Microbiological Quality and Safety in Dairy Industry

Module 3. Plant hygiene and sanitation

Lesson 16
ENVIRONMENTAL HYGIENE

16.1 Introduction

Foods can become contaminated during growth and harvesting of raw materials, storage and transport to the factory, and processing into finished products. The final product may then become re-contaminated during subsequent storage and transport to shops, and during storage and preparation by the consumer. The main sources of contamination are the environment, animals and people. The main transmission routes (vectors) of contamination are contaminated surfaces, air, water, people and pests. Processing, packaging material and equipment and transport vehicles may also act as vectors. Contact between food material and an inert surface leaves residual food debris that favours the growth of microorganisms. Over time, these can multiply to significant numbers and become endemic in a processing plant. Lubricants, often unavoidable in equipment with moving parts, may also contribute to chemical contamination. Non-contact surfaces, such as floors, walls, ceilings, overhead beams and equipment supports, are potential reservoirs of microbial contamination and can also be a source of physical and partly based on chemical contaminants (e.g. from flaking plaster and its associated chemicals). They need to be designed so that they are durable and can be cleaned effectively.

Production animals are important reservoirs of microorganisms and slaughter animals introduce large numbers of microorganisms into the processing plant. Among them are many so-called zoonotic pathogens that are present on the skin and in the gastro-intestinal and respiratory tracts. Pathogens carried on hands are also a major source of contamination.

Air can be a significant medium for the transfer of contaminants to food products. Unless the air is filtered, microorganisms will be present, and air may also carry ‘light’ foreign bodies, such as dust, straw-type debris and insects. Water is used in the food industry as an ingredient, a processing aid and for cleaning. Its use as an ingredient or processing aid can give rise to both microbial and chemical contamination, so it is important to use water of a high microbiological and chemical quality (i.e. potable quality). Water used in hand washing facilities poses a potential problem, as does that from condensation of steam or water vapour, leaking pipes and drains, and rainwater. Stagnant water is particularly hazardous, since microbial levels can increase rapidly under favourable conditions. The water used in cleaning programmes also needs to be of adequate quality. Personnel can transfer enteric and respiratory pathogens to food, e.g. via aerosol droplets from coughing near the processing line. People can equally be vectors of physical contaminants, such as hair or fingernail fragments, earrings, plasters and small personal belongings.

Pests, such as birds, insects and rodents, are potentially a major contamination problem, and particular care needs to be taken to prevent their entry into food production areas. Buildings must be designed to keep them out. Floors, ceilings and walls should not allow insects and other invertebrates the chance to live and breed. This chapter will highlights the environmental hygiene issues aimed at improving or maintaining the standard of basic environmental conditions affecting the well being of people, clean and safe water supply, clean and safe ambient air, protection of food from biological and chemical contaminants, and adequate housing in clean and safe surroundings.

16.2 Air Control

Movement of people, products, packaging and machinery creates unavoidable airborne contamination within the factory and transfer contamination from outside the factory to inside. Although microorganisms do not multiply in air, this is an effective method of distributing bacteria to surfaces within a dairy plant. In chilled rooms, evaporator fans draw large quantities of air over the evaporator cooling coils and distribute it around the room. Any contaminants in the air are likely to pass over the evaporator surfaces, some will be deposited, and, if conditions are suitable, attachment, growth and further distribution of airborne contaminants may occur. In addition to being a potential source of contamination, the development of a microbial biofilm on evaporator cooling coils may affect heat transfer rates of the equipment.

Air-control systems are effective in controlling airborne contamination, such as endospores of Bacillus species, various species of non-spore-forming bacteria and yeasts, as well as a range of mould spores, transmitted by untreated air being drawn into the area, condensation, blow lines from equipment and compressed air lines from packaging equipment. These control systems are, however, not as effective in controlling contamination from other sources, for example, personnel, traffic, buildings and raw materials. Chemical taints can, for instance, enter the production area through airborne transmission.

