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plant leaf surfaces against red spider mites. The EPA defines a spot application as 20 or less of the infested area of a home.
14.4.2.2. Crack-and-crevice applications
Crack-and-crevice applications involve spraying these building features to control such pests as silver fish, cockroaches and ants – for example, on baseboards in living and
accommodation areas, in cracks and holes in wooden floors, and areas such as door fra- mes.
14.4.2.3. General surface applications
General surface applications involve spraying such large surfaces as carpets or couches – for example, to control dust mites or fleas.
14.4.2.4. Air space applications
Air space applications involve spraying of living, working or accommodation areas against flying insects. In these applications, the user stands in the middle of the room and
sprays all four of its upper corners.
14.4.2.5. Differences between application types
These spray applications differ from each other in the manner and extent to which the person applying the pesticide and bystanders are exposed. For example, the exposures
for a crack-and-crevice application and for a general surface spray are expected to be dif- ferent, due to the longer application time of the latter treatment. The height and angle
at which the spraying occurs also account for a difference in exposure – for example, above the head, which is common during an air space application, or aimed at the floor,
which is common during a general surface spray. Among other things, after applying these sprays, the size of the wipeable surfaces differs. In the worst case, the entire sprayed
surface is assumed to be within the reach of crawling children.
14.4.3. Baits
Baits are used to kill mice, rats, ants and cockroaches and are very specific for the target pest. Some products deliver enough toxicant for a lethal dose in one feeding, while others
are fed upon a number of times before the pest dies. The pesticide products used against rats and mice are composed mainly of grains to which the AI has been added. Because it
is a poison, the product is always dyed. To prevent children and non-target species and pets from being poisoned, rodenticides usually require a bittering agent as well. Most bait
products are sold in child-resistant packaging or locked in boxes, to prevent access to all but the target pest.
For consumer use, the net contents of a single packet may not be higher than 200g, and bait stations must be included. For use in rooms, the bait must be placed in feeding boxes
that are closed at the top. For outdoor use, it must be placed in specially designed feeding
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In dogs treated for a year, convulsions, twitching, tremors, ataxia, unsteady gait, rigidity of limbs, nervous behaviour, hyper- or hypoactivity, vocalization, nodding, aggression,
resistance to dosing, lack of appetite and abnormal neurological responses were obser- ved at 2mgkg BW per day and higher. No effects were observed at 0.2mgkg BW per
day.
Fipronil and its metabolites are not genotoxic. Thyroid tumours observed in rats are not relevant to human beings. Fipronil is a slight skin irritant and a weak skin sensitizer in
animals. In a study of developmental neurotoxicity, higher sensitivity of young animals to the neurotoxic effects of fipronil was not seen. The ADI was 0–0.0002mgkg BW per
day, and the ARfD was 0.003mgkg BW.
14.4. Pesticide use patterns: application scenarios
Information on the tasks involved in using a product, the method used to apply it, and the training and choice of the person applying it are all essential in ascertaining how expo-
sure will arise. This section covers applications scenarios for spray products, baits, rodent tracking powders, and cat and dog spot-on formulations.
14.4.1. Spray products
Broadcast spray pest control products are available on the market in many formulation types and delivery devices. The target organisms for these pest control products are
arthropods, mainly such pests as fleas, mosquitoes and ticks.
For these applications, two main aspects characterize exposure: a the processing needs of the product before application, such as diluting or mixing a concentration then loa-
ding the end-use dilution into a sprayer, and b the target site of the application. Mixing and loading differ for liquids and powders: concentrated liquid products, which are dilu-
ted and dispensed from a sprayer, evaporate during dilution; powdered and granular products, which are dissolved in water and dispensed from a sprayer, disperse the dis-
solved powder into the air.
14.4.2. Liquid spray application types
With regard to the target, one can distinguish between the following four types of appli- cation: spot applications, crack-and-crevice applications, general surface applications and
air space applications.
