Formaldehyde-releasers in clothes: durablepress chemical finishes. Part 1
Anton C. de Groot1, Christophe J. Le Coz2, Gerda J. Lensen1, Mari-Ann Flyvholm3, Howard I. Maibach4
and Pieter-Jan Coenraads1
1Department of Dermatology, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RBGroningen, The Netherlands, 2Cabinet de Dermatologie and Laboratoire de Dermatochimie, 4 rue Blaise Pascal, 67070
Strasbourg cedex, France, 3National Research Centre for the Working Environment, Lerso Parkalle 105, DK-2100Copenhagen, Denmark, and 4School of Medicine, Department of Dermatology, University of California San Francisco,
San Francisco, CA, USA
This is one of a series of review articles on formaldehyde-releasers and their relationship to formaldehydecontact allergy and in this paper formaldehyde-releasers used as durable press chemical finishes (DPCF)in textiles are discussed. The literature on allergy to DPCF since 1980 is presented in two parts. Part1 (this article) presents a short historical overview of the problems with formaldehyde in clothes anddiscusses the chemistry of durable press chemical finishes, legislation in various countries, and studieson the amount of formaldehyde present in clothes. In addition, the DPCF that have caused contactallergy are presented with CAS, synonyms, molecular formula, chemical structure, applications, andpatch test studies. In the forthcoming part 2, the frequency of sensitization to DPCF, occupationalcontact sensitization, relevance of patch test reactions, and relationship to formaldehyde contact allergywill be reviewed, followed by a discussion of both parts of the article together.
Conflicts of interest: The authors have declared no conflicts.
This forms part of a series of review articleson formaldehyde and formaldehyde-releasers.Formaldehyde contact allergy was reviewed and aninventory was made of formaldehyde-releasers (1).Formaldehyde-releasers in cosmetics was dis-cussed (2, 3). Another group of chemicals whichmay release formaldehyde resulting in skin con-tact with this potent sensitizer is the durablepress chemical finishes (DPCF)∗. DPCF havebeen used on fabrics since the mid-1920s toimpart wrinkle resistance during wear and launder-ing. Their application primarily concerns cotton,viscose, linen, and their blends with syntheticfibres. DPCF can also facilitate bleaching and
∗Synonyms used in literature include: formaldehyde-releasing permanent-press finishes, formaldehyde textileresins, textile finish resins, durable press resins, perma-nent press clothing finishes.
dyeing, make fabrics waterproof, non-shrinkable,and moth-proof, they can ameliorate nylon andmake it electrically antistatic. They give textilebody, and improve their quality, touch, and appear-ance. The early DPCF based on urea–formaldehyderesin† and melamine/formaldehyde resin‡ releasedlarge amounts of formaldehyde in clothes; levels of5000 to 12 000 p.p.m. (0.5–1.2%) of formaldehydewere found in rayon and cotton (4). Consequently,
†The INCI name for urea–formaldehyde is poly-oxymethylene urea. As the name urea–formaldehydeis used in virtually all articles (and the INCI namenearly never and thus unfamiliar), this name will be usedthroughout this article.
‡The INCI name for melamine/formaldehyde ispolyoxymethylene melamine. As the name melamine/formaldehyde is used in virtually all articles (and theINCI name nearly never and thus unfamiliar), this namewill be used throughout this article.
260 DE GROOT ET AL. Contact Dermatitis 2010: 62: 259–271
allergic contact dermatitis due to formaldehydepresent in textiles was commonly reported in the1950s and 1960s, especially in Europe (4–9). Ofall allergic reactions to formaldehyde, between 11%and 65% were related to clothing dermatitis (4,5, 7). In the 1950s presensitization by formalde-hyde deodorants was important (5). Despite theirdisappearance by 1960, clothing dermatitis casescontinued to increase. Repeated exposure to fabricstreated with DPCF served as the primary sensitizerin many of the cases. In different clinics a sim-ilar proportion of all patients with formaldehydesensitivity had acquired the allergy from clothing:Copenhagen 36% (5), Bergen 33% (4), and Oslo42% (6). Of the 30 patients with textile dermatitisreported by Cronin in London, a staggering 90%had been sensitized by the clothes themselves (7)and in Australia, of 41 patients allergic to formalde-hyde, clothes had been the sensitization source in34 patients (83%) (10). The frequency of reports offormaldehyde textile dermatitis from Europe, espe-cially the Scandinavian countries, sharply contrastedto the scarcity of such reports from USA (11, 12).Suggested explanations were the extensive use offormaldehyde antiperspirants in Scandinavia but notin the USA, lower amounts of free formaldehydein clothes in the USA, and more thouroughly wash-ing the clothes by American manufacturers beforethey were sold (13). In 1962, US manufactureresof textiles were quoted stating that US fabrics soidentified contained no more than 0.075% (750p.p.m.) of free formaldehyde (13). However, in thetrade literature of the fabric manufacturers, Reid in1960 (14) reported on the amount of free formalde-hyde released from fabric samples treated withfive different N-methylol finishing agents. His freeformaldehyde values ranged from 3000 to greaterthan 7000 p.p.m. Washing led to a considerabledecrease in free formaldehyde content, but amountswere still in the range of 1000–5000 p.p.m. (14).Since the 1960s, the textile industry started usingfinishes releasing less formaldehyde, notablydimethylol dihydroxyethyleneurea (DMDHEU).Nevertheless, in the early 1970s, all samples of 112fabrics obtained from American textile manufactur-ers and distributors contained free formaldehyde,ranging from 1 to 3517 p.p.m. and 18 samples (16%)had a free formaldehyde content greater than 750p.p.m. (15). By 1981 the US textile industry claimedthat levels of formaldehyde release had decreasedso that 100–200 p.p.m. was standard (16). Theselevels would appear to be safe: Fisher et al. (13)were unable to produce formaldehyde dermatitis in20 patients known to be allergic to formaldehydeby having them wear clothing made of fabrics con-taining – according to their manufacturers – between300 and 750 p.p.m. of free formaldehyde and
according to Berrens et al. (8), 300–500 p.p.m.would be the lower limit for highly formaldehyde-sensitive patients to develop dermatitis. In spiteof this, there has been a resurrection of reportsof allergic contact dermatitis to formaldehyde inclothes from 1990 onwards in the USA (17–20)and in Israel (21–23). The availability of DPCF forpatch testing (Table 1) facilitated the investigationof patients suspected of textile dermatitis. In thefirst years after the introduction in 1994 of the testmix ethylene urea, melamine/formaldehyde 5% petin the North American Contact Dermatitis Group(NACDG) standard series, 5.0–7.2% of routinepatients had positive patch tests (24–26). Some30% of the patients allergic to DPCF did not reactto formaldehyde, which led to the conclusion thatthe DPCF per se must be sensitizers as well.
