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Environmental and Health Assessment of Substances in Household Detergents and Cosmetic Detergent Products

9. Bleaching Agents

Bleaching agents of either the peroxygen type (perborates and percarbonates) or the chlorine type (cyanurates and hypochlorite) are used in laundry detergents, dishwashing agents and cleaning agents. The bleaching agents oxidize and decolorize stains originating from natural substances (e.g. protein, tea, red wine, and fruit juice). The peroxygen type bleaching agents are especially efficient at high temperatures, and an activator is usually added to enhance the bleaching effect at lower temperatures. The most common bleaching activator in European product is tetraacetylethylenediamine (TAED).

9.1 Tetraacetyl ethylenediamine

Tetraacetyl ethylenediamine (TAED; CAS No. 10543-57-4) is a bleach activator in products containing perborates and percarbonates. The concentration used typically ranges from 1 to 3%.

9.1.1 Environmental fate and effects

TAED has been shown to be readily biodegradable according to OECD criteria, and, e.g., a typical biodegradability of TAED is 95% DOC removal during 28 days (OECD 301E; IUCLID 2000). Highly water-soluble materials are unlikely to bioaccumulate to any significant degree. The octanol/water partition coefficient (log K_ow) is 1.8 for TAED which indicates a low bioaccumulation potential for this substance.

Aguatic toxicity

The toxicity of TAED towards algae is scarcely investigated. A NOEC > 500 mg/l was found in a test over 14 days with Chlorella vulgaris (IUCLID 2000).

TAED has a low toxicity towards crustaceans as indicated by the effect concentrations determined for Daphnia magna (LC50 > 500 mg/l) and Gammarus pulex (LC50 > 800 mg/l) (IUCLID 2000).

TAED has a low toxicity towards fish as indicated by the reported LC50 values that are all above 250 mg/l (IUCLID 2000).

9.1.2 Effects on human health

Toxicokinetics and acute toxicity

TAED is rapidly absorbed from intestinal tract and metabolized by hydroxylation and deacetylation to N,N-diacetyl N glycolyl ethylenediamine, TriAED, N acetyl N glycolyl ethylene diamine and DAED, which are excreted via the urine (Gilbert 1992). Test with radioactively labelled TAED applicated on the skin of rats showed minimal absorption through the skin (SFT 1991). TAED has a low acute toxicty (Table 9.1).

Table 9.1
Acute toxicity (LD50) of TAED.

Skin and ryr irritation

TAED has a low irritation potential (Gilbert 1992).

Sensitization

TAED was not a sensitizer in guinea pigs using the Magnusson Kligman maximization test (Gilbert 1992).

Mutagenicity

TAED was non-mutagenic in Ames test using Salmonella typhimurium strains, with and without activation (rat liver enzymes, S9 mix) (Gilbert 1992).

Reproductive toxicity

TAED administered orally to rats daily from day 6 to 15 of gestation at doses of 0, 40, 200 and 1,000 mg/kg body weight/day showed no embryotoxic effects and no significant increase in malformations (IUCLID 2000).

Classification

TAED is not included in Annex 1 of list of dangerous substances of Council Directive 67/548/EEC.

9.2 Perborates and percarbonates

Sodium perborate tetrahydrate (Cas No. 10486-00-7) and sodium percarbonates (Cas. No. 15630-89-4) are used primarily as bleaching agents in detergent powders and in bleaching powders. They are also to a smaller extent used as mild disinfectants in cosmetics and pharmaceutical preparations. Sodium perborate monohydrate (Cas No. 10332-33-9) is primarily used as a bleaching agent in detergent powders (IPCS 1998).

9.2.1 Environmental fate and effects

Sodium perborate is rapidly hydrolysed to boron, peracetic acid and acetic acid in the aquatic environment, whereas sodium percarbonate is rapidly hydrolysed to sodium carbonate, hydrogen peroxide, peracetic acid and acetic acid. Boron is a naturally occurring element which is found in the form of borates in the oceans, sedimentary rocks, coal, shale, and some soils. The boron content of environmental samples in inland surface waters is generally in the range 0.001-0.5 mg/l and up to 5 mg/l in seawater or in concentrated sewage (IPCS 1998). The octanol/water partition coefficients (log K_ow) are 0.175 for boric acid, -1.25 for peracetic acid and –0.17 for acetic acid, which indicate a low bioaccumulation potential for these substances.

