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Mapping and health assessment of chemical substances in shoe care products

7 Exposure scenarios

7.1 Exposure scenarios
     7.1.1 Scenario 1 - Shoe polishing
     7.1.2 Scenario 2 - Impregnation
7.2 Exposure evaluations for shoe polish
     7.2.1 Turpentine oil
     7.2.2 Mineral turpentine
     7.2.3 C_9-12 isoalkanes
7.3 Exposure evaluation for impregnation products
     7.3.1 Propan-2-ol
     7.3.2 Heptane
7.4 Conclusion

7.1 Exposure scenarios

The below exposure evaluations have been carried out as worst-case scenarios according to the principles stated in Technical Guidance Document (TGD2003).

When calculating the exposure, a room volume of 20 m³, which illustrates application in a small and badly ventilated room (e.g. a hallway) has been used along with a volume of 2 m³, which illustrates a short-term situation in which the 2 m³ is the amount of air surrounding the person, in the following called the person's immediate zone.

Only exposure through application is calculated, not the subsequent use of the footwear.

The amount of shoe polish and impregnation product respectively used has been established based on experiments with varying types of footwear in which the products were weighed before and after application.

Table 25 Used amount in grammes for treatment of different shoe types

7.1.1 Scenario 1 – Shoe polishing

In this scenario, a pair of shoes is polished. The amount used is set at 2.56 g which is the amount corresponding to the maximum consumption stated in table 25.

It is assumed that the person polishes 2 pairs of shoes once a week. The application takes place using a cloth and takes 5 minutes.

When polishing the shoes, the skin is exposed to an amount corresponding to 10% of the amount used of the product.

7.1.2 Scenario 2 – Impregnation

In this scenario, a pair of boots is impregnated. The amount used is set at 27.8 g corresponding to the largest consumption in the experiments summarised in table 25.

It is assumed that 4 pairs of boots are impregnated twice a year corresponding to impregnation of 8 pairs of boots annually.

It is assumed that the impregnation takes 3 minutes, that the person is in the room for 5 minutes. During impregnation, the skin is exposed to an amount corresponding to 10% of the amoutn of the product used.

7.2 Exposure evaluations for shoe polish

7.2.1 Turpentine oil

A shoe polish contains 25% turpentine oil. Exposure through inhalation, skin and the total exposure can be seen in table 26.

Table 26 Exposure evaluation for turpentine oil in shoe polish

If the calculated air concentration is compared to 2 m³ and 20 m³ respectively with the irritation threshold in humans (420 mg/m³) it can be concluded that there may be a risk of irritation effects by application in a very small room as the concentration in the immediate zone is close to the irritation threshold.

The zero-effect-level for irritation effects and acute effects on the central nervous system by inhalation is set as equal to the limit value in the working environment. However, the limit value cannot be used directly as consideration must be paid to exposure 24 hours a day, 7 days a week (168 h) instead of a 40-hour work week. In addition, the limit value stated as an air concentration must be omregnet to a daily dose by using a respiration volume of 20 m³/day and a body weight of 70 kg: These values for respiration volume and body weight are equal to the default values used by EUSES.

The Margin of Safety (MOS) for acute irritation effects as well as acute effects on the central nervous system by inhalation can be calculated to be

As turpentine oil can be absorbed through the skin, a MOS-value for the total exposure can furthermore be calculated resulting in

A MOS-value of 100 or above provides a reasonable security against effects on the consumer. However, when using the total exposure and by EUSES calcuations, values below 100 is reached for both room volumes.

Based on the exposure evaluation for turpentine oil it can thus be concluded that the consumer is exposed to airway irritation and acute effects on the central nervous system when using a shoe polish containing 25% turpentine oil.

In addition, turpentine oil is classified as allergenic by skin contact an as no clear ”zero-effect-level” can be defined for this effect it is in any case important that skin contact is avoided when using products containing turpentine oil.

7.2.2 Mineral turpentine

A shoe polish containing 75% mineral turpentine is used.

Exposure by inhalation, skin and total exposre can be seen in table 27.

Table 27 Exposure evaluation for mineral turpentine in shoe polish

The limit value in the working environment is used as a zero-effect-level for irritation effects as well as acute and chronic effects on the human central nervous system. If the limit value is converted to a daily dose you get

The Margin of Safety (MOS) for acute irritation effects as well as acute and chronic effectes on the central nervous system by inhalation can then be calculated to be

As some of the components in mineral turpentine can be absorbed through the skin, a MOS-value for the total exposure can be calculated instead givning

The MOS-value for total exposure is probably too low as a 100% skin absorption of mineral turpentine was calculated which is not likely to be realistic.

If the starting point is instead the MOS-values for inhalation alone it can be seen that the value for 2 m³ is below 100 while the value for 20 m³ is above 1000. On this basis it can be concluded that there is a potential risk that the concentration in the inhalation zone when applying a shoe polish containing 75% mineral turpentine may lead to irritation effects and in serious cases also acute effects on the nervous system.

7.2.3 C_9-12 isoalkanes

A shoe polish containing 26.5% C₉-C₁₂ isoalkanes is used.

