Glyoxal Acid-Free (GAF)

Glyoxal Acid-Free (GAF)


Our project proposes the replacement of Formalin with GAF, a non-toxic and non-cancerogenic fixative solution, with equivalent (if not better) histological efficacy, responding to the need to protect the health of workers involved and, at the same time, the health of patients.

Gliossale Acid Free


fissativo istologico a base di gliossale

Furthermore, the project is aimed at protecting the environment by reducing the use and disposal of a toxic product such as Formaldehyde. In fact, Formaldehyde’s carcinogenic and toxic vapours absorbed by the hoods are partially released into air, while the disposal of liquid Formalin is complex and expensive. It is desirable that the amount of toxic waste released in the environment, although somehow controlled, be strongly reduced.

Therefore, the replacement of Formalin is recommended for both environmental and health reasons. Furthermore, they are now normatively mandated by EU legislation. Glyoxal (a di-aldehyde similar to Formaldehyde) is not volatile nor toxic. When deprived of troublesome acids, Glyoxal Acid-Free (GAF) represents a safe histological fixative and a Formalin alternative, providing results as good (or even better) than Formalin. This has been proved by histological, immuno-histochemical and molecular analyses.


GAF Safety Datasheet

GAF Technical Datasheet


Tissue fixation, leading to preservation of structural components by fixation and permeabilization of cells and tissues, plays a critical role in histopathological diagnosis.

The fixative of choice is still represented by Formalin (a water solution of Formaldehyde).

This reagent is toxic and cancerogenic, but is still used worldwide in the lack of alternative fixative solutions guaranteeing similar results.

fissazione medicina
istologia dei tessuti

GAF (Glyoxal, acid free) fixative solution is an innovative reagent that allows optimal tissue fixation at the structural and molecular level, combined with the absence of toxicity and carcinogenic activity.

The validation of GAF fixative, as compared to Formalin, was conducted on parallel samples, obtained with core needles or punch devices from surgical specimens and fixed alternatively in Formalin and in GAF.

The first Validation trial was conducted in December 2017 at the San Giovanni Battista Hospital of Turin.


Glyoxal solution in Endoscopic Biopsies Project (Prot. N. 111243 of 6.11.17). COMPLETED

The clinical Trial performed at the Molinette Hospital (Turin) was aimed to validate the histopathological use of GAF as a fixative solution for small endoscopic biopsies (300 biopsies).

Results: The team involved in the validation study expressed a highly favourable opinion regarding both the sampling in endoscopy and the histo-pathological diagnostic aspects, without finding any problems or negative features involving the routinely use of the GAF fixative.

Performance evaluation of Glyoxal Acid Free (GAF) used as histological fixative in comparison with Formalin. An open label, comparative non inferiority study. COMPLETED

A controlled trial (CRO: 1MED, Lugano, CH), carried out in three European Countries (Italy, Spain and UK), evaluated the overall values and merits of GAF as a fixative solution compared to Formalin. The study based on a large number of small oncological biopsies. Samples from large surgical specimens have been randomly labelled, fixed in parallel in GAF or in Formalin, and processed for the routinely diagnostic tests. The slides have been scanned and scored in parallel by a central reviewer in blind. The results of the tests carried out acted as a European-level technical validation of our GAF product.

GAF Trial on Kidney Biopsies. ONGOING

The study will determine if GAF fixative can serve as a combined transport medium and fixative solution for kidney core biopsies examined with all types of microscopy (light microscopy, immunofluorescence and electron microscopy), and is currently performed at the Albert Einstein College of Medicine, Montefiore Medical Center, NY.

Evaluation of GAF for veterinarian application. ONGOING

The trial is aimed at studying the efficacy of GAF for veterinarian use (on oncological and non-oncological surgical specimens), and is current ongoing in collaboration with the University of Padova and Perugia.


Validation of GAF fixative, as compared to Formalin, is conducted through national and international Trials evaluating results of parallel samples, obtained from surgical specimens, fixed alternatively in Formalin and in GAF. The first Validation trial was conducted at the San Giovanni Battista Hospital of Turin, Italy. The results confirmed the feasibility and validity of GAF fixation as alternative to Formalin fixation.

