Search

Many paper products, including newspapers and paper goods used in packaging foods, contain lead. The lead content of newspapers, an important constituent of recycled paper, varies with color of ink, type of printing process, and source of newsprint. Recycled newsprint is richer in lead than virgin newsprint. Lead on or in food packages ranged from 2 to 10,000 ppm, and varied with the quantity of printing and color of ink. Printed packages contained more lead than unprinted material, although some unprinted ones contained up to 58 ppm. The potential for introducing lead into meat and milk by feeding waste paper to ruminants is explored. Negligible amounts of lead are introduced into soils and plants from news-paper mulch.

SAMPLES of human urine have been examined for indole and phenol acids as a matter of routine in this laboratory for several months; the methods used for extraction and two-dimensional paper chromatography were described earlier1,2. The chromatograms were satisfactory until certain days in April, when the normally pink and purple spots given by indoles with p-dimethylaminobenzaldehyde showed a diminished colour intensity and brown discoloration. The colours became so weak in May that indole spots could not be seen with certainty. Unlike the indoles, the phenolic acids gave colours which were normal immediately after spraying with diazotized sulphanilic acid, but which faded and were discoloured afterwards to an increasing extent. No improvement was obtained when the components of the chromatographic solvents were purified extensively.

The use of silver nitrate-impregnated radioiodine filters was evaluated under laboratory and field conditions. Preliminary laboratory tests indicated radioiodine filter efficiencies of 91-96%. When sampling a stack effluent containing a variety of reactor waste products, radioiodine filter efficiencies of less than 8% were obtained. Sampling effluent gases from hot cells where reactor fuel elements are handled resulted in a median radioiodine filter efficiency of 20% with efficiencies as high as 96-100% under certain operating conditions. Test results show that silver nitrate-impregnated radioiodine filters do not provide a reliable method for monitoring the release of iodine to the atmosphere. (auth)

An ultraviolet chamber for decontaminating single sheets of paper seeded with mycobacteria was investigated. The ultraviolet killing effect ranged from 50% for Mycobacterium kansasii to more than 99% for M. tuberculosis.

During the analysis of small samples of peats, the concentration of sodium in the blank solutions was observed to be high in relation to that found in the sample solutions. Sodium contamination by filter paper was suspected and confirmed. For accurate measurement of low sodium concentrations in peat samples, the filter paper should be washed with dilute hydrochloric acid before the acid solution of the ash is filtered.

DURING the continuation of an investigation1 into the factors affecting the resistance of paper to attack by atmospheric pollution, we found that fingerprints were affecting our results. Further investigation suggested that a method for detecting fingerprints on paper could be developed. Fuller details are to be published shortly; but in essence the method consisted of exposing the sample of paper to radioactive sulphur dioxide at a concentration of about 10 p.p.m., followed by autoradiography. Sulphur dioxide was picked up preferentially in the regions contaminated by the fingers, and this caused a greater darkening of the X-ray film. An example of one of the prints obtained is shown in Fig. 1. The specific activity of the sulphur dioxide was about 1 mc./m.mole, the time of exposure about 12 h and the time for autoradiography one week.

A simple technique is described for drying sera on washed, dry sand or ordinary sugar cubes for the sero-diagnosis of leptospirosis. The results are shown to be very similar to those obtained with fluid sera or sera dried on filter paper discs. Sera adsorbed on sand or absorbed in sugar eliminated some of the problems associated with sera dried on paper. This method is suitable for use in the field and is expected to be of value in epizootiological studies where contamination and chemical denaturation of fluid serum samples held without refrigeration is a problem.