We review the literature on allergy to DPCF since1980, in two parts. Part 1 (this article) presents thechemistry of DPCF, legislation in various countries,and studies on the amount of formaldehyde presentin clothes. In addition, the DPCF that have causedcontact allergy are presented with CAS, synonyms,molecular formula, chemical structure, applications,and patch test studies. In forthcoming part 2, the fre-quency of sensitization to DPCF, occupational con-tact sensitization, relevance of patch test reactions,and relationship to formaldehyde contact allergy willbe reviewed, followed by a discussion of both partsof the article together.
Chemistry, Legislation, and Amount ofFormaldehyde in Clothes
Chemistry of DPCF
Cellulose fibres and especially cotton are still themost important kind of fibres for textiles (28, 29).One main disadvantage is wrinkling after washing,which is caused by swelling of the cellulosic fibresfrom moisture absorption. This can be overcome bythe use of DPCF. Two different chemical approacheshave been used. The original is the incorporationof a polymerized finish in the pores of the fibres,so that water molecules cannot easily penetrate thefibre. This is the mechanism for urea–formaldehydeand melamine/formaldehyde products. The newerapproach is the reaction of multifunctional cross-linking agents with the hydroxyl groups of adja-cent cellulose molecules that hinder cellulose fibreswelling. This is the mode of action of the cyclicurea derivatives, of which DMDHEU is the proto-type. Most textile finishes release formaldehyde, dueto the necessity of formaldehyde in resin synthe-sis, to a subsequent degradation of the resin duringstorage, during wearing because of sweat and byacid washing, or from the use of chlorine duringlaundering.
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Table 1. Durable press chemical finishes for patch testing (27)
Name CAS Test concentration and vehicle Trade name
1,3-Dimethyl-4,5-dihydroxyethyleneurea 3923-79-3 4.5% aqua Fixapret NFDimethylol dihydroxyethyleneurea (DMDHEU) 1854-26-8 4.5% aqua Fixapret CPNDMDHEU, modified Not available 5.0% aqua Fixapret ECODimethylol propyleneureaa 3270-74-4 5% aqua Fixapret PHEthylene urea, melamine/formaldehyde Not available 5% pet. Fixapret ACb
Melamine/formaldehyde resin 9003-08-1 7% pet. Kaurit M70Tetramethylol acetylenediureaa 5395-50-6 5% aqua Fixapret 140Urea–formaldehyde resin 9011-05-6 10% pet. Kaurit S
aSince 1999 no longer available.bFixapret AC is not supplied any more by BASF, but prepared by Chemotechnique® under the same (former) trade name.
Urea–formaldehyde and melamine/formaldehydeproducts. Urea–formaldehyde (methylolurea) re-sins are derived from the polymerization of ureaand formaldehyde with a curing agent. The interme-diate products are monomethylol urea, dimethylolurea (carbamol, oxymethurea), and methyleneurea.The second stage consists of the condensationof the methylolureas to low-molecular polymersby methylene and methylene–ether linkages thatsecondarily polymerize within the interstices ofthe textile fibres to three-dimensional resin struc-tures. These resins contain large amounts of freeformaldehyde (>1000 p.p.m.). They have a lowstability to hydrolysis, which results in the releaseof formaldehyde, particularly under moist and heatconditions. In most countries these finishes may nolonger be used for clothing. However, it was esti-mated that in 1990, 6% of US durable press textilesstill contained urea–formaldehyde finishes (18, 30).