Algae

The effects of borate towards algae have been reviewed by Guhl (1992) who found that low concentrations generally promoted the growth of algae, whereas higher concentrations inhibited algal growth. In a growth inhibition test with Scenedesmus subspicatus an EC50 value of 34 mg B/l was determined (Steber 1992). The toxicity of peracetic acid has been reported in the range of 0.7-16 mg/l (IUCLID 2000).

Invertebrates

In a study of the acute toxicity of boric acid to daphnia the static 48 h-LC50 was found to be 95 mg B/l (Bringman and Kuhn 1977). In a study by Steber (1992) it was concluded that chronic effects of boron to daphnia may occur at a concentration of > 10 mg/l. The toxicity peracetic acid towards crustaceans has been reported in the range of 2.2-3.3 mg/l (IUCLID 2000).

Fish

The toxicity of boron is often higher in soft water than in hard water. The acute toxicity of boron towards Danio rerio (96 h-LC50) has been determined to 14.2 mg B/l (Guhl 1992). In a fish early life stage test with rainbow trout NOEC levels of boron have been determined in the range between 0.009 and 0.103 mg B/l, whereas the EC50 ranged from 27 to 100 mg B/l dependent on the water hardness (Birge and Black 1977). For peracetic acid the toxicity towards fish is reported in the range of 13-89 mg/l (IUCLID 2000).

Hydrogen peroxide

Besides being a product from the hydrolysis of percarbonate, hydrogen peroxide (Cas No. 7722-84-1) is used as a bleaching agent and disinfectant. Hydrogen peroxide is a very reactive chemical and will decompose to water under release of oxygen. The half-life of hydrogen peroxide in fresh water has been determined to be between 8 and 31 hours. The half-life in waste water is between minutes and hours and in sludge only a few seconds. Hydrogen peroxide which is used in cleaning agents is decomposed to water before it is released to the environment. Hydrogen peroxide is thus not expected to cause adverse effects in the environent.

9.2.2 Effects on human health

Toxicokinetics and acute toxicity

Sodium perborate hydrolyses to give hydrogen peroxide plus metaborate (WHO 1998). Sodium perborates are hydrolytically unstable salts because they contain boron-oxygen-oxygen bonds that react with water to form hydrogen peroxide and stable sodium metaborate (ECETOC 1995). Borate excretion occurs mainly through the kidneys in which about half is excreted within the first 12 hours and the remainder is eliminated over a period of 5-7 days (HSDB 1998). Ingested borates are readily absorbed and do not appear to be metabolised via the liver. Borates are excreted primarily in the urine regardless of the route of administration (ECETOC 1995). Both sodium perborate and percarbonates have a low acute toxicty (Table 9.2).

Table 9.2
Acute toxicity (LD50) of sodium perborates.

Skin and eye irritation

In the OECD Guideline test No. 404 for irritation/corrosion on the skin of rabbits, sodium perborate monohydrate (solid) was found to be slightly irritating (ECETOC 1995). The substance appears to have little effect on the skin in normal handling operations. However some drying and minor irritation have been observed and prolonged or continuous contact should be avoided (Kirk-Otmer 1994). Perborate powders were tested for eye irritation and found severely irritating to the rabbit eye (100 mg in one eye). A 1% solution of sodium perborate tetrahydrate was non-irritating to the rabbit eye (ECETOC 1995). Sodium perborate (conc. about 1.5%) will provide a local environment with a pH of around 10, which may be partially responsible for some of the acute inflammatory and tissue reactions (ECETOC 1995). Sodium peroxyborate tetrahydrate is irritating to the eyes and mucous membranes, which should be washed promptly with water in the event of contact (Kirk-Otmer 1994).

Sensitization

Sodium perborate monohydrate did not cause skin sensitization in guinea pigs (ECETOC 1995).