SUMMARYIn view of recent food-borne outbreaks of salmonella infection in which cooked-meat slicing machines have been implicated in the spread of organisms from contaminated meat products to other meats, experiments have been made to provide laboratory evidence that a contaminated slicing machine will easily cross-contaminate other products passing through it. Chopped pork inoculated with coagulase-positive staphylococci was cut on a slicing machine; staphylococci were isolated up to the 41st slice of various cooked meats cut on the same machine. The experiments were repeated withSalmonella oranienburg; this serotype was isolated up to the 31st slice of various cooked meats cut on the same machine, and from pieces of damp cloth wiped over the gravity feed, knife centre disk and cutting blade.The importance of efficient and regular cleaning of slicing machines with hot water containing detergent/disinfectant, or detergent followed by disinfectant, applied with clean cloths or preferably disposable paper, is stressed.I thank Dr Betty C. Hobbs, Director of the Food Hygiene Laboratory, and Dr J. C. Kelsey, Administrative Director of the Central Public Health Laboratory, for their help throughout the work and the compilation of the paper.

A systematic method for micro semi-quantitative determination of mixed metals has been developed as a combined technique of the Weisz's ring oven and the liquid extraction methods which is availabole to the conventional and rapid measurement for the hygienic purposes. By this technique the metal in question in the test solution is extracted with organic solvents, which dissolve the element specifically by ion association or chelate formation recation, and after separation from the other elements coexisting in the test solution the element is recovered in a shape of a thin solid ring (15s43 mm diameter) on a filter paper put on a ring oven apparatus. The semi-quantitave analysis was done by contrasting the stndard colour series previously prepared with the series of sample solutions at known concentration levels. The higher sensitivity in detecting the trace of metal with less contamination by the other coexisting elements on the procedure and the increased rapidity in the determination have been realized by the use of the solvent extraction rather than the use of inorganic separating reagents in the analytical procedure. Basic analytical experiments were carried out in order to assess the rate of separability of the respective element from the others at several amounts of constituent, and the sensitivity in detection of each element. Out of test solutions containing metal fumes taken from the environmental atmosphere in the working fields, Fe-Ni-Cr and Sb-Sn-Cu-Pb components as most popular examples of metal fume mixture, were determined semi-quantitavively with selected combination of separating solvents and colour reagents in order to attain the most sensitive and precise systematic separation procedures of each element.

The length of time by which any frying oil may become to show the strong foaming during the deep fat frying is presumed to depend on several factors, principally temperature of frying, surface area of oil exposed to air and degree of contamination of oil by the fried foods. This paper deals factors that affect the rate of oil deterioration during the deep fat frying, such as degree of heating, amount of steam blown into oils, kind of gases passed in oils, kind of metals used as frying pans and so on. To compare the effects of defference in amount of steams blown into oils, 700 gr or 1, 000 gr of soybean oil placed in iron frying pan was heated for 2.5 hrs at 240°C, blowing the steam through a glass plate filter, then the chemical and physical properties of oils thus obtained were measured. The more the steam blown, the more the oil deteriorates. Blowing of air and oxygen into oil affected much the rate of deterioration of oil, while blowing of steam or heating in absence of air seemed to prevent oil deterioration. With regard to the factors resulting from contamination of the oil by the fried soybean curd, “Tofu” didnot affect on the deterioration except the colour. The kind of metals used for vessels such as iron, stainless steel, coppor and aluminium didnot show any significant difference of effect on oil deterioration except the changes in colour and flavor in the case of copper.

In past years polychlorinated biphenyls were incorporated into a coating material used on the inside of many concrete silos. These residues subsequently diffuse into silages and ultimately pass into food products produced by livestock that consume the contaminated silage. Twelve coating materials were evaluated to determine if they would form a barrier to residues. Coating materials were evaluated by coating contaminated stave blocks, on test sections in a contaminated silo, and on dairy farm silos that were contaminated. When surfaces contaminated with polychlorinated biphenyls were treated with various barrier coatings and exposed to silage, 9 of 12 coatings reduced the concentration of biphenyls in silage compared to silage adjacent to control surfaces. Coatings carried by water or a solvent in which biphenyls are not readily soluble were the most effective barriers. Coating materials with a base coat to seal the surface prior to application of the surface coating were more effective than two applications of a single formulation. Hydraulic cement with an acrylic bonder and water-carried epoxy effectively reduced residues in silage from contaminated dairy farm silos. Concentrations in milk from cows fed these silages were below Food and Drug Administration “temporary tolerance.”

