Survey of liquid hand soaps, including health and environmental assessments

7 User exposure

7.1 Exposure assessment

Exposure assessment of the hand soaps is based on exposure to the 26 fragrance chemicals, which the EU has assessed as contact allergens, and exposure to Methyleugenol and Lyral®. The guidelines for amount per application and frequency of use as stated in the EU Technical Guidance Document (TGD) (28) and in SCCNFP's guidelines (29), toxicological profiles of the fragrance chemicals as described above in chapter 6, and the analytical results in chapter 5 have been used in the following to estimate the exposure in a worst-case scenario for two standard persons: an adult of 60 kg and a child of 18 kg (3-5 years). The daily exposure has been calculated based on the highest measured content of fragrance chemicals in the tested hand soaps.

7.1.1 Used amounts of liquid hand soaps

The typical amount of hand soap used when washing hands is determined in the EU Technical Guidance Document (TGD) to 0.8 g for solid soap bars and with a user frequency of 3-6 times daily (28). No value has been determined for the amount of liquid hand soap used when washing hands (28,29). To calculate the exposure to liquid hand soaps the dosage was based on the measurement of the actual consumption when washing hands. In an exposure test at two workplaces the amounts used of selected hand soaps were measured. In one workplace an assessment was carried out of the dosage per hand wash based on the hand soaps that were accessible at the workplace. By using an automatic dispenser the amount used per hand wash was calculated at 0.6 g for a foam product in which the density is assumed to be lower than for gel/cream products. In a laboratory the dosage of a liquid hand soap with a dispenser device was measured at 1.8 g per wash. Kitchen staff was assessed to be among the working groups who wash their hands most frequently and when interviewing them it was informed that they wash their hands with soap 20-30 times daily on average.

Two exposure assessments were carried out in a workplace during a period of five days with five selected liquid hand soaps purchased for this survey. The foam product was not included as only one foam product had been selected and purchased. The liquid hand soaps were placed at the lavatories. All products contained fragrance and had different viscosities. All the soaps had a pumping device which, however, varied from product to product. In one of the products it was particularly easy to pump the soap. Adults (both female and male) from 28-61 years participated in the test. None of the test persons required washing hands after particularly dirty labour. Each of the test persons recorded the amount used each time they washed their hands. The amount used was found as an average of the recorded number of dosages for each product. The amounts used of the five hand soaps appear from table 7.1.

Table 7.1 Amounts used for five of the hand soaps

Product no. Number of doses Amount used Weight per dose Description of product
2 43 43 g 1.00 g Viscous
2 26 25 g 1.04 g
9 36 21 g 0.58 g Viscous, strong fragrance
9 43 37 g 0.86 g
12 81 71 g 0.88 g Viscous
12 35 26 g 0.74 g
22 52 60 g 1.15 g Viscous, east to squeeze from dispenser
22 22 28 g 1.27 g
24* 28 27 g 0.96 g Viscous
Σ 366 338 g Average dosage: 0.92 g  

*: Single determination only

The study was carried out on a selected user group and is only indicative of the consumption. The average consumption was 0.92 g/hand wash.

The study indicated that the consumption of liquid hand soaps per hand wash was higher than the TGD value of 0.8 g for solid soap bars. Furthermore, it is possible that the fragrance of the product may influence the amount used when washing hands. Also the actual pumping device may influence the amount used.

The average amount of soap used per hand wash has been determined at 1.0 g in the below exposure scenario by comparing the average dosage of 0.92 g with the amounts used of 0.6 g and 1.8 g in occupational use.

7.1.2 Exposure scenarios

Based on the used amount of soap per hand wash of 1 g found in the above study, realistic "worst-case" scenarios have been drawn up for exposure to fragrance chemicals of adults and children at skin contact.

The exposure scenarios are based on common use of the products with the TGD frequency of 6 times per day from. The exposed area is the surface of the hands. Data for skin absorption of fragrance chemicals have not been found in literature and as a worst-case scenario it is assumed that 100% of the substances is absorbed through the skin. However, this will clearly give too high results as the products are rinsed off with water. Therefore, the EU has introduced a term "Retention factor" which takes into account the rinsing-off and dilution of the hand soap in connection with common use. For products such as hand soaps the EU has set a retention factor of 0.01 (29).

Exposure results, in the EU termed SED or Systemic Exposure Dosage (29), is stated in mg substance per kg body weight at a time and/or day based on the following data:

Weight of person, adult: 60 kg
Weight of person, child, 3-5 years (30): 18 kg
Daily applications (28): 6 times a day
Amounts used per application (28): 1.0 g product
Maximum measurement of the fragrance chemical
(e.g.: D-limonen in hand soap cf. table 7.2):
2400 mg/kg product
Dermal absorption (worst-case) 100%
Retention factor: 0.01

Daily amount of exposure, D-limonen, adult:

Daily amount of exposure, D-limonen, adult

Daily amount of exposure to D-limonen in hand soap for an adult, dilution taken into account (Retention factor: 0.01):

Daily amount of exposure to D-limonen in hand soap for an adult, dilution taken into account (Retention factor: 0.01)

Daily amount of exposure to D-limonen in hand soap, child 3-5 years:

Daily amount of exposure to D-limonen in hand soap, child 3-5 years:

Daily amount of exposure to D-limonen in hand soap for a child, dilution taken into account (Retention factor: 0.01):

Daily amount of exposure to D-limonen in hand soap for a child, dilution taken into account (Retention factor: 0.01)

For kitchen staff the exposure is not 6 times daily but informed to be up to 30 times daily.

