Introduction

You may not have heard of ethylene glycol before, but you may have used it at some point.

Ethylene glycol, a colourless and odourless liquid, is a chemical commonly found in antifreeze formulations and various industrial contexts. It has garnered attention not only for its practical applications but also for its potential to pose a significant health hazard if used incorrectly. Ethylene glycol poisoning, resulting from accidental ingestion, occupational exposure, or intentional consumption, has emerged as a serious and life-threatening medical concern. 

Sources of Exposure

1. Accidental ingestion of antifreeze

This common household liquid may not always be stored safely. The natural inquisitiveness of children and pets puts them at risk of accidentally ingesting even a small amount of antifreeze. Ethylene glycol, a major component of antifreeze, can quickly transform from a simple household substance to a life-threatening hazard. 

Raising awareness about proper storage and prompt action in case of accidental ingestion is essential to safeguarding the wellbeing of our pets and young ones. 

2. Deliberate ingestion

Due to its easy access, ethylene glycol can be used in some cases of intentional overdose. Access to mental health resources and other forms of support are vital in these cases. In some cases, there have been instances of intentional ingestion in the absence of alcohol (which is made of ethanol, which has a similar chemical structure) but it is much more toxic.¹

3. Occupational exposure in industries

Forms of ethylene glycols are used on an industrial level during the production of polyester fibres, soaps and paints. Workers engaged in various manufacturing, cooling, and heating operations of might encounter ethylene glycol as a routine part of their job.

High levels of these can put workers at risk of exposure, emphasising the need for rigorous workplace safety protocols, comprehensive training and proper personal protective equipment to ensure the safeguarding of the health and wellbeing of workers. 

Mechanism of Toxicity

Once ethylene glycol finds its way into the body, be it through ingestion or exposure, it's quickly absorbed through your stomach and intestines. 

1. Metabolism in the liver to toxic metabolites

Once ethylene glycol is inside, your liver plays a large role in why this substance becomes toxic.² The liver breaks down ethylene glycol into two main chemicals: glycolic acid and oxalic acid. It is these chemicals that cause damage to the body, rather than the substance itself. 

2. Impact on the central nervous system and vital organs

The compounds created by the breakdown of ethylene glycol first affect the central nervous system (the brain and the spine), leading to serious consequences. These include symptoms such as confusion and altered mental states, and more seriously, it can lead to seizures. 

After affecting the central nervous system, the chemicals start to affect the heart, and finally the kidneys. This multiorgan failure occurs due to the damage that the chemicals have on a cellular level, affecting how the cells survive, grow and multiply. This can lead to changes in heart rhythms (arrhythmias) and even heart failure.³ Kidney failure can occur around 24-72 hours after ethylene glycol ingestion, showing just how potent and dangerous the substance is.  

3. Formation of calcium oxalate crystals leading to organ damage

Oxalic acid combines with calcium to form a compound called calcium oxalate. Because the calcium in the body is now combined with the toxic oxalic acid, there is less for the body to use. This results in hypocalcaemia (low calcium levels), which can lead to symptoms such as numbness, tingling and muscle spasms. The calcium oxalate created can also deposit in the walls of blood vessels and cause inflammation and damage to brain cells.⁴ 

Clinical Symptoms 

Early signs and symptoms 

Ethylene glycol absorbs through the stomach very quickly, as quickly as within 1 hour. This means that there are some early symptoms, namely nausea, vomiting and abdominal pain due to irritation of the stomach. Initially, early symptoms may seem similar to alcohol intoxication. 

Progression of symptoms 

As the chemical is further absorbed and metabolised by the body, it starts to affect the heart and nervous system. This may present as changes in heart rate, blood pressure, and even confusion. 

Renal complications and potential kidney failure 

The build-up of substances that ethylene glycol breaks down into:glycolic acid and oxalic acid,. can be very dangerous as it can lead to renal failure.  

Recognising the delayed onset of symptoms 

Although the majority of symptoms present quite quickly, some later symptoms have been reported less frequently. Notably the cranial nerves can be affected even up to 20 days after exposure to ethylene glycol, which can cause issues with speech, facial expressions or hearing issues.⁵ 

The delayed onset of symptoms may make it harder to identify ethylene glycol poisoning, highlighting the importance of keeping a watchful eye for potential symptoms after an initial exposure.