14.4.2.1. Spot applications
Spot applications refer to spraying hiding places of crawling insects and spraying ant tun- nels. Although a relatively small surface area is sprayed, sometimes it is difficult to access
the area, both for the applicator and for the bystander. Such an area may be behind a refrigerator or radiator, or in or under kitchen cabinets. When considering the method
and extent of exposure, spot applications can be compared with the spraying of indoor
property outside a home such as use of a lawn pesti-
cide product is also conside- red a residential use; exam-
ples include products that are used on pets, lawns or
gardens.
For people, residential expo- sure to biocides can be cate-
gorized as primary and secondary exposures Fig.
14.4. Primary exposure to biocidal products occurs to
the individual who actively uses the products that
contain biocides the user. Secondary exposure occurs
to non-users or bystanders; these are individuals who do
not actively use the biocidal products, but are indirectly
exposed to biocides released during or after product use by another person the user.
Primary exposures are invariably higher than secondary exposures; however, some spe- cific subgroups of the population may experience higher secondary exposures because of
their specific behaviour – for example, children crawling on the floor. In addition, secon- dary exposure can be experienced over a much longer period of time than primary expo-
sure, particularly for persistent products.
14.5.1.1. Primary exposure of non-professional users and secondary exposures
Non-professional users are usually consumers – who may or may not read a product label. Although they are expected to comply with instructions for use of a product, there is little
guarantee of this. Also, they have no access to controls or formal personal protective equipment PPE, though they may use household protective equipment, such as garde-
ning or kitchen gloves.
The groups residential bystanders, as defined by the EPA at risk through secondary exposure are less easy to identify. However, the intended location of use – for example,
indoors, outdoors, residential or recreational – will provide useful indicators. Secondary exposure results from contamination of the indoor environment caused by residential
applications. The following two post-application scenarios for the residential environ- ment are examples of secondary exposure. The first applies to toddlers less than 8kg,
while the second is a bystander exposure applicable to all age groups.
1. Hand-to-mouth ingestion
includes children playing on the floor where biocides have
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stations, in such a way that the bait is not within the reach of children, cattle, pets or birds.
14.4.4. Rodent tracking powders
Rodenticides are used for rodent control and, in most cases, are formulated as ready-for- use products. For special purposes, some concentrates are available and some rodentici-
des are formulated as tracking powders. It is a general rule that rodenticides are formu- lated and kept in such a way that people and non-target animals are not exposed.
Tracking powders, which are rodent poisons in the traditional sense that they must be eaten to kill the pest, are placed along rodent runways, in and around buildings. When
the animal passes by, its fur picks up the powder, which is then ingested during groo- ming. Consequently, the concentration of rodenticide in contact powders is much larger
than in food baits. In view of the possible exposure of people and other non-target spe- cies, the treated areas should be covered EC, 2002.
14.4.5. Cat and dog spot-on formulations
Spot-on insecticides are becoming a popular type of flea control for pets. The products may be applied monthly for flea control or every two weeks for tick control. People are
exposed to the insecticide when residues are transferred from the treated fur to the hand or body of an adult or child. Children are most likely to be exposed in this manner,
because they are often in direct contact with the animal. Residues on hands can be trans- ferred to the mouth, especially by toddlers.
14.5. Residential exposure 14.5.1. The nature of residential exposure
The term residential refers to the generic conditions of non-occupational exposures, regard- less of where they occur. The term general population exposure could be easily substituted.
If exposures occur as a result of activity directly related to an application, they are refer- red to as handler exposures – for example, the handler can be someone who mixes or
applies a pesticide product. On the other hand, if exposures occur as a result of activities in a previously treated area, they are referred to as post-application exposures. The other
distinction that is made by the EPA is the one between the terms residential and homeow- ner
.
• Homeowner, handler exposures
result from an individual, not as a condition of hisher employment, applying a pesticide.
• Residential, post-application exposures
result from entry and activity in an environ- ment previously treated with a pesticide. These exposures may result from both occu-
pational or homeowner applications and may occur in a variety of settings, including homes, schools, day-care facilities and other public places, such as parklands.
The term home is not limited to the inside of the actual building. Use of a pesticide on the
Primary exposure Secondary exposures
Outdoor application
Indoor application Children on contamined floor
Residues on furniture surfaces
Fig. 14.4. Primary and secondary residential exposure