Studies were conducted on the microbiological quality of fluids associated with different types of dialysis systems located in six dialysis centers and 14 homes. Included were (i) single-pass systems employing either parallel flow (Kiil or Gambro) or capillary cartridge dialyzers and (ii) recirculating single-pass and batch recirculating systems using coil dialyzers. Microbiological assays were performed on the water used to prepare dialysis fluid, the concentrated dialysate, and either pre- and postdialyzer dialysate (single-pass systems) or the dialysate contained in storage reservoirs and recirculating cannisters (recirculating systems). The levels of microbial contamination consisting of gram-negative bacteria were directly related to the type of dialysis system, method of water treatment, distribution system, and in some instances, the type of dialyzer. Recirculating single-pass and batch recirculating systems consistently contained significantly higher levels of contamination than single-pass systems. These results were directly related to the design of recirculating systems which permits carbon- and nitrogen-containing waste products dialyzed from the patient to accumulate, be used as nutrients by microorganisms, and subsequently allow for 2- to 4-log increases in contamination levels during a dialysis treatment. In contrast, levels of contamination in single-pass machines were related more to the quality of the water used to prepare dialysis fluid and the adequacy of cleaning and disinfection procedures than to the design of the system.

INTRODUCTION MANY modifications have taken place in the techniques used to process poultry during recent years. The findings of Gunderson et al. (1954) led to warm evisceration of poultry in practically all commercial processing plants. Drewniak et al. (1954) made an extensive study of bacterial contamination during commercial evisceration but changes in techniques and processing equipment since this report may have established a different contamination pattern during evisceration. Walker and Ayres (1956 Walker and Ayres (1959) reported on the number and kinds of microorganisms associated with commercially dressed chickens and turkeys. Their work did not include variations in microbial numbers during the evisceration procedure since their samples were taken before and after evisceration but not at intermediate points. The research reported herein was initiated to determine the pattern of contamination at intermediate stations during the evisceration process and to study possible measures to reduce contamination. EXPERIMENTAL PROCEDURE Thirteen commercial poultry processing plants were …

A model system was used to simulate commercial cleaned in-place (CIP) conditions. Alterations in the system were made to determine the effect on the microflora, as potential food product contaminants. By the use of Serratia marcescens as a tag, contamination was shown to be more complex than a simple residue from the daily operation. Also, the use of S. marcescens revealed that contamination did not move from outside surfaces of the equipment into the liquid food even with severely corroded equipment. Increasing corrosion provided greater harborage for microorganisms. The harborage could be limited somewhat by drying the surfaces, but a much greater reduction in harborage was obtained by storing the system filled with a solution at pH 11. With manipulations that reduced the total contaminants, there was an increase in the relative frequency of Gram-positive asporogenous rods, certain genera of which show promise as indicators of un-satisfactory equipment condition.

Post-pasteurization contamination constitutes a major problem for quality control and regulatory sanitarians in the market milk industry. The bacteria of most concern are gram-negative, aerobic, resistant to surface active agents, catalase-positive, and grow rapidly on the surface of solid media. Knowledge of these characteristics was utilized to provide the basis for a surface plating method to determine their numbers. Bacteria in this group account for most growth during low temperature storage and at warm temperatures. Results with the surface plate method were available in 16 to 20 hr. Preliminary data showed the test to be useful in indicating a lapse in proper pasteurization, cleaning, and/or sanitization.

SUMMARY: A theoretical treatment of continuous culture is given, which allows quantitative prediction of the steady-state concentrations of bacteria and substrate in the culture, and how these may be expected to vary with change of medium, concentration and flow-rate. The layout and operation of a small pilot plant for the continuous culture of bacteria are described. This plant has been operated continuously for periods of up to 4 months without breakdown or contamination of the culture. No alterations in the properties of the organisms studied have occurred during such periods of continuous culture. Results are given of a series of experiments on the continuous culture of Aerobacter cloacae in a chemically defined medium, designed to allow quantitative comparison with the results predicted by the theory. The relative advantages of batch and continuous culture as production processes are discussed, and it is concluded that continuous culture may usually be expected to show a five to tenfold increase in output as compared with a batch process.

