Table 12. Difference of heavy metals content of the roasted coffee beans in sale areas

	No. of samples	Pb (mg/kg)	Cd (mg/kg)
		Mean ± S.D. (min. – max.)	Mean ± S.D. (min.– max.)
Wholesale store	18	0.055 ± 0.101 (0.000 – 0.393)	0.011 ± 0.008 (0.000 – 0.028)
Franchise coffee store	17	0.063 ± 0.050 (0.000 – 0.184)	0.007 ± 0.005 (0.002 – 0.017)
Market	20	0.085 ± 0.024 (0.004 – 0.121)	0.005 ± 0.002 (0.001 – 0.012)

Means within a vertical column are significantly different by Kruskal-Wallis test (p<0.05).