Chemicals in fly sprays under spotlight

There's emerging evidence that chemicals found in fly sprays and flea collars may be more harmful than we thought.

spraying a can

They’re found in products readily available at supermarkets and hardware stores. Synthetic pyrethroids are used in fly sprays as well as flea collars and bed bug treatments. They’re also used on carpet to prevent insect damage.

They’ve gained favour because their toxicity has been considered relatively low compared with the nasties they’ve replaced. However, there’s emerging evidence of the risks these chemicals – and the way we’re using them – have for our health and the environment.

In October, the Environmental Protection Authority (EPA) announced it was investigating products containing synthetic pyrethroids.

Dr Fiona Thomson-Carter, general manager of the EPA’s hazardous substances group, said the investigation was sparked by new information from regulators in Canada, the EU and the United States identifying risks to people and animals from products containing these chemicals.

“This information concerns risks to children from accidental exposure to flea collars and treated carpets, as well as people reporting a burning or prickling sensation, known as paraesthesia, after coming into contact with synthetic pyrethroids,” she said.

How they’re used

Synthetic pyrethroids are used as insecticides. They’re synthetic versions of pyrethrins, found in chrysanthemum flowers. However, these manufactured versions are much more toxic to insects and last longer in the environment.

The chemicals are common in pest control products used in agriculture and in the home. They work by attacking an insect’s nervous systems, effectively paralysing the bug and leading to its death.

Various pyrethroids can be found in consumer products. Permethrin is among the most common. You’ll find it listed as an ingredient in fly sprays and flea treatments. It’s one of nine pyrethroids the EPA has put on its priority list for review.

The EPA concluded the likely exposure of children to the tetramethrin in the product exceeded acceptable levels and chronic exposure could result in adverse health effects.

Some products contain more than one pyrethroid. In 2017, the EPA declined an application to import Expra Odourless, a fly and insect spray in an automatic dispenser, because it contained the pyrethroid tetramethrin along with permethrin and d-phenothrin.

The EPA concluded the likely exposure of children to the tetramethrin in the product exceeded acceptable levels and chronic exposure could result in adverse health effects.

Tetramethrin isn’t approved for use in the EU and is being reviewed in the US. Other pyrethroids are also under scrutiny in the US and elsewhere. Controls have been tightened as a result. Canada, for example, restricted the agricultural use of the pyrethroid bifenthrin following a 2017 safety review.

Evidence of harm

The EPA said it wasn’t aware of any specific incidents here from the use of fly sprays or insecticides used in the home, but some may go unreported.

Data from the National Poisons Centre shows it received 1544 inquiries about synethetic pyrethroids between 2008 and 2012. These inquiries related to a range of products including agricultural insecticides, fly sprays, household bug bombs and liquid insecticides.

Among the cases reported was a patient who developed a burning and tingling sensation on his face and neck after spraying his house with a pyrethroid insecticide. Another case involved a patient who developed nausea and a skin rash when treating livestock with one of these chemicals.

What’s happening now?

The EPA has issued a caution notice alerting consumers to the risks of products containing synthetic pyrethroids. Its advice: these chemicals are hazardous substances and safety instructions on product packs need to be followed.

The EPA has also put out a public call for information about the use of synthetic pyrethroids. The closing date was 1 February, 2019. It’s now assessing the information received before deciding next steps.

Up for review

Nine synthetic pyrethroids are on the EPA’s list of priority chemicals flagged for review:

  • Bifenthrin
  • Bioresmethrin
  • Cyfluthrin
  • Cyhalothrin
  • Cyhalothrin, lambda
  • Cypermethrin
  • Cypermethrin, alpha
  • Deltamethrin
  • Permethrin.

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