Use of Residual Spray Materials in a Typical Food Industry EDWARD L. HOLMES and LLOYD J. SALATHE
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American Institute of Baking, Chicago, III.
The plant inspection program of the American baking industry has shown that 80% of sanitation problems can be avoided by good housekeeping. Proper use of residual spray material, such as DDT and chlordan, will control casual invaders—roaches, ant, flies, silverfish, dermestids, fungus beetles, and meal worms— without contamination of food products.
Following passage of the Federal Food, D r u g , and Cosmetic A c t of 1938, the baking industry established a broad program of education i n sanitation among its manufacturing members. M u c h of this program has centered about the activities of the American I n stitute of Baking, which is the scientific advisory foundation maintained by the baking industry to accomplish just this objective. The first concrete idea materialized from the industry's program was the realization that approximately 8 0 % of sanitation problems can be avoided i n a baking establishment if good housekeeping is maintained. This means: (1) proper building maintenance, with provision for adequate rodentproofing, screening, and removal of interior structural harborages for insects as well as rodents; (2) good storage practices, which include the development of an inspection system for all incoming ingredients, storage away from walls and i n stacks of such size as to permit easy inspection, proper turnover of ingredients, and proper handling of damaged goods; and (3) generally good housekeeping practices, adequate cleanup of flour-handling equipment, overhead proofers, and removal of flour dust throughout the plant, cleaning of machinery and working areas to remove accretions, proper cleaning of mobile equipment, proper maintenance of floors, maintenance of generally good appearance, and removal of unused equipment from production or i n gredient storage areas. Unfortunately, no bakery so far has been able to maintain these criteria of good housekeeping to absolute perfection, although i t is not possible to say that 100% maintenance of such criteria would keep a bakery absolutely free from insect infestation. The American Institute of Baking, i n advising the industry, feels that i t must regard baking establishments as subject to constant danger from casual invaders. This theory has been well borne out by the facts developed during the plant inspection program. A t present, the American Institute of Baking is inspecting some 150 to 200 bakeries per year. Such inspections involve painstaking appraisal of the conditions of infestation within the plants over a period of 3 or 4 days by an individual scientifically trained b y years of experience i n this work. During the year 1948 approximately 100 bakeries were so inspected.
Invading Insects Results of these inspections have shown that the following insects must definitely be regarded as a casual invasion threat : 28
AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.
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HOLMES AND SALATHE—USE OF RESIDUAL SPRAY MATERIALS
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1. Roaches, of all four common varieties. The Oriental variety comes from outside the plant and invades individually wherever possible b y getting i n through broken screens, open doors, etc. The brown-banded roach has no particular habitat and flies into the plant i n areas where i t is common. The German and American roaches ordinarily come i n with cartons of ingredients. 2. The common ants, particularly the Pharoah and Thief varieties, are common invaders of a bakery. 3. Flies of all types are common invaders. However, the housefly and vinegar fly or gnat are the two most common varieties. These w i l l invade the plant under their own power. 4. Silverfish and firebrats come into the plant i n cartons and incoming paper stocks. They are particularly likely to infest returnable cartons from old deliveries. 5. Dermestids. The two most common invaders are the carpet beetle and the drugstore beetle or cigaret beetle. The latter, although not exactly identical species, are comparable i n their habitat and habits. They are all likely to fly into the plant. 6. Fungus beetles, another family that feeds upon decomposed flour and other cereal products, are brought into the plant i n ingredient containers or they mayflyi n . 7. M e a l worms. The three most common are the light meal worm, dark meal worm, and lesser meal worm. M a n y other insects are occasional casual invaders; the ones described are merely those most commonly seen. Ordinarily, when one or two specimens of an insect species invade a clean bakery, nothing is seen of them until they have bred and developed into a definite focus of subsequent infection; i n other words, until there is a colony i n the place where the original invader sought harborage. I t has been common practice to seek out the colonies visually and spray them with a contact spray. This contact spray killed the adults and larva which i t touched, but all too often left eggs and pupae to develop u n harmed. Experience i n the baking industry since World W a r I I has shown that proper use of residual spray materials such as D D T and chlordan will most effectively control these casual invaders. When housekeeping i n a bakery is maintained as near perfect as possible, the application of a residual layer of toxic insecticide on areas upon which casual invaders are most likely to travel i n seeking harborage will effectively k i l l the invader individual before i t has an opportunity to nest. Experience has borne out this theory i n a general way, and specific data are now being" collected which will describe i t i n more scientific terms.
