question: Why does cutting onions open hurt our eyes?
comment: When you cut an onion, the onion releases a gas which combines with the water in your eyes to form a mild acid. This acid is the burning feeling you get.
passages: Eye irritation can be avoided by cutting onions under running water or submerged in a basin of water. Leaving the root end intact also reduces irritation as the onion base has a higher concentration of sulphur compounds than the rest of the bulb. Refrigerating the onions before use reduces the enzyme reaction rate and using a fan can blow the gas away from the eyes. The more often one chops onions, the less one experiences eye irritation.
   Some people suffer from allergic reactions after handling onions. Symptoms can include contact dermatitis, intense itching, rhinoconjunctivitis, blurred vision, bronchial asthma, sweating, and anaphylaxis. Allergic reactions may not occur when eating cooked onions, possibly due to the denaturing of the proteins from cooking.
  
  Section::::Composition.:Eye irritation.
   Onions are cultivated and used around the world. As a food item, they are usually served cooked, as a vegetable or part of a prepared savoury dish, but can also be eaten raw or used to make pickles or chutneys. They are pungent when chopped and contain certain chemical substances which irritate the eyes.
  
  Section::::Taxonomy and etymology.
   Guinea hen weed and honey garlic contain a similar lachrymatory factor. Synthetic onion lachrymatory factor has been used in a study related to tear production, and has been proposed as a nonlethal deterrent against thieves and intruders.
  
  Section::::Cultivation.
   The amount of sulfenic acids and lacrimal factor released and the irritation effect differs among "Allium" species. In 2008, the New Zealand Institute for Crop and Food Research created "no tears" onions by genetic modification to prevent the synthesis of lachrymatory factor synthase in onions. One study suggests that consumers prefer the flavor of onions with lower LFS content. However, since the LFS-silencing process involves reducing sulfur ingestion by the plant, it has also been suggested that LFS− onions are inferior in flavor. A method for efficiently differentiating LFS− and LFS+ onions has been developed based on mass spectrometry, with potential application in high-volume production; gas chromatography is also used to measure lachrymatory factor in onions. In early 2018, Bayer released the first crop yield of commercially-available LFS-silenced onions under the name "Sunions." They were the product of 30 years of cross-breeding; genetic modification was not employed.
   BULLET::::- (Takes out onion) is a mock stage direction inserted in articles when someone is allegedly faking sorrow (crocodile tears). Onions are well known for inducing tears when close to the eyes and were a useful prop for actors who were required to "cry" in dramatic scenes, regardless of whether they would naturally be feeling sadness or despair. To this end, the phrase is therefore usually used to denote hypocrisy. It occurs as early as 1915, in cartoons by W. Heath Robinson.
   Jews in Afghanistan and Iran hit each other over the head with green onions during the refrain beginning with the ninth stanza (Even if you had supplied our needs in the desert for 40 years but not provided us with manna). This may be due to a passage in Numbers 11:5–6, where the Israelites see manna and recall Egypt. "We remember the fish that we used to eat in Egypt, the cucumbers, the melons, the leeks, the onions and the garlic. Now our gullets are shriveled. There is nothing at all. Nothing but this manna to look at." It is thought that by beating each other with the onions they taught themselves not to yearn for Egypt or to forget Egyptian slavery.
   Freshly cut onions often cause a stinging sensation in the eyes of people nearby, and often uncontrollable tears. This is caused by the release of a volatile liquid, "syn"-propanethial-S-oxide and its aerosol, which stimulates nerves in the eye. This gas is produced by a chain of reactions which serve as a defence mechanism: chopping an onion causes damage to cells which releases enzymes called alliinases. These break down amino acid sulfoxides and generate sulfenic acids. A specific sulfenic acid, 1-propenesulfenic acid, is rapidly acted on by a second enzyme, the lacrimatory factor synthase, producing the "syn"-propanethial-S-oxide. This gas diffuses through the air and soon reaches the eyes, where it activates sensory neurons. Lacrimal glands produce tears to dilute and flush out the irritant.
   Onions have particularly large cells that are readily observed under low magnification. Forming a single layer of cells, the bulb epidermis is easy to separate for educational, experimental, and breeding purposes. Onions are therefore commonly used in science education to teach the use of a microscope for observing cell structure.
  
  Onions are toxic to dogs, cats, guinea pigs, and many other animals.
  
  Section::::Composition.
  
  Section::::Composition.:Nutrients.
   Section::::Legacy segments.:Johnny's Bit Idea of the Week.
   Section::::Cultivation.:Pests and diseases.
   Arcs can also produce a broad spectrum of wavelengths spanning the visible light and the invisible ultraviolet and infrared spectrum. Very intense arcs generated by means such as arc welding can produce significant amounts of ultraviolet radiation which is damaging to the cornea of the observer. These arcs should only be observed through special dark filters which reduce the arc intensity and shield the observer's eyes from the ultraviolet rays.
  
  Section::::See also.
  
  BULLET::::- Arc lamp
  
  BULLET::::- Arcing horns
  
  BULLET::::- Corona discharge
  
  BULLET::::- Electric arc
  
  BULLET::::- Ignition system
  
  BULLET::::- Model T Spark Coil
  
  BULLET::::- List of electronics topics
   They are going to the test in Jones' van, but Walker has been using it to fulfil a blackmarket order for Warden Hodges, the greengrocer, and has half a ton of onions. These cause the platoon (especially Pike) some discomfort on the journey and Hodges is so incensed about the non-delivery of the onions that he follows them.
   BULLET::::- Lamentations 2:18: "Their heart cried unto the Lord, O wall of the daughter of Zion, let tears run down like a river day and night: give thyself no rest; let not "the apple of thine eye" cease".
  
