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Survey and Health Assessment of Products for Interior Car Care

9 Exposure scenarios - calculations

• 9.1 Method
  • 9.1.1 Inhalation
  • 9.1.2 Absorption through the skin
• 9.2 Exposure scenarios
  • 9.2.1 Exposure by inhalation when applying products for interior car care
  • 9.2.2 Exposure during skin contact in connection with application of products for interior car care
  • 9.2.3 Total exposure
  • 9.2.4 Overall conclusion

In the light of the analysed four products for interior car care and limit value considerations, the following compounds were selected for the exposure calculations as it was assessed that they might have a potential health effect on the consumer.

The selected compounds in focus during the exposure calculations are:

• Hydrocarbons C₅-C₈
• Hydrocarbons C₁₀-C₁₄
• Butane
• 2-propanol
• Ethyl acetate
• Butyl acetate
• Limonene
• 1-propanol
• 1-methoxy-2-propanol
• 2-butoxy ethanol
• 1-butoxy-2-propanol
• Xylenes
• Benzyl chloride.

The exposure calculations represent the use of interior car care products in a closed car cabin (worst-case situation). The exposure scenarios comprise inhalation and intake through the skin.

9.1 Method

The exposure scenarios comprise a number of hypothetical cases where the consumer can be exposed to compounds in products for interior car care. The calculations are based on the following scenario that is described closer in chapter 4:

An adult applies car care agent inside his car (generally speaking with closed doors) and then goes for a car drive. Minimum exposure is set to 30 minutes as it is anticipated that application takes place at the local service station where the car is filled with petrol, the car is washed and finally car care products are applied on the interior, after which the car is driven home. Maximum exposure is set to 5 hours, because after that time measurable values of the substances in the car no longer exist for most substances. The measured values were applied in (almost) closed chambers to illustrate a more or less closed car. During the tests a certain amount of car care product was applied to a plate. Application took place quickly (in a few minutes) and then the test chamber was closed to illustrate the worst-case (application during almost closed car). The cloth with car care product remained in the test chamber for 15 minutes. After the 15 minutes the cloth was removed from the test chamber to illustrate that the user throws the cloth away or removes it to be washed. During application and afterwards, the person was exposed to the compounds via the air (substances that evaporate and are sprayed into the car cabin (for waterproofing spray)) and via the skin (direct skin contact during application).

In connection with the exposure calculations, a starting point was taken in the EU Technical Guidance Document (TGD) that describes methods for risk assessment of chemical substances (TGD, 2003).

It is anticipated that the consumer of interior car care products is an adult. The body weight of the person is set to 70 kg (men) which is the standard weight of an adult male in TGD, 2003.

In connection with the calculations a starting point was taken in the formulas in the TGD of the EU, 2003.

9.1.1 Inhalation

The calculation of the amount of substance the consumer inhales is described in the below formula. In the calculations it is anticipated that as worst-case there is no air change of importance in the car i.e. application of the interior car care products takes place when the doors are closed.

The number of times the user is exposed to the substance per day was set to 1. The inhalable or respirable part of the substance was set to 1 as worst-case unless information in the health assessments says something else.

The speed of inhalation during application was set to 1.75 m³/hour based on the EU TGD, 2003, of an adult male with light activity (upper limit for light activity applied (42 m³/day)), as it was anticipated that only a light activity is required to apply interior car care products. In the subsequent period in the car (irrespective of it being 15 minutes or 5 hours) the speed of inhalation is set to 0.45 m³/hour based on the EU TGD of an adult male at rest (upper limit for rest is applied (10.8 m³/day)). The speed of inhalation for resting was used for car driving, as light activity is not in question when sitting and driving the car. However, the upper limit was used which is specified for resting.

9.1.2 Absorption through the skin

Absorption through the skin was calculated by means of the below equation.