Subchronic and chronic toxicity

Oral administration of sodium perborate tetrahydrate in a 28-day study gave no specific toxic effects. The observed findings were considered to be of secondary nature, due to local effects on the gastric mucosa (ECETOC 1995).

Mutagenicity

Sodium perborate induced a weak mutagenic effect in some strains of Salmonella typhimurium (Ames test) (Seiler 1989).

Reproductive toxicity

In a study performed according to OECD Guideline No. 414 (teratogenicity), sodium perborate tetrahydrate was given dose levels of 0, 100, 300 and 1,000 mg/kg body weight/day by gavage on day 6 to15 of gestation. A statistically significant dose related to lower mean body weight gain and mean daily food consumption were observed in the 300 and 1,000 mg/kg/day groups. These doses were maternally toxic doses. An increase of malformations (mainly related to the skeletal and to the cardiovascular system) was present at 1,000 mg/kg/day. On the basis of these results perborates do not seem to be toxic to development (Bussi et al. 1996).

9.3 Sodium hypochlorite

Sodium hypochlorite (CAS No. 7681-52-9) with the chemical structure of NaOCl is used for cleaning, desinfection, and bleaching. Hypochlorite is widely used in the food processing industry. Household applications of hypochlorite include cleaning of toilet bowls, removing stains from hard surfaces and bleaching of textiles in connection with washing. Sodium hypochlorite is always found dissolved in water as the pure substance is very unstable. The sodium hypochlorite solution is strongly alkaline and the strength of a solution is stated in % active chlorine. Solutions contain up to 15% active chlorine with a pH of up to 11. In cleaning products containing bleach the concentration of sodium hypochlorite is 0.5-2%. All hypochlorite salts in aqueous solutions produce equilibrium mixtures of hypochlorous acid, hypochlorite ion and chlorine (IARC 1991).

9.3.1 Environmental fate and effects

Hypochlorite is a strong oxidant which oxidizes other substances and thereby reduces itself to chloride ions. Halogenated organic compounds may be formed by the reactions of hypochlorite with organic substances. The possible reaction products include trihalomethanes (e.g. chloroform), haloacetic acids, haloacetonitriles, and chloronitromethanes. Some of these halogenated compounds may be toxic and slowly degradable in the aquatic environment. Several studies have examined the halogenation of organic compounds by reactions with hypochlorite. When hypochlorite is used in the household the typical degree of NaOCl-to-halogenated organic compound conversion has been shown to vary within the interval of 0.5 to 3% of the chlorine added as hypochlorite of which up to 15% is represented by chloroform (Rasmussen 1998 and references therein).

Aquatic toxicity

Most of the consumed amounts of hypochlorite end in the sewer, and a large proportion of the hypochlorite will be converted to chloride ions before entering the wastewater treatment plant. Possible effects of hypochlorite on operational parameters in wastewater treatment plants have been examined by frequent additions of NaOCl to activated sludge (up to 25 mg/l) which did not affect the removal of BOD, COD, NH₃-N and suspended solids (AISE 1997). Due to the rapid reactions with other substances, the inherent toxicity of hypochlorite, with EC/LC50 values below 1 mg/l, is of little, if any, relevance for aquatic environments. Inherent environmental properties of possible hypochlorite reaction products are shown in Table 9.3.

Table 9.3
Acute aquatic toxicity and aerobic biodegradability of possible products formed by the reactions between sodium hypochlorite and organic substances (data from IUCLID 2000).

9.3.2 Effects on human health

Toxicokinetics and acute toxicity

HO³⁶Cl was readily absorbed into the blodstream after oral administration. The highest ³⁶Cl activity was in the plasma and whole blood, whereas the lowest activity was measured in the liver, ileum and adipose tissue. Hypochlorite is converted and eliminated in the chloride form and the excretion was found to be mainly through the urinary route (Abdel-Rahman et al. 1983).

Ingestion causes irritation and corrosion of mucous membranes, pain, vomiting, and oedema of the pharynx and larynx; reduced blood pressure, delerium and coma may occur (Richardson 1992-1994). Inhalation of hypochlorous fumes causes coughing, respiratory tract irritation and pulmonary oedema (Richardson 1992-1994). When hypochlorite preparations come into contact with acidic substances or dirt particles, chlorine gas may be formed. Acute toxicity values of sodium hypochlorite is given in Table 9.4.