  BULLET::::- Zechariah 2:8: "For thus saith the L of hosts; After the glory hath he sent me unto the nations which spoiled you: for he that toucheth you toucheth "the apple of his eye"".
   Squinting is also a common involuntary reflex, especially among people with light colored eyes, during adaptation to a sudden change in lighting such as when one goes from a dark room to outdoors on a sunny day to avoid pain or discomfort of the eyes. The pupillary light reflex caused by adjustment to light takes around five minutes in people with healthy eyes, so squinting and pain after that could be a sign of photophobia.
   Section::::Former Guests and Co-Hosts.:Mike Bridenstine.
   Ramsay gives up, goes out and sends in an NAAFI canteen girl. Remembering Wilson's advice from before, the platoon grab her, knocking over her trolley and pulling her hair, believing it is a wig, to which she responds, "Oh, you're worse than the Regulars!" Told to get rid of the urn, Pike throws it through the (closed) window, where it hits Hodges and the Verger, and empties all over the Verger.
   Corneal ulcers are painful due to nerve exposure, and can cause tearing, squinting, and pawing at the eye. There may also be signs of anterior uveitis, such as miosis (small pupil), aqueous flare (protein in the aqueous humour), and redness of the eye. An axon reflex may be responsible for uveitis formation — stimulation of pain receptors in the cornea results in release inflammatory mediators such as prostaglandins, histamine, and acetylcholine.
  
  Section::::Superficial and deep corneal ulcers.:Diagnosis.
   Section::::Structure.:Nerve supply.
  
  The cornea is one of the most sensitive tissues of the body, as it is densely innervated with sensory nerve fibres via the ophthalmic division of the trigeminal nerve by way of 70–80 long ciliary nerves. Research suggests the density of pain receptors in the cornea is 300-600 times greater than skin and 20-40 times greater than dental pulp, making any injury to the structure excruciatingly painful.
   BULLET::::- Optic nerve damage on the left (e.g. transection of left optic nerve, CN II, somewhere between retina and optic chiasma, therefore damaging the left afferent limb, leaving the rest of the pupillary light reflex neural pathway on both sides intact) will have the following clinical findings:
  
  BULLET::::- The left direct reflex is lost. When the left eye is stimulated by light, neither pupils constrict. Afferent signals from the left eye cannot pass through the transected left optic nerve to reach the intact efferent limb on the left.
   Onions suffer from a number of plant disorders. The most serious for the home gardener are likely to be the onion fly, stem and bulb eelworm, white rot, and neck rot. Diseases affecting the foliage include rust and smut, downy mildew, and white tip disease. The bulbs may be affected by splitting, white rot, and neck rot. Shanking is a condition in which the central leaves turn yellow and the inner part of the bulb collapses into an unpleasant-smelling slime. Most of these disorders are best treated by removing and burning affected plants. The larvae of the onion leaf miner or leek moth ("Acrolepiopsis assectella") sometimes attack the foliage and may burrow down into the bulb.
   Nutritional deficiencies affect the whole body, so pain or loss of sensation in the arms and legs (peripheral neuropathy) is often seen in patients with nutritional optic neuropathies. There was an epidemic of nutritional optic neuropathy among afflicted Allied prisoners of war of the Japanese during World War II. After four months of food deprivation, the prisoners of war developed vision loss in both eyes that appeared suddenly. They also had pain in their extremities and hearing loss. There is an endemic tropical neuropathy in Nigeria that may be due to a nutritional deficiency, but this has not been proven.
   Cases of severe, refractory pain and related symptoms attributed to this condition have been described in medical publications. The severe and constant nature of the pain, as well as the difficulty in effective pain management are characteristics of severe cases. Oxford Academic described a case of a post-Lasik corneal neuralgia patient whose pain was refractory to years of aggressive ophthalmological and pain management treatments, and required surgical intervention to manage the constant, debilitating pain. Prior to surgery, the patient reported daily pain which varied from 6 to 10 on a numerical rating scale (where 0 signifies no pain and 10 the worst imaginable pain), depending on environmental factors. The pain was described as sharp, non-radiating, felt like paper cuts in both eyes, and the pain had persisted for 7 years prior to successful treatment with an implanted intrathecal pain pump.
   A segment in which Patrick discusses situations that make one want to cringe in disgust. Fans are encouraged to email or call in with their cringe fantasies. An example of a cringe moment would be taking a pair of toenail clippers, sliding them over your front teeth, and clamping down as hard as you can. And twisting, if you're feeling fancy.
  
  Section::::Legacy segments.
  
  Section::::Legacy segments.:Bad Podcast of the Week.
   Seigel and Kosuga made millions of dollars on the transaction due to their short position on onion futures. At one point, however, of onions were selling in Chicago for less than the bags that held them. This drove many onion farmers into bankruptcy. A public outcry ensued among onion farmers who were left with large amounts of worthless inventory. Many of the farmers had to pay to dispose of the large amounts of onions that they had purchased and grown.
  
  Section::::Commodity trading.:Regulatory action.
  