increasing its water-contact area." These frits are commonly referred to as diffuser for the way that they diffuse (or disperse) the smoke as it exits the downstem, and usually consist of small holes or slats at the end of the downstem. This study suggests that a bong's smoke is less harmful than unfiltered smoke. Adverse health effects Bongs that are cleaned regularly eliminates yeast, fungi, bacteria and pathogens that can cause several symptoms that vary from allergy to lung infection. Plastic bongs It has been reported that it is possible to taste the chemicals in the water from a plastic water bottle left sitting in a hot car because "...chemicals have leached into the contents of the bottle." It was also reported that it is possible to imagine that this process of chemicals leaching into water occurring with "...a homemade water bottle bong where the bottle is routinely heated up." It was also reported that "According to Cancer Research UK, plastic bottles heated up to 60°C contain unhealthy levels of toxic chemicals." Legal issues In the United States, under the Federal Drug Paraphernalia Statute, which is part of the Controlled Substances Act, it is illegal to sell, transport through the mail, transport across state lines, import, or export drug paraphernalia. In countries where marijuana and hashish are illegal, some retailers specify that bongs are intended for use with tobacco in an attempt to circumvent laws against selling drug paraphernalia. While technically "bong" does not mean a device used for smoking mainly cannabis, drug-related connotations have been formed with the word itself (partly due to punning with Sanskrit bhangah "hemp"). Thus for fear of the law many head shops will not serve customers who use the word "bong" or "bongs", or any other word typically associated with illegal drug use. Some brand name bong manufacturers (notably RooR) have sought to curb the counterfeit market for their products by suing stores accused of selling fake merchandise. See also Drug paraphernalia Hookah One-hitter (smoking) Gravity bong Operation Pipe Dreams Thuoc lao Vaporizer (inhalation device) References Further reading Erika Dugas, Michèle Tremblay, Nancy C.P. Low, Daniel Cournoyer, Jennifer O'Loughlin: Water-Pipe Smoking Among North American Youths, Pediatrics, Published online May 10, 2010, (Full Text free) External links Erickson, William V. et al. Water pipe or bong. US Patent 4,216,785. 2400-year-old Scythian bongs excavated Cannabis smoking Russian inventions Chinese inventions Australian inventions Drug paraphernalia Drug delivery