For products where air quality does not limit shelf-life and safety, the air quality should be controlled so that it does not become a limiting factor. Air control will be important in controlling the risk of contamination for products that are minimally processed, and where growth of microorganisms is controlled by preservation systems. In high-care areas, air supply is critical, if the area can be physically isolated, air systems should provide a positive air pressure and further reduce the risk of casual microbial contaminants. This will prevent microbiological contamination from potentially contaminated areas to non-contaminated areas. Ducting of incoming air through a primary filter to remove gross contamination (5.0–10.0 μm diameter), followed by a filter capable of removing 90–99% of particles above 1.0 μm, is essential for areas containing open vats of food. Special consideration should also be given to airflow in cheese factories, especially where mould, smear-ripened or soft cheeses are produced. Routine monitoring to maintain air quality is essential. Temperature, humidity, airflow and pressure and microbiological monitoring are all aspects that should be included. The location of air intakes and outlets, the method and frequency of cleaning filter-holders, and routine for replacing filters are aspects that merit inclusion within the HACCP plan. Adequate means of natural or mechanical ventilation should be provided, in particular to: minimize air-borne contamination from aerosols and condensation droplets; control ambient temperatures, humidity and odours to ensure safety and suitability of food. Ventilation systems should be designed and constructed so that air does not flow from contaminated to clean areas.

16.2.1 Air-quality control

16.2.1.1 Dairy processing areas

The most practical approach to control microbial airborne contamination indoors is the removal of all potential contamination sources from sensitive areas where the product might be exposed to air. Good ventilation is necessary to remove moisture released during the processing of dairy products, and it will also prevent condensation and subsequent mould growth on surfaces. Attention is nowadays given to air cleaning in food plants, interalia, by establishing air-flow barriers against cross-contamination from the environment. The air entering processing rooms is normally chilled and filtered to remove practically all bacteria, yeasts and moulds. It is essential that filtered sterilized air be supplied to areas where sterile operations are to be carried out. Rigid-frame filters or closely packed glass fibres are available to achieve contamination-free air for culture transfer, and manufacturing and packaging of sterilized milk and milk products. The use of high-efficiency particulate air (HEPA) filters will remove 99.99% of airborne particles 0.3 μm and larger, while ultra-low-penetration air (ULPA) filters remove 99.999% of particles as small as 0.12 μm. Passage of air through a combined HEPA/ ULPA filter is usually considered suitable for use where contamination-free work is to be carried out. Standard high-efficiency air filter systems allow more air into the room than normal, thereby establishing a positive air pressure. Upon opening a door, filtered air flows out, thus blocking the entry of untreated air and minimizing microbial contamination. For optimal ventilation, sufficient air changes have to be made to prevent the build-up of condensation on surfaces. Specialist advice should be sought to choose the correct filter type/ system on the basis of the air quality required for the specific operation in each controlled area. There is a difference between high- care areas, where the aim is to minimize air contamination, and high-risk areas that are designed to prevent recontamination.

Rooms in which direct exposure to outside air is inevitable can have air-flow barriers installed, mounted over open doorways to secure a significant downward velocity of air flow, preventing contamination from outside. Compressed air can also contribute to contamination of products by dust and microorganisms and, in the case of lubricated compression systems, by oil fumes. Whenever air under pressure comes into direct contact with the product (pneumatic filling, agitation or emptying of tanks) or is directed at milk contact surfaces it should be of the highest quality. Sterile compressed air can be obtained by drying the air after compression in adsorption filters (e.g. chemically pure cotton, polyester or polypropylene) and to install a series of 0.2 μm pore- size filters downstream, immediately preceding the equipment where the air is needed. Air sanitation systems can also be applied to control airborne contamination and include

• Fogging to reduce the number of airborne microorganisms and also to disinfect surfaces that may be difficult to reach;
• UV light; and
• Ozone treatment.

The use of clean-room clothing, head covering, masks and gloves largely eliminates the release of microorganisms and skin particles into the processing environment. A good hygiene-training programme for factory personnel will also contribute to reducing contamination by workers.

16.2.1.2 Air filtration for indoor air quality

Air filtration is an important air process function which is one of the requirements for acceptable indoor air quality. Air which is filtered to remove particulate and gaseous products is required to maintain a wide range of processes and environmental conditions in good working order, and examples range from package air conditioning to electronics assembly, food processing and office buildings equipped with Heating, ventilating and air conditioning (HVAC) systems. The degree of air filtration is determined by the operational requirements such as:

• Primary coarse filtration for ventilation of warehouses and factories, and as pre-filters for secondary filters.
• Secondary ‘fine’ filtration for quality office and some processing environments.
• Semi-HEPA and HEPA filtration for food processing, electronics, hospitals, pharmaceutical manufacture and many more.

