049	0.027	0.092	−0.156	0.107		0.149	0.140	0.171	0.144	−0.283	−0.124	−0.047	0.009	0.205
O2•− (mmol NBT/min/L)	0.334*	0.076	0.060	0.059	0.199	0.149		−0.119	0.289	−0.184	0.153	−0.727**	−0.334*	−0.049	0.523**
TOS (µmol/L)	−0.013	0.178	0.201	0.005	−0.122	0.140	−0.119		−0.188	−0.089	0.156	−0.012	0.453**	−0.233	0.555**
PAB (HKU)	0.057	−0.064	−0.119	0.014	0.704**	0.171	0.289	−0.188		−0.134	0.241	0.156	−0.109	0.216	0.323*
SOD (U/L)	−0.366*	−0.161	−0.283	−0.186	0.026	0.144	−0.184	−0.089	−0.134		−0.390*	0.104	0.005	−0.008	−0.109
PON1 (U/L)	0.145	0.126	0.120	0.099	0.183	−0.283	0.153	0.156	0.156	−0.390*		−0.080	0.368*	0.333*	0.207
TAS (µmol/L)	−0.323*	−0.116	−0.036	−0.133	−0.273	−0.124	−0.727**	−0.012	−0.522**	0.104	−0.080		0.280	0.162	−0.806**
SHG (mmol/L)	−0.376**	0.237	0.195	0.036	−0.184	−0.047	−0.371*	0.453**	−0.109	0.005	0.368*	0.280		0.376*	0.069
Total proteins (g/L)	−0.178	0.113	0.043	0.049	0.326*	0.009	−0.049	−0.233	0.216	−0.008	0.333*	0.162	0.376*		−0.179
OSI (AU)	0.267	0.286	0.196	0.163	0.126	0.205	0.523**	0.555**	0.323*	−0.109	0.207	−0.806**	0.069	−0.179
Fe (mg/L)	0.080		0.752**	0.851**	−0.233	0.027	0.076	0.178	−0.064	−0.161	0.126	−0.116	0.237	0.113	0.286
Mg (mg/L)	0.065	0.752*		0.701**	−0.182	0.092	0.060	0.201	−0.119	−0.283	0.120	−0.036	0.195	0.043	0.196
Zn (mg/L)	0.165	0.851*	0.701**		−0.108	−0.156	0.059	0.005	0.014	−0.186	0.099	−0.133	0.036	0.049	0.163
Cu (mg/L)	−0.091	−0.233	−0.182	−0.108		0.107	0.199	−0.122	0.704**	0.026	0.183	−0.273	−0.184	0.326*	0.126

Plasma redox status parameters and blood trace metal levels in shoe factory workers exposed to a mixture of volatile organic compounds vs controls by sex (means and interquartile ranges)

Men				Women
Parameter	Exposed workers (N=11)	Control (N=25)	p-value	Exposed workers (N=38)	Control (N=25)	p-value
AOPP (µmol/L)	22.20 (19.10–38.00)	20.50 (17.53–23.06)	0.210	24.85 (21.90–26.93)	19.08 (16.37–22.69)	<0.001
O2•− (mmol NBT/min	91.00 (56.00–132.00)	29.00 820.50–34.50)	<0.001	199.00 (135.50–263.00)	29.00 (25.50–38.50)	<0.001
TOS (µmol/L)	17.50 (14.90–21.00)	8.50 (8.10–10.05)	<0.001	18.55 (17.08–19.80)	8.70 (7.90–12.00)	<0.001
PAB (HKU)	115.07 (89.33–136.20)	85.38 (70.63–91.27)	<0.001	175.70 (159.15–195.92)	88.59 (68.37–94.94)	<0.001
SOD (U/L)	133.0 (78.00–142.00)	22.00 (15.50–43.00)	<0.001	139.50 (105.75–146.00)	33.00 (21.00–41.50)	<0.001
PON1 (U/L)	230.00 (93.00–444.00)	347.00(205.50–435.50)	0.233	217.50 (72.75–326.75)	393.00(276.50–489.50)	<0.001
TAS (µmol/L)	1212.00 (1139.00–1261.00)	976.00 (779.00–1292.00)	0.071	996.50 (905.25–1159.00)	878.00 (760.00–1003.50)	0.008
SHG (mmol/L)	0.66 (0.63–0.69)	0.56 (0.45–0.63)	0.001	0.63 (0.60–0.67)	0.54 (0.50–0.59)	<0.001
Total proteins (g/L)	85.60 (82.00–89.00)	67.60 (65.50–69.20)	<0.001	94.30 (88.70–101.85)	67.60 (64.30–69.75)	<0.001
OSI (AU)	1.38 (1.31–1.82)	0.85 (0.68–1.13)	<0.001	1.84 (1.57–2.04)	0.99 (0.77–1.48)	<0.001
Fe (mg/L)	630.00 (530.40–691.20)	544.72 (527.82–564.32)	0.057	467.20 (360.40–599.40)	99.22 (77.75–117.07)	<0.001
Mg (mg/L)	46.48 (44.40–51.60)	33.91 (32.14–36.43)	<0.001	36.72 (29.89–41.18)	39.67 (32.83–48.70)	0.039
Zn (mg/L)	6.96 (6.08–8.52)	5.27 (4.26–5.80)	0.001	5.70 (2.95–7.47)	6.98 (5.28–9.04)	0.032
Cu (mg/L)	0.64 (0.60–0.84)	0.82 (0.79–0.85)	0.024	0.52 (0.38–0.66)	2.28 (1.35–2.66)	<0.001
Mn (µg/L)	<LOQ	4.86 (4.09–7.29)		<LOQ	3.17 (1.90–5.78)

