Scenario for consumer exposure

During mixing and loading, the user pours the bathroom cleaner straight into a bucket (no use of a measuring cup). By doing this, inhalation exposure from evaporation and dermal exposure to the pure product due to spills can occur. Next, the consumer cleans a shower cubicle (Prud’homme de Lodder et al., 2006a) with 4 walls of 2 m² and a shower floor of 1 m², making a total surface of 3 m². While cleaning the surface, the user is exposed dermally to diluted substance from dipping the cloth into the bucket. Inhalation exposure to volatile substances is expected from evaporation of the substance from the treated surface. It is assumed that the consumer will leave the bathroom 5 minutes after the cleaning task. Secondary exposure is not anticipated, since the treated surfaces will not be within the reach of small children during or directly after the cleaning task.

Frequency

According to AISE (2014), the use frequency of bathroom surface cleaning is 1–7 times per week. According to EPHECT (2012), most consumers use bathroom cleaners weekly (71%), i.e. at least once a week (80%). According to EPHECT, the 75^th percentile of the use frequency of bathroom cleaners is ‘several times a week’ (EPHECT, 2012; table Q 53). Analysis of the EPHECT survey data shows a probabilistically simulated 75^th percentile for the use frequency of 2.7 per week (Annex II). Garcia-Hidalgo et al. (2017) present summary data, from which it can be derived that ‘3–6 times per week’ represents the 75^th percentile for the frequency of cleaning the bathroom excluding the respondents that claim never to clean the bathroom. The summary data presented by Garcia-Hidalgo et al. (2017) proves to be internally consistent, as their 75^th percentile for the use frequency of liquid bathroom cleaner expressed in min/day (11-20 min/day) divided by their 75^th percentile for duration of the cleaning task (10–30 min) yields a range of 2.6–14 times per week. The 75^th percentile of 3–6 times per week falls within this range. A default frequency of 3 times per week, 156 per year, agrees with the use frequency of liquid bathroom cleaner according to EPHECT (EPHECT, 2012; Annex II) and Garcia-Hidalgo et al. (2017) as well as for the frequency of the task of cleaning the bathroom (Garcia-Hidalgo et al., 2017). The number of samples is high, the data from the different sets are consistent with each other and specifically collected for the use of bathroom cleaner. Therefore, the Q-factor of the default frequency is set to 4.

10.1.1.1. Mixing and loading

During the opening of the bottle and pouring of liquid bathroom cleaner into a bucket, volatiles evaporate from the bottle into the personal breathing zone of the consumer. Meanwhile, spills (droplets) end up on the back of the pouring (directing) hand. To estimate the expected exposure the inhalation–exposure to vapour–evaporation–constant release area model and the dermal–direct product contact–instant application loading model are used (see Section 4.1.2). Defaults for the parameters: product amount (inhalation), exposure duration, room volume, release area, application duration, exposed area and product amount (dermal) are described in the generic scenario (4.1.2).

10.1.1.2. Application: cleaning

During cleaning, the hands and forearms come into contact with the diluted product and volatile substances evaporate from the treated surface. To estimate exposure during cleaning the inhalation– exposure to vapour–evaporation–increasing release area model and the dermal–direct product contact–instant application loading model are used. Defaults for the parameters: product amount for dermal exposure and exposed area are described in the generic scenario for the application of diluted products (4.2.3).

Scenario for consumer exposure

The consumer treats a shower cubicle with 4 walls of 2 m² and a floor of 1 m² with a trigger spray. Since spray bathroom cleaners are ready-to-use products, mixing and loading is not required before application. The product is first sprayed onto the surface (application). At this moment inhalation exposure is expected from aerosols generated by the trigger spray, whereas dermal exposure is also expected from sprayed aerosols depositing on the unprotected skin of the consumer. Once the cleaning product has been sprayed onto the surface of the walls it is left to soak (leave-on) for several minutes. Finally, the surface is rinsed or wiped with a wet cloth. Exposure during leave-on is, however, not calculated, because inhalation exposure to volatile substances in sprays is already covered by exposure during spray application (4.2.2). Dermal exposure is also not expected during leave-on, because the consumer will not touch the treated surface until it is rinsed or wiped. Upon wiping the surface, dermal exposure is expected from hand contact with the cloth. Such dermal exposure is considered equal to that of cleaning the bathroom with liquid cleaner. The treated surface is assumed not to be within reach of small children and the consumer will leave the shower cubicle after the cleaning task, so that secondary exposure is not expected.

