scope:

Introduction

The presented Maximum Immission Values (MI-Values) serve to protect farm animals kept in stables, on pastures, and in grazing padlocks from any impairment by fluorides which would lower their value.

The MI-Values derive from long-term experiments in which dose-effect relationships for farm animals were determined [1 to 3]. However, MI-Values are presented only for those animal species which are imperiled as herbivores kept and fed under customary conditions. Because of their high forage consumption and long years of milk production, cows are particularly vulnerable [4 to 6] while beef cattle, sheep, and goats tolerate higher fluoride concentrations in the fodder. For horses and wild ruminants roaming freely or kept in padlocks no tolerable values can be presented at the time.

The effects are defined as impairment of functions which, upon long-term intake of fluoride, lead to disease and lower product yield. Combined effects are not taken into account. The earliest signs of longterm fluoride intake are tooth development problems indicated by brown spots on the permanent teeth which are due to defects in the dental enamel [13; 14]. In addition, higher than normal fluoride concentrations are stored in the bones with increasing age [15]. None of these two changes have disease status or affect product yield.

The transition between an increased but non-hazardous and an increased hazardous and production lowering fluoride intake is continual and may be additionally influenced by numerous factors (age, kind of breed, feeding and lodging conditions etc.) [16 to 18].

The MI-Values are valid for farm animals kept and fed under conditions customary in animal husbandry. An insufficient supply of minerals (primarily calcium and phosphate) or trace elements (mainly copper) may raise the responsiveness of animals towards fluorides [19; 20].