FAQ (Frequently Asked Questions)


Reference Value: calculated daily maximum safe exposure levels via food and water based on lifetime intake without significant adverse health effects

Background Value: The amount of the metal consumed daily from food and water

Available for Tool: The difference between reference value and background value

Why is there a negative value under "Available for HMS tool" (For Lead Only)? A negative value will appear under the “Available for HMS tool” when the total background-exposure level of a metal exceeds the safe reference value. This suggests further risk analysis should be conducted with extra precaution.
Lead at Superfund Sites: Software and Users' Manuals

In the previous version of the Metal Dietary Exposure Screening Tool, trivalent chromium and hexavalent chromium were present. Why are they not included in this version of the tool? While chromium (trivalent and hexavalent) is a heavy metal that can potentially be found in food or water, it was not considered a significant public health concern in foods due to relatively low occurrence and exposure. The FDA is currently more concerned with heavy metals such as lead, arsenic, cadmium, and mercury because of their toxicity and level of exposure, particularly to susceptible populations such as children.

Default Values for the Tool

Heavy Metal/Metalloid Default Reference Value Background Value
Arsenic0.3 ug/kg/day
(EPA 1991) Inorganic As
0.18 ug/kg/day
[0.02 ug/kg/day + 0.16 ug/kg/day]
(Xue 2010, Adults) + (EPA 2001 MCL)
Inorganic As
Cadmium1 ug/kg/day
EPA 1989
0.26 ug/kg/day
[0.18 ug/kg/day + 0.08 ug/kg/day]
(JECFA 2013, Adults) + (EPA 2016 MCL)
Lead0.26 ug/kg/day
Young Children (0-6 years old), FDA 2018
0.24 ug/kg/day
[0.11 ug/kg/day + 0.13 ug/kg/day]
(Spungen 2019) + (Median Levels from Water Quality Reports)
Lead0.16 ug/kg/day
Older Children and Adult, FDA 2018
0.11 ug/kg/day
[0.03 ug/kg/day + 0.075 ug/kg/day]
(JECFA 2011, Adults) + (Median Levels from Water Quality Reports)
Mercury0.1 ug/kg/day
(EPA 2001), MeHg
0.05 ug/kg/day
[0.02 ug/kg/day + 0.03 ug/kg/day]
(Xue 2012, Adult MeHg) + (EPA 2016, inorganic Hg)