Table 8.

Comparative between concentration levels of Pb, Cd and As in henna and walnut tree bark samples.

Element	Concentration of Heavy Metal (µg·g−1)		F Value	p Value
	Henna Sample	Walnut Tree Bark Sample
	Mean ± SD	Mean ± SD
Pb	15.13 ± 11.51	23.16 ± 8.89	18.37	0.001
Cd	6.30 ± 3.59	10.18 ± 4.35	2.233	0.000
As	0.68 ± 0.33	1.17 ± 0.75	47.80	0.002

SD = Standard deviation.