Melamine/formaldehyde resins result from thecondensation of formaldehyde and melamine.Trimethylolmelamine and hexamethylolmelamineare the main compounds, resulting from the conden-sation of melamine with three and six formaldehydemolecules, respectively. They polymerize into resinsin the interstices of the fibres to three-dimensionalresin structures. Some unpolymerized methylolresidues contained in such resins can subsequentlybe degraded into free formaldehyde. These textilefinish resins also contain and release large amountsof formaldehyde (>1000 p.p.m.) (albeit less thanurea–formaldehyde finishes), but are said to bevirtually no longer used (28) (which may not becorrect). However, it was estimated that in 1990,20% of US durable press textiles still containedmelamine/formaldehyde finishes (18, 31).
Cyclic urea derivatives.Formaldehyde-containing finishes. During the
1960s and 1970s, concern about formaldehydeencouraged development of cellulose cross-linkingfinishes with low free formaldehyde levels and laterproducts completely formaldehyde free. The current
textile finish resins are the cyclized urea deriva-tives. These are reticulating agents based on N-alkoxymethylated cyclized urea. With acid catalystssuch as magnesium chloride or zinc nitrate to ini-tiate the reaction, their N-methylol (N–CH2 –OH)groups crosslink with the hydroxyl (OH) groupsof cellulosic textile fibres to form stable etherbonds. Some cyclized urea derivatives are shownin Table 2.
With the exception of 1,3-dimethyl-4,5-dihy-droxyethyleneurea (Fixapret NF®, NF = non-for-maldehyde), these DPCF release a varying amountof free formaldehyde during polymerization(Table 2). DMDHEU is the chemical basis ofabout 90% of the currently used finishes (29).The amount of formaldehyde released can bedecreased by methylation or by reaction withmethanol or diethylene glycol, leading to ether-modified DMDHEU products. These alcohols arealso formaldehyde scavengers and are often addedto commercial finish products for that purpose.Diethylene glycol has the additional advantage ofhaving a high boiling temperature. Therefore, asignificant portion can remain in the cured fabricand reduce the free formaldehyde content via acetalformation. Other formaldehyde scavengers such asurea or ethylene urea can lower the formaldehydelevels of the final fabric further. The glycolatedDMDHEU finishes are referred to as ‘ultralowformaldehyde’ finishes with less than 50 p.p.m.released formaldehyde in the American Associa-tion of Textile Chemists and Colorists (AATCC)Test Method 112-1993, which is the standard USmethod for quantitative analysis of formaldehyde intextiles (29).
Formaldehyde-free finishes. There are alsoDPCF which do not contain formaldehyde,the best known of which is 1,3-dimethyl-4,5-dihydroxyethyleneurea. It has, however, a poorcost performance ratio, which is one reason fora relatively small market penetration. Anotherreason is that a completely formaldehyde-free fin-ish is not as commercially important since theadvent of the ultralow formaldehyde products.
262 DE GROOT ET AL. Contact Dermatitis 2010: 62: 259–271
Table 2. Examples of currently used DPCF: cyclized urea derivatives (18, 28, 29, 31)
Compound class and name CAS Amount of formaldehyde released (9, 16, 18, 28, 29, 31, 32)
However, it is popular in a 1:1 mixture with DMD-HEU (29). Other formaldehyde-free finishes include1,2,3,4-butanetetracarboxylic acid and similar poly-carboxylic acids and polyacrylic acids, for example,maleic acid anhydride copolymers.
Miscellaneous cross-linking agents. Other che-mical cross-linking agents used to provide durablepress properties to cellulose include diglyoxal urea,carbamate derivatives, diepoxides, diisocyanates,and polycarboxylic acid systems. However, owingto either high cost or limited technical advan-tages, few are actually used commercially, some-times as minor components or mixtures for specialeffects (29).
Legislation and voluntary restrictions
Legislation. Some countries have legally limited theformaldehyde content of textile products to reducethe risk of contact dermatitis and other adverseeffects among their populations. Japan was the
first in 1973 (which led to a sharp decrease inthe prevalence of sensitization to formaldehyde inthe years thereafter) (33) followed by Finland (34).Other countries with legal limitations include China,Norway, France, Japan, and the Netherlands (35,36). The regulations differ, but usually garmentsfor babies and infants should contain <20–30p.p.m. formaldehyde, for clothes in direct contactwith the skin a maximum of 75–100 p.p.m., andfor clothing and textiles without direct skin thereare upper limits of 300–400 p.p.m. formaldehyde(Table 3). USA has no restrictions on formaldehydein textiles, but in July 2008, the Congress ofthe USA passed the Consumer Products SafetyCommission Modernization Act of 2008 requiringthat (within 2 years) a study should be performedon the use of formaldehyde in the manufactureof textile and apparel articles to identify any riskto consumers. Quantitative formaldehyde assays inclothes will most likely be a part of this study.
Table 3. Examples of international limits for formaldehyde in clothing and other textiles (p.p.m.) (35, 36)
Country Infants and babies Textiles in direct contact with the skin Textiles not in direct contact with the skin
Australiaa 30 100 300Austria Textiles that contain 1500 p.p.m. or above must be labelledb
China ≤20 ≤75 ≤300Finland 30 100 300France 20 100 400Germany Textiles that contain 1500 p.p.m. or above must be labelledb
Japan Not detectable 75The Netherlands 120c
New Zealandd 30 100 300Norway 30 100 300
aProvisional (‘interim’) limits.b“Contains formaldehyde. Washing this garment is recommended prior to first time use in order to avoid irritation of the skin.”cTextiles in direct skin contact must be labelled ‘Wash before first use’ if they contain more than 120 p.p.m. formaldehyde and the productmust not contain more than 120 p.p.m. after wash.dProposed New Zealand Government Limits.