Studies were made on the susceptibility to bacterial contamination of rubber milk tubes as affected by deterioration of the inside surfaces. Even with used tubes having only microscopic breakdown, contamination was much greater than with new tubes. The average contamination in the used tubes averaged 15 times as great as in new tubes under laboratory conditions and 12 times as great under practical operating conditions with dry storage. When lye storage was used bacterial counts were lower and differences were smaller. Even inconspicuous deterioration of the interior surfaces of rubber milk tubes is a potential hazard in milking machine sanitation.

The main cause of the corrosivity of sweat is the content of chloride, other constitutents contributing to a negligible extent. Other factors of importance are the number and activity of sweat glands on the transferring skin surface, its size and temperature, the secretion rate of the sweat, the hygroscopicity of the dried sweat residues, the corrosion resistance of the metal, the size, and shape and finish of the contaminated metal surface and the relative humidity, temperature and content of pollutants of the surrounding atmosphere. As this corrosion problem is to a great extent one of cleanliness, no absolute solution is available. An optimum reduction will be obtained by a suitable combination of preventive measures determined by economic, personal, production and technical factors. A brief survey is given of the chemical composition of sweat and its corrosivity, preventative measures and test methods.

Greene , V. W. (University of Minnesota, Minneapolis) and D. Vesley . Method for evaluating effectiveness of surgical masks. J. Bacteriol. 83: 663–667. 1962.—A portable isolation box, provided with a filtered air supply and a means of access for a test subject's head, was attached to an Andersen Sampler and used to measure orally expelled bacterial contaminants before and after masking. This technique yielded more detailed quantitative information than was obtained by either sedimentation plates or Andersen sampling in an unconfined space. During talking, unmasked subjects expelled more than 5,000 bacterial contaminants per 5 ft 3 ; 7.2% of the contaminants were associated with particles less than 4 μ in diameter. Masked subjects expelled an average of 19 contaminants/5 ft 3 ; 63% were less than 4 μ in diameter. Mask efficiencies varied according to particle size of the contaminants. This technique is adaptable for routine evaluation of an individual's contribution to environmental contamination.

Salmonella, Ascaris ova and Endamoeba coli cysts were recovered from more than 50 per cent of irrigation water samples contaminated with either raw sewage or primary-treated, chlorinated effluents. Only one of 97 samples of vegetables irrigated with this water yielded Salmonella, but Ascaris ova were recovered twice from 34 of the vegetable samples. The public health implications of these results are discussed.

IN INVESTIGATING the role of zinc, manganese, and copper in plant nutrition, the use of suitable experimental methods for growing plants assumes particular importance. The amounts of these socalled microelements required by plants are so small that they are frequently supplied in considerable part or in toto by the incidental impurities included in the culture medium. A successful demonstration of the indispensability, as well as any study of the quantitative aspects of the importance of microelements in the nutrition of higher plants, depends directly on the removal of contaminants from the culture medium. The purpose of this investigation was to develop an experimental technique which, with the use of ordinary laboratory and greenhouse facilities, would permit the undertaking, on a fairly large scale, of experiments to study the physiological importance of zinc, manganese, and copper in the nutrition of higher plants. The object was attained by using the water culture method and, by proper selection of materials and purification procedures, reducing the contaminations derived from water, chemicals, and containers. The use of very sensitive chemical tests to determine the amounts of contaminants present in the culture medium after purification made it possible to prepare nutrient solutions of equal degrees of purity. It was possible, using this technique, to obtain consistent and reproducible responses in plants from adding minute amounts of metals to the nutrient medium (for example, 1 part of zinc in 200,000,000 parts of culture solution, which amounted to 1 y [0.001 mg.] of zinc to a plant). GENERAL CONSIDERATIONS.-The metal contaminants found in nutrient solutions are derived from three sources: containers, water, and chemicals. Previous investigators (Steinberg, 1919, 1935; Hopkins, 1933), studying the effect of microelements on lower plants, have described successful methods for nutrient solution purification in which metal impurities were removed by precipitation and adsorption at high temperatures and slightly alkaline reactions in the presence of calcium and phosphate ions. They have applied these purification procedures to either the complete nutrient solution (Steinberg, 1919, 1935) or to one divided into two portions (Hopkins, 1933), removing in one or two operations such impurities as were derived from the several nutrient compounds, water, and containers.2

