Household toxicity has generally been connected with accidental swallowing or minor irritations such as dermatitis. But extensive research including that of my own team, is now showing a direct link with the number of cleaning chemicals and the risk of allergies, asthma and other adverse health effects. Some preliminary research is also showing a link with cancers. Further, in the cleaning products industry, it is widely accepted that detergent manufacture poses risks in the form of respiratory and skin sensitisation.
An examination of the ingredients in detergents and new research regarding secondary effects of using these products reveal that there could be some serious toxicological problems related to detergent use. For instance, liquid detergents release benzene vapours that could pose a carcinogenic risk to users. It also appears that as detergents break down in waterways, they release hormone mimics that can interfere with the normal reproductive functions of human beings. Research is only just beginning to address some of these problems. In many areas there is still a grave paucity of knowledge, meaning that many people may unknowingly be putting themselves at risk.
As detergents break down in waterways they release seemingly innocuous substances, which, in turn, break down into nonylphenol, an oestrogen-like substance. These types of chemicals have been named synthetic or foreign oestrogens, xenoestrogens or endocrine disrupters. Because they are so similar in structure to the oestrogen produced by our bodies, our cells will receive xenoestrogens and try to make use of them. Although similar to oestrogen in structure, they are synthetic compounds and have many unwanted and unpleasant side effects. Once introduced into our bodies they can alter our hormonal activity, disrupting our normal reproductive functioning.
Dishwashing detergents emit vapours of xylene, n-undecane and n-dodecane. Laboratory tests on rats and mice have shown immune system suppression and the possible development of cancers after exposure to such detergents. Dishwashing detergents are particularly insidious because the user is in close contact with the products and usually inhaling the chemicals in them from the steam rising from the hot water in the sink. This problem is exacerbated by the fact that pleasant, "natural" scents are (chemically) added to mask any chemical smells and to give the perception of improved cleaning.
Most laundry detergents are produced entirely from petrochemicals or coal and contain a large number of ingredients, a high percentage of which are either toxins or have an indirect detrimental effect on the environment. An average laundry detergent composition includes 15 to 25 per cent synthetic surfactant, 30 to 40 per cent condensed phosphate, 5 per cent anti-corrosive silicate and one per cent or less of anti-redeposition and optical brightener.
Within these basic categories is an impressive list of toxic chemicals including xylene, n-undecane, n-dodecane and benzene vapours which can cause an increase in weight (yes, weight gain!), a decrease in white blood cells (shown in rats) and the promotion of tumour activity in mice. Phenol, sodium nitrate, ethanol, sulphuric acid and caustic soda are also common ingredients and are either toxic or combine to create toxic compounds.
Detergent residues in clothes and linen can cause skin irritation such as rashes, itchiness and inflammation. A simple strategy is often to use fewer and safer detergents, followed by medical advice if the rash persists.
In Japan, there have been tests on pregnant mice where exposure to everyday laundry detergents resulted in 100 per cent of the embryos haemorrhaging, 70 per cent having spinal deformities and 40 per cent having harelips and other deformities. Two per cent had brains protruding through or completely outside the skull. A high proportion of the mature mice suffered disorders of the internal organs. Male mice had reduced sperm production, shortened tails, malformed heads and altered DNA structures. Another study showed workers with four to 27 years of exposure to the manufacture of soaps and detergents had a higher than normal rate of laryngeal cancer and lung cancer.
Abuse of laundry products can often lead to hospitalisation. Detergents are poisonous if swallowed and children are particularly susceptible. Swallowing liquid detergents commonly leads to nausea, vomiting and diarrhoea. Powder detergents are far more dangerous as they can burn the mouth and throat.
Laundry detergents contain some products that have a history of being toxic to humans, plus other substances, the use of which has been restricted (phenol is contained in some detergents, but its use in cosmetic products that come in contact with the skin has been restricted in the UK).
There are basically three paths by which any toxin is taken up by a living organism: by swallowing or otherwise injecting the toxin, by absorbing it across the skin or by inhaling the vapours. Detergents would not normally be swallowed unless by accident. But traces of detergents and their components are now found in most drinking water due to normal disposal processes. There is also the possibility of detergents and their components entering waterways in greater concentrations through accidental leaks and spillages at manufacturing sites. This has happened in relation to many detergent components. Phenol, for instance, has been involved in at least three separate industrial spillages in the US, and widespread poisoning was reported after local populations ingested the substance through the water supply.
In the case of direct accidental swallowing, detergents can be highly corrosive. Bleaches contained in laundry powders contain strong oxidising agents such as sodium perborate. Bleach is an irritant and will cause vomiting if accidentally swallowed. If detergents are swallowed there is the possibility of surfactants entering the circulatory system. Here they can cause damage - including cell destruction - in even very low concentrations.