Spearman’s non-parametric correlation between oxidative status parameters, employment duration, and trace metal levels in male workers exposed to a mixture of volatile organic compounds in the shoe industry

	Employment years	Fe (mg/L)	Mg (mg/L)	Zn (mg/L)	Cu (mg/L)	AOPP (µmol/L)	O2•− (mmol NBT/min/L)	TOS (µmol/L)	PAB (HKU)	SOD (U/L)	PON1 (U/L)	TAS (µmol/L)	SHG (mmol/L)	Total proteins (g/L)	OSI (AU)
AOPP (µmol/L)	0.323	−0.145	0.410	0.245	0.215		0.036	0.827**	−0.036	0.264	0.382	−0.545	0.418	0.755**	0.827**
O2•− (mmol NBT/min/L)	0.790**	0.182	0.264	0.418	−0.174	0.036		−0.091	0.336	0.709*	0.291	−0.136	−0.155	0.418	−0.009
TOS (µmol/L)	−0.037	−0.036	0.437	0.309	0.050	0.827**	−0.091		−0.136	−0.091	0.282	−0.482	0.745**	0.733**	0.918**
PAB (HKU)	0.199	0.318	0.292	0.145	−0.037	−0.036	0.336	−0.136		0.445	−0.073	−0.091	−0.400	0.291	0.027
SOD (U/L)	0.707*	0.255	0.528	0.518	0.110	0.264	0.709*	−0.091	0.445		0.509	−0.336	−0.418	0.309	0.036
PON1 (U/L)	0.323	−0.082	0.387	0.509	0.238	0.382	0.291	0.282	−0.073	0.509		−0.464	0.173	0.264	0.300
TAS (µmol/L)	−0.065	0.400	−0.387	0.009	−0.783**	−0.545	−0.136	−0.482	−0.091	−0.336	−0.464		−0.055	−0.318	−0.673*
SHG (mmol/L)	−0.240	0.145	0.251	0.255	−0.307	0.418	−0.155	0.745**	−0.400	−0.418	0.173	−0.055		0.436	0.618**
Total proteins (g/L)	0.430	0.155	0.497	0.473	−0.174	0.755**	0.418	0.733**	0.291	0.309	0.264	−0.318	0.436		0.745**
OSI (AU)	−0.028	−0.100	0.501	0.136	0.293	0.827**	−0.009	0.918**	0.027	0.036	0.300	−0.673*	0.618*	0.745**
Fe (mg/L)	−0.092		0.661*	0.673*	−0.709*	−0.145	0.182	−0.036	0.381	0.255	−0.082	0.400	0.145	0.155	−0.100
Mg (mg/L)	−0.002	0.661*		0.720*	−0.103	0.410	0.264	0.437	0.292	0.528	0.387	−0.387	0.251	0.497	0.501
Zn (mg/L)	0.286	0.673*	0.720*		−0.517	0.245	0.418	0.309	0.145	0.518	0.509	0.009	0.255	0.473	0.136
Cu (mg/L)	−0.095	−0.709*	−0.103	−0.517		0.215	−0.174	0.050	−0.037	0.110	0.238	−0.783**	−0.307	−0.174	0.293