Penicilloylated proteins which are found as an impurity in 6-aminopenicillanic acid can be exhaustively digested by pronase to yield amino acids and small peptides. This degradation converts the potent polyvalent antigens into a mixture of mostly monovalent haptens which are much less immunogenic and less capable of eliciting immune reactions in sensitized animals. The degradation of the protein impurity can be carried out in 6-aminopenicillanic acid preparations, since even a large excess of 6-aminopenicillanic acid does not appreciably inactivate or inhibit the enzyme. In order to avoid the contamination of 6-aminopenicillanic acid with a proteolytic enzyme, pronase was converted into a water insoluble form by coupling it with bromoacetyl cellulose or carboxymethyl Sephadex. These insoluble derivatives of pronase were found to retain their activity and broad specificity. Thus, they can be readily removed from the medium upon completion of the impurity degradation, to be used repeatedly in a continuous process.

This monograph includes the problem of microbial contamination of cosmetics, as well as the practical methods used for the microbiological control of cosmetics.The microbial contamination was discussed separately as primary (contamination of the product itself) and secondary contamination (contamination by the consumer)Author has reservations on the application of bacteriological standards for cosmetics at this time, however author's temporary proposal for then is as follows;Viable aerobic count: less than 100 bacteria/ml or gram.Pathogenic bacteria: not detected.None of the preservatives commonly used in cosmetics to-day is universally active against all kinds of microorganisms. Therefore, preservatives should be used only for the prevention of secondary contamination.Auther tried to examine antimicrobial spectrum of some preservatives now commonly used in cosmetics. The results are shown in the table.The readily applicable methods as a quality control produce to determine the total aerobic counts and pathogenic bacteria were described. In conclusion, it seems to author that a more logical approach and goal at this time is the production of cosmetics under controlled conditions to assuer maximum sanitation.

Summary A small fermentation system was devised for continuous automatic propagation of dairy cultures. The fermentor is a circulatory, 1-in. diameter, stainless steel pipe assembly of 1,000-ml. capacity, in which skimmilk is continuously and slowly circulated. Acidity is controlled with a pH meter and meter-relay which activates a solenoid valve controlling the skimmilk inflow. The fermentation system has been operated for 12 wk., but not without contamination and undesirable fementations. Successful trials free from contamination have been conducted for 3 wk. These have provided information regarding the throughput rate at various temperatures between 50 and 90° F. At 90° F. the retention time or growth rate was 30 min. The critical pH level was 5.3, below which the rate of growth was reduced. Dairy cultures can be propagated continuously at maximum growth rates without impairment of flavor or activity, with constant temperature and pH (above 5.3 for maximum rate) and in continuous motion.

Microbiological contamination levels of suture samples taken at various stages of the manufacturing process in a new hygienically controlled plant were determined by employing a membrane filturation technique. Both raw material and materials handled manually in the production process were tested to assess the effect of manual handling on the product contamination level. Evaluation of the efficacy of contamination control, however, was directed primarily to the finished, packaged products, just prior to the processing with cobalt 60. The suture material for testing was divided into two groups, namely, wet and dry products, the wet being packaged in a special “tubing” fluid consisting mainly of isopropyl alcohol. Initial contamination results are reported as the average of values obtained on the test day and the preceding 9 consecutive production days. A total of 1,787 suture samples tested in the dry group showed daily averages varying between 2.1 and 14.8 contaminants per suture. The 2,980 wet-packaged suture samples tested gave daily averages varying from 0.7 to 4.2 contaminants per suture. The highest values obtained for an individual suture were 400 for the dry and 89 for the wet. Identification studies of the contaminants revealed that fungi predominated. Most of the bacterial contaminants proved to be spore-forming rods.

