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Administrative data

Endpoint:
repeated dose toxicity: other route
Adequacy of study:
other information
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Taken from OECD SIDS on Sodium bicarbonate (2002), where a similar reliability was assigned. Unsuitable and not relevant test system. The study was perfomed to assess the buffer mechanisms of NaHCO3 in cattle, and was not intended to cause adverse effects. The use of cattle is not common in toxicity tests, and little is known about adverse effects of test substances in comparison to humans or other more widely used test animals like the rat.

Data source

Reference
Reference Type:
publication
Title:
Controlled ruminal diffusion of sodium bicarbonate. 3. Influence of infusion dose on systemic acid-base status, minerals, and ruminal milieu
Author:
Tucker, W.B., et al.
Year:
1993
Bibliographic source:
J.Dairy Sci., vol 76: 2222 -2234

Materials and methods

GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Sodium hydrogencarbonate
EC Number:
205-633-8
EC Name:
Sodium hydrogencarbonate
Cas Number:
144-55-8
Molecular formula:
CH2O3.Na
IUPAC Name:
sodium hydrogen carbonate
Details on test material:
SOURCE: Not reported.
PURITY: Not reported.
IMPURITY/ADDITIVE/ETC.:Not reported.
ANY OTHER INFORMATION: Not reported.

Test animals

Species:
cattle
Strain:
other: Holstein
Sex:
female
Details on test animals or test system and environmental conditions:
- Age: Pluriparious, age not specified.
- Weight at study initiation: Not reported.
- Number of animals: 4

Administration / exposure

Route of administration:
other: intraruminal
Duration of treatment / exposure:
no data
Frequency of treatment:
twice daily 2 to 4 hrs post feeding
Doses / concentrationsopen allclose all
Dose / conc.:
0 other: g/L
Dose / conc.:
29 other: g/L
Dose / conc.:
57.9 other: g/L
Dose / conc.:
86.8 other: g/L
Control animals:
yes

Results and discussion

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

LOAEL: 29 g/l.

The intention with the study was to examine the mechanisms by which the dietary buffers widely used in livestock production excert their effect. Specifically the influence of ruminal infusion of various amount of NaHCO
3 on ruminal and systemic acid-base status and mineral metabolism. Infusion of buffer increased ruminal fluid buffering capacity transiently at 4.5 hrs post-feeding but otherwise did not markedly affect ruminal acid-base status. Systemic acid-base status was unaffected by the buffer primarily because renal excretion of base succesfully
reduced systemic base load. Urine volume increased in response to NaHCO
3 infusion. Buffer infusion increased urinary excretion of Na, Mg, and K but decreased Ca excretion for 12 hrs post feeding; Cl excretion was not affected. Buffer infusion tended to increase total volatile fatty
acids in ruminal fluid. The authors' data indicate that homeostatic mechanisms can eliminate exogenous base via the kidneys; hence, acid-base
status was not perturbed by infusion of NaHCO
3. The authors further claim that increased excretion of Mg and K with buffer infusion indicates that the dietary requirements for these minerals may be increased by NaHCO3. The diuresis accompanying large doses of NaHCO3 may increase dietary requirements for some minerals. There was little effects on milk production or composition.

Applicant's summary and conclusion

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