Potassium iodide

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The published literature fulfilled basically scientific principles.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1984

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Iodide (in KI) was fed to male and female rats before and during breeding, to females only during gestation and lactation, and to their offspring after weaning (day 21 after birth) through to day 90, at levels of 0, 0.025, 0.05 or 0.1% (w/w) of the diet. The screening test battery of Cincinnati Psychoteratogenicity for rats as the method for assessing the psychotoxic potential of potassium iodide was used to investigate the hazard effects to parents and developmental toxic effects to embryo and offspring in 90 days.

GLP compliance:

no

Remarks:

Publication

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

iodide in KI

IUPAC Name:

iodide in KI

Details on test material:

Food grade potassium iodide (Mallinckrodt Inc.) was purchased from the Tab Chemical Company, Chicago, IL.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

Dietary treatments were given continuously to both males and females for 14 days before mating and for l-14 days during breeding, and to females only during gestation (22 days) and lactation (21 days).

Duration of treatment / exposure:

Parents (males and females): 14 days before mating; l-14 days during breeding.

Female only (mother): during gestation (22 days) and lactation (21 days)

Offspring: given dietary potassium iodide, at the level their parents had received, throughout the remainder of the experiment (up to 90 days of age for most animals and somewhat longer for those in avoidance testing).

Frequency of treatment:

Dietary treatments were given continuously to both males and females for 14 days before mating and for l-14 days during breeding, and to females only during gestation (22 days) and lactation (21 days). After weaning, the offspring were given dietary potassium iodide, at the level their parents had received, throughout the remainder of the experiment (up to 90 days of age for most animals and somewhat longer for those in avoidance testing).

Duration of test:

Parents (males and females): 14 days before mating; l-14 days during breeding.

Female only (mother): during gestation (22 days) and lactation (21 days)

Offspring: given dietary potassium iodide, at the level their parents had received, throughout the remainder of the experiment (up to 90 days of age for most animals and somewhat longer for those in avoidance testing).

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
(two control groups) parents
Basis:
nominal in diet
0

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0.025% (w/w)
Basis:
nominal in diet
0.025% (w/w)

Doses / concentrations 3

Remarks:

Doses / Concentrations:
0.05% (w/w)
Basis:
nominal in diet
0.05% (w/w)

Doses / concentrations 4

Remarks:

Doses / Concentrations:
0.1% (w/w)
Basis:
nominal in diet
0.1% (w/w)

No. of animals per sex per dose:

no data

Control animals:

yes, concurrent no treatment

Results and discussion

Results: maternal animals

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

1 ppm

Based on:

test mat.

Remarks:

0.1 % in diet.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

1 ppm (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects. Remark: There was no evidence suggesting that potassium iodide was embryotoxic. Litter size was significantly reduced, but birth weights and external morphology among those born alive were not significantly altered.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The concentration up to 142 mg/kg bw of iodide, it just shows no effects to parental reproductivity and teratogenicity to embryo. There was only slight developmental toxicity to growing rats in 90 days, but these effects are not dose related.

Executive summary:

Potassium iodide (KI) was fed to male and female rats before and during breeding, to females only during gestation and lactation, and to their offspring after weaning (day 21 after birth) through to day 90, at levels of 0, 0.025, 0.05 or 0.1% (w/w) of the diet.

There was no evidence suggesting that potassium iodide was embryotoxic. Litter size was significantly reduced, but birth weights and external morphology among those born alive were not significantly altered.

No change in thyroid weight was observed indicating that these doses were not overtly thyrotoxic. Thyroid hormones were not assessed, however, and it is possible that thyroid function could have been altered in these animals. Nevertheless, the data are consistent with a picture of impaired thyroid function.
Several tests of post-weaning behaviour showed effects at the lowest dose, 0.025 % potassium iodide. M-maze errors were increased at this dose and rotorod performance decreased. However, because these effects were not found at the higher doses it appears unlikely that they were related to potassium iodide. At present, these effects can only described as 'false positives'.
The only effect on post-weaning behaviour that appeared to be consistently related to potassium iodide exposure was the reduction in nocturnal running-wheel activity found among the tested females. It may be that female cyclicity makes them more sensitive to the influence of chronic moderate iodide exposure than males and this could explain the contrast with the results of an acute test of activity and exploration, the open-field test, on which no consistent iodide-related effects were found.

Therefore it can be concluded that the iodide is not reproductive, embryonic toxicity, and developmental toxicity at dose of 0.1% in diet.