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Voluntary restrictions. The American Apparel andFootwear Association (AAFA) (the national tradeassociation) published a 2008 Restricted SubstanceList (RSL) requesting that its members (367 com-panies) abide voluntarily to the standards listed.For formaldehyde, the RSL suggests no detectableformaldehyde for infant clothing (0–36 months),a maximum of 75 p.p.m. for clothes for people>36 months with direct skin contact, and 300 p.p.m.for textiles with no direct skin contact (37).
The International Association for Research andTesting in the Field of Textile Ecology (Oeko-Tex), which represents a large group of worldwidetextile research institutes, developed the Oeko-Tex100 standards. These voluntary standards placelimitations on free formaldehyde in clothing andtextiles similar to the AAFA guidelines (38). Theirtag is a stamp of approval that informs the consumerthat the textile does not contain dangerous levels ofharmful substances. In Europe, manufacturers maypresent the ‘European Ecolabel’ when their textilesnot in direct contact with the skin contain <300p.p.m. and those with direct skin contact <30 p.p.m.(Commission Decision 2002/371/EC) (39).
Amount of formaldehyde present in clothes
There are several recent reports on analytical stud-ies determining the amount of formaldehyde inclothes; their results are summarized in Table 4.In a 2007 large-scale EU survey on the release of
formaldehyde from textiles (40), 221 samples werepurchased in 21 of 27 EU Member States fromseveral sources, including department stores, shops,and open air markets, and with various composi-tions, such as cotton, mixtures with cotton, andmixtures with wool. About one fourth were pro-duced in Europe, one fourth in the rest of the worldexcept China, one fourth in China, and it was notpossible to establish the origin for 27%. About 94%of all the samples were textile clothing, whereas6% were classified as linen (bedding pillow casesand sofa cushion covers). Several types of garmentswere considered, such as shirts, T-shirts, underwear,socks, pyjamas, trousers, and dresses, both for men,women, and children. To evaluate the release offormaldehyde from these textiles, all samples wereanalysed with the standard method EN ISO 14184-1(water extraction method, 41), which tries to sim-ulate the real conditions of use though an extrac-tion in water at 40◦C. Samples were analysed intriplicate and uncertainties at 95% of probabilitywere calculated.Results. In 89% of samples intended to come intocontact with the skin (including bedding pillow-cases and sofa cushion covers) the amounts offormaldehyde were <30 p.p.m. and 97% did notexceed 75 p.p.m. Only three samples containedmore than 100 p.p.m. (105.2 ± 6.4, 108.8 ± 3.1,162.5 ± 9.3). No differences were observed in therelease of formaldehyde from samples manufactured
Table 4. Analytical studies of formaldehyde in clothes
Country and year Number and type of clothes Formaldehyde content Reference
The Netherlands∗ (recent) 153 clothings and textiles Clothes all <120 p.p.m. (law requirement) 45USA 2008 11 pants <20–136 (two items >100 p.p.m.) 42
linen (bedding pillowcases and sofa cush-ion covers)
89% <30 p.p.m.; 97% <75 p.p.m.; three samplescontained >100 p.p.m. with a maximum of 162.5± 9.3 (EN ISO 14184-1 method)
40
Australia 2007 ‘Broad range’ No formaldehyde detected in any item 43New Zealand 2007 99 textiles from China 97/99 <20 p.p.m. (detection limit) or very low
levels; two samples >100 p.p.m., which wasreduced to safe levels after washing
44
Denmark 2003 10 textiles No formaldehyde (detection limit 20 p.p.m.) inseven samples; 35, 43, and 82 p.p.m. in the otherthree
46
USA 1998 16 randomly selected fabrics from theUSA and other countries
In eight samples no formaldehyde; all otherscontained <200 p.p.m.
19
Finland 1988 >1400 imported textiles 100–300 p.p.m. in 8.3%; >300 p.p.m. in 3.9% 34Maximum 2200 p.p.m.
1993 >1400 imported textiles 100–300 p.p.m. in 4.4%; > 300 p.p.m. in 0.3% 34Maximum 643 p.p.m.
Finland 1987–1994 144 fabrics and textiles, unspecified 12 samples (8.3%) contained 100–300 p.p.m., 4(2.7%) >300 p.p.m.
264 DE GROOT ET AL. Contact Dermatitis 2010: 62: 259–271
in various geographical areas (Europe, China, restof the world) and purchased from various sources(shops, department stores, and open air mar-kets). The maximum estimated dermal uptakes offormaldehyde calculated based on data obtainedwith the standard method EN ISO 14184-1 were1.2 and 3.1 mg/kg body weight for an adult and achild, respectively (40).