Frequency

Analysis of EPHECT (2012) data gives a 75^th percentile of the use frequency of bathroom spraying products of 120 per year (n=740) (Annex II), whereas Westat (1987) gives a 75^th percentile of 52 times per year. A 75^th percentile of ‘1–10 min/day’ is derived from the summary data (n=611) of Garcia-Hidalgo et al. (2017). The task duration of cleaning the bathroom with spray cleaner is set to 10 min based on the data of AISE (2009, see below). Assuming that the task takes 10 min, the use frequency derived from the summary data of Garcia-Hidalgo et al. (2017) of 1–10 min per day can be recalculated into a frequency of 37–365 per year. Nonetheless, it is not certain to what extent this frequency (expressed in min/day) is due to the duration of the task (min) or how often the task is performed (per day). Therefore the EPHECT data (Annex II) are more appropriate for deriving the default frequency. Still, the summary data of Garcia-Hidalgo et al. (2017) indicate that their frequency expressed in min/day is consistent with the frequency expressed as per day by EPHECT (2012). The 75^th percentile derived from Westat (1987) is considerably smaller. The data of EPHECT (2012) and Garcia-Hidalgo et al. (2017) are preferred over those of Westat (1987) because they are more recent and are consistent with each other. The default frequency is thus set to 120 per year. The Q-factor is set to 4, because the underlying datasets are large, consistent and specifically collected to calculate the use frequency of bathroom spray cleaner.

10.1.2.1. Application: spraying

Inhalation exposure to non-volatile substances in sprayed aerosols is estimated using the inhalation–exposure to spray–spraying model. Dermal exposure is estimated using the dermal–direct product contact–constant rate loading model. The defaults for the parameters: mass generation rate, density non-volatiles and contact rate area are in accordance with the generic scenario (4.2.1). Inhalation exposure to volatile substances in bathroom cleaner sprays is estimated using the inhalation–exposure to spray–instantaneous release model. The defaults for the parameters: exposure duration, room volume, ventilation and inhalation rate for non-volatiles in bathroom cleaner sprays also apply to volatile substances.

10.1.2.2. Application: rinsing

Dermal exposure to bathroom spray during the rinsing task is expected, as the consumer touches a wet cloth that contains the sprayed product. According to the generic exposure scenario for cleaning with a wet cloth (4.2.2), dermal exposure is estimated using the dermal–direct product contact–instant application loading.

Frequency

The previous Cleaning Products Fact Sheet (Prud’homme de Lodder et al., 2006a) prescribes a default frequency of 260 per year based on Weegels (1997). These authors investigated the use of toilet cleaners and derived a mean frequency of 2 times per week (St. Dev=4.2, n=10) and a 75^th percentile of 5 times per week (Weegels, 1997). According to the AISE survey (2014), the maximum use frequency is 2 times a week. According to the summary data of Garcia-Hidalgo et al. (2017), the 75^th percentile value for the frequency of cleaning the toilet corresponds to ‘3–6 times per week’, the duration ‘1–10 min per task’ or ‘1–10 min per day’. Hence, the summary data presented by Garcia-Hidalgo et al. (2017) prove to be internally consistent. The default frequency is set to 156 per year (3 times per week) in accordance with the different data sources. The Q-factor is set to 4, because the underlying dataset is large and was collected specifically to measure the task of cleaning the toilet.

Emission duration

According to AISE (2014), it takes ‘less than 1 min’ to clean the toilet bowl. Weegels (1997) found a mean value of 72 s (St. Dev=41 s) and a 75^th percentile of 100 s (total range 10–150 s). According to the summary data of Garcia-Hidalgo et al. (2017), the 75^th percentile for application duration would be ‘1–10 min per task’ or ‘1–10 min per day’ for a frequency of ‘3–6 times per week’. The default value remains 2 min, because this duration agrees with the data of Weegels (1997) and of Garcia-Hidalgo et al. (2017) for task duration (1–10 min per task) and frequencies (1–10 min a day; 3–6 times a week). The Q-factor is set to 4, because the data of Weegels (1997) and Garcia-Hidalgo et al. (2017) are consistent, and the dataset of Garcia-Hidalgo et al. (2017) is large and specifically collected to measure the duration of cleaning a toilet bowl.

Exposure duration

The previous Cleaning Products Fact Sheet (Prud’homme de Lodder et al., 2006a) prescribes a default of 3 min. Recent studies by Andra et al. (2015) and Kalyvas et al. (2014), however, show that 3 min is an underestimation of the exposure duration. Rather, the questionnaire data of Andra et al. show a median duration for the entire cleaning task of 8 min (n=57), whereas the questionnaire data of Kalyvas et al. presents a 75^th percentile of 7 min (n=224). A new default is set at 7 min, based on the data of Kalyvas et al. (2014), which comprises the largest number of investigated individuals. The Q-factor is 4, because the underlying dataset is large and specifically collected to measure the task of cleaning a toilet.

Room volume

The previous Cleaning Products Fact Sheet (Prud’homme de Lodder et al., 2006a) prescribes a default of 2.5 m³.This is a worst-case approach, as it is assumed that the toilet is in a separate room and the door is closed. The default remains at 2.5 m³, but the Q-factor is lowered to 2 as the underlying data and assumptions are based on a combination of expert judgment and data on toilet volumes from the General Fact Sheet.

