Toilet-related injuries and deaths
In young boys, one of the most common causes of genital injury is when the toilet seat falls down while they are standing at the toilet. Smaller children run the risk of drowning if they fall headfirst into the toilet bowl. Injuries to adults include bruised buttocks, tail bones, and dislocated hips from unsuspectingly sitting on the toilet bowl rim because the seat is up or loose. Injuries can also be caused by pinching due to splits in plastic seats or by splinters from wooden seats, or if the toilet itself collapses under the weight of the user. Older high tank cast iron cisterns have been known to detach from the wall when the chain is pulled to flush, causing injuries to the user. The 2000 Ig Nobel Prize in Public Health was awarded to three physicians from the Glasgow Western Infirmary for a 1993 case report on wounds sustained to the buttocks due to collapsing toilets. Furthermore, injuries are frequently sustained by people who stand on toilet seats to reach a height, and slip. There are also instances of people slipping on a wet bathroom floor or from a bath and concussing themselves on the fixture.
Toilet related injuries are also surprisingly common, with some estimates ranging up to 40,000 injuries in the US every year. In the past, this number would have been much higher, due to the material from which toilet paper was made. This was shown in a 1935 Northern Tissue advertisement which depicted splinter free toilet paper. In 2012, 2.3 million toilets in the United States, and about 9,400 in Canada, were recalled due to faulty pressure-assist flush mechanisms which put users at risk of the fixture exploding.
Injuries caused by animals
There are also injuries caused by animals. Some black widow spiders like to spin their web below the toilet seat because insects abound in and around it. Therefore, several persons have been bitten while using a toilet, particularly an outhouse toilet. Although there is immediate pain at the bite site, these bites are rarely fatal. The danger of spiders living beneath toilet seats is the subject of Slim Newton's comic 1972 country song The Redback on the Toilet Seat.
It has been reported that in some cases rats crawl up through toilet sewer pipes and emerge in the toilet bowl, so that toilet users may be at risk of being bitten by a rat. However, many rat exterminators do not believe this, as pipes, at generally six inches (15 centimeters) wide, are too large for rats to climb and are also very slippery. Reports by janitors are always on the top floor, and could involve the rats on the roof, entering the soil pipe through the roof vent, lowering themselves into the pipe and then into the toilet.
In May 2016, an 11 ft snake, a reticulated python, emerged from a squat toilet and bit the man using it on his penis at his home in Chachoengsao Province, Thailand. Both victim and python survived.
Some instances of toilet-related deaths are attributed to the drop in blood pressure due to the parasympathetic nervous system during bowel movements. This effect may be magnified by existing circulatory issues. It is further possible that people succumb on the toilet to chronic constipation, because the Valsalva maneuver is often dangerously used to aid in the expulsion of feces from the rectum during a bowel movement. According to Sharon Mantik Lewis, Margaret McLean Heitkemper and Shannon Ruff Dirksen, the “Valsalva maneuver … occurs during straining to pass a hardened stool”. “If defecation is suppressed over long periods, problems can occur, such as constipation or stool impaction. Defecation can be facilitated by the Valsalva maneuver. This maneuver involves contraction of the chest muscles on a closed glottis with simultaneous contraction of the abdominal muscles.” This means that people can die while "straining at stool." In chapter 8 of their Abdominal Emergencies, David Cline and Latha Stead wrote that "autopsy studies continue to reveal missed bowel obstruction as an unexpected cause of death".
In the Victorian era, there was a perceived risk of toilets exploding. These scenarios typically include a flammable substance either accidentally or deliberately being introduced into the toilet water, and a lit match or cigarette igniting and exploding the toilet. In 2014, Sloan's Flushmate pressure-assisted flushing system which uses compressed air to force waste down the drain was recalled after the company received reports of the air tank failing under pressure and shattering the porcelain.
In 1945, the German submarine U-1206 was sunk after a toilet malfunctioned, resulting in water coming in to the submarine, which when coming into contact with a battery, created chlorine gas, meaning the submarine had to resurface. At the surface, they were sunk by Allied Forces. This case may not be due to toilet malfunction, due to the possibility that the pressurized flushing system in the U-Boats, which was incredibly complex and required a training course to operate, may not have been properly operated.
George II of Great Britain died on the toilet on October 25, 1760 from an aortic dissection. According to Horace Walpole's memoirs, King George "rose as usual at six, and drank his chocolate; for all his actions were invariably methodic. A quarter after seven he went into a little closet. His German valet de chambre in waiting heard a noise, and running in, found the King dead on the floor." In falling he had cut his face.
Ioan P. Culianu was shot dead while on the toilet in the third-floor men's room of Swift Hall on the campus of the University of Chicago on 21 May 1991, in a possibly politically-motivated assassination. His killer has never been caught. 
- Edmund II of England died of natural causes on November 30, 1016, though some report that he was stabbed in the bowels while attending the outhouse. Similarly, Uesugi Kenshin, a warlord in Japan, died on April 19, 1578, with some reports stating that he was assassinated on the toilet.
- Lenny Bruce died of a heroin overdose on August 3, 1966 while sitting on the toilet, with his arm tied off.
- Air Canada Flight 797 was destroyed on June 2, 1983 with 23 fatalities after an in-flight fire began in or around the rear lavatory. Investigators could not determine the cause or exact point of origin for the fire.
- Michael Anderson Godwin, a convicted murderer in South Carolina who had his sentence reduced from death by the electric chair, sat on the metal toilet in his cell while fixing his television. When he bit one of the wires, the resultant electric shock killed him. Another convicted murderer, Laurence Baker in Pittsburgh, was electrocuted while listening to the television on home-made earphones while sitting on a metal toilet.
- A collision between a disabled Cessna 182 and a row of portable toilets on May 2, 2009 at Thun Field (south-east of Tacoma), despite an engine failure at 150 feet (46 m) altitude, ended without fatalities; the toilets "kind of cushioned things" for the 67-year-old pilot.
- British businessman and Conservative politician Christopher Shale was found dead in a portable toilet at the Glastonbury Festival on June 26, 2011. It is suspected he died of a heart attack.
- Aboard ship the head and fittings associated with the head are cited as one of the most common reason for the sinking of tens of thousands of boats of all types and sizes. Heads typically have through-hull fittings located below the water line to draw flush water and eliminate waste. Boats are sunk when fittings fail or the toilet back siphons.
Urban legends have been reported regarding the dangers of using a toilet in a variety of situations. Several of them have been shown to be questionable. These include some cases of the presence of venomous spiders Except for the Australian redback spider who has a reputation for hiding under toilet seats. These recent fears have emerged from a series of hoax emails originating in the Blush Spider hoax, which began circulating the internet in 1999. Spiders have also been reported to live under seats of airplanes, however, the cleaning chemicals used in the toilets would result in an incompatibility with spider's survival. In large cities like New York City, sewer rats often have mythical status regarding size and ferocity, resulting in tales involving the rodents crawling up sewer pipes to attack an unwitting occupant. Of late, stories about terrorists booby trapping the seat to castrate their targets have begun appearing. Another myth is the risk of being sucked into an aircraft lavatory as a result of vacuum pressure during a flight.
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