High efficiency filters are in great demand for a wide range of applications, and many office building HVAC systems now use filters which are very efficient down to one micron particles.

16.2.1.3 HVAC (Heating, ventilating and air conditioning)

It refers to technology of indoor or automotive environmental comfort. HVAC (Figure 16.2) system design is a major sub-discipline of mechanical engineering the principles of thermodynamics, heat transfer and fluid mechanics.

Fig. 16.1 HVAC system design

Gas phase filtration is usually installed in Britain where a particular odour or fume emanating from outside of the building must be removed. Some general examples would be the smell of refuse, sewage processing, high concentrations of engine exhaust and aircraft fumes. There is a limited application for an adsorption system to control odours generated within buildings, and the application of such filters requires careful consideration. In some cases a chemisorptions process may be an alternative solution.

16.2.1.4 Outdoor environment

The control of airborne microorganisms in the immediate surroundings of dairy premises is more difficult than in closed, indoor environments where more controlled measures can be taken (Figure 16.1). One aspect that could be helpful in reducing the microbial load in outdoors is the control of organic materials. UV light, humidity, temperature, wind direction and speed have a significant influence on the total number of airborne microorganisms in the outdoor atmosphere. Air quality in processing areas, the factory environment (e.g. walls, floors, drains) and air used in the manufacturing of dairy products should be monitored regularly. Future trends will be focused on the local air control of production lines, instead of controlling production areas and also on the type of clothing that is used by personnel in food production areas.

Fig. 16.2 Air filtration at outdoor environment

16.2.1.5 Clean room operations

Cleaning procedures should effectively remove food residues and other soils that may contain microorganisms or promote microbial growth. Most cleaning regimes include removal of loose soil with cold or warm water followed by the application of chemical agents, rinsing and sanitation. Cleaning can be accomplished by using chemicals or combination of chemical and physical force (water turbulence or scrubbing). High temperatures can reduce the need for physical force. Chemical cleaners suspend and dissolve food residues by decreasing surface tension, emulsifying fats and peptizing proteins.

16.2.3 Air quality monitoring

There are many techniques used for the determination of microorganisms in air such as settling plate techniques

16.2.3.1 Settling plate technique

Petri dishes containing 20 ml of culture media like PCA, PDA, VRBA or BPA distributed at the dairy processing area and exposed for about 15-30 minutes. The Petri dishes were closed and incubated at 35°C for 48 hours for aerobic plate count, 25°C/ 3-5 days for yeast and mould, 37°C/ 48 hours for S. aureus and total coliforms. The results were expressed as CFU. cm-2 week-1

16.2.3.2 Impaction technique

In this technique, a volume of 100, 500 or 1000 ml of air suctioned by using air sampler and impressed on solid medium surface contained on Petri dishes, according to APHAs recommendations. First the sampler’s lid should be sterilized at 121°C for 15 minutes, was sanitized with alcohol (70%), before and after sampling. The Petri dishes were incubated in the same conditions as the settling plate technique. The results were expressed as CFU m^-3 of air.

The numbers of CFU m^-3 are determined by using a formula:

Pr = N [1/N+1/N-1+1/N-2+1/N-r+1]

Where

Pr = Portable number of CFU/ air volume; N= total number lid pores (400), r = lid pores that have already been crossed by viable particles.

16.3 Water Quality

A variety of microorganisms can gain access into water from different sources. The characteristic microflora of water consists of Achromobacter, Alcaligenes, Bacillus spores, Flavobacterium, Pseudomonas and to a certain extent Chromobacterium and Serretia depending upon the sources of water supply. Micrococci may also be present but their number varies considerably. Water contaminated by faecal sources may chiefly contain intestinal gram negative coccobacilli namely coliforms (E .coli), enterococci (S. faecalis) as well as anaerobic sporefromers as Clostridium welchii (perfringens). In addition to these some potential pathogens belonging to family Enterobacteriaceae (Salmonella, Shigella) and Vibrio cholera may also gain access into water sources.

