Table 1: Socio-demographic, anthropometric characteristics and life style of the participants. Results are shown as arithmetic mean, standard deviation and percentage [median].

	Category I (< 25 µg/dL) (n = 367)	Category II (> 25 - < 45 µg/dL) (n = 87)	Category III (> 45 µg/dL) (n = 26)
Age (years)	28.3 ± 8.3 [28.0]	21.0 ± 3.7* [21.0]	18.3 ± 2.5* [17.0]
Gender Female Male	311 84.7% 56 15.2%	58 66.6%* 29 33.3%	18 69.2%* 8 30.7%
BMI	27.2 ± 7.9 [27.0]	25.7 ± 7.5 [25.1]	24.9 ± 9.5 [25.5]
Years of residence	21.9 ± 11.5 [21.6]	19.0 ± 6.1* [19.0]	16.3 ± 5.5* [17.0]
Years of school	11.1 ± 3.33 [11.0]	11.4 ± 3.2 [11.0]	12.3 ± 2.7 [12.0]
Occupation Housewife Several^&	178 48.5% 189 51.5%	27 31.0%* 60 69.0%	5 19.2%* 21 81.8%
Years of work	5.4 ±10.0 [3.0]	10.8 ± 23.48 [2.0]	1.7 ± 0.44 [2.0]
Occupational exposure to chemical compounds^# Yes No	27 7.4% 340 92.6%	14 16.1%* 73 83.9%*	6 15.4% 22 84.6%
Smoking Yes No	94 25.6% 273 74.3%	23 26.4% 64 73.5%	7 26.9% 19 73.0%
Alcohol intake Yes No	198 53.9% 169 46.0%	48 55.1% 39 44.8%	14 53.8% 12 46.1%
History of renal diseases Yes No	101 27.6% 266 72.4%	20 23.0% 67 77.0%	6 23.1% 20 76.9%
History of bladder infection Yes No	55 14.9% 312 85.0%	11 12.6% 76 87.3%	6 23.0% 20 76.9%
History of bladder-renal co-infection Yes No	17 4.6% 349 95.3%	3 3.4% 84 96.5%	0 26 100.0%
History of regular analgesic intake® Yes No	196 53.4% 171 46.5%	39 44.8% 39 44.8%	16 61.5% 10 38.4%
History of drug abuse Yes No	7 1.9% 360 98.0%	1 1.1% 86 98.8%	0 26 100.0%
History of lupus Yes No	5 1.3% 362 98.6%	0 87 100.0%	0 26 100.0%
History of diabetes mellitus Yes No	21 5.7% 346 94.2%	4 4.6% 83 95.4%	0 26 100.0%

*p < 0.05 Student’s t test, or Mann-Whitney test or Chi² test (category I vs category II or III).

^&Office job 30%, self-employed 31.8%, trader 19.6% and student 18.5%.

^#Organic solvents, heavy metals, welding fumes, pesticides and fertilizers, oil derivate, dust, exhaust smoke, paint and aniline. ^® Paracetamol, ibuprofen, salicylates and naproxen were the analgesics exclusively used by participants.