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Dublin: 15 °C Thursday 21 August, 2014

Explainer: The dangers of slurry

Just one breath of ‘rotten egg’ hydrogen sulphide can kill.

Image: Slurry Tank via Shutterstock

A FARMING COMMUNITY in Antrim is today morning the tragic loss of a young boy following a slurry accident in Dunloy over the weekend.

The locals are also hoping for the speedy recovery of the boy’s father, Bertie Christie, who was also taken ill after being overcome by slurry fumes at a friend’s farm.

The father and son had been helping out, mixing slurry, for the elderly farmer.

It is one of many tragic accidents that occur on Irish farms every year. This time last year, a man’s body was discovered in a slurry tank in Tipperary.

Both incidents come after high-profile Ulster rugby star Nevin Spence died along with his father and brother in a similar accident in county Down almost two years ago.

An investigation has been launched following the death of Robert Christie. The Health and Safety Executive said the tragedy show the stark dangers of farming.

“The facts tell us that farming is our most dangerous industry,” he added.

Ireland’s Health and Safety Authority have launched various campaigns, highlighting personal experiences of amputations, chronic injury, near deaths and illnesses from toxic slurry pit gasses.

A Galway farmer Eoin Goldrick tells his story of when he was overcome by the toxic fumes.

He said the dangers posed by any deviation from best practice in dealing with slurry tanks were massive:

It’s like running into a fire. You will be caught.

Another farmer, Noel Tierney, remembers the day in 1993 when his son Fergal died trying to save him after he was exposed to the lethal substances.

Speaking about the dangers of slurry handling, Agriculture Minister Simon Coveney remarked, “The tragedy experienced by Noel Tierney and many other farm families over the years shows us that it is often the rescuer who rushes in to save a loved one that ends up being killed.

“When dealing with something that is as lethal as slurry gas, we must do everything in our power to minimise the risks and protect family, workers and animals alike.”

What is slurry?

Slurry is a mix of waste material from animals (for example, cow manure) and water.

Farmers keep the waste under barns during the winter and then use it during the warmer months as a natural fertiliser.

Before it can be spread, the manure must be broken up and mixed with water. This usually happens in a slurry tank. It is at this point, that the killer gases are created.

In Ireland, over 40 million tonnes of slurry are stored, handled and spread each year.

Why is it so dangerous?

There are two main dangers – drowning and asphyxiation. And there are very few warning signs. The gases – at a dangerous, high level – are both odourless and invisible so they are, essentially, a silent killer.

While in the tank, toxic gases are released during the bacterial decomposition of slurry. The gases include hydrogen sulphide, ammonia, methane and carbon dioxide. They can all be lethal.

  • Methane is flammable. 
  • Hydrogen Sulphide is poisonous.
  • All of the gases are heavier than air so they displace oxygen.

Hydrogen sulphide is particularly dangerous and is extremely poisonous. It affects the nervous system and even the smallest concentrations can cause death.

Hydrogen sulphide has a ‘rotten egg’ smell at low levels, but cannot be smelt at higher levels. High levels can be released when slurry is agitated.

The HSA warns that one breath or lung-full of hydrogen sulphide at this high level will cause instant death.

Highest risk when slurry is being agitated. The gases are trapped in the slurry and are released when it is mixed. Studies indicate that levels are greatest shortly after mixing commences in the tank, when slurry is stored for several months, when slurry is mixed in deep tanks, after silage effluent is added and when slurry is mixed in cold weather.

Exactly how dangerous is it?

Between 2000 and 2010, 30% of child farm deaths were caused by drowning in slurry and water or asphyxiation from gas poisoning. In the same period, 8% of deaths to elderly farmers were caused by drowning. There have been six people (including one child) killed in and around slurry tanks since 2010.

Drowning in slurry and water, and asphyxiation (gas poisoning), caused 14% of farm deaths between 2000 and 2009.

Accident statistics now indicate that drowning in slurry storage tanks is the cause of more fatal accidents than poisoning by slurry gases, according to the HSA.

What precautions do farmers take?

The HSA has a list of best practices for farmers who handle slurry. It also issued a safety DVD earlier this year. The list includes:

  • Evacuate and ventilate before you agitate.
  • Never agitate slurry in still air conditions.
  • Move all animals out of the shed before commencing.
  • Work upwind at all times.
  • At least two people should be present at all times.
  • Open all doors and outlets to provide a draught.
  • Never stand over slats or near tank access points when agitation is in progress.
  • Gases can build up and remain in partially emptied tanks above the slurry, never enter a tank for any reason.
  • See more here.

What else does the HSA say?

CEO Martin O’Halloran had this to say in April this year:

While the majority of slurry related fatalities we investigate involve drowning, there is concern that low levels of toxic gases emitted may have played a part. Even in very small doses these gases can cause dizziness and disorientation which can cause a person to fall into a tank or pit and drown. I appeal to farmers to follow the simple rules to stay safe while handling slurry.

Read: Funeral of Robert Christie to be held tomorrow

Video: “One moment off-balance and my leg was gone”

More: Ulster star Nevin Spence dies in accident on Co. Down farm

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