The number of times the user was exposed to the substance per day was set to 1. The retention factor R_f was introduced by SCCNFP (Scientific Committee on Cosmetic Products and Non-Food Products) to consider ”rinse-off” products (SCCNFP 0690, 2003) (cosmetics). The retention factor was set to 0.01 by SCCNFP when the products are rinsed off after use. The corresponding factor was used in this connection as it must be anticipated that the user washes hands after application. All the car care products have an oil-like smell and/or are greasy and therefore it is anticipated that the user will wash hands if he/she gets some of the car care product on the hands. If hands are not washed after use the calculated absorption will be 100 times higher (retention factor = 1 instead of 0.01).

The factor D_f is introduced as it is not the entire applied amount of the product that ends on the skin. The products for interior car care will typically be applied with a cloth and therefore there is no direct skin contact with the entire applied amount. It is anticipated that max. 5% of the applied amount will end on the skin (D_f = 0.05). In connection with fabric waterproofing products it is anticipated that the amount that ends on the skin will be negligible and therefore exposure calculations for skin contact were only carried out for products applied with a cloth.

By using the formula, it was not considered that volatile substances to a certain degree are liberated to the air instead of penetrating the skin. Besides, 100% permeability for the skin is assumed for the applied substances unless other values are found in the health assessments or the log P_ow values indicate something else. Regard has not been given to the fact that car care products applied in a thick layer will not give the same exposure as the same amount of car care product applied to a larger area in a thin layer. Therefore, it is possible that exposure via the skin is overestimated in the exposure scenarios that were carried out.

9.2 Exposure scenarios

In connection with the calculations, a starting point was taken in the measured and calculated concentrations stated in chapter 6. For each substance, the highest concentration/amount was determined under the chemical analyses selected for the exposure scenarios. Therefore, the scenarios will state the worst possible exposure with each individual focus substance that realistically can be expected in the light of the measured and calculated values.

The values applied in the exposure calculations are described under the health assessments for each individual substance and are repeated in the table below (Table 9.1Table 9.1). In connection with substances that were not assessed in this project, values of the health assessments in previous analysis projects carried out by the Danish EPA were applied. The reference from which the values were taken is stated in parenthesis under the individual substances.

* The values were calculated in this report.
1 NOAEL stands for No Observed Adverse Effect Level, i.e. the highest exposure value/concentration where no serious effect is observed.
2 TDI stands for Tolerable Daily Intake and is the max. tolerable dose of a chemical. RfD stands for Reference Dose and is the max. acceptable dose of a chemical. Normally, TDI/RfD appears by dividing the NOEAL value with a safety factor of 1000, 100 or 10, respectively, depending of the quality of the data from the NOAEL value.

Comments to the previously assessed substances

For butyl acetate, a NOAEL value of 7.230 mg/m³ is stated in Glensvig and Pors (2006) in a 16 day gestation test with rats. The value is not stated per kg. body weight. If it is anticipated that a female rat weighs max. 300 g^[17] and that the respiration volume of a rat is max. 130 ml/min^[18] then that will correspond to a NOAEL of 4.512 mg/kg bw/day. Corrections have not been made for the rats only inhaling the mixture 7 hours per day, as described in Glensvig and Pors (2006). If a safety factor of 1000 is used (10 for interspecies variation, 10 for intraspecies variation and 10 for sub-chronic to chronic) that gives a tolerable dose of 4.5 mg/kg bw/day. This TDI value was used in the exposure calculations.

For 2-propanol, one NOAEL value of 420 mg/kg bw/day for humans is stated in Engelund and Sørensen (2005). It is supposed to be the human dose that will not result in reproductive toxic or development effects in foetuses. If a safety factor of 10 is used (10 for intraspecies variation) that gives a tolerable dose of 42 mg/kg bw/day. This TDI value was used in the exposure calculations.

9.2.1 Exposure by inhalation when applying products for interior car care

In connection with the four products for interior car care, where measurements were carried out in the box to find out which chemicals evaporate to the air, the substances listed in Table 6.15Table 6.15-Table 6.22Table 6.22 were identified. Of the identified substances, exposure calculations were carried out of the substances that are on the List of Dangerous Substances.