Diagnosis and Medical Evaluation 

The most important first step in diagnosing ethylene glycol poisoning is to take a thorough medical history to identify possible exposure and to identify any of the early signs of poisoning. 

Further steps include blood tests and urine analysis, which can identify the presence of glycolic and oxalic acids that ethylene glycol breaks down into.⁶ These tests play a pivotal role in confirming the poisoning, enabling timely intervention.  

If there is a suspicion of poisoning, radiological imaging techniques may be warranted. There are features of the effects of the chemical that may be seen on CT or MRI scans, which allow doctors to assess any potential organ damage. 

Importantly, a differential diagnosis is conducted to exclude other conditions that might mimic the symptoms of ethylene glycol poisoning, such as ethanol excess.

This intricate diagnostic process highlights the importance of combining multiple approaches to ensure the best possible identification and treatment of ethylene glycol poisoning. 

Treatment and Management 

Immediate Measures for Ingestion Cases

• Gastric lavage: If ingestion is recent and the person is conscious, gastric lavage (stomach pumping) may be considered to remove any remaining ethylene glycol from the stomach. 
• Activated charcoal: This can bind to the chemicals produced when ethyl glycol breaks down,  to reduce its absorption in the gastrointestinal tract. 

Administering antidotes

Fomepizole is a competitive antagonist of of the enzyme alcohol dehydrogenase.⁷ This enzyme breaks down ethylene glycol but, in the presence of fomepizole, its activity is inhibited. 

Ethanol can also be used as an alternative antidote. It competes with ethylene glycol for the alcohol dehydrogenase enzyme, meaning that the ethanol will be broken down instead of the toxic ethylene glycol. 

Supportive Care

• Intravenous (IV) fluids: Hydration is crucial to maintain kidney function and promote the removal of ethylene glycol and the chemical it breaks down into from the body. IV fluids also help counteract the potential for dehydration caused by vomiting and increased urination. 
• Electrolyte balance: Monitoring and correcting electrolyte imbalances, particularly focusing on maintaining normal potassium levels, are important to prevent cardiac complications. 
• Haemodialysis: In severe cases, where ethylene glycol levels are dangerously high or if acid-base imbalances persist despite other interventions, dialysis may be necessary to directly remove the toxin and its metabolites from the bloodstream. 

Monitoring Vital Signs and Organ Function 

Continuous monitoring of vital signs such as heart rate, blood pressure, and respiratory rate after ingestion helps to detect any sudden deterioration. 

In addition, frequent blood tests are conducted to assess kidney function, electrolyte levels, and acid levels. Monitoring these helps to guide the treatment plan and to help decide whether further interventions are required. 

Prevention 

Proper Storage and Labelling of Antifreeze Products 

Antifreeze products containing ethylene glycol should be stored out of reach for children and pets. Additionally, clear labelling with warnings about the toxicity of the product and its potential hazards can help prevent accidental ingestion. 

Educating the Public 

Raising awareness about the dangers of ethylene glycol toxicity is crucial. Public education campaigns, especially targeting households with young children and pets, can help people recognise the risks and take necessary precautions. 

Occupational Safety Measures 

Industries using ethylene glycol need to implement strict safety protocols to prevent accidental exposure among workers. This includes providing proper training, safety equipment, and guidelines for handling the substance safely. 

Mental Health Support 

For intentional cases of ingestion, addressing underlying mental health issues is essential. Providing access to psychological support and counselling can help individuals cope with their emotional struggles and reduce the likelihood of intentional ingestion. 

Summary

Although it may seem like a harmless product in the cupboard, ethylene glycol can have serious impacts if ingested or if you are exposed to it in high concentrations.  

Once broken down into its toxic compounds, its initial effects on the central nervous system to its progression to renal failure and acidosis can become detrimental if not treated within the window of opportunity.  

Rapid medical attention, proper antidote administration, supportive care, and ongoing monitoring are critical for successful management. While prevention efforts like raising awareness and work safety measures can help to prevent further cases from occurring.