„Agencija za zaštitu okoliša
Development of the Croatian soil monitoring programme with a pilot project
...
Threshold values of heavy metal levels in soil are defined by the Rulebook on Soil Protection from Contamination by Harmful Substances (Official Gazette 15/1992) and are given in Table 4.“
( www.azo.hr/lgs.axd?t=16&id=2072 )


TheFreeDictionary :
The Threshold Limit Value (TLV) of a chemical substance defines the reasonable level to which a worker can be exposed without adverse health effects. Strictly speaking, TLV is a reserved term of the American Conference of Governmental Industrial Hygienists (ACGIH). It is however sometimes loosely used to refer to other similar concepts used in occupational health and toxicology. TLVs (along with biological exposure indices or BEIs) are published annually by the ACGIH.
( http://encyclopedia.thefreedictionary.com/Threshold Limit Va... )


D. Pešić et al, Rečnik ekologije i zaštite životne sredine:
threshold value - granična vrednost
threshold level - nivo praga
threshold limit value - granična vrednost praga