The Harms of Using Cleaning Products Improperly

Home life is the centre of everyday life for the great majority of people, and the home is also the living environment each of us encounters most often. To keep the house tidy and to protect personal health, using all kinds of cleaning products (such as soap, disinfectants, bleach, air fresheners, polishes, and bathroom and drain cleaners) to clean a messy home is almost unavoidable. Although household cleaning products are necessary, if they are used improperly or a poor product is chosen, they may cause acute or chronic harm to health, especially for young children and older people who spend a lot of time at home. In the United States, for example, of the poisoning cases reported to poison centres nationwide, about 10% are related to household cleaning products, and more than half of those cases are children under six. Past figures from poison centres in Taiwan, although the proportion is a little lower, have essentially found a similar situation.

The possible effects of household cleaning products on health differ according to the properties of the substance. Strong acids or strong alkalis used to clear bathroom and drain pipes do the greatest harm, followed by strongly oxidising cleaners (such as cresol, and cationic surfactants), or the more volatile bleaches and ammonia. In acute cases, household cleaning products may cause skin irritation, allergies or chemical burns; in the eyes, they may cause irritation, conjunctivitis or chemical burns; in the airways, they may cause irritant symptoms, allergies, asthma, or even inflammation of the lungs, and the irritation may lead to dizziness and headaches. If they are accidentally swallowed, they may cause nausea, vomiting, abdominal pain, diarrhoea, or even bleeding or perforation of the gastrointestinal tract. In chronic cases, besides possible chronic harm to the skin, eyes and airways, with symptoms such as dermatitis and asthma, household cleaning products may also interfere with the endocrine system, and even increase the risk of cancer. By briefly introducing, below, ingredients in household cleaning products that may increase the risk of cancer, this article hopes to help readers protect themselves, and make the home a safer place to live.

1. Formaldehyde: Formaldehyde is a colourless industrial chemical with a strongly irritating smell, widely used in the manufacture of building materials and furniture. It is also used in the manufacture of glues and adhesives, and as a paint or as formalin. In indoor cleaning products, formaldehyde may be present in some polishes, car cleaners, car waxes, paints and related products; composite boards, particle board, hardwood plywood panelling and medium-density fibreboard also mostly contain formaldehyde resins. Formaldehyde is highly volatile, so the main harm to the body is to the airways. At concentrations of 0.1 ppm or higher, it can already cause itchy eyes, tearing, stinging, a sore throat, coughing, difficulty breathing, triggering of asthma, and still more serious symptoms. Besides its irritant effect on the eyes, airways and skin, formaldehyde is also classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen — that is, a substance known to cause cancer in humans — so excess exposure to formaldehyde in the home must be treated with particular care. Formaldehyde has so far been linked to cancers of the nasal cavity, nasopharynx and sinuses, and to leukaemia; it may also be linked to cancers of the lung, mouth, pharynx, pancreas and brain, but the evidence is still insufficient.
Besides cleaning products that may contain formaldehyde, some hand-wash and automatic-dishwasher detergents may contain quaternium-5, and quaternium-15, used as a preservative in cosmetics, skincare formulas, inks and paints, may also release formaldehyde and harm health.

2. Sulfuric acid: Sulfuric acid is often used at home as a drain cleaner for bathroom pipes. It is strongly irritant and corrosive, so accidental over-exposure can cause poisoning symptoms similar to those of formaldehyde, or more serious still (such as corrosion of the eyes, pulmonary oedema, or death). Besides possible acute poisoning, whether sulfuric acid may cause cancer is also a question worth taking seriously. According to IARC’s reviews, mists containing strong inorganic acids such as sulfuric acid have been found, in occupational exposures in various industries (such as the manufacture of phosphate fertilisers, isopropanol, ethanol, sulfuric acid, nitric acid and lead-acid batteries), to have a positive association with cancer. IARC therefore classifies the related occupational exposure as a Group 1 carcinogen: besides cancers of the pharynx and lung, it may also be linked to cancers of the nasal cavity and sinuses. Consumers should therefore do their best to avoid using household cleaning products that contain sulfuric acid indoors, and when they do use them they must remember to leave the area immediately afterwards, and to ventilate the bathroom thoroughly after clearing a drain or cleaning the bathroom, to reduce residual sulfuric-acid mist indoors.