In the most recent US study, only 3/23 itemscontained >100 p.p.m. formaldehyde with a maxi-mum of 136 p.p.m. (42). In Australia, a broad rangeof clothes was investigated for formaldehyde levelsafter concern had been raised that formaldehydemay lead to skin and other health problems, but innot a single item was formaldehyde detected (43). Asimilar situation occurred in New Zealand in 2007,where textiles from China were suspected of con-taining dangerous formaldehyde levels. In response,the government had 99 garments from China anal-ysed. Ninety-seven of the ninety-nine contained<20 p.p.m. (detection limit) or very low levels.Two samples contained >100 p.p.m. formaldehyde,which was reduced to safe levels after washing (44).In a recent Dutch study all specimens of 153 clothesand textiles contained less than 120 p.p.m. formalde-hyde, which is their allowed upper limit (45). InDenmark, in 2003, 10 textiles were investigated forthe presence of formaldehyde. In three, formalde-hyde was found (detection limit 20 p.p.m.) with con-centrations of 35, 43, and 82 p.p.m. After one wash,formaldehyde was no longer detectable in two sam-ples and the sample previously containing 35 p.p.m.now contained 21 p.p.m. formaldehyde. Maximumdermal absorption was calculated to be 0.307 mg/kgbodyweight for an adult and 1.075 mg/kg body-weight for a child (46). Data from studies made upto this point are presented in Table 4.
It is to be noted that there are many methods fordetermining formaldehyde in products and that theresults using different test protocols may vary con-siderably. The current standard methods for deter-mining formaldehyde in textiles are the AATCC-112method (USA), the Japanese Law 112 method, andthe EN ISO 14184-1 or 14184-2 method (41, 47).The values recorded with the AATCC-112 methodare (as a mean) 4.4 times higher than the JapaneseLaw 112 method (34). Above 30 p.p.m., the vapourabsorption method (EN ISO 14184-2, which is actu-ally meant for estimating inhalation of formaldehydeand not dermal exposure) gives frequently higherresults than the water extraction method (EN ISO14184-1) (40).
Characterization of DPCF and Reported PatchTest Studies
Many DPCF may release formaldehyde. Only thoseDPCF which have been reported to cause contact
allergy or induce positive patch test reactions arediscussed here.
Unselected patients. There have been no reportsof routine patch testing with this chemical.
Selected patients. Ten patients who had previ-ously reacted to ‘older’ formaldehyde textile finisheswere retested in 1997 in the USA with a seriesof DPCF including methylated dihydroxydimethylo-lethyleneurea 5% aqua (Freerez PKF®§.), to whichthere was one positive reaction. Note that this patienthad nine positive patch test reactions, so an irritantreaction due to the Excited Skin Syndrome may wellhave occurred. Relevance was not established andcontrol tests were not performed. The patient wasalso allergic to formaldehyde (19).
Applications: non-formaldehyde textile finishesPatch test studies
Unselected patients. 1,3-Dimethyl-4,5-dihydro-xyethylene urea (Fixapret NF) 4.5% aqua was rou-tinely tested between 1999 and 2002 in Israel in644 consecutive contact dermatitis patients and 11(1.7%) had a positive patch test reaction. Current
§Currently, Freerez® PFK is a glyoxal-based reactant:www.emeraldmaterials.com
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clinical relevance was not specified for this DPCF,but was 81% in a group of 83 patients allergic toDPCF and/or dyes (21).
Selected patients. Ten patients who had pre-viously reacted to ‘older’ formaldehyde textilefinishes were retested in the USA in 1997 witha series of DPCF including 1,3-dimethyl-4,5-dihydroxyethyleneurea (Fixapret NF) 5% aqua, towhich there were two positive patch tests. It is to benoted that these patients had eight and nine positivepatch test reactions, so irritant reactions due tothe Excited Skin Syndrome may have occurred.Clinical relevance was not established; the patientswere also allergic to formaldehyde (19).
Unselected patients. Results of routine testingwith DMDHEU are summarized in Table 5.
Selected patients. Results of testing with DMD-HEU in selected patients are summarized in Table 6.
Dimethylol dihydroxyethyleneurea,modifiedCAS Not availableSynonyms: Fixapret ECO®Molecular formula: not availablePatch test studies
Unselected patients. DMDHEU, modified (Fix-apret ECO) 5% aqua was routinely tested between
1999 and 2002 in Israel in 644 consecutive contactdermatitis patients and 14 (2.2%) had a positivepatch test reaction. Current clinical relevance wasnot specified, but was 81% in a group of 83 patientsallergic to DPCD and/or dyes (21).
Applications: textile finishes. Is said not to be usedany more (20), but this may not be correct.Patch test studies
Unselected patients. Routine testing withdimethylolpropyleneurea 5% aqua has beenperformed in one study from Israel only (22)with 286 patients. Six patients (2.1%) had a pos-itive patch test reaction. Of the entire group ofpatients with positive reactions to DPCF and/ordyes, 69% was considered to be relevant; fordimethylolpropyleneurea there were no separatedata.
Selected patients. Studies with testing in selectedpatients are summarized in Table 7. In 1999,Chemotechnique Diagnostics (R) (Vellinge, Swe-den) stopped the distribution of the test substancewith dimethylolpropyleneurea.
