Sodium metaphosphate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: The study does not meet some study design and analytical criteria

Principles of method if other than guideline:

Sodium hexametaphosphate (HEX), the solvent of calcium alginate wool used in swabbing inanimate surfaces was studied relative to its effect on various bacterial populations, both pure cultures and wild.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

not specified

Test organisms (species):

activated sludge

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

24 h

Details on results:

It was found that bacteria in wild populations were greatly inhibited, and that a percentage reduction of count was directly related to concentration of HEX.

Most gram-positive bacteria were prevented from growing on a medium containing 0.1 % HEX. This, or a higher concentration, occurred in the final medium when the method
recommended in Standard Methods for the Examination of Dairy Products was followed. Growth of Sarcina lutea occurred on media with higher concentrations than that of
inhibition (0.05 %), if MgSO4 7H20 was incorporated in the medium. Gram-negative bacteria were capable of growing in higher concentrations, even up to 10 % HEX.

A large percentage of the cells of some strains (represented by Pseudomonas fluorescens) were lysed on contact with HEX. Lysis could be prevented by the addition of NaCl or MgSO4-7H20. The evidence presented suggests that HEX, a phosphate-glass water-softening sequestrant, interferes with divalent cation metabolism, notably magnesium ion, and possibly others, producing cell division inhibition and loss of cell-wall integrity.

Validity criteria fulfilled:

not applicable

Conclusions:

It was found that bacteria in wild populations were greatly inhibited, and that a percentage reduction of count was directly related to concentration of HEX.

Most gram-positive bacteria were prevented from growing on a medium containing 0.1 % HEX. This, or a higher concentration, occurred in the final medium when the method
recommended in Standard Methods for the Examination of Dairy Products was followed. Growth of Sarcina lutea occurred on media with higher concentrations than that of
inhibition (0.05 %), if MgSO4 7H20 was incorporated in the medium. Gram-negative bacteria were capable of growing in higher concentrations, even up to 10 % HEX.

A large percentage of the cells of some strains (represented by Pseudomonas fluorescens) were lysed on contact with HEX. Lysis could be prevented by the addition of NaCl
or MgSO4-7H20. The evidence presented suggests that HEX, a phosphate-glass water-softening sequestrant, interferes with divalent cation metabolism, notably magnesium ion, and possibly others, producing cell division inhibition and loss of cell-wall integrity.

Executive summary:

The result of the study is that it was found that bacteria in wild populations were greatly inhibited, and that a percentage reduction of count was directly related to concentration of Sodium hexametaphosphate (HEX).

Most gram-positive bacteria were prevented from growing on a medium containing 0.1 % Sodium hexametaphosphate (HEX). This, or a higher concentration, occurred in the final medium when the method recommended in Standard Methods for the Examination of Dairy Products was followed. Growth of Sarcina lutea occurred on media with higher concentrations than that of inhibition (0.05 %), if MgSO4 7H20 was incorporated in the medium. Gram-negative bacteria were capable of growing in higher concentrations, even up to 10 % Sodium hexametaphosphate (HEX).

A large percentage of the cells of some strains (represented by Pseudomonas fluorescens) were lysed on contact with HEX. Lysis could be prevented by the addition of NaCl or MgSO4 7H20. The evidence presented suggests that HEX, a phosphate-glass water-softening sequestrant, interferes with divalent cation metabolism, notably magnesium ion, and possibly others, producing cell division inhibition and loss of cell-wall integrity.

Description of key information

Supporting Study:

The result of the study is that it was found that bacteria in wild populations were greatly inhibited, and that a percentage reduction of count was directly related to concentration of Sodium hexametaphosphate.

Most gram-positive bacteria were prevented from growing on a medium containing 0.1 % Sodium hexametaphosphate (HEX). This, or a higher concentration, occurred in the final medium when the method recommended inStandard Methods for the Examination of Dairy Productswas followed. Growth of Sarcina lutea occurred on media with higher concentrations than that of inhibition (0.05 %), if MgSO4 7H20 was incorporated in the medium. Gram-negative bacteria were capable of growing in higher concentrations, even up to 10 % Sodium hexametaphosphate.