There are mainly two types of microorganisms that might be found in water i.e. non-pathogens and pathogens. The non–pathogens are mainly spoilage type organisms that can cause off-flavours, odours and slimes but are little concern to the public health. The contamination of water by potential pathogens could, on the other hand, be of great public health significance because the consumption of such contaminated water may lead to outbreaks of diseases caused by Salmonella, Shigella and Vibrio such as typhoid fever, dysentery and cholera respectively.

16.3.1 Water in contact with food

Water is used as an ingredient, as a production-process aid and for cleaning, and may be supplied from external sources or recovered water. Consequently, the overall water requirements of a dairy plant are large, and water conservation and water management have become major issues. While not all supplies need to be of potable quality or better, if used as an ingredient, there exists the potential for microbial and chemical contamination. If a water company supplies water, the water will mostly comply with quality standards, suitable for dairy processing. Only occasionally, toxic algae or protozoa (e.g. Cryptosporidium spp.) in reservoirs cause problems. Furthermore, Escherichia coli, Listeria monocytogenes or Salmonella spp. cannot grow in water and are sensitive to the levels of chlorine found in drinking water. However, these organisms may survive in water, and so it is important that water used for rinsing equipment, or curd, or flavourings components of cottage cheese, should be of a higher quality than mains water. The level of chlorination in potable water is usually ineffective against spoilage groups like Pseudomonas spp. Since these bacteria cause taints under aerobic conditions, bacterial standards have been proposed for bacterial groups and are given in Table 16.1. Consequently, chlorinating plant water supplies to >21 mg L⁻¹ and monitoring that the level is maintained throughout processing contributes significantly to assuring the safety and shelf-life of the products produced. If ground water is utilized, it must be pre-treated to comply with the mentioned safety and quality standards.

Table 16.1 Microbiological specifications of drinking and process waters

According to IDF, water can be recovered from recycled, rinsing or cooling water. If the recovered water should be used for purposes where it comes into indirect or direct contact with food, it must not present a risk of microbiological contamination. Water from hand washing, unwanted water from steam and leaking pipes can all be vectors of contamination and stagnant water is especially hazardous. Water storage time should not exceed 24 hours and storage tanks should be constructed of stainless steel, easy to clean and closed.

Adequate supply of potable water with appropriate facilities for its storage, distribution and temperature control, should be available to ensure the safety and suitability. Potable water should be as per latest edition of WHO guidelines of high standard. Non-potable water (for use in, for example, fire control, steam production, refrigeration and other similar purposes where it would not contaminate food) shall have a separate system. Non-potable water systems shall be identified and shall not connect with, or allow reflux into, potable water systems.

16.3.2 Water treatment methods

Once water is analyzed for that unwanted constituents which are safety concern for using at dairy farm, processing. The water must be treated to remove anti-quality factors. This has been accomplished successfully and economically in some dairy farms. There are different methods available for treatment of water used in dairy plant as described below.

16.3.2.1 Activated carbon filters (ACF)

Activated carbon filters are used to filter water through carbon granules. Contaminants (constituents) attach to the granules and are removed. Chlorine, some compounds associated with coloration, odour and off-taste of water; mercury; some pesticides; radon gas; and volatile organic compounds can be removed by ACF. Depending upon the amount of water treated, the filters may have to be replaced frequently and regularly or in time contaminants will not be able to attach to the filter. Infrequent filter maintenance may result in bacterial growth on the filter and ineffectiveness.

16.3.2.2 Air stripping (AS)

It involves passing water down a tube while air is forced up through the tube. Contaminants are transferred from water to air and vented off. Whereas this method is effective to remove hydrogen sulphide, some odours and tastes, radon gas and some volatile organic chemicals; it typically is not recommended for household or small commercial use because of high energy costs and high noise generation. Bacterial growth also is a potential problem.

16.3.2.3 Chlorination

Chlorination is an effective and widely used method to kill many kinds of microorganisms in water. It also will aid in removal of unwanted colour, odour, or taste from water. This method also will remove hydrogen sulphide and dissolved iron and manganese, if followed by mechanical filtration or an ACF. Radon gas and volatile organic compounds also can be removed by chlorination. Chlorine is pumped directly into the water in proportion to water flow and it may have some residual effects in the system. If the chlorination is not properly operated, it can be expensive and potentially hazardous if chlorine by-products are allowed to escape.