3. Silicon dioxide (quartz, crystalline silica): Silicon dioxide may be present in many cleaning products and paints. According to past studies of miners and other workers (such as those in ceramics, stonework and the manufacture of refractory bricks), long-term occupational exposure (inhalation) to silica dust has a clear positive association with silicosis and lung cancer, and occupational exposure to silica has also been classified by IARC as a known human carcinogen (a Group 1 human carcinogen). Although the amount of silica exposure from household cleaning products, even over a long period, should not be enough to cause silicosis or lung cancer, more care in choosing and using related household cleaning products can reduce unnecessary exposure of the body to harmful substances.

4. Nitrosamines: Some multi-purpose cleaners may contain foaming agents such as diethanolamine (DEA) or triethanolamine (TEA), and some furniture polishes and car waxes contain morpholine. If these compounds come into contact with nitrites, which may be used as a preservative or may be latent in some products (such as radiator fluid), they produce nitrosamines (such as N-nitrosodiethylamine). Nitrosamines are currently classified by IARC as Group 2A carcinogens — that is, substances known to cause cancer in animals and probably carcinogenic to humans. Nitrosamines are known to be linked to stomach cancer in humans, and may be linked to cancer of the oesophagus or the liver.

5. Tetrachloroethylene (perchloroethylene): Tetrachloroethylene was formerly often used as a dry-cleaning solvent, and may also be used as a solvent for removing grease. Acute, heavy exposure to tetrachloroethylene may cause irritation of the skin and mucous membranes, nausea, headache, dizziness, flushing of the face, harm to the liver and kidneys, trembling in the hands and feet, loss of consciousness, and even more serious poisoning. Chronic exposure to tetrachloroethylene is thought likely to lead to various cancers in humans, including possible links to higher rates of cancers of the oesophagus, pharynx, lung, cervix, breast, rectum and liver, and of leukaemia and lymphoma. IARC currently classifies both tetrachloroethylene and the similar chemical trichloroethylene as Group 2A human carcinogens.

6. Naphthalene mothballs (commonly called camphor balls) used to keep insects out of kitchen cupboards or to deodorise bathrooms, and the insecticide paradichlorobenzene, are classified by IARC as Group 2B carcinogens — that is, substances that are probably carcinogenic in animals and possibly carcinogenic to humans. Naphthalene has been found in animal experiments to be linked to tumours such as neurofibromas of the olfactory epithelium in rats, adenomas of the nasal cavity, and lung adenomas in mice (mainly female mice). Paradichlorobenzene has been found to be possibly linked to a higher incidence of tumours of the liver and kidneys. Besides doing one’s best to keep the home clean, one might therefore also consider using natural alternatives, such as plants or plant essential oils, when using insect-control products.

Besides a possible carcinogenic effect, naphthalene can, in people who lack the enzyme G6PD (commonly known as favism), cause haemolysis and methaemoglobinaemia, leading to cyanosis of the skin and tissue hypoxia, so households with favism should avoid using mothballs. Excess exposure to dichlorobenzene may cause toxicity to the liver and kidneys, so although its acute toxicity is not high, it should still be used with care.

