Supplemental Material

Associations of cadmium, mercury and lead in kidney cortex and serum ferritin with urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG)in living kidney donors

Journal: International Archives of Occupational and Environmental Health

Mohammad Bakhtiar Hossain1,2,*, Lars Barregard, Gerd Sallsten, Karin Broberg

1Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, LundUniversity, Lund, SE-22185 Sweden

2International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Dhaka, Bangladesh

* Corresponding author: Mohammad Bakhtiar Hossain, Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, LundUniversity, SE-22185 Lund, Sweden. Telephone: +46 (0) 46 173148. Fax: +46 (0) 46 143201. E-mail: .

Supplemental Table 1. Spearman’s rank correlations for metals in kidney, urinary 8-oxodG concentration and excretion rates, age, body weight, body mass index (BMI), smoking, and serum ferritna

K HgK PbU24 8-oxodG UON 8-oxodGU24 8-oxodG UON 8-oxodGAgeBody weight BMISmokingS Ferritin concentration concentration excretion rate excretion rate

Kidney cadmium0.20*0.11-0.18-0.14-0.23*-0.24*0.29**-0.29**-0.20*0.26**-0.19

(109) (109)(95)(106)(93)(106)(109)(107)(107)(109)(108)

Kidney mercury-0.90-0.13-0.069-0.19-0.20-0.021-0.11-0.060-0.075-0.12

(109)(95)(106)(93)(106)(109)(107)(107)(109)(108)

Kidney lead0.130.100.0270.066-0.0570.038-0.0180.0300.062

(95)(106)(93)(106)(109)(107)(107)(109)(108)

U24 8-oxodG concentrationb0.80**0.60**0.48**0.150.24**0.0500.0170.43**

(126)(127)(126)(130)(128)(128)(129)(129)

UON 8-oxodG concentrationb0.61**0.58**0.110.130.0140.0750.37**

(123)(141)(141)(138)(138)(140)(140)

U24 8-oxodG excretion rate 0.78**0.0600.42**0.140.20*0.55**

(122)(126)(124)(124)(125)(125)

UON 8-oxodG excretion rate0.110.34**0.140.0910.51

(141)(138)(138)(140)(140)

Age-0.0100.0076-0.0390.32**

(149)(149)(151)(151)

Body weight0.78**-0.0430.41**

(149)(148)(148)

Body mass index-0.0510.20*

(148)(148)

Smoking0.015 (150)

a*p<0.05; **p<0.01; number of subjects in each correlation are given in brackets. Abbreviations: U24, 24 hour urine sample; UON, overnight urine sample.

bAdjusted for specific gravity of urine (1.015 g/ml).

Supplementary Table 2: Linear regression analyses between 8-oxodG concentration (adjusted to specific gravity) and elements in kidney, iron status, and other covariates

PredictorUnivariate analysesa

U24UON

Nβb (95% CI)p-valueNβ (95% CI)p-value

Kidney Cd (µg/g)95-0.068 (-0.21 to 0.076)0.35106-0.072 (-0.23 to 0.080)0.35

Kidney Hg (µg/g)c88-0.47 (-1.74 to 0.79)0.4698-0.23 (-1.52 to 1.06)0.72

Kidney-Pb (µg/g)c940.95 (-0.63 to 2.53)0.241050.83 (-0.78 to 2.43)0.31

Serum ferritin (µg/L)1290.048 (0.032 to 0.065)<0.00011400.047 (0.026 to 0.067)<0.0001

Age (years)1300.095 (-0.010 to 0.20)0.0761410.082 (-0.040 to 0.20)0.19

Gender130-3.34 (-5.47 to -1.21)0.0024141-2.09 (-4.55 to 0.36)0.094

Body weight (kg)1280.13 (0.050 to 0.22)0.00191380.067 (-0.030 to 0.16)0.18

BMI (kg/m2)1280.22 (-0.15 to 0.58)0.241380.083 (-0.32 to 0.49)0.68

Smokingd1290.56 (-2.00 to 3.13)0.671400.58 (-2.31 to 3.47)0.69

aUnivariate analyses: 8-oxodG concentration (nmol/L)= α1 + β1 X element/covariate. U24=24h urine sample, UON=overnight urine sample

bβ= unstandardized regression coefficient

cNatural log-transformed

dcurrent yes/no

Supplementary Table 3: Linear regression analyses between 8-oxodG excretion rates (nmol/hr) (natural log transformed) and elements in kidney, iron status, and other covariates

