Photobacterium test for evaluation of toxicity of fibrous products

A rapid Photobacterium rest has been developed to measure the toxicity of fibrous samples. Cultivation of the test bacterium and sample preparation are simple, and the test procedure is highly automated. The result of the rest is expressed as a curve representing light emission versus concentration of the frbrous suspension. The repeatability Of the method is good and the use of external references allows the results to be compared directly with those from other toxicity determinations. In the Photobacterium test, the toxicity of a fibrous sample is determined from an aqueous suspension. The solubility of the different fibre components is therefore an important issue. For example, packaging boards represent multicomponent materials and the toxicity of the board depends on the raw materials and additives used. Toxicity is also affected by coating chemicals, which differ greatly in terms of preparation and composition from one mill ro another. The toxicity of all the components and the way they interact with each other in the test suspension determines che resulting toxicity of the sample in the Photobacterium test. The test gives a "toxicity profile" typical of each paper and board grade, provided the manufacturing concept does nor change. The test can be used by a mill for internal control purposes by evaluating the Photobacterium toxicity of raw materials and products. However, the suitability of a paper or board intended for food contact should nor: be assessed on the basis of the Photobacterium test for the time being, as nothing is known about the applicability of the results.