For kitchen staff the exposure is not 6 times daily but informed to be up to 30 times daily

Dilution taken into account (Retention factor: 0.01):

Dilution taken into account (Retention factor: 0.01)

The daily exposure to the 19 fragrance chemicals that were found in the analysis is estimated per kg body weight per day for the two standard persons. The results appear in table 7.2.

Table 7.2 Content and daily exposure to the 19 fragrance chemicals that were found in the analysed hand soaps.

Fragrance chemical weight-%
(maximum measured value)
Daily exposure estimated with retention factor,
adult, 60 kg
(mg/kg bw**/day)
Daily occupational exposure estimated with retention factor,
adult, 60 kg
(mg/kg bw**/day)
Daily exposure,
child, 18 kg, estimated with retention factor,
(mg/kg bw**/day)
Linalool 0.016* 0.00016 0.0008 0.00052
Geraniol 0.12* 0.0012 0.006 0.00396
Citronellol 0.07* 0.0007 0.0035 0.00231
Hexylcinnamaldehyde 0.076* 0.00076 0.0038 0.0025
Lilial 0.028* 0.00028 0.0014 0.00092
Benzyl alcohol 0.045* 0.00045 0.00225 0.00148
Benzyl salicylat 0.045* 0.00045 0.00225 0.00148
Eugenol 0.0044 0.00004 0.0002 0.00014
Amyl cinnamal 0.0052 0.00005 0.00025 0.00017
Benzyl benzoat 0.011* 0.00011 0.00055 0.00036
Cinnamyl alcohol 0.0049 0.00004 0.0002 0.00016
Citral 0.0013 0.00001 0.00005 0.00004
D-limonen 0.24* 0.0024 0.012 0.00792
Coumarin 0.0036 0.00003 0.00015 0.00011
Hydroxycitronellal, 0.0069 0.00007 0.00035 0.00023
-Isomethylionon 0.011* 0.00011 0.00055 0.00036
Lyral® 0.007 0.00007 0.00035 0.00023
Isoeugenol 0.0028 0.00003 0.00015 0.00009
Farnesol 0.004 0.00004 0.0002 0.00013

* : The maximum measured weight-% is above 0.01% which is the EU limit for labelling of the 26 allergen fragrance chemicals in rinse-off products

** bw: body weight

The chemical analyses show that the concentrations of the total content of the 19 allergen fragrance chemicals in the examined hand soaps are from 0.0013% - 0.24 weight-%. The content of fragrance chemicals reported as contact allergens in the hand soaps is low compared with the 0.5 – 1% which is stated in the literature as the typical fragrance content in shampoos and liquid soaps (31). It is possible that other fragrance chemicals than those reported as contact allergens are also found in the products.

7.2 Safety assessment of selected substances

When calculating the Margin of Safety (MoS) of a substance the estimated daily exposure (= SED) of each fragrance chemical is used in the following:


7.2.1 D-limonen

Of the 26 fragrance chemicals reported as contact allergens D-limonen occurs in the largest amount in the hand soaps. The substance has been evaluated in a previous survey for the Danish Environmental Protection Agency (32). With a NOEL value for D-limonen of 250 mg/kg body weight/day for liver injuries and based on the estimated daily exposure of 0.0024 for adults and 0.008 for children gives the following safety margins:

MoS, adult:

MoS, adult:

MoS, adult, occupational use:

MoS, adult, occupational use

MoS, child:

MoS, child

7.2.2 Other fragrance allergens

For the fragrance chemicals reported as contact allergens Hexylcinnamaldehyde, Lilial, Amyl cinnamal, Coumarin, a-Isomethylionon and Lyral®, which are assessed in chapter 6 of this survey, the NOAEL is given in table 7.3. When calculating the MoS, the SEDadult and SEDchild from table 7.2 are used. The MoS results also appear from table 7.3.

Table 7.3 NOAEL used for calculation of MoS for selected fragrance chemicals

Fragrance chemical NOAEL, (mg/kg bw/day) SEDadult
from table 7.2
from table 7.2
MoSadult MoSchild
Hexylcinnam-aldehyde No information available - - -- -
Lilial 25 0.00028
*: 0.0014
0.00092 8.9 x 104
1.8 x 104
2.7 x 104
Amyl cinnamal 290 0.00005
*: 0.0025
0.00017 5.8 x 106
1.2 x 105
1.7 x 106
Coumarin 10 0.00003
*: 0.00015
0.00011 3.3 x 105
6.7 x 104
9 x 104
-isomethylionon 4 0.00011
*: 0.00055
0.00036 3.6 x 104
7.3 x 103
1.1 x 104
Lyral® No information available - - - -

*: occupational use

MoS should at least be 100 to take into account a safety factor of 10 for extrapolation of data from animals to humans and a safety factor of 10 to take into account particularly sensitive consumers. The calculations show that the safety margins are far from being exceeded, both for consumers and in connection with frequent occupational use. However, it must be emphasized that the MoS has not been calculated for allergy but for other critical effects, cf. the health assessments in chapter 6.

The fragrance chemicals have all been reported by SCCNFP as contact allergens at skin contact. As there is no "zero effect level" for allergy it is essential to point out that skin contact with these fragrance chemicals should be avoided (3).

7.2.3 Conclusion of safety assessment

The exposure assessments showed very low daily exposure and a high safety margin for the hand soaps for both adults and children and in connection with frequent occupational use. As it concerns assessment of substances reported as contact allergens it must be concluded that for particularly sensitive consumers including persons with allergy the use of products with a high content of fragrance chemicals may cause adverse health effects. This is supported by the fact that the EU has determined an obligation of labelling of these fragrance chemicals above a certain concentration in the finished products. In table 7.2 can be seen the fragrance chemicals which exceed this limit (indicated by an *) and which must thus be stated on the product label.


Version 1.0 June 2006, © Danish Environmental Protection Agency