Acute and subacute oral toxicity of periodate salts in rats.

Periodate salts are being developed as potential replacements for perchlorate due to potential health hazards associated with exposure to perchlorate. The aim of this study was to investigate acute and subacute effects of periodate salts in rats. Acute oral toxicity of potassium and sodium periodate was determined using the Sequential Stage-Wise Probit method. The LD50 for potassium periodate was 732 (95% CI = 539-838, slope = 13.4) and 685 mg/kg (95% CI = 580-809, slope = 10.6) for females and males, respectively. The LD50 for sodium periodate was 318 (95% CI = 292-347, slope = 24.3) and 741 mg/kg (95% CI = 704-779, slope = 31.2) for females and males, respectively. In the subacute study, rats were administered sodium periodate at five doses (1/16 LD50 up to LD50) or distilled water for 14-days via oral gavage. Female rats in the 318 mg/kg-day group and male rats in the 185, 370, and 741 mg/kg-day groups exhibited moribundity, kidney toxicity, uremia, and a stress response. BMDL10s of 17.2 and 33.7 mg/kg-day were derived for females and males, respectively. Comparison with the NOAEL for perchlorate-induced thyroid toxicity in rats (0.009 mg/kg-day) suggests sodium periodate is less toxic than perchlorate on a subacute basis.

Iodine supplementation of laying hen feed: a supplementary measure to eliminate iodine deficiency in humans?

Iodine deficiency still exists in many countries worldwide, to a certain degree this is also true for Germany. Food of animal origin can be a good source for iodine depending on the feed. To investigate the possible use of laying hen feed enriched with iodine, we conducted a feeding experiment with 40 laying hens receiving feed with different amounts of iodine either as KIO3 or in the form of seaweed. Iodine concentration in eggs increased significantly depending on iodine intake after a 2 week period. Seaweed could also be used as an iodine source by the hens. A subsequent consumption study with 24 volunteers showed that eggs enriched with iodine can increase human's iodine excretion and therefore improve human's iodine supply. This new strategy is thought to accompany salt iodization programs, not to replace them.

In vivo modulation of macrophage tumoricidal activity: enhanced tumor cell killing by peritoneal macrophages from mice given injections of sodium periodate.

Sodium periodate (NaIO4) administered ip to mice was nontoxic and enhanced the in vitro tumoricidal activity of their peritoneal macrophages. The injection ip of 1 ml of 5 mM NaIO4 caused an influx of polymorphonuclear leukocytes (PMN) at 5-24 hours followed by an accumulation of macrophages and disappearance of the PMN at 48-72 hours. These peritoneal macrophages from mice given injections of NaIO4 were noncytotoxic and nontumoricidal in the absence of lipopolysaccharide (LPS), but in the presence of 5-25 ng/ml or more LPS in vitro, they became markedly cytotoxic and cytocidal for tumor cells. Peritoneal macrophages from mice given injections of phosphate-buffered saline became cytotoxic or cytocidal only with amounts of LPS exceeding 100-500 ng/ml in vitro. Like the peritoneal macrophages from BCG-infected mice that demonstrated selective tumor cytotoxicity, macrophages from mice given injections of NaIO4 had minimal lytic activity for nontransformed normal embryo fibroblasts. Thus when given ip to mice, the simple chemical NaIO4, much like complex and heterogeneous biologic preparations such as BCG, caused differentiation of peritoneal macrophages toward the tumoricidal state.