Squeaky Clean:  at what cost?
© Robert Anderson PhD
Originally published in Organic New Zealand, January/February 2005, Vol. 64 No. 1

There is little doubt that the chemical industry has excelled itself as far as keeping dishes squeaky clean. There is a plethora of dish washing liquids, powders, and additives to ensure dishes and eating irons remain clean and bug free. My grandmother, a wise old Yorkshire woman, kept a quaint little wire basket into which she put all the left over bits of soap. This would be vigorously swished around prior to washing dishes and for some reason the process always fascinated me. Even at an early age, it made me appreciate her frugal use of what, today, is simply discarded. And her dishes were always immaculate.

There is now an enormous pressure from the detergent manufacturers as one brand fights to outdo a competitor. Never a TV programme goes by without viewers being drowned in the intervals by a glut of commercials to remove stains, wash dishes whiter than white and at the same time maintain hands as soft as silk. Common sense would tell us that if we are able to remove “the most stubborn grease” from dishes, it is most unlikely that it would not do the same to the oils in skin. It is certainly worth investigating just what some of these chemical wonders are and what they can do.

These detergents are divided into two categories: automatic dishwasher detergents and dish washing detergents for manual washing. Machine dish washing detergents have been known to produce skin irritations or burns, and it is obvious they are poisonous if swallowed. Hand dish washing detergents are generally safer than machine dish washing detergents. If swallowed, they are generally not lethal, but can still cause irritation to the mouth and throat, together with nausea. They are also safer for the environment. Even so, they should be kept away from small children to minimize the risk of accidental poisoning.

The (US) Centre of Science in the Public Interest[i]discovered that dish washing detergents are responsible for more household poisonings than any other home cleaning products. Ingredients used can be alkaline phosphate salts, naphtha, a central nervous system depressant, and cleaning agents such as diethanolsamine, a liver poison, chlorophenylphenol, a toxic metabolic stimulant, and chlorine, a poison. These chemicals are released into the air around you during the dish washing process. Formaldehyde is in many cleaning products, including laundry detergents and shampoo.

Thousands of New Zealand homes are now equipped with dish washing machines, consuming millions of kilograms of machine dish washing detergents annually. This represents a potentially significant burden on our environment in terms of waste water loading and disposal of packaging.

The main components in machine dish washing detergents are phosphate alkaline silicates and builders. Tripolyphosphates are the most commonly used builders and may constitute as much as 30 percent by weight of machine dish washing detergents.

Alkaline ingredients, such as sodium metasilicate, add to soil removal and are highly corrosive if accidentally swallowed.

Another common chemical used in most detergents is sodium lauryl sulfate (SLS). This is a caustic detergent used for removing the grease. Sodium laurel sulfate and other forms of this substance can irritate skin, lower brain function, and contribute to blindness, yet they are commonly used in shampoos, toothpastes and other personal hygiene products. Alkyl phosphates are shown on the label as alkaline salts and control sudsing where suds would interfere with the action of the machine. In hand detergents, where suds level is an important indicator of cleaning power, we require high sudsing.

We also find alkanolamides or alkylamine oxides used as surfactants.[ii]These act to reduce the surface tension of the water so that it spreads more readily and wets the dishes.[iii]Detergent surfactants were developed during World War II in response to a shortage of oleochemical surfactants derived from animal and vegetable fats and oils. Petroleum was found to be a plentiful source of surfactants which were also useful in hard water. Detergent surfactants today are made from a variety of petrochemicals and oleochemicals (derived from fats and oils). Surfactants perform other important functions in cleaning, such as loosening, emulsifying (dispersing in water) and holding dirt in suspension until it can be rinsed away. Surfactants can also provide alkalinity, which is useful in removing the remains of acidic food.

Particular Hazards

Automatic dishwasher detergents are generally more hazardous than hand washing in three important ways:

First- most dish washer detergents contain chlorine in a dry form, which becomes activated when in contact with water, releasing chlorine fumes into the dish washer and into the air. Air in the home is effectively enclosed and thus allows for a build-up of toxic gases, such as chlorine. A five-year study conducted by the US Environmental Protection Agency (EPA) showed many samples of indoor air to be 70 times more toxic than those outside. New Zealand homes may not be vastly different.

People have reported symptoms such as headaches, burning eyes, and difficulty breathing when exposed to dishwasher chlorine fumes; thus the release of chlorine from automatic washing machines could pose a serious problem. Dioxin and formaldehyde can also be by-products created during chemical changes taking place in a dishwasher.

