A longitudinal study of environmental tobacco smoke exposure in children: Parental self reports versus age dependent biomarkers

Table 2 Reported parental smoking habit and cotinine levels in children's urine (ng/mL) at 4 years

Parental smoking status	Urinary cotinine at 4 year (ng/mL)
	N	Median	Mean (SD)	Range	p-value
At 4 year:
No smoker	94	4.60	6.50 (6.68)	0.20 – 36.00	-
Only father	64	6.45	10.57 (11.23)	1.10 – 57.40	0.004
Only mother	52	16.30	27.78 (30.58)	2.60 – 170.20	<0.001
Both mother and father	96	19.60	33.06 (41.47)	2.10 – 300.90	<0.001

ISSN: 1471-2458