1 00:00:00,040 --> 00:00:03,680 VOICE-OVER: Welcome to one of ConsExpo Web's online tutorials. 2 00:00:03,800 --> 00:00:07,280 This video will give you insight into the dermal exposure models... 3 00:00:07,400 --> 00:00:10,720 that are used in the ConsExpo Web software. 4 00:00:10,840 --> 00:00:14,320 The dermal exposure route is an important route of exposure... 5 00:00:14,440 --> 00:00:16,800 to many consumer products. 6 00:00:16,920 --> 00:00:19,880 While some products are applied to the skin deliberately... 7 00:00:20,000 --> 00:00:23,280 such as cosmetics and personal care products... 8 00:00:23,400 --> 00:00:26,880 others may come into unintended contact with the skin... 9 00:00:27,000 --> 00:00:32,000 due to spills, contact with contaminated surfaces or deposition. 10 00:00:32,120 --> 00:00:35,440 In addition, substances may migrate from materials... 11 00:00:35,560 --> 00:00:38,320 that come into contact with the skin. 12 00:00:38,440 --> 00:00:42,440 The dermal exposure models that are included in ConsExpo Web... 13 00:00:42,560 --> 00:00:48,040 provide the means to determine direct dermal exposure in various scenarios. 14 00:00:48,160 --> 00:00:51,400 The following dermal exposure models are included. 15 00:00:51,520 --> 00:00:55,240 Instant application, constant rate. 16 00:00:55,360 --> 00:00:58,520 These are followed by the scenario-based models. 17 00:00:58,640 --> 00:01:03,080 Rubbing off, migration, diffusion. 18 00:01:03,200 --> 00:01:08,720 We will now run through the models, starting with instant application. 19 00:01:08,840 --> 00:01:12,080 The instant application model is typically used... 20 00:01:12,200 --> 00:01:16,000 to simulate the use of cosmetics and personal care products... 21 00:01:16,120 --> 00:01:19,280 as consumers apply these directly onto the skin. 22 00:01:19,400 --> 00:01:22,720 It provides a conservative estimate of dermal exposure... 23 00:01:22,840 --> 00:01:26,960 in cases where information on the use of the product is lacking. 24 00:01:27,080 --> 00:01:30,440 The elements that are relevant for dermal exposure are: 25 00:01:30,560 --> 00:01:35,560 the product amount, the weight fraction of the substance of interest... 26 00:01:35,680 --> 00:01:39,240 the skin area that comes into contact with the product... 27 00:01:39,360 --> 00:01:42,960 and the body weight of the consumer who is exposed. 28 00:01:43,080 --> 00:01:49,120 For certain toxicological end points, the relevant dosage metric is dermal load. 29 00:01:49,240 --> 00:01:53,080 It can be estimated by multiplying the applied product amount... 30 00:01:53,200 --> 00:01:55,440 with the substance concentration... 31 00:01:55,560 --> 00:01:59,480 and subsequently dividing by the skin surface area... 32 00:01:59,600 --> 00:02:02,400 that comes into contact with the product. 33 00:02:02,520 --> 00:02:06,200 To obtain the dermal exposure expressed as a dose... 34 00:02:06,320 --> 00:02:12,200 exchange skin surface area with body weight in the formula. 35 00:02:12,320 --> 00:02:16,520 The constant rate model introduces the element of time. 36 00:02:16,640 --> 00:02:19,560 The dermal contact is constant over time... 37 00:02:19,680 --> 00:02:23,160 and expressed as an amount per unit of time. 38 00:02:23,280 --> 00:02:27,040 It is used when the dermal exposure has a continuous character... 39 00:02:27,160 --> 00:02:30,720 such as when applying spray-based products to the skin. 40 00:02:30,840 --> 00:02:35,320 The first two dermal exposure models are relatively straightforward. 41 00:02:35,440 --> 00:02:40,640 The next models are more sophisticated and require detailed information. 42 00:02:40,760 --> 00:02:43,360 The rubbing-off model is used in scenarios... 43 00:02:43,480 --> 00:02:48,600 whereby the substance is rubbed off contaminated or treated surfaces... 44 00:02:48,720 --> 00:02:50,800 during normal activities. 45 00:02:50,920 --> 00:02:54,840 A typical scenario is that of a child playing on a floor or lawn... 46 00:02:54,960 --> 00:02:57,000 that has been treated with a product. 47 00:02:57,120 --> 00:02:58,760 The model describes the process... 48 00:02:58,880 --> 00:03:03,720 of coming into contact with a known contaminated surface during play... 49 00:03:03,840 --> 00:03:08,360 during which the product is rubbed off and transferred onto the skin. 50 00:03:08,480 --> 00:03:13,680 This model introduces two new exposure parameters to describe that process. 51 00:03:13,800 --> 00:03:18,840 The transfer coefficient and the dislodgeable amount. 