PredictorUnivariate analysesa

U24UON

Nβb (95% CI)p-valueNβ (95% CI)p-value

Kidney Cd (µg/g)92-0.0059 (-0.015 to 0.0036)0.22106-0.0061 (-0.014 to 0.0020)0.14

Kidney Hg (µg/g)c85-0.047 (-0.13 to 0.034)0.2598-0.058 (-0.12 to 0.0063)0.077

Kidney-Pb (µg/g)c910.020 (-0.088 to 0.13)0.721050.021 (-0.065 to 0.11)0.62

Serum ferritin (µg/L)1250.0038 (0.0026 to 0.0050)<0.00011400.0032 (0.0020 to 0.0044)<0.0001

Age (years)1260.0027 (-0.0051 to 0.011)0.491410.0053 (-0.0019 to 0.012)0.15

Gender126-0.43 (-0.58 to -0.29)<0.0001141-0.41 (-0.54 to -0.28)<0.0001

Body weight (kg)1240.015 (0.0092 to 0.021)<0.00011380.013 (0.0077 to 0.018)<0.0001

BMI (kg/m2)1240.027 (0.00040 to 0.054)0.0471380.028 (0.0047 to 0.051)0.019

Smokingd1250.26 (0.065 to 0.45)0.00901400.075 (-0.10 to 0.25)0.40

aUnivariate analyses: 8-oxodG excretion rate (nmol/hr) (natural log transformed) = α1 + β1 X element/covariate.

bβ= unstandardized regression coefficient

cNatural log-transformed

dcurrent yes/no

Supplementary Table 4: Gender specific multivariable regression analysis of the relationship between 24 h urinary 8-oxodG excretion rate (nmol/hr) (natural log transformed) and elements in kidney, considering body weight and serum ferritina

MaleFemale

Nβb (95% CI)p-valueNβ (95% CI)p-value

Model 1

Kidney Cd (µg/g) 410.0021 (-0.011 to 0.015)0.7449-0.0018 (-0.013 to 0.010)0.75

Body weight (kg)410.011 (0.0025 to 0.020)0.013490.0026 (-0.011 to 0.016)0.70

Serum ferritin (µg/L)410.0012 (-0.00040 to 0.0027)0.14490.0059 (0.0028 to 0.0090)0.00041

Model 2

Kidney Hg (µg/g)c39-0.047 (-0.15 to 0.060)0.3844-0.030 (-0.12 to 0.059)0.50

Body weight (kg)390.010 (0.0014 to 0.018)0.024440.0049 (-0.0085 to 0.018)0.47

Serum ferritin (µg/L)390.0013 (-0.00031 to 0.0029)0.11440.0056 (0.0026 to 0.0087)0.00064

Model 3

Kidney Pb (µg/g)c410.047 (-0.10 to 0.20)0.53480.012 (-0.11 to 0.13)0.84

Body weight (kg)410.011 (0.0026 to 0.019)0.011480.0025 (-0.011 to 0.016)0.71

Serum ferritin (µg/L)410.00096 (-0.00067 to 0.0026)0.24480.0057 (0.0027 to 0.0088)0.00048

aModels 1 (Cd)/2 (Hg)/3 (Pb): 8-oxodG concentration (nmol/L)= α1 + β1 X Kidney element (µg/g) + β2 X gender + β3 X body weight + β4 X serum ferritin.

bβ= unstandardized regression coefficient

cNatural log-transformed

Supplementary Fig. 1: Scatterplot of the association of 8-oxodG levels in 24-hr and overnight urine samples ( = 0.80, p = 2.84E-29). The values were adjusted for specific gravity of urine (1.015 g/ml).