Human environmental and occupational exposures to boric acid: reconciliation with experimental reproductive toxicity data.
The reproductive toxicity of boric acid and borates is a matter of current regulatory concern. Based on experimental studies in rats, no-observed-adverse-effect levels (NOAELs) were found to be 17.5 mg boron (B)/kg body weight (b.w.) for male fertility and 9.6 mg B/kg b.w. for developmental toxicity. Recently, occupational human field studies in highly exposed cohorts were reported from China and Turkey, with both studies showing negative results regarding male reproduction. A comparison of the conditions of these studies with the experimental NOAEL conditions are based on reported B blood levels, which is clearly superior to a scaling according to estimated B exposures. A comparison of estimated daily B exposure levels and measured B blood levels confirms the preference of biomonitoring data for a comparison of human field studies. In general, it appears that high environmental exposures to B are lower than possible high occupational exposures. The comparison reveals no contradiction between human and experimental reproductive toxicity data. It clearly appears that human B exposures, even in the highest exposed cohorts, are too low to reach the blood (and target tissue) concentrations that would be required to exert adverse effects on reproductive functions.
Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany. bolt@ifado.de
Hermann M
HM
Bolt
Nurşen
N
Başaran
Yalçın
Y
Duydu
D000818:Animals; D001888:Boric Acids / Q000009:adverse effects* / Q000633:toxicity*; D001895:Boron / Q000032:analysis; D002681:China; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005298:Fertility / Q000187:drug effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D051379:Mice; D019055:No-Observed-Adverse-Effect Level; D016273:Occupational Exposure / Q000009:adverse effects*; D010599:Pharmacokinetics; D051381:Rats; D012098:Reproduction / Q000187:drug effects*; D014421:Turkey
D001888:Boric Acids; D001895:Boron; C032688:boric acid