In typical systems the chlorine content of the treated water should not be high enough to cause problems for cattle. From time to time, high concentrations of chlorine were released to the dairy water system when the city was cleaning its system; in this case (1,000 to 1,500 ppm chlorine in water at the dairy) water intake and performance of cows was reduced when chlorine content was high. This practice may affect water intake because spikes in chlorine content in the water tank may affect consumption; even with the slow-release tablets. Alternative methods (cleansers, brush and thorough rinsing) to keep tanks clean are recommended.

16.3.2.4 Ultraviolet radiation (UR)

Ultraviolet radiation, in which water is passed by a special light source, is another method to kill bacteria in water. There is no residual effect with UR. However, it is difficult to know if UR is working and it may not work if the water is too cloudy or water is passing by the light source too fast. Also as the penetration power of UV rays is quite low, only the surface layer of water can be sterilized.

16.3.2.5 Ozonation (O₃)

Ozonation in which water is exposed to ozone gas, also destroys microorganisms. The equipment typically is quite expensive; however there are no residual effects on the environment or treated water. This method also can be used to remove colour, off-taste, odours, hydrogen sulphide, solubilised iron and manganese; if the water is subsequently passed through a mechanical or ACF system.

16.4 Pest Control

Pests such as insects, birds have been recognized as important carriers of pathogens and other microorganisms. In one interesting case a Salmonella outbreak has been traced back to amphibians, which had accidentally entered the production facility. While massive direct recontamination can be excluded, sporadic cases may be attributed to these vectors. More important, however, is the transport and ingress of pathogens into food processing environments and their possible establishment in suitable niches. Pest control is therefore, essential in dairy food industries.

16.4.1 Risks posed by pests

1. The spread of pathogens are transferred from the gut or external surface of the pest
2. Damage to property
3. Contamination of work surfaces and foodstuffs
4. Adverse public opinion and loss of reputation
5. Prosecution and closure
6. Poor staff relations

16.4.2 Pests are the carriers of pathogens

Rodents can cause damage to food intended for humans, by consumption, contamination with faeces and urine, as well as other physical and microbiological contaminants (Table 16.2). Rodents have the capability to spread many human pathogens, such as Cryptosporidium parvum, Escherichia coli, Leptospira spp, Listeria spp, Salmonella spp, Hantaviruses, bubonic plague and toxoplasmosis. Sparrows, pigeons and gulls may also carry bacteria causing salmonellosis. Pigeons carry ornithosis, a disease similar to viral pneumonia that can be transmitted to man through infected droppings or respiratory droplets. Ornithosis is often mistaken for flu in humans and so is possibly far more common than is realised. Cockroaches also contaminate food directly as they move from filth to food indiscriminately and are therefore implicated in the mechanical transmission of many pathogens, such as those causing food poisoning and wound infections.

Table 16.2 Food borne pathogens isolated from rodents

16.4.3 Pest management in food-handling and other specialized facilities

16.4.3.1 Pest prevention

The objective of the pest management programme is the maintenance of pest-free conditions in all areas of the site. The following systematic approach should be taken to all pest control and pest prevention issues, that being:

16.4.3.2 Exclusion

This includes any measure used to prevent entry of organisms indoors through openings in the building structure, doors, windows, or on infested plant or food materials. Exclusion is often neglected or ignored with entire reliance being placed on destruction, in many cases after infestation has occurred. Some techniques include screening openings to prevent entry of flies, mosquitoes, and beetles; caulking cracks and crevices to remove existing or potential harbourages of pantry pests and cockroaches; and sealing or repairing exterior openings to prevent entry of bats, mice, bees, and wasps. The use of pesticides may then fail to achieve the desired result because building structure and conditions within are incompatible. Plants and food products must be carefully inspected for infestations at the time of purchase and before they are brought indoors.

