- A report for the International Scientific Forum on Home Hygiene in 2011 summarised at least 18 outbreaks of illness where caused by laundry
- Types of bacteria that could spread through laundry include salmonella or E.coli
- Temperature is by far the most important as the heat actively kills bacteria
A report for the International Scientific Forum on Home Hygiene in 2011 summarised at least 18 outbreaks of illness where caused by laundry
DIRTY LAUNDRY CAN MAKE YOU ILL
It may not be the first place you’ll pick up bacteria in your home — dirty kitchen cloths, incorrect food or hand hygiene, or picking up bugs from hard surfaces such as doorknobs are more likely routes of transmission.
‘But dirty laundry is still an important part in the hygiene picture,’ says Professor Sally Bloomfield, a microbiologist and honorary professor at the London School of Hygiene and Tropical Medicine.
A report for the International Scientific Forum on Home Hygiene in 2011 summarised at least 18 outbreaks of illness where the source was attributed to laundry, she explained.
Such outbreaks, when reported in scientific journals, tend to be from industrial laundries, but the point is that illness can be spread by incorrectly washed clothing, she says.
The types of bacteria that could spread through laundry include salmonella or E.coli, usually found in traces of faeces or on cloths used in the kitchen (and which can cause stomach upsets), yeast or fungal infections such as thrush or athlete’s foot, cold and flu bugs, Staphylococcus aureus (which can lead to boils if it enters a cut on the skin) and even MRSA.
The bugs get on to the clothing as we wear it and can then transfer through the wash.
'CLEAN' CLOTHES COVERED IN BUGS
Although we’re encouraged to wash at lower temperatures — either to protect the garments, to save money, or for environmental reasons — that could mean bacteria survives through a wash.
An analysis from Dettol in 2013, where scientists swabbed articles of clothing, soft toys and pet blankets before and after a wash, found that laundry done at 40c had just 14 per cent fewer bacteria after washing than before.
One in four items of clothing also still contained faecal bacteria, some of which have the potential to cause an upset tummy.
WASHING POWDER WON'T KILL GERMS
Temperature, how long the wash lasts, the agitation of the machine and the detergents used all combine to clean clothes — but they don’t all eliminate bacteria to the same extent.
Temperature is by far the most important as the heat actively kills bacteria by breaking down their structure.
‘A wash of over 60c, maybe even 50c, will kill most bacteria,’ says Dr Dirk Bockmühl, a microbiologist from Rhine-Waal University of Applied Sciences, a leading authority on laundry hygiene.
At lower temperatures, bugs can survive. A landmark study at America’s University of Montana in 1975 found that a cycle at 38c left 1,000 times more micro-organisms in a wash than one of 49c.
If you want to use a lower temperature, you need a longer washing time, as this increases the chance that bugs will physically be removed from the clothes by the movement of the machine, even if they’re not actually killed.
A 2014 study published in the Journal of Applied Microbiology found it took German researchers 90 minutes to remove the same amount of bacteria at 37c as it did in 15 minutes at 47c.
Types of bacteria that could spread through laundry include salmonella or E.coli
KEEP UNDIES OUT OF IT!
Most of us sort our wash by colour, but hygiene experts suggest we should sort it so items likely to carry more harmful bacteria don’t mix with cleaner items.
You should also never mix cloths used in the kitchen (such as tea towels) with clothing. ‘To me, if you mix up underwear and tea towels on a low-temperature wash, it’s the same as wiping your dishes with your knickers,’ says Dr Lisa Ackerley, a visiting professor of environmental health at the University of Salford.
Items at high risk of carrying lots of bacteria include the clothing of healthcare workers or carers, anything containing faeces or vomit (including baby clothes), sweaty sports clothing, kitchen cloths, clothing of those with skin diseases such as psoriasis or eczema, clothes worn by people with infections such as athlete’s foot and anything from pets.
These sorts of items should always be washed separately at 60c. Ideally, they should be stored in a different wash basket from other clothes to prevent bacteria moving from one item to another.
Surprisingly, even though each pair of worn undies contains an estimated tenth of a gram of faecal matter, unless you have an active stomach upset, undies are not classed as a high-risk item and can be washed at temperatures of 30-40c with the right powder —though it’s still suggested that you wash them separately from other clothing.
ENSURE YOU USE TWO DETERGENTS
While washing at temperatures of more than 60c will kill bacteria whatever washing product you use, at lower temperatures you need to use a product that contains an ingredient called activated oxygen bleach (AOBs).
These compounds turn into hydrogen peroxide on contact with water and have strong bug-killing powers. Liquid detergents rarely contain AOBs, nor do powders aimed at coloured washes. They’re often in products aimed at white washes, but you’ll need to check the list of ingredients.
‘AOBs can lighten fabric so you might not want to use these regularly on your normal clothing,’ says Dr Bockmühl. Keep one bacteria-killing powder for ‘high-risk’ items such as gym kit and kitchen cloths and another detergent for the rest of your wash.
Note that biological washing powders contain enzymes that lift stains from clothes, but these don’t have any specific powers against bacteria.
BEWARE CREEPY CRAWLIES
If anyone in the house has allergies to dust mites, you also need a hotter wash.
In 2007, when researchers from South Korea’s Yonsei University washed samples containing dust mites at 37c, only 6.5 per cent of the mites died.
When they increased the heat to 60c, 100 per cent of them died.
Nits and lice — which can survive short periods on pillowcases without their human host — can also survive lower heat washes.
In one trial published in 2006 in the journal Clinical Infectious Diseases, 31 (out of 36) nits and 165 (out of 215) lice survived a wash at 40c — but they all died when washed at 50c.
WASHING BY HAND MAY NOT KILL BUGS
If you handwash your clothes, you’re unlikely to use water of a hot enough temperature or spend long enough washing them to remove optimum levels of bacteria, says Dr Bockmühl.
While usually this won’t matter, if you have a condition such as thrush or an upset stomach it’s better to wear undies you don’t mind throwing in a hot wash.
NO LAUNDRY ON THE WORKTOP
As for the question of whether you should have a washing machine in the kitchen: no, it’s not ideal, says Dr Ackerley.
‘There is a risk of cross infection. If you put dirty or soiled laundry on the worktop before you load the machine, you could transfer bacteria or viruses to food.’
Likewise, kitchen bugs could transfer to clean washing if you take it out and put it on the kitchen counter.
‘If you don’t have the option of putting the machine elsewhere,’ she adds, ‘then at least keep the dirty laundry off the work surfaces and wash your hands after putting a load in.’
Clean your machine to get rid of fungus
When researchers at the University of Arizona analysed the water left in the drum of washing machines, they found 10 per cent of them carried bacteria such as E.coli
When researchers at the University of Arizona analysed the water left in the drum of washing machines, they found 10 per cent of them carried bacteria such as E.coli.
On top of this, a study from Slovenia, published in the journal Fungal Biology, found 79 per cent of machines contained bacteria known to cause skin, eye or nail infections in the powder and softener drawers or seals around the door.
Lab tests by the manufacturers of Canespro Fungal Nail treatment this month have also found that foot fungus microsporum gypseum could be transferred from socks to the machine’s seals after one cycle. Such nasties can then enter the wash the next time you use the machine. And, while it’s unlikely to cause you much harm, ‘it can cause your clothing to smell musty, even after washing’, says microbiologist Dr Bockmühl.
He suggests that once a month you run the machine empty, or with something such as white towels that can undergo a super-hot 90c wash, to kill any lingering lurgies.
It’s also a good idea to leave both the drawer and the door open for a while after washing to let moisture — which makes bacteria more likely to thrive — dry out.