Table 5. Patch test studies with dimethylol dihydroxyethyleneurea in patients suspected of contact dermatitis
CountryYears of
studyNumber of
patientsTest conc.
and vehicleNumber
positive (%)Current
relevance (%) Comments/setting Reference
USA 2005–2006 4424 4.5% aqua 27 (0.6%) 48/28a Multicentre study, NACDG 50USA 2003–2004 5138 4.5% aqua 41 (0.8%) NS Multicentre study, NACDG 51USA 1999–2004 398 4.5% aqua 9 (2.3%) 100 30USA 2001–2002 4889 4.5% aqua 54 (1.1%) 19/43a Multicentre study, NACDG 52Israelb 1999–2002 644 4.5% aqua 8 (1.2%) 81c 21Israelb 2001 (?) 286 4.5% aqua 2 (0.7%) 69c 22
NS, not specified.aDefinite and probable relevance (first number)/possible relevance (second number).bProbably considerable overlap with the other Israeli study.cPercentage relevant for the entire group of patients allergic to finishes and/or dyes.
266 DE GROOT ET AL. Contact Dermatitis 2010: 62: 259–271
Table 6. Patch test studies with dimethylol dihydroxyethyleneurea in selected patients
CountryYears of
studyNumber of
patientsTest conc.
and vehicleNumberpositive
Currentrelevance (%)
Mode ofselection/comments Reference
USA 2001–2005 411 4.5% aqua 8 (1.9%) 75 NS; selected from 3848 patients 53USA 1994–1999 188 4.5% aqua 16 (8.5%)a 100 History and physical findings
compatible with textile resincontact dermatitis and at least tworeactions to DPCF
20
USA 1997 10 4.5% aqua 10 (100%) NS Patients had previously reacted toDPCF
19
USA 1988–1991 NS 4.5% aqua n = 1 100 Suspicion of clothing dermatitis 17Total patch test population = 462
USA 1988–1990 NS 4.5% aqua n = 5 100 NS; total patch test population = 1022 18Denmark 1970–1980 426 10% pet.b 1 (0.2%) 0 Eczema patients suspected of
having textile dermatitis54
426 10% pet.c 3 (0.7%) 0211 10% pet.d 0 (0%)
aThe actual percent age may have been higher, as 11 patients with one reaction to a DPCF were not included.bPrepared from Calaroc PK® (43–47% aq. sol.).cPrepared from Calaroc PG® (50% aq. sol.).dPrepared from Fixapret CPNS®.
Table 7. Patch test studies with dimethylolpropyleneurea in selected patients
CountryYears of
studyNumber of
patientsTest conc.
and vehicleNumberpositive
Currentrelevance (%)
Mode ofselection/comments Reference
USA 1994–1999 188 5% aqua 23 (12.2%)a 100 History and physical findingscompatible with textile resin contactdermatitis and at least two reactionsto DPCF
20
USA 1997 10 5% aqua 4 (40%) NS Patients had previously reacted toDPCF
19
Israel 1991–1997 55 5% aqua 3 (5.5%) NS Patients with suspected textiledermatitis
23
USA 1988–1991 NS 5% aqua n = 2 100 Suspicion of clothing dermatitis. 17Total patch test population = 462
USA 1988–1990 NS 5% aqua n = 11 100 NS; total patch test population = 1022 18Denmark 1970–1980 211 10% pet. 5 (2.4%) 60 Eczema patients suspected of having
textile dermatitis54
NS, not stated.aThe actual percent age may have been higher, as 11 patients with one reaction to DPCF were not included.
Dimethylol ureaCAS 140954Synonyms: 1,3-bis(hydroxymethyl)urea; N ,N ′-bis(hydroxymethyl)urea; carbamol; dihydroxyme-thylurea; N ,N ′-dimethylolurea; dimethylurea;oxymethureaMolecular formula: C3H8N2O3Chemical structure
Applications: dimethyol urea is derived fromthe combination of urea and formaldehyde in a1:2 molar ratio. It is used in the production ofurea–formaldehyde resins as an unisolated inter-mediate. Dimethylol urea is present in these resinsas residual starting material or breakdown prod-uct (55). Also used as textile finish.
Patch test studiesUnselected patients. The Informationsverbund
Dermatologischer Kliniken (IVDK, Germany,Austria, Switzerland) in 2004–2005 tested143 patients with suspected metalworking fluiddermatitis with dimethylol urea 1% pet.; no positivereactions were observed (56).
Selected patients. In a Dutch study 14 patientsallergic to diazolidinyl urea were tested with anumber of other formaldehyde-releasers includingdimethylol urea 8% aqua. Of the 14 patients, 6 werealso allergic to formaldehyde. In these patients, butnot in the other eight unresponsive to formalde-hyde, dimethylol urea caused positive patch testreactions. These were considered to be the result offormaldehyde released from the dimethylol urea testmaterial (57).
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Table 8. Patch test studies with ethylene urea , melamine/formaldehyde in patients suspected of contact dermatitis
aDefinite and probable relevance (first number)/possible relevance (second number).bPercentage relevant for the entire group of patients allergic to finishes and/or dyes.cPercentage includes ‘possible relevance.’
