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Meesters JAJ, te Biesebeek JD, ter Burg W. Air Fresheners Fact Sheet: Default parameters for estimating consumer exposure – Version 2021 [Internet]. Bilthoven (NL): National Institute for Public Health and the Environment; 2022.
Air Fresheners Fact Sheet: Default parameters for estimating consumer exposure – Version 2021 [Internet].
Show detailsAnimal odour mask products are consumer products that are used to treat objects or surfaces that smell bad because of the presence of a pet. Bad odours from urine stains, hair, dander or sweat are eliminated or masked by these products, which release substances into the room air to create a pleasant scent or ambiance, so that bad smells are less perceived. The animal odour mask products included in this Fact Sheet are pet urine odour remover sprays, foams and liquids; and pet odour sprays.
10.1. Pet urine odour remover sprays
Scenarios for consumer exposure
Pets that are not house-trained may leave urine stains on carpets. To sanitise the stains and to mask the bad smells from the urine, a consumer can use pet urine odour remover spray. Odour remover sprays are available as pump and trigger sprays. User directions of pet urine odour remover sprays indicate that urine stains need to be saturated with the spray product in order to effectively remove the urine crystals that are the source of the odour (UrineOff, 2020). Thus, the volume of the sprayed product is considered to be equal to the volume of urine in the stain. Large pets with large bladders thus require more spray product to be used. Dogs are therefore considered the most exemplary domestic animal for a conservative exposure scenario relating to the treatment of pet urine stains, because they are relatively large and are well known to urinate in the home on account of old age, behavioural problems or medical conditions. The location of the exposure scenario is set to an unspecified room (Te Biesebeek et al., 2014), because a pet urine stain is not limited to a specific room but may occur in any (carpeted) room of the house (see Section 4.6.1). The consumer treats a urine stain by spraying the product onto it until it is completely saturated. Then the product is left to soak up the urine and then dry. After the soaking period the consumer rinses off the stain with water. Inhalation exposure is expected during the spraying activity, as the consumer can inhale volatile substances that evaporate from the sprayed droplets. Non-volatile substances in sprayed droplets small enough to reach the lower areas of the lungs, i.e. the alveolar region (Delmaar & Schuur, 2017), are available for inhalation exposure as well. Substances in droplets too large to pass the nasal region are not inhaled. The use of pet urine odour remover sprays is considered to be a general surface spraying activity, so that the option to ‘include oral ingestion of non-respirable material’ is not offered by default (4.1.4). Dermal exposure is expected from droplets depositing from the spray cloud onto the unprotected skin of the hands and arms of the consumer. The inhalation–exposure to spray–spraying model is used to estimate inhalation exposure to non-volatile substances, whereas the inhalation–exposure to spray–instantaneous release model is used to estimate inhalation exposure to the volatile substances in pet urine odour remover sprays. The ‘spraying towards person’ option is considered not relevant as the spray is directed towards the stain and not the person. The mass generation rate, airborne fraction and aerosol diameter are set equal to those of fabric freshener sprays (9.1 and 9.2), because the function and intended use of both products is comparable, i.e. the consumer sprays them onto a fabric and substances soak into the fabric to eliminate, trap and mask bad odours. The dermal–direct product contact–constant rate model is selected for the estimation of the dermal exposure to droplets from the spray cloud that are deposited onto the skin of the consumer. The consumer may touch the spray product after the soaking period while cleaning up the stain by rinsing and brushing. The dermal–direct product contact–instant application model is selected for the estimation of such dermal exposure.
Frequency
An incidental pet urine stain on a carpet is a reason to clean the carpet. The Cleaning Products Fact Sheet (Meesters et al., 2018) gives a frequency of 52 per year for treating a carpet with a cleaning product, based on the survey data of Garcia-Hidalgo (2017), with a Q-factor of 4. The default frequency for treating pet urine stains on a carpet is therefore set to 52 per year as a conservative estimate. The Q-factor is, however, set to 1, because it is unclear how often the consumer in the original survey of Garcia-Hidalgo (2017) cleans a carpet because of an incidental urine stain from a pet.
10.1.1. Spraying
The inhalation–exposure to spray–instantaneous release model is used to estimate inhalation exposure to the volatile substances in fabric sprays, whereas the inhalation–exposure to spray–spraying model is used to estimate inhalation exposure to non-volatile substances. The dermal–direct product contact–constant rate model is selected for the estimation of the dermal exposure to droplets from the spray cloud that are deposited on the skin of the consumer.
Spray duration
The spray duration is calculated from the amount of product that is required to treat the stain and the mass generation rate of the spray. Product information states that a urine stain needs to be saturated with the product in order to effectively eliminate the odour (UrineOff, 2020). Thus, it is assumed that the volume of product used is equal to the volume of urine excreted by the dog. Scientific publications in the field of veterinary science indicate that 0–1-year-old dogs release about 50 ml of urine at one time (Atalan et al., 1999; Karthikraj & Kannan, 2019). The density of urine eliminator is about 1 g/ml (Clorox, 2019), so that 50 g of product is needed to treat the dog urine stain. The mass generation rate of an odour mask trigger spray is set to 1.7 g/s and that of a pump spray to 0.34 g/s (see Sections 4.1.1.4 and 4.1.1.5), so that the default spray duration is set to 50 g/1.7 g/s = 30 s for trigger sprays and 50 g/0.34 g/s = 150 s for pump sprays. The Q-factor is set to 1, because the derivation of the defaults depends largely on expert judgement.
