. 2021 Jan 4;18(1):317. doi: 10.3390/ijerph18010317

Table 2.

Fluoride concentration in toenails.

Author	n	M	F	Age (yrs)	Design	Fluoride Exposure ± SD	Mean F^– ± SD (µg/g)	p-Value
Buzalaf et al. (2006)	10	NS	NS	20–35	Longitudinal	a 0.6 b, c 1.626 ± 0.774	1.53	<0.05
Buzalaf et al. (2011)	121	NS	NS	4–6	Cross-sectional	d 0.6–0.8 b, c 0.065 ± 0.03	1.42 ± 0.54	<0.001
						d 0.6–0.9 b, c 0.084 ± 0.029	2.24 ± 0.82
						b, c, e 0.088 ± 0.044	6.70 ± 3.03
						f 250/1.0 b, c 0.088 ± 0.052	2.63 ± 0.58
						b, c 0.027 ± 0.022	1.62 ± 0.47
Carvalhoa et al. (2017)	242	107	135	4–6	Cross-sectional	d 0.6–0.8	1.61 ± 1.06	>0.05
						g	DF = 1.65 ± 1.08 no DF = 1.58 ± 1.06
						h	DF = 1.90 ± 1.30 no DF = 1.59 ± 1.04
						c 1571	DF = 1.87 ± 1.37 no DF = 1.55 ± 0.96
						i	DF = 1.55 ± 1.17 no DF = 1.63 ± 0.96
Charone et al. (2012)	54	NS	NS	3–14	Cross-sectional	d	1.85 ± 1.32 1.58 ± 0.78	0.38
Corrêa-Rodrigues et al. (2004)	10	NS	NS	2–3	Longitudinal	d 0.6–0.8 c 1571	2.70 ± 1.17 (for the first 4 weeks and the last 6 weeks)	<0.01
Elekdag-Turk et al. (2019)	42	22	20	NS	Cross-sectional	d ≥ 2.0 d ≤ 0.05	2.34 ± 0.26 0.98 ± 0.08	<0.001
Fukushima et al. (2009)	300	NS	NS	3–7 14–20 30–40 50–60	Longitudinal	d 0.09 ± 0.01, c *	1.14 ± 0.07	<0.001
						d 0.15 ± 0.01, c *	2.27 ± 0.13
						d 0.66 ± 0.01, c *	1.98 ± 0.12
						d 0.72 ± 0.02, c *	4.46 ± 0.32
						d 1.68 ± 0.08, c *	5.94 ± 0.35
						Mean	3.16 ± 0.14
Idowu et al. (2020)	61	NS	NS	4–5	Cross-sectional	d 0.04	3.378 ± 2.19	<0.001
Idowu et al. (2020)	61	NS	NS	4–5	Cross-sectional	d 3.05	10.371 ± 3.90	<0.001
Sankhala et al. (2014)	40	23	17	41–60	Cross-sectional	d 4.1	82.38 ± 6.89	0.001
						d 4.8	86.14 ± 9.77
						d 5.6	103.92 ± 16.89
de Sousa et al. (2018)	30	NS	NS	2–6	Longitudinal	d, j 0.181 ± 0.132	2.85 ± 1.35	<0.05
						d 0.03 ± 0.04	1.46 ± 0.27
						j 0.057 ± 0.045	1.46 ± 0.27

M: Male. F: Female. F-: Fluorine. yrs: Years old. SD: Standard deviation. NS: Not specified; DF: Dental fluorosis. a: Fluoridated solution NaF (mg/mL); b: Diet (mg/kg); c: Dentifrice (mg/kg); d: Naturally fluoridated water (mg/L); e: Fluoridated salt; f: Fluoridated milk (ml/mg/L); g: Soy; h: No milk consumption; i: Supervised tooth brushing; j: Total daily fluoride intake (mg/kg/day). * 1500 mg/kg.