Once ingested, whether by accidental swallowing or through the trace amounts found in drinking water, the toxins in detergents vary in their rate of absorption in the human body. The solvents, including benzene and xylene, contained in detergents are highly volatile, making them easily absorbed after ingestion. Of concern is absorption of benzene due to its carcinogenic nature and xylene because it is suspected to cause birth defects.
Direct contact with detergents is known to cause allergic reactions. In fact, 15 to 30 per cent of people in developed countries suffer allergies and related diseases and many people are now questioning the extent to which household chemicals are responsible. While detergents would certainly not be the cause of all these reactions, relationships have been shown between detergents containing caustic alkaline substances and allergic or irritant dermatitis.
Under certain conditions, excessive exposure to soap and detergents leads to changes in the skin. The severity of the reaction will be influenced by environmental conditions, physical health (for example, stress) and contact with other cleaning agents such as bleaches and abrasives. Surfactants in detergents appear to be one factor in skin irritation. They have been shown to reduce the lipid barrier of the skin after prolonged contact leading to loss of moisture, increased permeability of the skin, dryness, and roughness and flaking.
This means that a significant proportion of the population is being put at risk through the breakdown of this important barrier. The skin prevents or slows down the entry of many toxins into the body. Damage to the skin's horny protective layer through detergent-related dermatitis is a serious condition because it gives chemicals easy access to the living cells below. People so affected by dermatitis should be particularly careful in handling chemicals due to increased vulnerability.
It is not only direct contact with detergents, but inhalation of vapours from liquid detergents and dusts from powders that can cause problems. Vapours from detergents can persist in the air for several hours.
Ammonia is found in oven cleaners, multipurpose cleaners and cloudy ammonia. Toxic effects include eye and nose irritation if contact is made with the vapour. Effects depend on level of exposure; for example, one per cent in the air causes mild irritation and three per cent in the air produces stinging sensations. Exposure to ammonia can cause headaches and vomiting and, in high concentrations, lung damage.
Solvents are highly volatile which makes them easily absorbed through the lungs. For example, 50 per cent of toluene would be retained if inhaled. Benzene fumes in liquid detergents are easily inhaled by humans. In fact, benzene can be found in the exhaled air of a person using a product containing benzene. The danger with detergents is that it appears a higher proportion of benzene is converted to toxic metabolites at low doses than at high doses. Xylenes are readily absorbed through inhalation, but it appears high doses are needed before chronic effects on the central nervous system and mucous membranes are observed. Xylene fumes are irritants of the eyes, nose and lungs.
Sodium nitrilotriacetate (NTA), present as a builder in laundry detergents, has been linked to tumour formation in animal studies. NTA is not fully removed in wastewater treatment and, as a result, NTA is now present in drinking supplies of countries that recycle water.
There is also danger in some of the perfumes used in detergents, such as nitro musks. Nitro musks are not easily biodegradable and can accumulate in breast milk. German studies found high levels in breast milk, which raised concerns about possible health effects. As a result, some manufacturers are now phasing out such perfumes.
Enzymes appear to contribute to asthma and an increase in respiratory disorders. The effect of enzymes appears irreversible in humans. While the risk increases with concentrations inhaled, symptoms can disappear after exposure, only to reappear again after re-exposure at low levels. Enzymes have been further connected with the incidence of asthma in detergent industry workers. While respiratory problems originally appeared to be reversible after removal from exposure, studies have found long term respiratory loss in some individuals. As a result, the use of enzymes in the detergent industry has been the subject of bans since 1971. This action led to Australian detergent manufacturers ceasing the manufacture of enzyme-containing detergents. But importing detergents containing enzymes has continued.
Another problem with detergents is that seemingly innocuous ingredients can break down under normal usage conditions into nonylphenol, an oestrogen mimic. Nonylphenols are the breakdown products of alkylphenol polyethoxylates (APEOs) a type of surfactant used in washing detergents and dishwashing liquids. These types of chemicals have been named synthetic or foreign oestrogens, xenoestrogens or endocrine disruptors. Once introduced into the body they can mimic the action of oestrogen produced normally in cells or alter hormonal activity. They do this by binding with and activating oestrogen receptors.
It appears that only relatively small exposures to these nonylphenols are needed to trigger reproductive effects compared with carcinogenic effects. For example, prenatal exposure to these endocrine disruptors can interfere with the normal establishment of gender and reproductive factors.
Environmental hormones such as nonylphenols appear to be increasing the risk of reproductive system abnormalities. Some reported effects include testicular cancer, undescended testes, urinary tract defects and lowered sperm counts. There is a particularly strong link with breast cancer. When these substances are introduced into the body they mimic the action of oestrogen and alter the hormone's activity.
Cleaning detergents are so well established in our daily lives that our bodies, our skin and our lungs, all come in close contact with the chemicals in these products. And while the effects of detergents on the human body can go unnoticed, the potential for toxicity should not.
Peter Dingle is an environmental and nutritional toxicologist and Associate Professor in Health and the Environment at Murdoch University.