Exposure duration
Product information (Nature’s Miracle, 2020) states that after the stain is treated it needs to dry for 24 hours. It is assumed that the consumer spends 4 of these 24 hours in the same room after the stain is treated. These 4 hours refer to the time the consumer may spend in a room uninterruptedly to perform leisure activities (see Section 4.3). The Q-factor is set to 1, because the default is derived from expert judgement.
Released mass
The released mass for volatile substances is considered to be equal to the amount of product used. Therefore, the default released mass is set to 50 g (see Spray duration above). The Q-factor is set to 1, because the derivation of the defaults depends largely on expert judgement.
Table 10.1
Default values for estimating consumer exposure to substances in pet urine spray during spraying.
10.1.2. Stain rinsing
The dermal–direct product contact–instant application model is selected for the estimation of dermal exposure from the rinsing of the urine stain.
Exposed area
The exposed area is considered to be the top phalanges of all five fingers of one hand. The General Fact Sheet gives a default surface area of a hand of 450 cm2 (Te Biesebeek et al., 2014). The surface area of fingers is 225 cm2, assuming that they represent half the surface area of the hand. The surface area of one finger is then 45 cm2, one phalanx is 15 cm2 and five phalanges is 75 cm2. The default is thus set to 75 cm2. The Q-factor is set to 3, because the underlying data described in the General Fact Sheet (Te Biesebeek et al., 2014) are of high quality but are lowered by the calculation described above.
Product amount
It is assumed that the amount per cm2 applied to treat the stain is equal to the amount per cm2 on the exposed skin area of the consumer. The exposed skin area is calculated as five fingertips, because the rest of the hand is protected by the cloth. The area of stain that needs to be treated is considered to be 1000 cm2 (Meesters et al., 2018), so an amount of product of 50 g/1000 cm2 = 0.05 g/cm2 is needed. The exposed skin area is considered to be 75 cm2, referring to the area of five fingertips (see above). The default product amount that is subject to dermal exposure is thus calculated as 0.05 g/cm2 × 75 cm2 = 3.75 g. The Q-factor is 1, because of the expert judgement-based assumption that the amount per cm2 applied to the stain is equal to the amount per cm2 on the exposed skin.
Table 10.2
Default values for estimating consumer exposure to substances in pet urine spray during stain rinsing.
10.2. Pet urine odour remover foams
The consumer uses a spray can that contains a foam product to treat the urine stain on a carpet in an unspecified room. The surface area of the urine stain is 0.1 m2 according to the Cleaning Products Fact Sheet (Meesters et al., 2018). Product information states that the foam needs to soak into the stain for 30 min (Nature’s Miracle, 2020). Inhalation exposure is anticipated during the leave-on period, as volatile substances may evaporate from the applied product. Next, the consumer treats the carpet stain with (paper) towels, and the surface is patted dry. Dermal exposure is expected from rubbing the carpet or upholstery with the towels. The inhalation–exposure to vapour–evaporation–constant release area model is used to estimate inhalation exposure to substances evaporating during the time the foam is left to soak. Dermal exposure from wiping and patting with towels is estimated using the dermal–direct product contact–instant application model.
Frequency
The frequency refers to the number of times per year the consumer needs to treat an incidental urine stain on a carpet. The default frequency for treating pet urine stains on a carpet is set to 52 per year based on the frequency of generic carpet cleaning (see Section 10.1). The Q-factor is set to 1, because the default is based on expert judgement.
Exposure duration
The spraying of pet urine odour remover foam is considered to be a time-limited release event, so that the exposure duration refers to a generic exposure duration of 4 hours with a Q-factor of 1 (see Sections 10.1.1 and 4.3).
Molecular weight matrix
Water is the base ingredient of pet urine eliminator foam (Nature’s Miracle, 2020). The molecular weight matrix is therefore set to the molecular weight of water, which is 18 g/mol. The Q-factor is set to 4.
Product amount – inhalation
The default product amount that is available for inhalation is set to 50 g. The stain needs to be saturated with the foam product (Nature’s Miracle, 2020). It is therefore assumed that the volume of foam needed to treat the stain is equal to the volume of the urine excreted by the dog, which is considered to be 50 ml (see Section 10.1.1). Since water is the base ingredient of the foam (see above), the density of the product is about 1g/ml, resulting in a product amount used of 50 ml × 1g/ml = 50 g. The Q-factor is set to 1, because the derivation of the default depends on expert judgement.
Room volume
The intended use of pet urine odour remover foam is not limited to a certain room in the home, because a dog may urinate anywhere. The default room volume is therefore based on an unspecified room according to the General Fact Sheet (Te Biesebeek et al., 2014), which is 20 m3 with a Q-factor of 4.