Scenario: 5-hour drive immediately after application

In the exposure calculations, a scenario was anticipated where the car care products are applied – duration 15 minutes. The application cloth is thrown away /washed and the person immediately goes for a longer 5-hour drive in the car (without ventilation). That gives the following amount of inhaled substance of the different analysed products for interior car care (see Table 9.2Table 9.2). Consideration has been given to volume as well as the amount factors i.e. the concentration is calculated for the amount of car care product that is used in the car and for the typical volume of a car.

In the calculations, the values stated in Table 8.1Table 8.1 of the concentration during the first 15 minutes and over the 5 hours are used. Table 8.1Table 8.1 states the total concentration of hydrocarbons whereas the concentration in Table 9.2Table 9.2 is divided into the individual hydrocarbon fractions. The column ”Conc. first 15 min (mg/m³)” the values have been taken directly from the column in Table 8.1Table 8.1 with corresponding headline whereas the values in the column ”Conc. over 5 hours (mg/m³)” are calculated values that are not stated anywhere else.

For instance, the calculation of TDI/I_pot was carried out for Product 1 vinyl make-up for hydrocarbons C₁₀-C₁₄:

Click here to see the formula

Click here to see: Table 9.2 Calculated inhaled amount of chemicals for application and subsequent 5-hour drive in the car (without ventilation)

With the values listed in Table 9.1Table 9.1 for tolerable daily intake the following calculated safety margins are obtained (see Table 9.3Table 9.3).

As it appears from Table 9.3Table 9.3 most of the substances have a safety margin of more than 1, which means that there is no health risk involved when applying the analysed products for interior car care and subsequent stay in the car for 5 hours (where the concentration of the substances has declined substantially).

In connection with the longer hydrocarbons in product 1, vinyl make-up, and for D-limonene in product 5, fabric waterproofing agent, the safety margin is below 1 which is tantamount to a health risk. However, it should be noted that the calculations were carried out with n (number of occurrences per day) = 1, i.e. that the same product for interior car care has to be applied every day for a longer period of time before exposure will constitute a health effect.

For hydrocarbons C₁₀-C₁₄ the safety margin is below 1 (TDI/I_pot = 0.4). The calculation is carried out per day. That means the safety margin is below 1 if interior car care is used on the car every day. The safety margin will exceed 1 as long as the car care agents only are used every third day (0.4*3 > 1). In that case, the tolerable daily intake (TDI) exceeds the inhaled amount per day (I_pot) which is tantamount to a safety margin exceeding 1 and therefore no health risk.

No measurements were carried out on the worst-case scenario where all four analysed products for interior car care are used immediately after each other and it is not immediately possible to calculate the situation. Therefore, the individual measurements have been added up, corresponding to a worst-case situation, where all four analysed products are used at the same time (in practice not possible, but is anticipated to be theoretically possible). The concentration of the individual substances will increase as the same chemical substances appear in several of the analysed products. This hypothetical situation will not give rise to a health risk as long as the car care products at a maximum only are used every third day. Adding up the concentration of the substances that appear in several of the four analysed products will not change the relation between the tolerable daily intake and the inhaled amount per day (TDI/I_pot). See Table 9.4Table 9.4 below.

If it is anticipated that not an adult male but a child is exposed to the substances, then all inhaled amounts per day (I_pot) will amount to app. 140-235% of the calculated inhaled amounts of an adult male (see calculation example below). That is because children have a lower weight, but a larger respiratory volume per weight unit compared to adults. Under normal conditions, the car care products will not be applied by children but they could e.g. be exposed to the substances if the family gets into the car and drives on holiday immediately after application of car care products. Therefore, a calculation has been carried out where it is anticipated that a child also is present during application of the car care products.

However, some of the substances (butane and ethyl acetate – butane which was found in nearly all spray products and ethyl acetate that mainly was found in fabric waterproofing (product no. 5) (see Table 2.1Table 2.1)) can be liberated in concentrations where irritative effects on the respiratory tracts can appear and therefore it is recommended to apply car care products with open car doors and to turn on the ventilation in the car if going for a car drive immediately after application.