52 00:03:18,960 --> 00:03:23,840 The transfer coefficient describes the surface area per unit of time... 53 00:03:23,960 --> 00:03:27,040 that the skin effectively comes into contact with. 54 00:03:27,160 --> 00:03:29,480 The dislodgeable amount is defined as the amount... 55 00:03:29,600 --> 00:03:32,040 that is transferred during that contact... 56 00:03:32,160 --> 00:03:37,400 and is expressed as an amount per surface area of the object or floor. 57 00:03:37,520 --> 00:03:41,880 Exposure is then determined by combining the duration of the contact... 58 00:03:42,000 --> 00:03:45,600 the contacted surface area, the transfer coefficient... 59 00:03:45,720 --> 00:03:47,520 and the dislodgeable amount. 60 00:03:47,640 --> 00:03:51,400 The exposure is limited to either the surface area... 61 00:03:51,520 --> 00:03:55,240 that the skin can come into contact with within the period of time... 62 00:03:55,360 --> 00:04:00,000 as specified by the transfer coefficient and the duration of the contact... 63 00:04:00,120 --> 00:04:04,360 or to the maximum treated surface area. 64 00:04:04,480 --> 00:04:09,440 Dermal exposure may also occur during prolonged contact with materials... 65 00:04:09,560 --> 00:04:12,360 for example the clothes that a person is wearing. 66 00:04:12,480 --> 00:04:17,200 During that contact, substances may leach from the textile to the skin. 67 00:04:17,320 --> 00:04:21,280 This scenario is best described using the migration model. 68 00:04:21,400 --> 00:04:24,600 The input parameter that is required for the migration model... 69 00:04:24,720 --> 00:04:26,800 is called the leachable fraction. 70 00:04:26,920 --> 00:04:33,120 This describes the fraction of the product that migrates, that is leaches, onto the skin. 71 00:04:33,240 --> 00:04:37,320 Another factor to note is the skin contact factor. 72 00:04:37,440 --> 00:04:39,280 This parameter accounts for the fact... 73 00:04:39,400 --> 00:04:42,880 that not all skin is in contact with the product or article. 74 00:04:43,000 --> 00:04:46,280 For example, when examining skin contact with bed sheets... 75 00:04:46,400 --> 00:04:48,440 of a person wearing pyjamas... 76 00:04:48,560 --> 00:04:53,600 only a certain fraction of their skin is in direct contact with the bed sheets. 77 00:04:53,720 --> 00:04:56,880 The fifth dermal model included in ConsExpo Web... 78 00:04:57,000 --> 00:05:01,640 describes exposure by means of the transfer of a substance from a product... 79 00:05:01,760 --> 00:05:05,280 only when the substance reaches the outer layer of the product. 80 00:05:05,400 --> 00:05:07,960 This is a type of diffusion model. 81 00:05:08,080 --> 00:05:11,840 Examples of its use include when hands are submerged in a liquid... 82 00:05:11,960 --> 00:05:15,600 or a known product layer comes into contact with the skin. 83 00:05:15,720 --> 00:05:18,200 The model requires information on the concentration... 84 00:05:18,320 --> 00:05:22,360 of the substance in the product, and the product layer thickness. 85 00:05:22,480 --> 00:05:26,560 An important parameter in this model is the diffusion coefficient. 86 00:05:26,680 --> 00:05:29,720 It describes the speed at which the substance transfers... 87 00:05:29,840 --> 00:05:31,440 through the product layer. 88 00:05:31,560 --> 00:05:35,640 Entering the exposure time allows the model to calculate the exposure... 89 00:05:35,760 --> 00:05:39,000 as the diffusion coefficient determines how much of a substance... 90 00:05:39,120 --> 00:05:43,400 has reached the outer layer and forms an exposure risk. 91 00:05:43,520 --> 00:05:47,040 The models that describe dermal exposure through rubbing off... 92 00:05:47,160 --> 00:05:49,120 migration and diffusion... 93 00:05:49,240 --> 00:05:53,080 require parameters that are often difficult to obtain. 94 00:05:53,200 --> 00:05:55,480 ConsExpo Web and the fact sheets... 95 00:05:55,600 --> 00:06:00,040 provide some helpful suggestions for defaults to aid users. 96 00:06:00,160 --> 00:06:06,280 We hope this tutorial has helped you to familiarise yourself with ConsExpo Web. 97 00:06:06,400 --> 00:06:08,640 Our support does not end here. 98 00:06:08,760 --> 00:06:12,160 Visit the ConsExpo website for help pages... 99 00:06:12,280 --> 00:06:16,880 that provide information on ConsExpo Web and a user manual. 100 00:06:17,000 --> 00:06:21,960 You can also access the 'i' and '?' icons within the software... 101 00:06:22,080 --> 00:06:25,240 which are there to give you extra help when needed. 102 00:06:25,360 --> 00:06:27,920 If you still have questions or need assistance... 103 00:06:28,040 --> 00:06:36,800 please contact us at consexpo@rivm.nl.