Table 9. Patch test studies with ethylene urea, melamine/formaldehyde in selected patients
CountryYears of
studyNumber of
patientsTest conc.
and vehicleNumberpositive
Currentrelevance (%) Mode of selection/comments Reference
USA 1998–2000 714 5% pet. 11 (1.5%) NS NS; selected from 1324 patients 58USA 1994–1999 188 5% pet.a 11 (5.9%)b 100 History and physical findings compatible
with textile resin contact dermatitis and atleast two reactions to DPCF
205% peta 11 (5.9%)b 100
USA 1997 10 5% pet. 6 (60%) NS Patients had previously reacted to DPCF 19USA 1988–1991 NS 5% pet. n = 1 100 Suspicion of clothing dermatitis 17
Total patch test population = 462USA 1988–1990 NS 10% pet. n = 14 100 NS; total patch test population = 1022 18Denmark 1970–1980 211 10% pet. 2 (0.9%) 0 Eczema patients suspected of having tex-
tile dermatitis54
NS, not stated.aThe substance was tested in duplicate.bThe actual percent may have been higher, as 11 patients with one reaction to a DPCF were not included.
Ethylene urea, melamine/formaldehydeCAS Not availableSynonyms: Fixapret ac®Molecular formula: not availableChemical structure: not available
Ethylene urea , melamine/formaldehyde is a mix-ture of ethylene urea and melamine/formaldehyde5% in pet. prepared by Chemotechnique® under thetrade name Fixapret AC. The trade name Fixapretis owned by the BASF company, but the nameFixapret AC is not found on their website, so it maybe assumed that this product is not used as such fortextile finishing.Patch test studies
Unselected patients. Results of routine testingwith ethylene urea, melamine/formaldehyde aresummarized in Table 8.
Selected patients. Results of testing with ethyleneurea, melamine/formaldehyde in selected patientsare summarized in Table 9.
Applications: in paper coating compositions and asa textile finishPatch test studies
In a Dutch study, 14 patients allergic to diazo-lidinyl urea were patch tested with a number ofother formaldehyde-releasers including glyoxalurea10% aqua. Of the 14 patients, 6 were also allergicto formaldehyde. In these patients, but not in theother eight unresponsive to formaldehyde, glyox-alurea caused positive patch test reactions. Thesewere considered to be the result of formaldehydereleased from the glyoxalurea test material (57).
268 DE GROOT ET AL. Contact Dermatitis 2010: 62: 259–271
Melamine/formaldehyde resinCAS 9003-08-1Synonyms: melamine, polymer with formaldehyde;nanoplast; polyoxymethylene melamine; 1,3,5-triazine-2,4,6-triamine, polymer with formaldehyde;Kaurit M70®Molecular formula: (C3H6N6.CH2O)x–Chemical structure (before polymerization)
Applications: Melamine/formaldehyde resin isan aminoplastic formed by the reaction offormaldehyde and melamine (2,4,6-triamino-1,3,5-triazine). There is always some unreactedformaldehyde in the resin. Typical formulations ofmelamine/formaldehyde resin contain two molesof formaldehyde per mole of melamine. One moleof formaldehyde splits off and is free in cer-tain solutions (59). Melamine/formaldehyde resinswere, together with urea–formaldehyde resins, thefirst resins to be used as textile finishes. Currentapplications include: surface coating and glues inthe furniture and wood industry, bonding agentsin plywood and particle board (medium densityfibreboard, MDF) (60), plastic composites manufac-turing, printing, dyeing, or finishing of textiles, pulp,and paper processing, in water-resistant orthopaedicplaster, surface coatings, baking enamels, and treat-ment of leather (59). Melamine/formaldehyde resinincreases the wet and folding strength of paperessential for the manufacture of currency, maps,shipping bags, towels, facial tissue, etc. (59)Patch test studies
Unselected patients. Melamine/formaldehyderesin 7% pet was routinely tested between 1999 and2002 in Israel in 644 consecutive contact dermatitis
patients and 17 (2.6%) had a positive patch testreaction. Current clinical relevance was not speci-fied for this DPCF, but was 81% in a group of 83patients allergic to DPCD and/or dyes (21). In anearlier report from the same author, there were sevenreactions (2.4%) in 286 routinely tested patients.Relevance (specified above) was assumed in 69% ofthe patients (22). Probably there was considerableoverlap between these studies (21, 22).
Selected patients. Results of testingmelamine/formaldehyde resin in selected patientsare summarized in Table 10.
Case reports. Six patients using melamine/formal-dehyde-reinforced orthopedic plasters developedallergic contact dermatitis under the plaster. Theywere formaldehyde positive on patch testing, but themelamine/formaldehyde resin was not tested (63).A man developed airborne allergic contact dermati-tis after sawing and sanding MDF. Patch tests werepositive to melamine/formaldehyde and formalde-hyde. The presence of melamine/formaldehydein the board was not established (64). Severalcase reports of occupational contact dermatitis tomelamine/formaldehyde are discussed in part 2.
Applications: Methylol urea is derived from thecombination of urea and formaldehyde in a 1:1molar ratio. It is used to treat textiles and woods andis mixed with fillers for use in molding adhesives. In
Table 10. Patch test studies with melamine/formaldehyde resin in selected patients
CountryYears of
studyNumber of
patientsTest conc.
and vehicleNumberpositive
Currentrelevance (%)
Mode ofselection/comments Reference
Finland 1999–2001 863 NS 15 (1.7%) NS NS 61USA 1994–1999 188 7% aqua 18 (9.6%)a 100 History and physical findings compatible
with textile resin contact dermatitis and atleast two reactions to DPCF
20
USA 1997 10 5% pet. 7 (70%) NS Patients had previously reacted to DPCF 19USA 1988–1991 NS 7% pet. n = 2 100 Suspicion of clothing dermatitis 17
Total patch test population = 462USA 1988–1990 NS 7% pet. n = 11 100 NS; total patch test population = 1022 18Canada 1981–1988 64 10% pet. 2 (3.1%) 50 NS; selected from 1670 patients 62Denmark 1970–1980 184 10% pet. 3 (1.6%) 0 Eczema patients suspected of having tex-
tile dermatitis54
NS, not specified.aThe actual percent may have been higher, as 11 patients with one reaction to a DPCF were not included.