Calculation example – children

The inhalation speed of children is anticipated to be 0.5 m³/hour during application and when driving in a car (corresponding to a light activity as defined in TGD, 2003).

Inhaled amount per day I_pot =

= 0.55 mg/kg bw/day.

If that figure is compared to the tolerable daily intake (TDI) of 0.1 mg/kg bw/day for medium chained hydrocarbons, then TDI/I_inh of 0.18 is obtained, i.e. a value below 1.

When a child, as worst-case, also is present in the car during the entire application process, then the relation TDI/I_pot will be above 1 in most cases, however, values for the relation TDI/I_pot will be below 1 for hydrocarbons C₁₀-C₁₄ and for limonene where the calculated values are 0.18 and 0.5, respectively. The lowest value of hydrocarbons C₁₀-C₁₄ gives a calculated safety margin below 1 (TDI/I_pot = 0.18). The calculation is carried out per day. That means that the safety margin is below 1 if interior car care products are used in the car every day. The safety margin will exceed 1 as soon as the car care products only are used once a week (0.18*7 > 1). Here the tolerable daily intake (TDI) exceeds the inhaled amount per day (I_pot) which results in a safety margin above 1 and therefore there is no health risk.

Scenario: 15 minute drive immediately after application

In the exposure calculations a scenario is anticipated in which the car care products are applied at the local service station – duration 15 minutes. The application cloth is thrown away/washed and the person then drives directly home in the car (without ventilation) – duration 15 minutes. Table 9.4 shows the amount of inhaled substance that will result in for the various analysed products for interior car care. Consideration has been given to volume as well as the amount factors, i.e. the concentration is calculated for the amount of car care that is used in the car and for the typical volume of a car.

Click here to see: Table 9.5 Calculated inhaled amount of chemicals for application and subsequent 15-minute car drive (no ventilation)

With the values listed in table 9.1 for tolerable daily intake, the following calculated safety margins are obtained (see Table 9.6Table 9.6).

As it appears from Table 9.6Table 9.6 there is no great difference in the safety margins from the scenario with 5-hour drive and merely 15-minute drive. That is because the largest exposure takes place within the first half hour as that is when the substance concentration is greatest. Then the concentration declines subsequently.

A similar picture develops as when driving 5 hours: The majority of the substances have a safety margin that is larger than 1, but for the longer hydrocarbons in product 1, vinyl make-up, and for D-limonene in product 5, fabric waterproofing agent, the safety margin is below 1, which is tantamount to a health risk. In that case, exposure can result in liver and blood changes (e.g. cell increases). However, changes seen in the liver of experimental animals were reversible, i.e. the changes might return to normal again. It should be noticed that the calculations were made with n (number of incidences per day) = 1, i.e. that the same product for interior car care has to be applied every day for a longer period of time before exposure will constitute a health effect.

As soon as the car care products only are used every other day (n = ½), the tolerable daily intake (TDI) exceeds the inhaled amount per day (I_pot), which results in a safety margin above 1 and therefore there is no health risk.

In worst-case, when all four analysed car care products for interior car care are used simultaneously (in practice not possible but anticipated to be theoretically possible), the concentration of some substances will increase as the same chemical substances appear in several of the analysed products. In this hypothetical case there will be no health risk as long as the car care products only are used max. every other day.

It must be anticipated that in practice products for interior car care are only used once or max. twice a month by the most punctilious people. In that case, the analysed products for interior car care will not give rise to health concern.

Discussion of duration of application and applied amounts

In connection with the above calculations it is assumed that application takes 15 minutes per product that is used. If a person is very careful and spends e.g. 30 minutes on applying one car care product, then the amount of used car care product might increase and the time during which the person is exposed to a higher concentration of vapours from chemical substances will increase.

Therefore, the inhaled amount per day has been calculated in relation to TDI for one substance (the hydrocarbon fraction C₁₀-C₁₄). That compound was chosen because in the calculations it gives the lowest safety margin (below 1) and therefore it is the most critical compound.