Ventilation rate
The default ventilation rate is that of an unspecified room, which is 0.6 per hour according to the General Fact Sheet (Te Biesebeek et al., 2014) with a Q-factor of 3.
Mass transfer coefficient
A number of models that are able to estimate the mass transfer coefficient for a flat surface have been evaluated (Meesters et al., 2018). The evaluation shows that different models estimate the mass transfer coefficient at between 2 and 16 m/h depending on the type of model used, the diffusivity of the substance in the air, its molecular weight and the air flow over the surface. Therefore, a generic default value for the mass transfer coefficient of 10 m/h is proposed in the Cleaning Products Fact Sheet (Meesters et al., 2018). The default mass transfer coefficient of 10 m/h is thus also used for urine odour remover foams with a Q-factor of 2, because the underlying data are generic.
Release area
The release area refers to the surface area of the urine stain, which is set in accordance with the Cleaning Products Fact Sheet (Meesters et al., 2018) to 0.1 m2. The Q-factor is set to 1, because the default refers to a stain surface area that was originally based on expert judgement (in the first Cleaning Products Fact Sheet, Prud’homme de Lodder, 2006a).
Emission duration
The emission duration refers to the length of time the foam product is left to soak into the stain. Product user instructions (UrineOff, 2020) indicate a duration of about 30 min. The default emission duration is thus set to 30 min. The Q-factor is set to 2, because the default is based on product information.
Exposed area
The exposed area refers to the top phalanges of five fingers of one hand (see Section 10.1.2), which is calculated to be 75 cm2. The Q-factor is set to 3, because the underlying data described are of high quality but are lowered by the calculation described in Section 10.1.2.
Product amount – dermal
It is assumed that the amount of product per cm2 applied to treat the stain is equal to the amount per cm2 on the exposed skin area of the consumer. The exposed skin area is calculated as five fingertips, because the rest of the hand is protected by the cloth. The area of the stain that needs to be treated is considered to be 1000 cm2 (Meesters et al., 2018), so an amount of product of 50 g/1000 cm2 = 0.05 g/cm2 is needed. The exposed skin area is considered to be 75 cm2, referring to the area of five fingertips (see above). The default product subject to dermal exposure is thus calculated as 0.05 g/cm2 × 75 cm2 = 3.75 g. The Q-factor is 1 because of the crude assumption that the amount per cm2 applied to the stain is equal to the amount per cm2 on the exposed skin.
Table 10.3
Default values for estimating consumer exposure to substances in pet odour remover foam during urine treatment.
10.3. Pet urine odour remover liquids
The default models and parameters used to estimate consumer exposure to substances in pet odour remover liquid are also used for pet urine odour remover foam, because both products are used for the same purpose of removing a pet urine stain; and both have water as the main ingredient of the product composition (Clorox, 2019; Nature’s Miracle, 2020; UrineOff, 2020). The parameters referring to how the consumer uses the two products (product amount and emission duration) are therefore also considered to be similar, as are the parameters referring to the product matrix (i.e. molecular weight matrix). Furthermore, both products are used in the same scenario where a pet has left a urine stain in the home, and thus the frequency and location of exposure (unspecified room) are also the same (see Section 10.2). See Section 10.2 for further details of the models and parameters used.
Table 10.4
Default values for estimating consumer exposure to substances in pet odour remover liquid during urine treatment.
10.4. Pet odour sprays
Scenario for consumer exposure
Pet odour spray is used to cover bad odours left by pet hair, dander or sweat. The odour may persist after these are absorbed into fabrics such as carpets, sofas and mattresses. The consumer may choose to treat the unpleasant-smelling fabric by using a pet odour spray. The realistic conservative scenario is to assume that the odour spray is regularly used on a sofa, because it is a large fabric object where pets may lie regularly. A carpet is an even larger area, but it assumed that the consumer would not treat the entire carpet for pet odours. The way consumers handle pet odour spray to treat bad odours is considered to be similar to the way consumers use interior fabric freshener spray to treat furniture (see Section 9.2.4).
Therefore, the same default models and parameters used in interior fabric freshener spray are used to estimate consumer exposure to substances in pet odour sprays (9.2.4).
The inhalation–exposure to spray–spraying model is used to estimate inhalation exposure to non-volatile substances in pet odour spray. The ‘spraying towards person’ option is not considered relevant. Furthermore, the use of pet odour sprays is considered to be a general surface spraying activity, so that the option to ‘include oral ingestion of non-respirable material’ is not offered by default (4.1.4). The inhalation–exposure to spray–instantaneous release model is used to estimate inhalation exposure to the volatile substances in pet odour spray. The dermal–direct product contact–constant rate model is selected for the estimation of dermal exposure to droplets from the spray cloud depositing onto the skin of the consumer. For the default parameter values, see Section 9.2.4.
Frequency
Pet hair, dander or sweat left on a sofa are a reason to clean the sofa. The default frequency is therefore set to 52 per year as a conservative estimate. The Q-factor is set to 1, because the default is based on expert judgement.
Table 10.5
Default values for estimating consumer exposure to substances in pet odour sprays during the spraying of furniture.
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