Release area

The release area is equal to the surface that needs to be cleaned, which is the inside of the toilet bowl. This surface area is calculated as that of a truncated cone plus the bottom of the toilet bowl. The radius of the rim of a standard toilet is about 20 cm and the radius of the bottom about 5 cm. The depth of the toilet is about 20 cm and the rim about 5 cm (Kohler, 2017a, b; Parisi Bathware 2016). The toilet rim is not considered to be part of the bowl, so that the depth of the surface to treat is 20 - 5 = 15 cm. The area of the truncated cone is calculated as:

The default release area is thus set at 1750 cm². The Q-factor is 2, because the data supporting the calculation are limited.

Product amount – inhalation

The toilet is cleaned with an undiluted cleaning product. The product amount depends on the type of toilet cleaner: acid- or bleach-based. According to Weegels (1997), the average amount bleach agents used is 55 g and the 75^th percentile is 80 g (St. Dev=37 g, n=9). For acid agents Weegels found an average amount of 40 g and a 75^th percentile of 55 g (St. Dev=22g, n=12). AISE only gives 30 g as a typical amount for liquid toilet cleaners, whereas for gel toilet cleaners the typical amount is set as 25 g with a range from 20 to 35 g (AISE, 2014). Therefore, the default product amounts for inhalation are still based on Weegels’ 75^th percentiles: 80 g for bleach and 55 g for acids. The Q-factor is 3, because the number of data points is limited (n=9 for bleach, n=12 for acids) but the data were specifically collected to measure the cleaning of toilet bowls.

Molecular weight matrix

The fraction of water in both toilet cleaner types (acid and bleach) is estimated as 0.85 (Table 10.6). Following the conservative approach, the default molecular weight matrix is calculated as the molecular weight of water (18 g/mol) divided by the fraction of water in the product (0.85), which yields 21 g/mol. The Q-factor is 2, because the supporting quantitative data are limited.

Exposed area

It is assumed that dermal exposure can be estimated using the same approach as the rough brushing application of biocides (ECHA, 2015b). The Guidance on the Biocidal Products Regulation indicates that during ‘rough brushing’ the hands and forearms of the person holding the brush are subject to dermal exposure. However, during toilet cleaning with a liquid toilet cleaner, only one hand is in the bowl. The default exposed area is thus set to 450 cm² with a Q-factor of 3, which is consistent with the default and Q factor presented in the General Fact Sheet (Te Biesebeek et al., 2014).

Contact rate

The consumer is dermally exposed through splatters of undiluted product from roughly brushing the toilet pan. It is assumed that dermal exposure can be estimated using the same approach as the rough brushing application of biocides (ECHA, 2015b), which describes a 75^th percentile contact rate of 193 mg/min. The default is thus set to 193 mg/min. The Q-factor is set to 2, because the original dataset (HSL, 2001) is large but refers to painting rough wooden joints. Hence, the quality of the data is compromised by assuming they are suitable for estimating dermal exposure from brushing a toilet.

Product amount

The product amount that is subject to inhalation is interpreted as the amount of product that is in the air. The air concentration is constant over time, which means there is a steady-state situation. For such a steady- state situation the amount of product in the air can be calculated from a mass balance equation (Mackay, 2001): m = E/k, where m is the amount of product in the air, E is the emission rate of the product to the air and k is the removal rate by means of ventilation. The ventilation rate in a toilet room is 2 room air changes per hour (Te Biesebeek et al., 2014). The emission rate is calculated as the mass of the rim block divided by service life time of the product. In the previous Cleaning Products Fact Sheet (Prud’homme de Lodder et al., 2006a) the default mass of a solid rim block is given as 30 g and its service life 30 days, whereas a liquid rim block contains 70 g of substance and has a service life of 60 days. Hence, the steady-state amount of product in the air is 0.021 g for solid blocks and 0.024 g for liquid blocks. The Q-factor remains 2, because the supporting data are limited.

Ventilation rate

For this specific calculation the ventilation rate is set to zero to avoid double calculation of the amount of substance removed. Ventilation is the process that removes the product from the air in the toilet room. However, this removal process is already included in the calculation of the steady-state product amount. The Q-factor is set to 3, referring to the default ventilation rate of a toilet in the General Fact Sheet (Te Biesebeek et al. 2014) used above to calculate the steady-state product amount.

Exposure duration

Exposure duration reflects the duration of a toilet visit by the consumer. It is considered healthy behaviour for a person to go to the toilet 10 times a day for 5 min (Heaton et al., 1992; B&B Community, 2017), so that the daily time spent on the toilet is about 50 min. The default exposure duration is therefore set to 50 min. The Q-factor for this default is 2, because the supporting data are limited.