Conservation and restoration of human remains  The conservation and restoration of human remains involves the long-term preservation and care of human remains in various forms which exist within museum collections. This category can include bones and soft tissues as well as ashes, hair, and teeth. Given the organic nature of the human body, special steps must be taken to halt the deterioration process and maintain the integrity of the remains in their current state. These types of museum artifacts have great merit as tools for education and scientific research, yet also have unique challenges from a cultural and ethical standpoint. Conservation of human remains within museum collections is most often undertaken by a conservator-restorer or archaeologist. Other specialists related to this area of conservation include osteologists and taxidermists. Museum collections contain human remains in many forms, including entire preserved bodies, discrete parts of the anatomy, and even art and artifacts created out of human body parts. Museum collections, especially those of the natural history variety, often contain osteological specimens derived from humans. These can include individual bones, bone fragments, entire skeletons, and teeth from both ancient and contemporary sources. Reconstruction of bone fragments should be conducted with great care and consideration. Due to the porous nature of bones, few adhering substances can be used on bone with an adequate level of reversibility, which is a key component of all conservation treatments. The word "mummy" can refer to both intentionally and naturally preserved bodies and is not limited to one geographic area or culture. Damage of mummified remains can be caused by several main factors, including poor environmental conditions, physical damage, and improper methods of preservation that have been applied in the past. Mummies, though most often thought of as an Egyptian phenomenon, exist in many cultures and have been found on nearly every continent. For examples of non-Egyptian mummies, see "Mummification in other cultures". Controlling environmental conditions is highly important in preserving the integrity of mummies. Fungi, pests, and microorganisms that cause decay are some of the possible repercussions of inadequate storage and environmental factors. There are a number of ways to mitigate the effects of improper conditions, however. Methods of stabilizing mummies and halting the deterioration process include inert gas control, where the mummy is placed in a chamber or bag into which fumigants are introduced; wet sterilization, where solutions are applied to the mummy to repel insects and the growth of fungi; controlled drying, which reduces the relative humidity in order to stop growth of microorganisms; and ultra-violet irradiation, which affects microorganisms by altering their cells.