Summary of Results
Scenario 1 – Triclosan Always Present at Max Use Levels
The only refinement introduced at this point is the use of a probabilistic model with which to assess consumer exposure that is based on real consumer habits and practices, as opposed to deterministically summing the contribution from each product category. All other assumptions regarding substance presence, concentration, product retention and penetration remain consistent as in the first case Tier 1 assessment (results in Table 4).
Moving to a probabilistic and subject oriented model can provide refinement of the estimates of exposure (although not always), but also offers a framework with which to introduce further inputs that can be used to improve estimates of exposure. In general, a probabilistic modelling methodology allows:
- The use of statistical distributions to characterise substance concentrations
- The use of presence probabilities to account for occurrence of chemicals
- The ability to stratify exposure by subpopulation
- The ability to examine the relative contribution of different sources to the overall exposure
Some of these refinements are examined in scenarios two (Table 7) and three (Table 8).
Table 7: Estimated exposure levels (absorbed dose) – Total Population
| Product | Mean (µg/kg) | P95 (µg/kg) |
| Toothpaste | 9.272 | 24.498 |
| Mouthwash | 20.555 | 104.629 |
| Shower Gel | 10.984 | 44.547 |
| Face Powder | 2.878 | 7.535 |
| Blemish Concealer | 0.288 | 0.754 |
| Body Lotion | 0.865 | 3.211 |
| Deo/AP non-spray | 0.662 | 3.227 |
| Soaps | 27.040 | 71.258 |
| All Assessed Products | 72.556 | 184.224 |
Table 8: Estimated exposure levels (absorbed dose) – Exposed Population
| Product | Mean (µg/kg) | P95 (µg/kg) |
| Toothpaste | 10.621 | 25.353 |
| Mouthwash | 53.339 | 155.883 |
| Shower Gel | 19.944 | 56.214 |
| Face Powder | 5.681 | 8.163 |
| Blemish Concealer | 0.568 | 0.816 |
| Body Lotion | 11.330 | 38.661 |
| Deo/AP non-spray | 1.469 | 4.370 |
| Soaps | 28.397 | 72.271 |
| All Assessed Products | 72.590 | 184.344 |
In this instance aggregate exposure results are very similar for the total and exposed population. In addition, aggregate estimates at the P95 level are similar to the maximum individual scenario Tier 1 value in Table 2 (164 ug/kg); the mean aggregate estimate is about a factor of 2 lower than this value.
Scenario 2 – Triclosan Present at Max Use Levels and Including Presence Probabilities
Here, it is no longer assumed that triclosan is always present in each product category, but rather it is assumed to be present with a probability of 10%. When the model runs and a subject in the database records using a given product category that can contain triclosan, then the presence of the substance is simulated with a probability of 10%. This means that on average, the subject will be exposed 10% of the time. Thus, the mean exposure is reduced by a factor of 10, which is not necessarily the case for higher percentiles as these will be driven by consumers exposed to triclosan with a higher frequency.
Note that for certain product categories in the Total Population, a P95 of zero is observed while the mean is non-zero. This is due to a combination of both a low proportion of product users and a low chemical occurrence giving rise to less than five percent of the population being exposure to the substance. This is not the case for the Exposed Population, where statistics are only calculated over the non-zero results. Such behaviour is not unusual in population based studies of exposure; however, care is required when communicating such results.
Table 9: Estimated exposure levels (absorbed dose) – Total Population
| Product | Mean (µg/kg) | P95 (µg/kg) |
| Toothpaste | 0.959 | 7.964 |
| Mouthwash | 1.962 | 0.000 |
| Shower Gel | 1.115 | 3.655 |
| Face Powder | 0.279 | 0.000 |
| Blemish Concealer | 0.030 | 0.340 |
| Body Lotion | 0.101 | 0.000 |
| Deo/AP non-spray | 0.067 | 0.000 |
| Soaps | 2.845 | 19.722 |
| All Assessed Products | 7.366 | 38.443 |
Table 10: Estimated exposure levels (absorbed dose) – Exposed Population
| Product | Mean (µg/kg) | P95 (µg/kg) |
| Toothpaste | 10.560 | 25.623 |
| Mouthwash | 49.476 | 138.437 |
| Shower Gel | 20.080 | 53.193 |
| Face Powder | 5.605 | 7.925 |
| Blemish Concealer | 0.570 | 0.815 |
| Body Lotion | 13.065 | 51.932 |
| Deo/AP non-spray | 1.451 | 4.521 |
| Soaps | 19.956 | 56.948 |
| All Assessed Products | 18.626 | 65.591 |
Table 9 & 10 show the results for the total population and the exposed population respectively. In this case the exposed population estimate is about twice that of the general population. The exposed population value at the P95 level is less than half of the maximal single use exposure predicted in Tier 1.
Scenario 3 – Triclosan Present at Max and Usual Use Levels and Including Presence Probabilities
In scenario 3 usual use levels of triclosan are modelled, so the only difference between scenarios two and three are a refinement of concentration levels. Results are shown in Table 11 and Table 12 for the total population and the exposed population respectively.
Table 11: Estimated exposure levels (absorbed dose) – Total Population
| Product | Mean (µg/kg) | P95 (µg/kg) |
| Toothpaste | 0.912 | 7.473 |
| Mouthwash | 1.323 | 0.000 |
| Shower Gel | 1.188 | 3.868 |
| Face Powder | 0.186 | 0.000 |
| Blemish Concealer | 0.014 | 0.162 |
| Body Lotion | 0.043 | 0.000 |
| Deo/AP non-spray | 0.066 | 0.000 |
| Soaps | 2.734 | 18.882 |
| All Assessed Products | 6.470 | 34.736 |
Table 12: Estimated exposure levels (absorbed dose) – Exposed Population
| Product | Mean (µg/kg) | P95 (µg/kg) |
| Toothpaste | 10.578 | 24.964 |
| Mouthwash | 35.471 | 105.851 |
| Shower Gel | 20.882 | 58.624 |
| Face Powder | 3.744 | 5.419 |
| Blemish Concealer | 0.280 | 0.401 |
| Body Lotion | 5.730 | 21.306 |
| Deo/AP non-spray | 1.449 | 4.306 |
| Soaps | 19.499 | 57.111 |
| All Assessed Products | 16.536 | 58.986 |
In this case, it is interesting to note that the exposed population P95 and mean values associated with a single product (mouthwash) exceed the aggregate exposures. This suggests that this single product, when used dominates total exposure. At the same time, it also suggests that its use is less frequent than many other products examined in the assessment. The Tier 1 value for this product (150 ug/kg) would have been conservative both for the exposed population at a higher tier, and also for the exposed population at an aggregate exposure level.