Contact Dermatitis 2010: 62: 259–271 FORMALDEHYDE-RELEASES IN TEXTILES 269
disinfectants and other biocidal products, methylolurea is used for disinfection of air, surfaces, mate-rials, and equipment. It is a preservative for liquid-cooling and processing systems and is also used asslimicide, e.g. on wood and paper pulp. Methylolurea is present in urea–formaldehyde resins as resid-ual starting material or breakdown product (55). Itreadily hydrolyses to release formaldehyde. As asolution, it is a mixture of formaldehyde gas in waterwith urea.Patch test studies
A man working with metalworking fluid reactedupon patch testing to his metalworking fluid, toseveral formaldehyde-releasers and (in a second ses-sion) to formaldehyde. The manufacturer indicatedthat the product contained methylol urea. The bio-cide itself, however, was not tested (65).
Applications: In textile finishes. Is said to be nolonger used (20), but is still commercially available.Patch test studies
Unselected patients. Tetramethylol acetylenedi-urea 5% aqua was routinely tested in 2001 (?) inIsrael in 286 consecutive contact dermatitis patients
and 7 (2.4%) had a positive patch test reaction. Cur-rent relevance was not specified for this DPCF, butwas 69% in the group of patients allergic to DPCFand/or dyes (22). In 1999, Chemotechnique stoppedthe distribution of this test substance.
Selected patients. The results of patch testing withtetramethylol acetylenediurea in selected groups ofpatients are summarized in Table 11.
Applications: Textile finishes, in cosmetics as bulk-ing agent and to form the outer shell of micro-capsules, adhesives, in polymers having incidentalcontact with food.Patch test studies
Unselected patients. Urea–formaldehyde resin10% pet was routinely tested between 1999 and2002 in Israel in 644 consecutive contact der-matitis patients and 15 (2.3%) had a positivepatch test reaction. Current clinical relevance wasnot specified for this DPCF, but was 81% ina group of 83 patients allergic to DPCF and/ordyes (21). In an earlier report from the same author,there were seven reactions (2.4%) in 286 rou-tinely tested patients. Relevance (specified above)was assumed in 69% of the patients (22). Proba-bly there was considerable overlap between thesestudies (21, 22).
Selected patients. Results of testingurea–formaldehyde resin in selected patients aresummarized in Table 12.
Table 11. Patch test studies with tetramethylol acetylenediurea in selected patients
CountryYears of
studyNumber of
patientsTest conc.
and vehicleNumberpositive
Currentrelevance (%)
Mode ofselection/comments Reference
USA 1994–1999 188 5% aqua 21 (11.2%)a 100 History and physical findings compati-ble with textile resin contact dermatitisand at least two reactions to DPCF
20
USA 1997 10 5% aqua 8 (80%) NS Patients had previously reacted toDPCF
19
Israel 1991–1997 55 5% aqua 1 (1.8%) NS Patients with suspected textiledermatitis
23
USA 1988–1991 NS 5% aqua n = 1 100 Suspicion of clothing dermatitis 17Total patch test population = 462
USA 1988–1990 NS 5% vehicle? n = 8 100 NS; total patch test population = 1022 18
aThe actual percent may have been higher, as 11 patients with one reaction to a DPCF were not included.
270 DE GROOT ET AL. Contact Dermatitis 2010: 62: 259–271
Table 12. Patch test studies with urea–formaldehyde resin in selected patients
CountryYears of
studyNumber of
patientsTest conc.
and vehicleNumberpositive
Currentrelevance (%)
Mode ofselection/comments Reference
USA 1994–1999 188 10% pet. 16 (8.5%)a 100 History and physical findings compatiblewith textile resin contact dermatitis and atleast two reactions to DPCF
20
USA 1997 10 10% pet. 5 (50%) NS Patients had previously reacted to DPCF 19USA 1988–1991 NS 10% pet. n = 10 100 Suspicion of clothing dermatitis 17
Total patch test population = 462USA 1988–1990 NS 10% pet. n = 10 100 NS; total patch test population = 1022 18Denmark 1970–1980 426 10% pet.b 8 (1.9%) 88 Eczema patients suspected of having tex-
tile dermatitis53
236 10% pet.c 2 (0.8%) 0
aThe actual percent age may have been higher, as 11 patients with one reaction to a DPCF were not included.bPrepared from Calaroc UFB® (70% aq. sol.).cPrepared from Kaurit S® (100% powder).
Discussion
The discussion of these data will be presented inpart 2 of this article.
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Address:Anton C. de Groot, MD, PhDDepartment of DermatologyUniversity Medical Center GroningenUniversity of GroningenPO Box 30.0019700 RB GroningenThe NetherlandsTel: +31 (0)52 132 0332e-mail: [email protected]
