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G Reybrouck

Publications and source records attributed to G Reybrouck.

At least 55 records · Page 3Linked to original sources
PubMed1975

[Air pollution due to the burning of thermoplastics II (author's transl)].

Following on from the first publication, (12) concerning the burning of plastics, another 13 chemical pure polymers were burnt in an electric oven to determine the level of solid and gaseous air pollution caused by their stackgases. All 13 polymers are highly combustible but require different burning temperatures (300-900 degrees C) in order to be burnt completely (i.e. without ashrest). With the exception of PMMA and PTFE, all plastics leave a very heavy tar- and soot deposit after burning. At the other end of the scale, burning at low temperature (300 degrees C) gives rise to high concentrations of alipathic aldehyds. The pH of the exhaust-gases, dissolved in water, is neutral to strong acid (PTFE), and will cause a severe corrosion. The nitrogen-containing polymers pollute by forming cyanides, nitrogenoxides and ammonia. PTFE gives off high concentrations of fluorid into the air. PMMA decomposes in its monomer methylmethacrylate and forms large amounts of aliphatic aldehyds. ABS and SBR cause a styrene pollution.

Air Pollutants↗
PubMed1975

[Critical assessment of methods for testing chemical disinfectants and disinfection procedures (author's transl)].

Since the earliest days of disinfectant testing two different methods have to be distinguished: one group simulating practical circumstances the other one allowing the determination of germ reduction, disregarding any practical conditions. At present the assessment of disinfectant substances is carried out according to the results of several methods, done in different countries. Usually standardised suspension-tests with no correspondance to-in-use conditions are done. These are for example the determination of the Rideal-Walker and the Chick Martin coefficient and the capacity test by Kelsey and Sykes as well. Results obtained by the use-dilution method (A.O.A.C.) are also just of theoretical value. The British Standard-Test 3286:1960 and the suspension-test of the Committee on Phytopharmacy (Netherlands), to be preferred in order to state germ reductions, do not imitate particulars of practice either. After establishing recommendations for the various disinfectant procedures, the unification of the test methods on international level should be the next aim. Besides evaluation of disinfectant substances (as it is done by suspension-tests) the testing of disinfectant procedures under conditions, copying those of real life ought to be required. The results of such in-use model tests should answer all the questions arising, for instance, what the concentrations or the exposure-time should be. We would plead in favour of testing disinfectant substances and procedures in two steps - preliminary testing and main tests under in-use conditions for each new preparation. The base for all these tests is the selection of a suitable inactivator.

Disinfectants↗
PubMed1975

A theoretical approach of disinfectant testing.

The purpose of this study is to compare six methods of disinfectant testing, currently applied in Europe. The testing techniques are analysed into the separate elements, which can influence the activity of the disinfectant. The differences observed in these components allow to explain why in each method other parameters are evaluated and consequently, why the interpretation of the results varies from method to method. The six tests examined are (1) the suspension test of the DGHM, (2) the suspension test of the Committee on Phytopharmacy, (3) the A.O.A.C. use-dilution method, (4) the KELSEY SYKES test, (5) the surface-disinfection test of the DGHM and (6) a modified version of this latter. First of all the final concentrations of the disinfectant in the medication mixture are calculated. On the KELSEY SYKES test differs from the others, in using a much lower final dilution, up to 50% in the 3 rd stage. It is also obvious that the longer the exposure time is, the greater the killing effect on the bacteria in the medication mixture will be. To determine the germicidal activity a method needs to pass the test, the germicidal effect has been assessed starting from the inoculum applied in the medication mixture and, in case of tests that consider the absence of growth in the subcultures as end-point, the minimum extinction required. The lowest number of bacteria is applied in the inoculum of the A.O.A.C. use-dilution method (ca. 10(6)) and the highest in the modified practical surface disinfection test (ca. 10(10)). So the required germicidal effect varies from 5 (in case of the Committee on Phytopharmacy's test and the modified practical test) to more than 8 (in case of the A.O.A.C. use-dilution method). Further on, the protein content of the bacterial suspension which is added to the medication mixture, is experimentically verified. Considerable differences are observed here. In some tests the presence of organic matter is negligible (the A.O.A.C. use-dilution method, the KELSEY SYKES test under clean conditions), whereas in others (the KELSEY SYKES test under dirty conditions and the practical surface disinfection tests) the protein added equals that of serum 10-30%. Finally it is mentioned that the dilutions in the KELSEY SYKES test are made with artificial hard water. From a comparison of the factors described above it clearly appears that in the distinct tests different parameters are used and that the results of one test cannot be applied to another.

Disinfectants↗
PubMed1975

[A comparison of the results of 4 national methods for the evaluation of disinfectants in 2 laboratories (author's transl)].

