## 1 Introduction  
Since 1885, gas lantern mantles containing the unstable element thorium have been used for indoor and outdoor lighting, thoriated gas mantles producing intense white light luminescence [1,2]. Typically in the manufacture of thoriated gas lantern mantles, rayon fibers are dipped into a nitrate solution formed of an active component containing 99% thorium and 1% cerium [3]. On pre-burning of the gas mantle, the thorium and cerium in the mantle are transferred to thorium oxide and cerium oxide, providing the basis of the brilliant white light emission at burn temperatures [4, 5, 6, 7].  
Thoriated gas lantern mantles are considered radioactive consumer products, NORM (Naturally Occurring Radioactive Materials) added. NORM are radioactive materials that can be found in nature, primarily the primordial radionuclides \({}^{238}\)U, \({}^{232}\)Th and \({}^{40}\)K [8]. The thorium content in the mantle represents a potential hazard from exposure to ionizing radiation [8]. A number of researchers have studied the radiation risk arising from the thorium contained in lantern mantles [9; 10; 11; 12], [PERSON], Yoshizawa [7] finding no differences in brightness in the use of thoriated gas mantles and competitor non-radioactive mantles. Even so, the thoriated mantle finds continued use in many countries, typically in the absence of any radioactive information on the mantle packing. Among the purveyors of such items little effort seems to be made in indicating the availability of choice between the use of thoriated and non-thorium based mantles.  
From a review of the literature concerning consumer products containing radioactive substances in the European Union, [PERSON] et al. [13] reported that in much of the developed world the sale of the radioactive gas mantle is either prohibited or subjected to licensing. As instances, European states prohibiting the importation of thoriated mantles include the Netherlands, Italy, Greece, and Switzerland [13]. Conversely, in Sweden, Denmark, Spain, Lithuania, and Norway, mantles are subject to licensing by regulatory bodies, the activity of thorium potentially exceeding the exemption limit 1 kBq [14; 15; 16]. In Germany and Finland, radioactive mantles are available to the public [13], a situation also found elsewhere, such as in Malaysia where thoriated gas mantles are freely available without control, including lack of demand for testing, handling, and disposal.  
Nowadays, gas lantern mantles are usually used in rural areas and for camping and night markets, as night lights [16; 17]. In Malaysia, the country of the present study, many types of the mantle are available for purchase online, also being widely used. In regard to radiation risks to health, as a minimum, it would seem necessary to make an evaluation of the thorium content in these types of mantle, also assessing the risk to users and sellers of these items. The gamma-radiation emitted from the mantles and the possible inhalation or ingestion of the fine thorium oxide powder during replacement operations could represent a health hazard for regular users [6].  
The present study seeks to investigate the thorium content of gas lantern mantles currently available in the Malaysian market. We have also performed radiometric characterization and analysis, examining radiological implications arising from contact with packaged thoriated gas mantles. In particular, such risks might be assumed to be greatest for purveyors storing these items in bulk amounts. The research includes estimating organ equivalent and effective dose rates, values obtained through the use of Monte Carlo simulation.  
Given the absence of Malaysian regulations on NORM, with gas mantles being sold devoid of details of the level of radionuclide, this study also seeks to influence the existing radiation protection guideline document (LEM/TEK/69) established by the Atomic Energy Licensing Board (AELB) [18], the particular document having the intent to address such issues.