Table 9.4
Acute toxicity (LD50) of sodium hypochlorite.

Skin and eye irritation

More concentrated solutions (15%) would naturally be expected to cause more serious injury from splash in the eye. In tests on rabbit eyes, 5% solutions (approx. pH 11) caused immediate pain. If washed off immediately, only slight edema was seen for about one day. If not washed with water, the reactions were more severe (Grant and Schuman 1993). A solution of 0.5% hypochlorite, applied to the cornea and conjunctiva of rabbit eyes for 3 to 5 minutes, caused considerable superficial disturbance, but the eyes returned to normal within two weeks (Delft et al. 1983).

Sensitization

Sodium hypochlorite is not found to be a sensitizing agent in animals (ICSC 1998). Positive patch tests with sodium hypochlorite have been reported (Eun et al. 1984; Joost et al. 1987; Ng and Goh 1989).

Mutagenicity and carcinogenicity

Sodium hypochlorite did not induce chromosome aberrations in the micronucleus test in mice (Hayashi et al. 1988). Sodium hypochlorite was tested in Salmonella/microsome test and chromosomal aberration test in vitro using a Chinese hamster fibroblast cell line. The Salmonella/microsome test is a reverse mutation test in which the number of induced revertant colonies (his+) is countered. Sodium hypochlorite was positive in both tests (Ishidate et al. 1984). Oral administration of hypochlorite to mice at doses of 1.6, 4.0 or 8.0 mg chlorine/kg body weight per day resulted in dose-related increases in the number of sperm-head abnormalities. The mouse sperm head assay was used to test the ability of the desinfectant to disrupt normal sperm morphology as a measure of mutagenic potential to a germ cell line (Meier et al. 1985).

The carcinogenic potential of sodium hypochlorite was examined in rats. Sodium hypochlorite in concentrations of 0.1 and 0.5 % was dosed to drinking water for 104 weeks. No dose related change in the incidence of tumors was observed for any organ or tissue (Hasegawa et al. 1986). The International Agency for Research on Cancer (IARC) has concluded that there is inadequate evidence for the carcinogenicity of sodium hypochlorite in animals, and sodium hypochlorite is not classifiable as to its carcinogenicity in humans (Group 3).

Classification

Sodium hypochlorite is included in Annex 1 of list of dangerous substances of Council Directive 67/548/EEC and classified as follows: Corrosive (C) with R34 (Causes burns) and R31 (Contact with acids liberates very toxic gas):

C > 10% active chlorine: R31 C; R34
5% < C < 10% active chlorine: R31, Xi; R36/38

The threshold limit value for chlorine in Denmark is 0.5 ppm (1.5 mg/m3) (Arbejdstilsynet 2000).

9.4 Dichloroisocyanurates

Besides the use as a bleaching agent, dichloroisocyanurates (e.g., sodium dichloroisocyanurate (CAS No. 2893-78-9); potassium dichloroisocyanurate (CAS No. 2244-21-5)) are used in the leather processing, and textile industry. Furthermore dichloroisocyanurates are used as disinfectants and as cleaning agents.

9.4.1 Environmental fate and effects

Chlorinated salts of isocyanuric acid hydrolyze in water to form cyanurate and hypochlorous acid (Hammond et al. 1986). Dichloroisocyanurates are inorganic compounds which implies that assessment of their biodegradation is not relevant. Dichloroisocyanurates are highly water soluble and practically insoluble in octanol (IUCLID 2000). The potential for bioaccumulation of dichloroisocyanurates in aquatic organisms is therefore considered to be low.

Dichloroisocyanurates are used as algaecides in swimming pools and are thus expected to be toxic towards algae at a level below 1 mg/l. Toxicity tests with Daphnia magna have shown EC50 values of 0.19 and 0.28 mg/l which correspond to the acute toxicity found in tests with fish (Table 9.5).

Table 9.5
Effects of dichloroisocyanurates to crustaceans and fish.