At present the testing and assessment of disinfectants is carried out according to different methods in different countries. The result of this is that certain preparations or concentrations are allowed for use in some countries while they are not in neighbouring countries. A study was carried out jointly at two universities with the object of testing the reproducibility of these methods and standardizing them. Furthermore, an attempt was to be made to arrive at common test methods. In 2 labortories (A,B) we tested and compared the disinfectant activity of three disinfectant standards (phenol, aldehyde, iodophor) against Staphylococcus aureus and Pseudomonas aeruginosa (1) in the suspension test according to the "Richtlinien für die Prüfung chemischer Desinfektionsmittel" (Directions governing the testing of chemical disinfectants) of the DGHM, (2) in the suspension test of the "Dutch Commission for Phytopharmacy," (3) according to the "Use-Dilution Method" of the A.O.A.C. and (4) in the capacity test according to KELSEY and SYKES. Every individual test was repeated ten times. In addition we determined the reproducibility of the results by repeating the tests several times with one and the same culture and with different cultures (on different days). The exact method is described elsewhere (7). The statistical evaluation of the mean values (Tables 1,3,5 and 7) and variances (Tables 2,4,6 and 8) leads to the following findings: The results obtained with the various methods depend on the lab. technique and were specific to the germs and preparations tested. The reproducibility was best in the DGHM suspension test and the capacity test according to KELSEY and SYKES; the mean values of the two laboratories were closest for the Dutch test of the Commission of Phytopharmacy. The greatest mean value differences and scatter were observed with the A.O.A.C. "Use-Dilution Method." The conclusion of this investigation is that for the preliminary testing of disinfectants a method should be recommended which enables the determination of the acturl germ count reduction after varying periods of action and with well-defined organic challenge. In order to assess the disinfectant action, however, such a test - which answers most of our questions and has optimum reproducibility - must be supplemented by main tests which simulate practical conditions as near as possible.

Aldehydes↗
PubMed1975

[Comparative study of four national disinfectant testing techniques (author's transl)].

Four methods for the evaluation of the bactericidal property of disinfectants have been compared. These methods are (1) the qualitative suspension test of the directives for the testing of disinfectants of the German Society for Hygiene and Microbiology, (2) the quantitative suspension test of the dutch committee on phytopharmacy, (3) the carrier or use-dilution method of the A.O.A.C. and (4) the KELSEY and SYKES' capacity test. Aim of this study has been the evaluation of (1) the repeatability and reproducibility of the test results of the four methods, and of (2) the agreement of the degree of efficiency as determined by the different techniques. At least three dilutions of the three disinfectant standards (a phenolic, an aldehyde solution and an iodophore) have been tested against Staphylococcus aureus and Pseudomonas aeruginoas. In this article the authors describe the methods used and the specific difficulties of these techniques. In the suspension technique of the DGHM, the use of only one subculture is stated as not sufficient for exact evaluation of the extinction. In the dutch suspension test, the use of pour plates leads to troubles. The preparative incubation time of the use-dilution method of the A.O.A.C. has been experienced as too long. The structure of the KELSEY and SYKES' test is complicated. Also the results by the two research-teams, are reported and summarized. It has been found that the transition from active to inactive dilution is most marked in the two suspension tests, whereas the distinction between the results of the use-dilution method of the A.O.A.C. is not so clear.

Aldehydes↗
PubMed1975

[The meaning of the results of four national disinfectant testing techniques (author's transl)].

The bactericidal activity of three disinfectant standards has been determined by four national methods (the qualitative suspension test of the German Society for Hygiene and Microbiology DGHM, the quantitative suspension test of the Dutch Committee on Phytopharmacy, the use-dilution method of the A.O.A.C. and the Kelsey and Sykes' test) in order to compare these four testing techniques. In previous publications the results of these experiments and the degree of standardisation of the four methods have been tested. The purpose of the present study is to evaluate to what extent the results obtained by the four testing techniques do correspond. The bactericidal activity can be expressed as a germicidal effect. In theory (Tab. 1) the values of germicidal effect can be similar for the four testing techniques. In practice (Tab. 2 and 3) it has been found that with the suspension technique of the DGHM systematically higher values are obtained than in the other tests. These can not be compared to each other, because the medication times differ. Although the values of the germicidal effect obtained are widely different, it can happen that the minimum effective concentration determined by the four methods be identical as each of these methods applies different criteria. The authors have therefore calculated the minimum effective concentration which is required for the disinfectant standard by the four disinfectant testing techniques (Tab. 4). Even here, no correspondence has been found between the four methods. The lethal concentration of the disinfectant standards determined by the use-dilution method of the A.O.A.C. is thus 2 to 16 times those required by the Dutch suspension test. The difference in effective concentrations, however, is not constant and is not related to the type of disinfectant or the test organism. In consequence, there is no way of establishing a comparison between the results of the four methods with a view to setting up a conversion table. Each disinfectant testing technique has its own characteristics.

Disinfectants↗