Exposure by inhalation, skin and the total exposure can be seen in table 28.

Table 28 Exposure evaluation for C₉-C₁₂ isoalkanes in shoe polish

The zero-effect-level for neuro-teoxic effects in humans can be estimated at approx. 200 g/m³ as stated in chapter 6.3.4.6.

At a concentration of 200 mg/m³ the dose that does not lead to neuro-toxic effects can be calculated to be:

The MOS-value for neuro-toxic effects by inhalation can be calcuated to be:

The MOS value based on the total absorption becomes

Absorption through the skin and thus the total absorption is, however, overestimated as the substance is not absorped 100% through the skin. The MOS-value for absorption through inhalation is thus considered as being the most valuable.

On this basis it can be concluded that there is no substantial risk of neuro-toxic effects to the consumer.

7.3 Exposure evaluation for impregnation products

7.3.1 Propan-2-ol

An impregnation product in a 200 ml spray is used. The product contains 93% propan-2-ol.

Exposure by inhalation, skin and the total exposure can be seen from table 29.

Table 29 Exposure evaluation for propan-2-ol in impregnation product

If the limit value in the working environment is used as zero-effect-level for narcotic effects and this concentration is converted to a daily dose you get

The MOS-value for irritation and narcotic effects by inhalation can thus be calculated to be:

Propan-2-ol is easily absorped through the skin and the MOS-value for irritation and narcotic effects by total absorption can be calculated to be:

By further comparing the calcuated air concentrations (12,900 and 1,290 mg/m³) to 980 mg/m³, which is the concentration that leads to slight irritation of eyes, nose and airways, it can be concluded that there will be a risk of irritation to the airways when using an impregnation product containing 93% propan-2-ol.

The NOAEL-value for teratogenic effects in humans by ingestion of propan-2-ol has be set at 420 mg/kg/d.

The MOS-value for this effect can, by absorption through inhalation, be set at:

and by total absorption at:

The MOS-values are of a size that indicates that the risk of foetal damage when using impregnation products containing 93% propan-2-ol is very small.

7.3.2 Heptane

An impregnation product in a 300 ml aerosol is used. The product contains 25-50% heptane. It is assumed that the content of the substance is equal to the upper concentration limit.

Exposure by inhalation, skin and the total exposure can be seen in table 30.

Table 30 Exposure evaluation for heptane in impregnation product

The zero-effect-leve for airway concentration has been reported at 715 mg/m³ and the limit value in the working environment is established at 820 mg/m³.

If a lower irritation concentration of 715 and 820 mg/m³ respectively is used, the daily dose that does not lead to effects can be estimated to be 48.6 – 55.7 mg/kg/d as NOEL is set as equal to NOAEL.

The zero-effect-level for airway concentration is set at 715 mg/m³ and the zero-effect-level for acute effects on the central nervous system is set as equal to the limit value in the working environment.

Of these tow NOEL-values, the lowest is used in the following calculations.

The MOS-value for airway irritation by inhalation can thus be calculated as:

The MOS-values for total exposure, at a volume of 2 og 20 m³ respectively becomes:

If the calculated concentrations in room volumes of 2 and 20 m³ respectively are further compared to the irritation limit of 715 mg/m³ it cannot be ruled out that there may be irritation from application of an impregnation product containing 50% heptane.

7.4 Conclusion

The MOS-values for exposure by inhalation and total expousre (inhalation and skin absorption) respectively in an immediate zone of 2 m³ and in a room volume of 20 m³ have been compared in table 31.

Table 31 Comparison of MOS-values for exposure scenarios

MOS-values less than 100 have in table 31 been marked in bold.

From the table it can be seen that all MOS-values for total absorption (except for teratogenic effects of propan-2-ol) are below 100 and that the difference between the 2 exposure scenarios is not worth mentioning.

This indicates that for all these substances there is a potential risk of health effects from the described use. For total absorption, however, the faction absorbed through the skin is set at 1 which in general will lead to an overestimation of the absorption through the skin and thus of the total absorption. The degree of overestimation depends on the actual skin absorption of the substance. For 2-propanol, this overestimation would thus be less than for heptane as propan-2-ol is absorbed through the skin more easily than heptane.

All critical substances are volatile and if you instead look only on exposure by inhalation, there is only a risk of effects by inhalation of mineral turpentine in the exposure scenario that illustrate the immediate zone of the user.

To sum up, it can be concluded that there is a risk of irritation and effects on the central nervous system when using products containing mineral turpentine and that it is therefore important when using this type of product that it is applied outside or in a well-ventilated room.

Furthermore, it can be concluded that there is no risk of teratogenic effects when using products containing propan-2-ol.

For the remaining solvents it is not possible to afvise, on the available basis, that there may be effects when using products containing these substances. The user should therefore ensure that there is adequate ventilation when using the products.

For products containing turpentine oil, which may by allergenic by skin contact, it is furthermore important to avoid skin contact.

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Version 1.0 June 2005, © Danish Environmental Protection Agency