Application of Sprays B o t h D D T and chlordan are used i n colorless, odorless, deobase-type solvent : D D T in 5 % solution and chlordan i n 2 % solution. The oil solvent is used because i t is a nonconductor and because experience has shown that the crystals from a film of oil solvent solution adhere more firmly to the surface sprayed. A pressure-type spray tank, either a hand pump or mechanical source of air pressure, is used, with a special nozzle which gives a fan-shaped nonmisting spray. A special dripless valve is used. Several valves and nozzles which meet these requirements are on the market. The appropriate areas are sprayed with this fan-shaped painting spray stream, so that the surface glistens with the wet film but there is not sufficient quantity to run down. Experience has shown that this will leave approximately 200 mg. of D D T per square foot or an equivalent amount of chlordan. This procedure is recommended by the U . S. Public Health Service i n its spraying technique for residences and food establishments treated i n its program of spraying D D T only for malaria control. I t has not as yet recommended chlordan for this use. Specifications for the sprayer nozzles procedure can be obtained from this source. The following areas of the bakery are treated with such a spray : screens, the window and door jambs, areas of wall immediately adjacent to windows and doors, all walls up to a height of 3 feet, the corners and areas of the floor next to the wall to a distance of 3 feet from it, light cords, electrical switchboxes, connection boxes and electrical motors, space behind sinks, space below the floor joists and the basements, where the ends of the joist are sprayed for a distance of 2 feet from the wall, bottom of the storage skids, the lockers, beAGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.
ADVANCES IN CHEMISTRY SERIES
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hind and on the top and i n the insides, the areas around urinals and stools i n lavatories, and floor drains generally. Objection has been raised to the use of D D T and chlordan i n food establishments because of the possibility that mists may spread onto the product zone of equipment and onto surfaces of food or ingredient mixes. Experience has shown that the use of the paint spray nozzle effectively prevents this. A s large a pressure is used as will lay a flat stream of liquid; there is no mist and should be no drip. Admittedly, other sprays are used i n baking establishments, and special precautions must be taken to keep D D T or chlordan solutions from being confused with these. A sound sanitation program for a baking establishment provides that only specific employees apply the D D T or chlordan spray. The spray materials are kept properly labeled and locked up with the spraying equipment, and only employees authorized to use it have keys to this equipment. The employees applying the equipment should be provided with rubber gloves and masks, although experience has shown that they will not consistently use masks and do not use rubber gloves. They are instructed, when undertaking an assignment of this character, to be sure that there is adequate ventilation i n the room and all windows are open, and they are told to wash their hands immediately, should any spray solution spill on them. So far, i n many thousands of applications, no i l l effects have been reported i n baking establishments following this procedure. In its program of bakery sanitation, the institute feels that it is allowing for control of insect infestation to the extent of about 2 0 % of its effort i n the use of these sprays. They give a tool that protects from possibility of casual invasion. This feeling of security is checked upon constantly by reinspections and plants that have followed this procedure faithfully, combined with the good housekeeping required, have had no infestations. Infestation of the interior of flour handling and other bakery equipment, which might arise from an entirely different source than the casual invader, requires different techniques and this problem is not a part of this paper.
Conclusions The baking industry feels that it needs residual sprays of the character of chlordan and D D T . I t has no fear of contamination of the finished product, for there is far less danger from contamination here than there has been i n the past from such poisons as sodium fluoride powders, which were used for many years without adverse publicity, despite infrequent food poisonings from their use. Residual sprays such as chlordan and D D T are needed i n the production of bakery goods and are an essential factor i n the production of these goods free of insect sources of filth. However, there is no need to establish a tolerance or acceptance of any amount of D D T i n bakery goods. N o residual sprays are to be employed i n any way i n any area where they could contaminate either ingredients or the finished product. This is i n contrast to the agricultural uses of these products, where they are necessarily incorporated i n a slight degree i n the finished product. Whatever is decided regarding agricultural use should not enter into the question of use i n food-manufacturing establishments.
AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.
