## 3 Results and Discussion
### Organ Equivalent and Effective Doses  
Organ equivalent doses were based on MIRD5 mathematical male and female phantoms, with the mantle simulated at 20 cm from the chest. Figure 5 shows the equivalent \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & **Candle Power (C.P)** & **Element** & **(mg/g)** & **(mg/Mantle)** \\ \hline M1 & (500–600 C.P) & Th & 1.50 & 4.05 [1] \\ M5 & (300–400 C.P) & Th & 507.9 & 1773 [2] \\ \hline \hline \end{tabular} \({}^{\dagger}\)Weight of the mantle M1 (2.7 g), \({}^{2}\) Weight of the mantle M5 (3.49 g).  
\end{table} 
Table 4: ICP-OES analysis for thorium content in the mantle. Figure 4: Build-up daughter nuclides during and after burning mantle. doses for the 21 predominant organs, the thymus, heart, and lung being the most greatly exposed organs due to their close proximity to the source. The greatest equivalent dose resulting from proximity to a single M5 mantle was indicated to be to the thymus, at 0.68 and 0.62 \(\upmu\)Sv/h for the male and female phantom respectively. Further, the equivalent dose to the stomach is also seen to be greater than that for most other organs due to the larger exposure area. Further investigation has been of the effective dose, as shown in Table 5.  
With regard to evaluation of the effective dose, the dose conversion factors (DCFs) have been calculated by MC simulation. Table 5 shows the results from a single mantle at separations from the chest of 10, 20, 50, and 100 cm; the effective doses for samples from M1 to M4 are very low to negligible compared to sample M5. It was observed that sample M5 recorded the maximum effective dose, at 3.41 \(\times\) 10\({}^{-1}\) at a distance 10 cm, reducing to 2.94 \(\times\) 10\({}^{-4}\) at 100 cm. The dose equivalent was also measured for mantle M5, using a calibrated IdentiFinder 2, FLIR Survey Meter, for exposure periods of 1, 4, 168, and 720 h, the meter being placed at distances of 0, 10, 20, 50, and 100 cm from the mantle. For a single  
Figure 5: Organ equivalent dose (\(\upmu\)Sv/h) for the 21 organs of the MIRD5 mathematical male and female phantom with mantle M5 simulated 20 cm from the chest. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **10 cm** & **20 cm** & **50 cm** & **100 cm** \\ \hline M1 & 4.96 \(\times\) 10\({}^{-4}\) & 4.67 \(\times\) 10\({}^{-4}\) & 1.81 \(\times\) 10\({}^{-4}\) & 3.18 \(\times\) 10\({}^{-7}\) \\ M2 & 3.87 \(\times\) 10\({}^{-4}\) & 3.77 \(\times\) 10\({}^{-4}\) & 1.93 \(\times\) 10\({}^{-4}\) & 2.27 \(\times\) 10\({}^{-7}\) \\ M3 & 2.54 \(\times\) 10\({}^{-4}\) & 2.00 \(\times\) 10\({}^{-4}\) & 7.60 \(\times\) 10\({}^{-5}\) & 1.14 \(\times\) 10\({}^{-7}\) \\ M4 & 2.46 \(\times\) 10\({}^{-3}\) & 1.87 \(\times\) 10\({}^{-3}\) & 8.90 \(\times\) 10\({}^{-4}\) & 8.00 \(\times\) 10\({}^{-7}\) \\ M5 & 3.41 \(\times\) 10\({}^{-1}\) & 2.95 \(\times\) 10\({}^{-1}\) & 1.45 \(\times\) 10\({}^{-1}\) & 2.94 \(\times\) 10\({}^{-4}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Effective dose (\(\upmu\)Sv/h) from mantles at separations from the chest of 10, 20, 50 and 100 cm. dose equivalent was 490 \(\mu\)Sv per 720 h (30 days), reducing to 144 \(\mu\)Sv at 20 cm (Table 6). For a package of six mantles placed on the surface of the survey meter, a dose equivalent of 1.368 mSv per 720 h was found, reducing to 0.187 mSv at 20 cm. The dose equivalent on the surface of a single mantle M5 was 0.68 \(\mu\)Sv/h and on the surface of the package of six mantles, it was 1.9 \(\mu\)Sv/h. It was observed that our results in Tables 5 and 6 for single mantle M5 are comparable. In Malaysia, gas lantern mantles are commercially available without restrictions and have been widely used in lighting in rural areas where electricity supply is limited, also for illumination of night food stalls as well as for fishing and camping activities.