If an adult instead spends 30 minutes applying vinyl make-up (product 1) – and uses the same amount (assumed that the concentration measured during the first 5 minutes appears for 30 minutes) then the relation between the inhaled amount per day/TDI can be calculated to 0.16. That means there is a health risk related to using the product every day (30 minute application and subsequent 5-hour drive). However, if the product is used max. once a week the relation inhaled amount per day/TDI will exceed 1, which is tantamount to no health effects.

If an adult spends 30 minutes on applying vinyl make-up (product 1) and uses twice the amount (assumed that the measured concentration has to be doubled when using twice the amount and assumed that the concentration measured during the first 5 minutes appears for 30 minutes), then the relation between inhaled amount per day/TDI can be calculated to 0.08. That means that there is a health risk when using the product every day (30 minute application and subsequent 5- hour drive). However, if the product is used max. once every fortnight the relation inhaled amount per day/TDI will exceed 1, which is tantamount to no health effects.

The calculated safety margin for the hydrocarbon fraction C₁₀-C₁₄ will also be below 1 if the application time and amount is doubled. If the product is used max. once every fortnight, then the relation inhaled amount per day/TDI will also exceed 1 which is tantamount to no health effects.

The calculations are based on tests with ”almost closed ” cabin, i.e. during ventilation (open car doors) one person will during application be exposed to substantially smaller concentrations.

Remarks to substances labelled with R67 – Vapours may cause drowsiness and dizziness

Several substances are labelled with the risk phrase R67 (Vapours may cause drowsiness and dizziness) which can be regarded as an especially interesting effect when car driving is in question. The following is a short summary of the knowledge collected in this project concerning the substances with that effect simultaneously measured in the box tests:

• Ethyl acetate
• 2-propanol
• Butyl acetate

The health assessment of ethyl acetate in this project shows that the measured concentrations of ethyl acetate (max. 11.7 mg/m³) at no time exceeds the concentrations where the substance causes inconvenience (at 720 mg/m³ the smell of the vapours is unpleasant while mild irritation of eyes, nose and throat was ascertained at 1440 mg/m³ (Jensen, 2003)).

Health assessments of 2-propanol and butyl acetate were carried out in previous analysis projects of the Danish Environmental Protection Agency. According to the safety data sheets of the products 2-propanol appears in eight different products (product 3, 4, 10, 21, 24, 29, 31 and 33). In three products, the content of 2-propanol is so large that they are labelled with R67 ” Vapours may cause drowsiness and dizziness”. Two of the products have that labelling. That means that one product has not been labelled with R67 although this should appear. The remaining products have a 13% or less content of 2-propanol which does not result in labelling with R67. That means that when using product 10 (vinyl cleaner), 31 (glass cleaner) and 33 (anti-mist product), lethargy might appear during use (no ventilation) – however, measurement of the concentration of 2-propanol during actual use of these products were not carried out in the project. According to the health assessment of 2-propanol, described in Engelund and Sørensen (2005), an air concentration of 980 mg/m³ can result in light irritation of nose, eyes and throat, and at concentrations of 1960 mg/m³ the symptoms are intensified without being serious. The highest labelled concentration of 2-propanol was 11 mg/m³, i.e. not in a concentration that should give irritative effects.

According to the safety data sheets of the products, butyl acetate appears in two products (product 5 and 12). None of the products has a content of butyl acetate that exceeds 10% and therefore labelling with R67 is not necessary. Butyl acetate is in Glensvig and Pors (2006) stated to have a LCI value of 7 mg/m³, which is the lowest amount that can give locally irritating effects when inhaled. The highest measured concentration of butyl acetate is 70 mg/m³, i.e. local irritation will only appear when using product no. 5, fabric waterproofing agent. No values are mentioned in Glensvig and Pors (2006) that state at which concentration butyl acetate vapours can give lethargy and dizziness.