Summary During the maple sap seasons of 1964 and 1965, sap collected from roadside stands of trees was stored in field holding tanks for as long as eleven days without deterioration, by continually irradiating the stored sap with germicidal ultraviolet lights emitting in the range of 260–300mμ. The bacterial populations of the stored, irradiated sap did not exceed 4.0 × 105 organisms per ml, and sirup made from the sap was light amber in color (fancy grade) with an excellent flavor.

Insect and rodent contamination in corn milling was studied to improve current methodology and recommend new methodology. Representative whole corn processing equipment, degerminators, grading equipment, and finished products were sampled. Whole corn samples were examined visually and by X-ray techniques; all samples were examined by heavy and light filth extraction methods similar to AOAC procedures. Whenever possible, contaminant counts throughout the system were weighted for stream flow before analyzing and presenting data. WRAP (Weighted Regression Analysis Program) was used in data analysis. The least number of equivalent whole exoskeletons gave the best correlations with radiograph data (r2 values ranging from 57.1 to 69.1%) of any of three methods used to report insects of kernel interior origin recovered in cracking-flotation of whole corn samples. The second trapping in light filth extractions was valuable in recovering additional rodent hairs, insects, and insect fragments from all types of corn and mill samples.

Care in the preparation and preservation of reagents, together with certain modifications in apparatus and technique, have eliminated the difficulties from plasma ammonia analysis. Ammonia contamination from the laboratory atmosphere has not proved an especial hazard, and no major setback has been encountered in the analysis of several thousand specimens over the last few years. The method has been found particularly suited to the performance of the occasional estimation, since, once prepared, all reagents are stable for a considerable time.

phenolic contamination of water supplies. It has since been applied successfully to other taste and odor problems, such as those caused by algae, decayed vegetation, weeds, sewage, and various types of industrial pollution. Aided by research in both laboratories and water plants, other factors of importance have been developed in the use of the process. For example, the effectiveness of chlorine dioxide as a bactericide is enhanced by its persistence in the distribution system. It is also useful in the removal

The investigations have been made on the effects exerted upon the operating conditions and yield of product by changing the properties and components of cracker feed stock, and the following results are obtained:(i) It is most desirable for the cracker feed to contain the oils of small contents of heavy metals dissolved, such as nickel, vanadium, iron, and copper.These desirable feed stocks are the vacuum distillates and the slack wax obtained from the solvent dewaxer. In general, the allowable limits of these metals dissolved in feed stock can not be determined clearly, because the contamination of catalyst by these metals is closely connected with its stack loss.(ii) The dissolved metals in feed stock are proportional to its carbon residue. It is possible to presume the metals contents in the stock by measuring its carbon residue.(iii) The yield of cracked gasoline is proportional to the aniline point of its feed stock. Therefore, the feed stock having high aniline points is recommended for the production of the gasoline with high yield.(iv) As the deasphalted oil contains more metals than the other distillates, it is desirable to use the feed stock containing less deasphalted oil or to use the highly refined deasphalted oil.(v) There is a linear relation between the contamination index and the nickel content in the stationary operation; therefore, it should be possible to indicate the contamination degree of the catalyst by nickel content in place of the contamination index.

moved by coarse sand. It is possible, of course, for diatomaceous silica to remove amebic cysts (1, 2) and a large proportion of bacteria or colloids without coagulation. On occasion, satisfactory clarity and purification can be produced without pretreatment of the raw water. The usual surface water, however, requires co gulation to provide economy of filtration through diatomaceous silica as well as an additional safeguard against contamination. Although the basic need may not be as great with diatomaceous silica, the degree of coagulation demanded is actually greater than with sand. Incomplete coagulation may be completed in a sand filter, in which the voids of the filter act as re

Three cleaners were tested of their washing power on the radioactive contaminated tea leaves, and some draining methods of washed wet leaves were investigated.In the cleaning tests, Dairy BON showed most effective on both points of view of excellent cleaning power and keeping qualities of tea. Lipon F followed the former in its effectiveness.In the manufacturing of washed leaves, six draining methods were tested. The draining method between steaming and primary heatingrolling process by a centrifuge and infrared radiation obtained the best effect on keeping the qualities of tea, and air-drying method before steaming process showed better than the others.

