The compound, which was used due to shortage of cyclohexane, left dozens of candidates and invigilators ill.
Those affected complained of chest pains, headaches and stomach discomfort.
Others suffered burns after the compound exploded on heating.
But Education Cabinet Secretary George Magoha dismissed reports of xylene posing danger to candidates and invigilators even after two teachers were hospitalised.
“Most of the substances we use in Chemistry are dangerous. The substance of xylene that they are talking about is not as dangerous as chemicals such as chlorine… and these substances have been used since I was in high school,” said Magoha.
So is xylene dangerous to human health? Does it cause cancer as officials of Kenya Union of Post Primary Education Teachers (Kuppet) claimed? And does it cause miscarriages?
Here is what you need to know about this compound:
Xylene is a colourless, sweet-smelling liquid or gas that occurs naturally in petroleum, coal and wood tar.
The aromatic hydrocarbon is mostly used in industry and medical technology as a solvent— a liquid that can dissolve other substances.
It occurs in three forms or isomers, which include meta-xylene, ortho-xylene and para-xylene.
Xylene highly flammable, evaporates easily and does not mix well with water.
However, it does mix with alcohol and many other chemicals.
Along with other solvents, xylene is widely used as a cleaning agent, a thinner for paint, as well as in varnishes.
Xylene evaporates quickly, meaning that most xylene that gets into soil or water is released into the air and broken down by sunlight and less harmful chemicals within a couple of days.
However, if xylene make its way down into underground water, it may remain for several months before being broken down.
When its vapour is released into the air, it may cause irritations.
Because of this, the nauseatingly sweet smell of xylene should serve as a warning for its toxic nature.
How are humans exposed to xylene?
According to the Journal of Clinical and Diagnostic Research, exposure to xylene primarily occurs via inhalation, ingestion, eye or skin contact.
In many cases, xylene is often from industrial sources, automobile exhaust, and during its use as a solvent as was the case in the KCSE chemistry practical paper.
As a result, those working in the paint industry, garages, and metal industries are at most risk for exposure.
Similarly, those who live close to these industries are at an equally high risk.
Contaminated soil
You may also be exposed to xylene by using products such as gasoline, paint varnish and rust preventatives.
Studies also show that small amount of xylene can even be found in cigarette smoke.
Xylene exposure can also occur thorough contact with contaminated soil and by drinking contaminated water.
Due to its harmful reactions to the body, it is important that people should take caution when around or when handling xylene, due to its inhalation and irritant risks.
What are the health risks of xylene?
According to the Centres for Disease Control (CDC), the primary risk of xylene exposure includes effects from inhalation or contact with the skin or eyes.
Although xylene is not classified as a carcinogen— having the potential to cause cancer— it is considered a central nervous system depressant, meaning it slows down the central nervous system.
The International Agency for Research on Cancer have found that there is insufficient information to determine whether or not xylene is carcinogenic and consider xylene not classifiable as to its human carcinogenicity.
Breathing in xylene can affect the nervous system, respiratory system, cardiovascular system.
It may cause dizziness, nausea, fainting, headache and even vomiting.
Visual impairment and difficulty may also result from xylene exposure.
Other drastic symptoms might include tremors, heart arrhythmias and pulmonary oedema.
- Laboured breathing
- Impaired pulmonary function
- Increased heart palpitation
- Severe chest pain
- Accumulation of fluid in lungs
- Respiratory depression or arrest
- Ventricular arrhythmias
Scientists are not quite sure how xylene results in toxicity in the body, however, studies indicate that it could be because of the high fat-solubility qualities that the compound has.
With this premise, it means that xylene could be soluble with lipids in the membranes of neurons, and as a result, could affect neuronal proteins.
According to the Journal of Oral and Maxillofacial Pathology, xylene also poses risks to skin and eyes and is considered a skin irritant.
The skin absorbs xylene quickly because xylene is so efficient at removing fats, thus, any contact with the skin will have the same effect.
This can lead to drying and cracking of the skin and dermatitis.
Effects on eyes and ingestion
When in contact with the eyes, studies show that xylene can damage the cornea.
Because of this, it is important to always wear safety goggles when working with xylene.
Any ingestion by mouth should be taken very seriously as well by quickly obtaining medical aid.
According to the CDC, longer exposure to xylene yields an even greater risk as even smelling it can affect major organs.
Effects on pregnant women
Although there are no conclusive studies in humans, studies show that it is possible that exposure of pregnant women to high levels of xylene may cause harmful effects to the foetus.
What are the symptoms of xylene exposure?
Blood and urine tests can determine exposure to xylene.
However, because xylene quickly leaves the body, the CDC advises that these tests must be taken within hours after exposure.
While these tests can indicate exposure to xylene, they cannot be used to predict which health effects may, if at all, develop as a result of the exposure.
Symptoms of xylene exposure include:
- Eye irritation and impaired vision
- Headaches, dizziness and fatigue
- Tremors
- Incoordination and paralysis
- Stomach discomfort, nausea and vomiting
- Impaired short-term memory
- Anxiety and inability to concentrate
- Lack of muscle coordination
- Skin irritation
- Coma and even death
What should you do if you have been exposed to xylene?
If you believe you may have been exposed to xylene and your health has been effected, you should seek medical attention, preferably from a doctor familiar with chemical exposure.
The US Department of Health and Human Services, also recommends the following:
- Eye exposure: If xylene or a solution containing xylene gets into the eyes, immediately flush the eyes with large amounts of water for a minimum of 15 minutes, lifting the lower and upper lids occasionally. Get medical attention as soon as possible.
- Skin exposure: The contaminated skin should be washed with soap and water for at least 15 minutes. If irritation persists, get medical attention.
- Inhalation: If xylene vapours are inhaled, move the victim at once to fresh air and get medical care as soon as possible. If the victim is not breathing, perform cardiopulmonary resuscitation; if breathing is difficult, give oxygen. Keep the victim warm and quiet until medical help arrives.
- Ingestion: If xylene or a solution containing xylene is ingested, give the victim several glasses of water to drink. Get medical help immediately. Keep the victim warm and quiet until medical help arrives. Do not induce vomiting if the person is unconscious as it is associated with the danger of pulmonary aspiration.
How can you prevent or reduce exposure?
- While using xylene as a solvent in paint or gasoline, ensure that the room is properly ventilated. Also store these products in tightly closed containers.
- Keep xylene products out of reach of children.
- Avoid drinking water from contaminated sources as it might contain xylene. Also, children should avoid playing in contaminated soil or dirt.
- If products containing xylene are spilled on the skin, then the excess should be wiped off and the area cleaned with soap and water.
- Those working at industries that handle xylene should always wear protective clothing that will prevent exposure to their eyes, skin and mouth.
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