7. Environmental hormones: The non-ionic surfactant “alkylphenol ethoxylates” (for example nonylphenol ethoxylate), formerly often added to cleaning products, has the effect of an environmental hormone. Although the effect is not strong, at too high a concentration it may still produce an oestrogen-like effect in the body, and may thereby interfere with hormone secretion, leading to infertility or, in people sensitive to oestrogen, an increased risk of breast cancer. Alkylphenol ethoxylates are not classified by IARC as carcinogens, but because these compounds (for example nonylphenol ethoxylate and its metabolite nonylphenol) may have a significant effect on environmental organisms and on the human endocrine system — especially the former — the European Union stipulated in 2003 that in industrial and household detergents, cosmetics and similar products, the content of both nonylphenol and nonylphenol ethoxylate must not exceed 0.1%. Taiwan’s Ministry of Health and Welfare likewise announced in 2007 that the concentration of both in food-contact detergents must not exceed 0.1%; and from 1 January 2008 the Environmental Protection Administration also banned the use of nonylphenol ethoxylate in the manufacture of household detergents.
Cleaning products that contain alkylphenol ethoxylates may sometimes also be mixed with 1,4-dioxane. 1,4-Dioxane is irritant to the airways and mucous membranes, also has the effect of an environmental hormone, and is a suspected carcinogen (classified by IARC as Group 2B, that is, possibly carcinogenic to humans). In animal experiments, 1,4-dioxane has been found to be linked to liver adenomas, liver cancer, gallbladder tumours, nasal-cavity tumours, mammary tumours, and peritoneal mesothelioma.
Besides alkylphenol ethoxylates, phthalates — commonly used as plasticisers, and which may be present in some adhesives, correction fluid, paints, coatings, cleaners, and personal products such as perfume — are also a well-known environmental hormone, and in 2011 caused a large-scale food-safety incident in Taiwan after contaminating food. The acute toxicity of phthalates is very low, but according to existing research these compounds mainly affect male animals and infant and young boys, and may be linked to allergies in children, abnormal development of boys’ genitals, the development of male sexual characteristics, low birth weight, obesity and breast cancer, and to tumours of the liver and testes in animals. According to IARC’s classification, phthalates are Group 2B carcinogens — that is, chemicals for which there is sufficient evidence of carcinogenicity in animals, but no evidence of carcinogenicity in humans.

8. Ortho-phenylphenol and related salts (such as sodium ortho-phenylphenol): Ortho-phenylphenol is present in some air fresheners and disinfectants. At a high dose it may be irritant to the body; chronic exposure in animal experiments may also lead to reproductive toxicity and cancer (bladder cancer). There is, however, currently no data on carcinogenicity in humans for ortho-phenylphenol, and even in animals the evidence of carcinogenicity is not sufficient, so IARC classifies ortho-phenylphenol as a Group 3 carcinogen — that is, a chemical that may be carcinogenic in animals but cannot be classified as carcinogenic to humans.

9. Nitrilotriacetic acid and its salts: Nitrilotriacetic acid and its salts (such as trisodium nitrilotriacetate) may be added to some bathroom cleaning products. Excess exposure to these compounds may have an irritant effect on the body; in animal experiments, nitrilotriacetic acid and its salts can cause renal tubular adenomas and cancer, transitional cell carcinoma and squamous cell carcinoma of the bladder, liver tumours, adrenal pheochromocytoma, and tumours of blood cells. There is, however, currently no related research on causing cancer in humans, and IARC therefore currently classifies nitrilotriacetic acid and its salts as Group 2B human carcinogens.

10. Colourants: Some colourants added to bathroom cleaners and deodorisers, such as Acid Blue 9 (Brilliant Blue, diammonium salt), have been found in animal experiments to be linked to fibrosarcoma, but there is currently no evidence that these substances cause cancer in humans, and IARC also classifies them as Group 3 carcinogens, so accidental exposure should not cause excessive worry.

Although household cleaning products may harbour various known or possible human carcinogens, their content is in most cases not high, and the body is not exposed every day over a long period, so the increase these toxins make to the risk of cancer should be extremely limited. Choosing safer products, however (for example natural products, properly labelled compliant products, and products that are not strong acids or strong alkalis), and using cleaning products strictly according to the instructions on the label, should bring the risk still lower. Of course the most important way of keeping the home clean and reducing the use of household cleaning products is still to clean and tidy the living environment diligently, so dirt has nowhere to hide. When choosing household cleaning products, choosing products that are friendlier to the environment (for example those advertised as biodegradable within a few days, low in phosphorus, and plant-based rather than refined from petroleum) can also reduce the possible adverse effects on the whole ecosystem (such as an environmental-hormone effect) when such products are discharged into the environment.