Arsenic modifies the effect of folic acid in spina bifida prevention, a large hospital-based case-control study in Bangladesh

Table 2 Arsenic concentrations in toenails and drinking water

	Mean (SD)	Median	IQR	Min	Max
*Mother’s toenail arsenic concentration (µg/g)*
Cases (n = 294)	1.04 (1.58)	0.45	0.28–1.05	0.07	13.77
Controls (n = 163)	1.13 (1.94)	0.47	0.30–0.96	0.09	12.30
*Water arsenic concentration (µg/L)*
Cases (n = 166)	15.35 (37.28)	2.00	1.00–7.00	0.71	255.00
Controls (n = 161)	20.91 (56.08)	2.00	0.71-7.00	0.71	451.00

a. Water arsenic concentrations were below the LOD (1 µg/L) for 41 cases and 52 controls. Arsenic was detected in all toenail samples, and the LOD for toenail arsenic was 0.01 ng/g for first 338 samples tested and 0.1 ng/g for remaining samples
b. Water samples were not available for participants enrolled during the COVID-19 pandemic due to travel restrictions in Bangladesh.
Abbreviations: IQR, interquartile range; LOD, limit of detection; SD, standard deviation.

ISSN: 1476-069X