16.4.3.3 Sanitation and inspection

Sanitation is the most important aspect of pest management in food-handling facilities. Food processing plants are subject to sanitation inspections, depending on the type of facility. The pest management professional should be aware of the problem areas. Pest control technicians must conduct a thorough inspection of the facility and notify the plant manager of potential or existing problems. This allows steps to be taken to prevent or correct problems before they are detected by regulatory inspectors or before complaints are received from customers. Sanitary measures include: disposing of garbage on a weekly basis during warm weather to control filth flies and cockroaches; discarding overripe fruits to control fruit flies and fungus beetles; removing bird nests as these harbour dermestids, clothes moths, mites and lice and vacuuming to reduce populations of fleas, carpet beetles, house dust mites, and several ground-dwelling insects and insect relatives. It is also important to keep kitchen areas clean to reduce incidence of pantry pests and cockroaches.

16.4.3.4 Habitat modification

This includes any method used to eliminate or disrupt areas where pests reside. For example, removing weeds and keeping well-mowed lawns reduces incidence of crickets and ticks. Removing debris and fallen leaves near foundations reduces sow bug and centipede populations. Wood or wooden piles, where carpenter ants, ground beetles, and spiders seek harbourage, must be stored away from structures. Creating a vegetation-free barrier around the perimeter of the building will reduce incidence of many ground-dwelling pests such as clover mites. The use of dehumidifiers is recommended, especially in basements, to create and maintain a dry environment to discourage incidence of sow bugs, centipedes, firebrats and house dust mites.

16.4.3.5 Temperature control

Artificially manipulating the temperature of substrates infested by pests or areas where pests reside is an inexpensive non chemical strategy. The time from treatment to death of a pest and numbers of the pest killed, may vary with the pest stage, temperature and duration of exposure. Pantry pests, clothes moths, and carpet beetles can be eliminated by subjecting infested foods, clothes, and carpets, respectively, to extremely hot or cold temperatures. In general, all developmental stages of pantry pests, clothes moths and carpet beetles can be killed within minutes to hours when exposed to temperatures below 0°C and above 40°C.

16.4.3.6 Mechanical control

A rolled newspaper or magazine and fly swatters are some tools used for killing visible and less mobile or immobile pests. On infested plants, hand-picking insects (e.g., hornworms) are a partially effective means of pest control. Infested leaves must be excised from plants, bagged, and discarded.

16.4.3.6.1 Traps

Traps are escape-proof devices that capture highly mobile and active pests. Live traps can be used for rabbits, pocket gophers and squirrels. Unbaited sticky traps such as red spheres, resembling apples, are useful for trapping apple maggot adults. Coloured (yellow) sticky traps are effective in capturing whiteflies and aphids. Sticky traps can be baited with commercial lures (pheromones and food attractants) to enhance trap catch. For example, sticky traps baited with lures for pantry pests, wasps, and flies are commercially available.

Traps are useful for early detection and continuous monitoring of infestations. They are not effective in reducing populations unless the pest population is isolated or confined to a small area. The chance of detecting the presence of pests in a given area is related to the number of traps used. Therefore, when pests are present in very low numbers, it is advantageous to use more than a few traps. Pests must be active or mobile to be captured in traps. Therefore, any environmental variable (temperature, humidity, wind, light, or food) or biological factor (age, sex, mating status, etc.) that influence pest activity, affects trap catch. Consequently, absence of pests in traps does not imply that the pests are not present in the sampled area.

16.4.3.6.2 Diatomaceous earth (DE)

Several DE formulations are commercially available. These products contain fossilized siliceous (silicon-containing) skeletons of aquatic diatoms (algae) of various shapes and sizes (<1 to 34 microns). DE formulations predominantly are made up of non-crystalline or amorphous silicon dioxide. Although the exact mode of action of DE products is not known, it is believed that DE kills insects and insect relatives by absorbing and abrading the water-proofing, waxy outer covering of the insect-skin (i.e. cuticle). Absorption and abrasion to the waxy layer of the cuticle leads to water loss and subsequently death due to dehydration. DE products are most effective on soft-bodied insects or insect relatives. Because the mode of action is mechanical, insects and insect relatives may not develop resistance to this natural product.