Representative slides (10 cases in parallel, fixed either in Formalin or in GAF) of this first Trial are shown below.

n. 24230/17 Formalin Fixation – A | CASE 1

n. 24230/17 GAF – B | CASE 2

n. 24748/17 Formalin Fixation – B | CASE 3

n. 24748/17 GAF – A | CASE 4

n. 24837/17 Formalin Fixation – A | CASE 5

n. 24837/17 GAF – B | CASE 6

n. 25462/17 Formalin Fixation - A | CASE 7

n. 25462/17 GAF – B | CASE 8

n. 25921/17 Formalin Fixation – A | CASE 9

n. 25921/17 GAF – B | CASE 10

n. 25936/17 Formalin Fixation – B | CASE 11

n. 25936/17 GAF – A | CASE 12

n. 26021/17 Formalin Fixation – B | CASE 13

n. 26021/17 GAF – A | CASE 14

n. 26315/17 Formalin Fixation – A | CASE 15

n. 26315/17 GAF – B | CASE 16

n. 26422/17 Formalin Fixation – B | CASE 17

n. 26422/17 GAF – A | CASE 18

n. 27004/17 Formalin Fixation – B | CASE 19

n. 27004/17 GAF – A | CASE 20


The research and technology transfer activity was conducted within the University of Turin, and has been the subject of a publication in a peer reviewed paper (Plos One 12: e0182965; 2017).

validazione fissativo istologico


In recent years, the high toxicity and carcinogenicity of Formaldehyde has been increasingly recognized worldwide from both a scientific and regulatory point of view. The numerous examples of this recognition, and the following normative restriction on the use of Formaldehyde, include: in the United States (at the federal level) – the Formaldehyde Emission Standards for Composite Wood Products, the Toxic Substances Control Act, the Resource Conservation and Recovery Act, the Clean Water Act, and the Clean Air Act; in Canada – the Canadian Environmental Protection Act, and the Hazardous Products Act; in Brazil – the Resolução nº 37 of 03/06/2008. Value limits to airborne concentration of Formaldehyde were also introduced, inter alia, in China and Japan.
In the European Union, Directive n.37/2004, Regulation n. 605/2014 and Regulation n. 895/2104 recognized Formaldehyde as a carcinogenic substance and severely restricted its use, production and commercialization from August 2017. More recently, the European Parliament Resolution of 27 March 2019 recommended the Member States to minimize exposure to Formaldehyde, and the EU Directive 983/2019 stressed Formaldehyde’s classification as a carcinogenic substance and recognized its nature as a contact allergen for the skin.
EU Directive 983/2019 also recognized that, due to its high degree of diagnostic accuracy, Formaldehyde is still routinely used in the healthcare sector across the Union. Indeed – at present, and not considering GAF – there is no valid (i.e., accepted by the scientific community) alternative to Formaldehyde to preserve cell or tissue specimen. For the health sector, Directive 983/2019 also introduced a transitional period of five years during which the allowed limit value of Formaldehyde in the workplace (airborne concentration) is increased.
However, it should be stressed that normatively (at least in the EU) there is still a legal obligation to seek for alternatives to Formalin. From a legal point of view, we are currently in a “transitional arrangement” phase, in which the use of Formaldehyde is tolerated, and subject to derogative authorization, only by virtue of the absence of valid substitutes. Formaldehyde is used in the impossibility of a primary prevention: i.e., the elimination of risks with the use of different substances. 
As a consequence, in particular in the healthcare system, thousands of workers (e.g., nurses, technicians, doctors, pathologists) are still exposed to Formaldehyde. Until now, the balancing point between the diagnostic (i.e., patient’s health) and the worker’s protection interests is based on the reduction of risks according to the principle of “As Low As Reasonably Achievable”. The risk deriving from exposure must be reduced by implementing an efficient technical, organizational and procedural framework (chemical fume cupboards, safety procedures, etc.). As a consequence, the use of Formaldehyde brings a consistent economic and legal burden for the employer and/or involved occupational physicians. Indeed, the number of lawsuits for employer’s liability concerning work-related diseases connected to the use of Formaldehyde is increasing (see, for instance, in the United States: the so-called “Lumber Liquidators Scandal” and the lawsuit filed against the FDA by Women’s Voices and the Environmental Working Group).

ADDAX Biosciences was born as a spin off of the University of Turin, which contribuited with support to the research activity.

bandiera unione europea

Our company has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 8157692.

The project “GAF – Towards a hospital without formalin” is realized thanks to the co-financing of POR FESR Piemonte 2014-2020, Ob.1 – “Research, technological development and innovation, I.1.b.4.1 “Support for creation and consolidation of innovative start-ups with a high intensity of application and knowledge and research spin-off initiatives”.

The project aims to validate, produce and market GAF, a histological fixative without carcinogenicity, that works as a substitute to Formalin. Achieving the project’s objectives will improve the working conditions of health and research professionals, protecting them from the risk of developing occupational diseases caused by inhaling Formalin vapours.


The information contained in this section is intended exclusively for Healthcare Professionals, in compliance with the Italian legislation, specifically with Art. 21 of the Decreto Legislativo 24 February 1997, n. 46, and the “Guidelines of the Ministry of Health” issued on the 17 February 2010, 28 March 2013 and 20 December 2017. If you intend to access the information, you have to declare and confirm to be a Healthcare Professional by clicking on this disclaimer.