Site observation and sampling collection
The incense making process was studied to consider the risk of dermal contact of each step and photos were taken to explain clearly incense making steps. Moo 12 of Ngooleum village had around 100 small household factories that making incense stick. Each small household factory had at least 5 incense workers, so male workers worked all of duties but incense packing step always work by female workers. Thirty-five small household factories were selected randomly by house number were representative groups of incense workers in the study area. Thirty sampling (n=30) is the least number in order to make a good estimation for population mean, so the case study selected 35 incense workers (Jaipieam, 2008; Ling, 2012). Each small household factory were collected the three sample groups as dissolved dye, incense stick, and hand wiping samples. The hand wiping technique was used to collected hand wiping samples from workers’ hands. The diagram of sample collection was showed in Figure 3.3.
A worker who packs incense from each small household factory should work on incense process at least 1 year. Each small household factory was selected one worker randomly to wipe hands three or four events, which started in morning to lunch or afternoon. Table 3.1 showed the number of hand wiping samples of each event that were collected from incense packing workers.