SUMMARYThe germicidal efficiencies of hot water (140–150° F.) under pressure (method 1), hot water + 2% (w/v) detergent solution (method 2) and hot water + detergent + 200 p.p.m. solution of available chlorine (method 3) were compared at six sites in a bacon factory. Results indicated that sites 1 and 2 (tiled walls) were satisfactorily cleaned by each method. It was therefore considered more economical to clean such surfaces routinely by method 1. However, this method was much less efficient (31 % survival of micro-organisms) on site 3 (wooden surface) than methods 2 (7% survival) and 3 (1% survival). Likewise the remaining sites (debarring machine, black scraper and table) were least efficiently cleaned by method 1. The most satisfactory results were obtained when these surfaces were treated by method 3.Pig carcasses were shown to be contaminated by an improperly cleaned black scraper. Repeated cleaning and sterilizing (method 3) of this equipment reduced the contamination on carcasses from about 70 % to less than 10 %.

1. Using 6 phytoplankton species and/or the copepodEuterpina acutifrons or larvae of the sea urchinArbacia lixula the potential inhibitory effects of chemicals released from some 70 different materials (mainly plastics) have been tested. In addition, the effects of 6 detergents have been examined. 2. Several materials, such as natural rubbers and polyvinyl chlorides, are highly toxic and should never be used when experimenting with living marine organisms. 3. Teflon (Algoflon), Perspex, Polyethylene, Tygon, Polypropylene, Polycarbonates (Makrolon) and Polyester (Gabraster) have been shown to be non-toxic and are, therefore, suitable for use in cultivation of marine organisms. Some materials had slightly negative effects on the organisms tested and should, therefore, be used only if no alternatives are available. 4. Some suggestions are advanced on how to construct non-toxic samplers and laboratory equipment used for experiments with marine organisms.

1. The bacteriological problems involved in the production of meat and fish pastes in sealed glass jars have been studied.2. Data are presented showing the normal flora of the raw materials used. Particular attention is drawn to the anaerobic species present in seasoning materials.3. Bacterial contamination due to manufacturing operations is discussed.4. The requirements of a satisfactory heat treatment are outlined, together with experimental methods of study used to overcome possible causes of failure.5. Bacteriological examinations of 14,365 samples of paste showed that 88% were sterile: the flora of the remainder was examined.6. Experimental evidence is presented to show that certain anaerobic spore-forming bacilli are the main possible cause of spoilage, and the significance of aerobic spore-forming bacilli has been established. An extremely heat-resistant anaerobe was isolated.7. Routine bacteriological control of the finished products is suggested.8. A simple, inexpensive, and rapid method of detecting anaerobic species has been devised, which can also be applied to other foodstuffs. Data are presented from the examination of a further 6110 samples using this method.

Serratia marcescens aerosols were generated under a hood covering the filler end of a model EPCF Pure Pak milk packaging machine. When water was packaged with the machine, contamination by the test organism occurred only when the defoamer was in operation. Milk samples were obtained from the supply line to the filler bowl, the filler bowl, and the filled package in three different plants. Airborne microorganisms were collected at the same time in the vicinity of the packaging machine by liquid impingement. Following incubation at 4.5 C and 7.0 C, the bacterial types in milk samples from the filler bowl and package but not from the supply line were similar to those in the impingement fluid for two of the trials at both incubation temperatures, and for the third at 4.5 C incubation. Air pulled through the filler bowl at rates of 3,000 to 6,000 liters/min by the defoamer contaminated the milk with psychrotrophic microorganisms.

A procedure is described for the activation analysis of particulate air contaminants collected on filter papers. Results are included from the identification of several radioactive species in a series of samples. The samples, together with a filter paper control, were irradiated in a reactor. Measurements of BETA activity were made with a proportional counter and gamma activities were measured with a pulse height analyzer equipped with a scintillation detector. Some samples were also analyzed with a multichannel analyzer. Data are included on the activation history of the samples and the radioisotopes identified. (C.H.)