Dog shampoos may trigger autism in children
COULD insecticides in pet shampoos trigger autism spectrum disorders?
That’s the suggestion of one of the first large-scale population-based studies to look at how environmental factors and their interactions with genes contribute to the condition.
Mothers of children with autism spectrum disorders (ASD) were twice as likely as those with healthy children to have reported using pet shampoos containing pyrethrin around the time of their pregnancy.
The findings from the Childhood Autism Risks from Genetics and the Environment Study, which was funded by the US National Institute of Health, have raised the possibility that pyrethrins found in some pet shampoos are linked to an increased risk of autism.
They were reported in May at the 7th International Meeting for Autism Research in London in a California case control study that looked at household pesticide use.
Lead study author, Professor Irva Hertz-Picciotto, PhD, from the University of California, Davis, stressed that the findings remain preliminary. She said the risk was greatest if anti-flea and anti-tick pet shampoos containing pyrethrin were used during the second trimester of pregnancy.
‘Autism is associated with an imbalance between excitatory and inhibitory neuro-transmitters within the brain, and one could hypothesise that children with an imbalance in this system may be more sensitive to the effects of pyrethrins,’ said Isaac Pessah at UC, Davis, who was also involved in the study.
The researchers found that products containing pyrethrin – typically pet shampoos and certain sprays for controlling flies, ants and cockroaches – were associated with an increased risk for autism spectrum disorders.
Dr Hertz-Picciotto and other experts, including Tony Charman of University College, London, are calling for further studies into the links between anti-flea pet shampoos containing pyrethrin and autism in children.
She said: ‘The bottom line here is (that pyrethrin) is something that really deserves further study’
Medicines for flea and tick control are one of the fastest growing areas of modern veterinary science. As fleas have become resistant to many products and with the explosion in the flea population as our climate becomes milder, so have efforts redoubled to control them.
Ticks can transmit a number of diseases affecting pets and humans, so their control has also become more important and is receiving more scientific attention.
Today’s insecticides for pets have made great advancements and a wide array of compounds are now on the pet product market, including pyrethrins, which have been used as insecticides for over 100 years.
Pyrethrins are natural extracts made from the flowers of chrysanthemum plants which grow naturally in the Middle East, Europe, Japan and Kenya.
There are six different pyrethrins: pyrethrin 1 and 2, cinevin 1 and 2, and jasmolin 1 and 2. All six are found in flea and tick products but, generally, the label only reads ‘pyrethrin’, regardless of which one of the six types is present.
They work by affecting the nervous system of insects and result in repeated and extended firings of the nerves. They do this by affecting the flow of sodium out of nerve cells. Eventually, the flea or tick dies.
Generally, pyrethrin-containing shampoos are ideal for larger dogs that spend a lot of time outdoors. All pyrethrins are easily hydrolyzed and degraded by stomach acids, so toxicity following ingestion by pets is very low.
Although rare, toxicities do sometimes occur. A cat or a dog with pyrethrin toxicity will generally salivate, tremor, vomit and may seizure. Generally, signs of toxicosis will disappear after 24 hours.
Whereas dog owners with one pet will only use such shampoos occasionally, professional dog groomers, veterinary nurses and dog breeders are likely to be exposed to risk much more often.
Anxiety about the use of pesticides in the home is nothing new. A VBD Market Survey carried out in January 2007 showed that two out of three pet owners were concerned about safety when using a pesticide-based flea spray in their homes.
There are many veterinary on-animal tick and household flea products on the market which have undergone rigorous testing to conform to the latest UK health and safety standards.
Vets should always be consulted before using topical pyrethrin-based dips and sprays on sick, pregnant, aged or nursing animals. Now it seems that pet owners, particularly those who are planning a family, should always seek expert advice about the possibility of exposure to the risks associated with pyrethrin-based products.
But Dr Hertz-Picciotto cautioned that pyrethrins are unlikely to be the only cause of autism. She said: ‘It is important to remember that autism is multi-factorial. Generally speaking, probably most cases of autism arise from multiple genetic, as well as multiple environmental factors.
‘Outdoors, pyrethrin has a very short half-life, but indoors it lingers for a long time, for example, in pet hairs, so that people continue to be exposed.’
Choosing Dog Flea Shampoos
Conditioners: Choose a dog flea shampoo with conditioners like aloe vera and oils like cedar wood, eucalyptus, tea tree, and pennyroyal to prevent your dog’s skin from drying.
Formulation: Choose a dog flea shampoo formulated to kill not only adult fleas but flea eggs as well.
Recommendation: Consult with your veterinarian before buying a dog flea shampoo, and get only the one recommended by him. You have to know beforehand if your dog is allergic to any of the pesticides in the shampoo.
Scent: Do not get a scented dog flea shampoo, as it can irritate your dog’s skin and attract more insects and pests.