A scientific paper delivered at the Indoor Air Conference in 1990[iv]in Toronto stated: “Because of household cleaners, housewives have a 55 percent higher risk of contracting cancer.” In the US alone, there has been an 80 percent increase in respiratory problems amongst children since 1960. One wonders if the asthma epidemic in New Zealand follows a similar etiology? Are these detergents a contributing factor?

Second -a thin film of detergent can dry on your dishes, which is ingested in small amounts every time you eat. This build up is undoubtedly detrimental to our health so rinsing is essential. Have you ever taken a sip of a cuppa and found you can taste detergent? Scientist, Myron Wentz, when researching micronutrients, discovered that washing-up detergent could form a film around individual cells in our bodies and thus reduce the cell’s ability to take in nutrients.[v]

Third- some automatic dish washing detergents still contain high concentrations of phosphates, which kill fish and other aquatic life. There is also a real risk of caustic burns if phosphates come into contact with the skin. However, according to the EPA, when manufacturers lower the levels of phosphates in their product, the level of toxicity increases by a 1000 times. This may take place because the highly alkaline phosphate salts tend to stabilize the release of excess chlorine gas. Lower the level of phosphates and the chlorine is left to go free.

Most of these products are classified as irritants and/or corrosives depending upon their concentration and physical form, but the general advice is to keep such chemicals well away from children and to carefully follow the instructions printed on the product.

New Zealand does not have an equivalent of the US Environmental Protection Agency and often has to depend on EPA findings. But the EPA depends on industry-sponsored tests for approval. In 1981, one company was found guilty of falsifying over 90 percent of more than 2000 studies. Its products are still readily available.

Public concern in New Zealand has not reached the same level it has in Europe, where environmental issues have had a significant influence on the manufacturing methods of companies producing detergents. Consequently, the focus there has not only been on the development of more innovative, effective, and refined products, but also on ways to reduce the impacts of their product on the environment and the user.

Here in New Zealand it is necessary to read the label and if possible buy only those New Zealand products with eco-friendly stickers[vi]and none of the chemicals above listed in their ingredients. Beware also those products which list only obscure general references such as “non-ionic surfactants” or “emulsifiers”.

Is there a recipe for a safer home? Here are two suggestions.

Hand dish washing liquid

Use a plain, liquid, vegetable-based soap (versus petroleum-based soaps), or rub a sponge with bar soap.

A few slices of lemon added to the water helps to cut the grease and give the dishes a lemon smell. Cut soap usage in half by using sodium hexametaphosphate in hard water. Dishes will dry spotless.

Hexametaphosphate can be obtained through any chemical supplier (in the NZ and pacific region from Albright & Wilson http://www.chemlink.com.au/albright.htmor from a photographers supplier.) It is also known by the informative name of Calgon or ‘SHMP.’ If the area has 'hard' water – carrying high levels of calcium and other minerals - they interfere with both washing and dyeing processes.

You can easily avoid the problems by using this water softener. About 1 cup of SHMP per washing machine load or 1/4 teaspoon per 8 oz. dye solution and it should do the trick.

N.B. Although hexametaphosphate can cause skin irritation, it is far safer than most of the other chemicals mentioned above.[vii]

Machine dish washing

Use sodium hexametaphosphate in place of detergent. Sodium hexametaphosphate does not remove dried on food so it pays not to leave the dishes too long before washing.

Never use dish washing liquid as a substitute. The suds will inhibit the water spray.


Robert Anderson BSc (Hons), PhD - 4 February 1942 to 5 December 2008

Robert Anderson was a Trustee of Physicians and Scientists for Responsible Genetics (now Physicians and Scientists for Global Responsibility) www.psgr.org.nz. He authored The Final Pollution: Genetic Apocalypse, Exploding the Myth of Genetic Engineering and several other books on environmental, health and social justice issues, and spoke extensively throughout New Zealand on a variety of related subjects.

View his lectures on this website

Address enquiries for Robert Anderson's publications in currently in print to naturesstar@xtra.co.nz


[iii] C.Tanford, the Hydrophobic Effect, 2nd ed., Wiley, New York (1980).
[iv] Pandora's Poison: Chlorine, Health, and a New Environmental Strategy., Thornton, Joe MIT Press, 2000.
[v] Personal communication at NZGP Conference
[vi] Standard No: AELA 18-2003 Issued: January 2004 The Australian Environmental Labelling Association Inc.
[vii] Final report on the safety assessment of Sodium Hexametaphosphate Int J Toxicol Vol:20, Suppl 3 (2001) pp 75-89