16.4.3.6.3 Biological control agents

Parasitic and predatory insects, mites, and nematodes are now commercially available to control pests. For example, lacewing larvae and ladybird beetle larvae and adults are predators of aphids. Parasitic and predatory organisms should be used only where pesticides are discontinued or were not previously used, because these beneficial organisms are highly susceptible to pesticides. The degree of control achieved with the use of beneficial organisms is variable and the cost-effectiveness for many such beneficial organisms has not been well-documented. Three different varieties of the bacterium Bacillus thuringiensis are available to control larvae of moths and butterflies (caterpillars), mosquitoes and black flies (maggots) and beetles (grubs). The varieties Kurstaki, israelensis, and San Diego are effective against caterpillars, maggots and grubs, respectively. The larvae succumb to the bacterial toxin after ingesting or consuming the treated substrate. For controlling Japanese beetle grubs on lawns, the use of Bacillus papillae may offer some control. Recent evidence suggests that caterpillars can develop resistance to the B. thuringiensis toxin.

16.4.5 Insecticides in food-handling establishments

Insecticides applied in food-handling establishments must not come in contact with or possibly contaminate food products. For this reason, it is important to distinguish between food and non-food areas of these establishments. Non-food areas may include locker rooms, lavatories, machine rooms, boiler rooms, rubbish rooms and garages. These are areas where food is not normally present, except perhaps as it is being transported from one area to another. Food areas include any location where food is stored or processed. Certain restrictions apply to the types of insecticides and treatments that can be used in food or non-food areas. Some definitions and general guidelines follow. For more specific details on whether a product can be used in food or non-food areas, refer to the product label.

16.4.5.1 Residual insecticides

Residual insecticides are those products applied to obtain insecticidal effect lasting several hours or longer. There are four types of residual applications: general, barrier, spot and crack and crevice. Each may be used in certain areas of food-handling establishments as directed by the product label.

16.4.5.2 General treatment

General treatment is application to broad expanses of indoor surfaces such as walls, floors and ceilings, or outside treatments. This is permitted only in non-food areas using only those insecticides so registered.

16.4.5.3 Barrier treatment

Barrier treatment is usually considered the application of pesticides to thresholds and other entrances, the foundation, and the soil adjacent to the foundation. A barrier treatment with residual sprays, dusts, or granules may be beneficial in controlling outdoor pests that may become invaders or nuisances when populations build up.

16.4.5.4 Spot treatment

Spot treatment is application to limited areas on which insects are likely to walk but will not be in contact with food, utensils, or by workers. Such areas may occur on floors, walls, and the bases or undersides of equipment. Spot treatments should not exceed two square feet. In many cases, spot treatment is allowed only in non-food areas. Check the label to be certain of the proper use of spot treatments.

16.4.5.5 Crack and crevice treatment

Crack and crevice treatment is the application of small amounts of insecticides into cracks and crevices in which insects hide or through which they may enter a building. Such openings commonly occur at expansion joints, between different elements of construction, and between equipment and floors. The openings may lead to voids, such as hollow walls, equipment legs and bases, conduits, motor housings, or junction or switch boxes. The crack and crevice treatment may entail the use of sprays, dusts, or baits. It can be used in food areas as long as the insecticide is placed into cracks and crevices. Residual insecticides may be applied when food establishments are in operation unless the label of the product being used specifically indicates that all operations must be stopped at the time of application.

16.4.5.6 Non-residual insecticides

Non-residual insecticides defined as those applied to obtain insecticidal effects only during the time of treatment) used in space treatments (aerosol, ULF and fog treatments), the application should be made while the food-handling establishment is not in operation and exposed foods are removed or covered. Also, food-handling surfaces should be cleaned before use. However, the use of non-residual insecticides as contact treatments (which means hitting the target pest with a wet spray for immediate insecticidal effect) can be done while the establishment is in operation. Both space treatments and contact treatments are considered general insecticide applications.

16.4.6 Rodenticides in food-handling establishments

Rodenticides are usually applied in attractive food baits or as liquids. Such baits ordinarily require “tamper resistant” containers that are designed to protect animals and children as well as to avoid contamination of food. When placing bait stations, special attention is required to protect the containers from damage and from being stolen or tampered with. Rodenticides may be used outside the facility to intercept rodents before they gain entry. They may be used inside the facility as long as they do not come in contact with food.