Health Orientation Value
|Health Orientation Value||
The HOV is a theshold value for substances present in drinking water which can either not be or only partially assessed from a human toxicological aspect. It is used by the German Commission for Drinking Water Safety ("Trinwasserkommission"). From a hygienic aspect values > 3 μg/l can be permanently tolerated without further testing if at least one chronically oral study is present, on the basis of which the contaminants are toxicologically (almost) completely appraisable and the assessment does not refer to a value below 3 μg/l. Indications of this type for tentatively hygienically tolerable concentrations of non or only partially appraisable substances in drinking water above the HOV = 0.1 μg/l should however only be approved on a case by case basis by the German Federal Environmental Agency at a national level. (https://www.umweltbundesamt.de/sites/default/files/medien/374/dokumente/gow-empfehlung_2003_46.pdf, https://www.umweltbundesamt.de/sites/default/files/medien/374/dokumente/kommentar_stoffe_im_tw_n_bewertbar.pdf)
The HOV value is measured in such a way that a later, complete human toxicological evaluation of a non-genotoxic material/material with effectiveness threshold and the majority of genotoxic materials/materials without an effectiveness threshold securely leads to a lifelong hygienically tolerable or acceptable hygienic guide value at the level of the guide value of the HOV. For the lesser number of "strongly" genotoxic substances which can enter drinking water, the restriction of the HOV to a maximum exposure time of 10 years is recommended.
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