9.2.2 Exposure during skin contact in connection with application of products for interior car care

In the light of the quantitative analyses carried out on 15 selected products for interior car care (see Table 6.4Table 6.4 - Table 6.14Table 6.14), exposure calculations were carried out for skin contact with the substances found in the products in concentrations of 1% or more and that simultaneously have a relevant health classification. However, benzyl chloride was also selected due to the carcinogenic properties of the substance.

Table 9.7 Calculated absorbed amount of chemicals through the skin during application of the products.

As it appears in Table 9.7Table 9.7, all of the listed substances have a safety margin of min. 23 (>> 1), which is tantamount to no health risk during application of the analysed products for interior car care although the products are applied without using gloves. However, in the calculations a retention factor of 0.01 has been used by SCCNFP (Scientific Committee on Cosmetic Products and Non-Food Products) to take ”rinse-off” products (SCCNFP 0690, 2003) in cosmetics into consideration. If hands are not washed after use it means that the calculated absorption will be 100 times higher (retention factor = 1 instead of 0.01) and the calculated safety margins will therefore be between 0.2 and 12 and the safety margin will in six cases be below 1 (i.e. health risk). It should be noted that the calculations were carried out with n (number of occurrences per day) = 1, i.e. the same product for interior car care has to applied every day for a longer period of time before exposure will contribute to a health effect.

It is recommended to use gloves as the compounds may degrease skin and result in dry skin.

9.2.3 Total exposure

The inhaled amount and the absorbed amount by skin contact have to be added up for each substance to obtain the total exposure. However, exposure during skin contact is substantially smaller than during inhalation of the same substances (a factor 3 – 177) and therefore the conclusion remains the same: As long as the analysed products for interior car care only are used every third day or less then there is no health risk when using the products.

9.2.4 Overall conclusion

The exposure calculations for inhalation of the chemical substances that evaporate from the four analysed products show that no matter if you go for a short drive (15 minutes) or a long drive (5 hours) in the car immediately after application of the car care product (duration 15 minutes), then there is no health risk when using the analysed products for interior car care unless the products are used every day for a longer period of time. In that case, exposure can result in changes in liver and blood (e.g. increased cells). However, changes seen in the liver of test animals were reversible, i.e. the changes can go back to normal again. As long as the products are only used once a week – or a couple of times a year, which probably is most realistic, then there is no health risk when using the products that have been investigated closer in this project. The products must be used in double amounts and more frequent than every second week before a long term risk is possible.

The exposure calculations for skin contact show that even though the products for interior car care are applied without using gloves (but with an application cloth), then there will be no health risk connected with using the analysed product as long as the user washes hands after use or only uses interior car care products every fortnight. That also goes for cleaning tissues when there is direct contact with the compounds.

The inhaled amount and the amount absorbed via skin contact have to be added up for each compound in order to obtain total exposure. However, exposure during skin contact is much less than during inhalation of the same substances and therefore the conclusion remains the same: As long as the analysed products for interior car care during normal use only are used max. twice a week or less, then there is no health risk when using the products investigated in this project.

No substances evaporate in concentrations that exceed the individual work threshold limit values of the compounds. Calculations show, that in worst-case more than one full can has to be used (in this case vinyl make-up) at once in order to exceed the limit value of the compounds. Even though no limit values are exceeded, some of the compounds can be liberated in concentrations where irritating effects may appear and therefore it is recommended to apply car care products with the car door open and to ensure good ventilation in the car if going for a drive in the car immediately after application. It is also recommended to use gloves as the compounds may degrease the skin and result in dry skin.

In general, the following is recommended when using interior car care products:

• Ensure proper ventilation during application of products (open the car doors).
• Use as small an amount as possible.
• When using spray products – spray away from the inhalation area and avoid inhalation of spray mist.
• Wash hands after using the products or use gloves.

[17] Weight of Sprague Dawley rats which the test is based on is 250-300 g for female rats and 450-520 g for male rats according to http://aceanimals.com/SpragueDawley.htm.

[18] Found at http://gray.hmgc.mcw.edu/pipermail/rat-forum/2000-April/000531.html.130 ml/min corresponds to app. 2% of the respiratory volume of a human at rest.

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