Alternative to formaldehyde in fluid preservation of biological specimens.
22 alternatives were assessed as alternatives to formaldehyde in preserving biological specimens. DMDM-hydantoin was regarded as a suitable alternative. DMDM-hydantoin is also used in pharmaceutical and cosmetic products.
There is limited evidence of carcinogenic effect of formaldehyde and formaldehyde can cause sensitization by skin contact. Formaldehyde is in the database of hazardous substances according to SUBSPORT criteria. Ethanol is flammable. The proposed alternative DMDM-hydantoin is not classified and is not in the database of hazardous substances according to SUBSPORT criteria. It is a formaldehyde releasing substance allowed in pharmaceutical and cosmetic products.
Despite that new antiseptic mixtures are introduced in the pharmaceutical and cosmetic industry every year, fluid preservation of biological specimens are still based on formaldehyde and ethanol. Ethanol is highly flammable and formaldehyde is recognized as a highly toxic substance. The aim of the study was to determine the suitability of biocides used in the pharmaceutical and cosmetic industry to preserve biological specimens. The biocide was assessed according to six parameters: antiseptic range, water/fat solubility coefficient, pH range, stability/reactivity, toxicity and flammability. A biocide out of range of the preset parameters was not considered to be a suitable alternative. First the substances were assessed according to the technical parameters. The substances that passed these were assessed according to the safety parameters. 22 substances were reviewed according to this process: ethanol, isopropanol, formaldehyde, glutaraldehyde, soium benzoate, methylparaben, ethylparaben, propylparaben, butylparaben, chlorhexidine, triclosan, trichlorcarban, hexachlorophene, DMDM-hydantoin, chloroxyenol, silver nitrate, bronopol, phenol, phenoxetol, sodium propionate, benzalkonium chloride, potassium sorbate.
Only DMDM-hydantoin was considered to be a suitable alternative, although DMDM-hydantoin is a formaldehyde-releasing agent. A 55% solution contains 2% released free formaldehyde and 17-18.5 % bound formaldehyde. Only the free formaldehyde is volatile. In products such as shampoos and skin lotions it is regarded as safe in concentration of 1%.
Ethanol passed all technical parameters but was discarded because of the flammability.
The study concludes, that most biocides used in food, cosmetic and pharmaceutical products are not considered to be suitable for preservation of biological specimens. DMDM-hydantoin passes all 6 parameters. DMDM-hydantoin has never been used for this purpose and therefore its long term effect on the integrity of the specimens is not known.
Most of the 22 evaluated alternatives were not technical suitable. Formaldehyde is classified both concerning carcinogenic and sensitizing effect and therefore DMDM-hydantoin is a better alternative. Ethanol also performed well and could be taken into account where flammability is not a problem.
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Publication or last update: 23-05-2012