J.G. RYCROFT, MD, FRCP, FFOM
he major occupational dermatosis among metalworkers remains that of contact dermatitis from water-based metalworking fluids.iJ The prognosis of such dermatitis in metalworkers has consistently been found to be poor. 3 Appropriately, much that is newly published about dermatitis in the metalworking industry concerns this endemic problem, although neat cutting oils also continue to provide sporadic case reports of allergic contact dermatitis.*,5 Skin-care products themselves can cause their own sensitization problems in metalworkers.6,7
The current practice of predictive testing of metalworking fluids for irritant (and sensitization) potential by manufacturers is still unsatisfactory.7 A recent human study demonstrated the usefulness of a simple one-day occlusion, followed by reapplication to the same site for two further days, in the assessment of the irritancy of water-based metalworking fluids.8 Measurement of transepidermal water loss has been recommended as a sensitive indicator of such irritancy.9 More prolonged test protocols may also have a role in their irritancy assessment.10
Changes in Irritancy
A group of investigators attempted unsuccessfully to link varying levels of acetaldehyde and formaldehyde in two large metalworking fluid systems with prevalence of &ritation of the skin and mucous membranes; however, they did find an association in one of the systems between high variability in pH and irritant symptomsli
Since the mid 198Os, alkanolamine borates have become widely incorporated into water-based metalworking fluids at lo-30% as corrosion inhibitors/preservatives.12 They are difficult to use in patch tests, because their alkalinity readily gives rise to false-positive reactions; but genuine contact allergy has been established From fhe St. John’s Institute of Deumafology, St. Thomas’s Hospital, London, England. Address correspondence lo Dr. Richard J. G. Rycroff, St. John’s Institute Dermatology, St. John’s Hospital, London SE1 7EH, England.
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by means of careful patch testing using an acidic buffer.i2 As yet, the specific sensitizers in alkanolamine borates have not been identified, and patients still need to be tested with the actual alkanolamine borate in their water-based metalworking fluid (1% in buffer); there is no single screening test available.
Bioban P1487 Bioban I?1487 is a formaldehyde-releasing water-based preservative for metalworking fluids; it has been in use for more than ten years. It has two active ingredients, 4-(2nitrobutyl)-morpholine (M) and 4,4’-(2-ethyl-2-m tro-1,3-propanediyl)-bis morpholine (DM). A recent sensitization study in guinea pigs demonstrated M to be a moderate sensitizer and DM to be a strong one.13 The manufacturer has subsequently reduced the content of DM from 20% to 5%. On patch testing metalworkers, Bioban I’1487 remains an important allergen to test (0.5% petrolatum), while it is still not clear which is the more frequent sensitizer of the two active ingredients: M, which is present in higher concentration, or DM, which appears to be the stronger sensitizer.l*
Bronopol The preservative, 2-bromo-2-nitropropane-1,3-diol (Bronopol) is quite frequently positive when patch testing metalworkers,7 though possibly more from its presence in skin-care products than in metalworking fluids themselves.
Coconut Diethanolamide The surfactant coconut diethanolamide (DEA) can sensitize metalworkers from its presence, not so much in metalworking fluids themselves, but more in skin cleansers and ‘barrier’ creams.6 Its inclusion in a special patch-test series for metalworkers (0.5% petrolatum) therefore remains important.
Oleyl Alcohol Oleyl alcohol (octadecanol) has been identified for the first time as one of the sensitizers in a water-based metalworking fluid (the other being ethanolamine). This is not yet in a special patch-test series for metalworkers; it might be important to test (10% petrolatum), if it was found to be contained in a positively reacting metalworking-fluid dilution. It may also be present in 0738-081X/97/$32.00
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surfactants, printing inks, textile-finishing tifoaming agents, and plasticizers.
Neat Cutting Oils Sporadic outbreaks of allergic contact dermatitis still occur from neat cutting oils, epoxides used to stabilize chlorinated paraffins being a recurrent example.5 Crosssensitivity to standard diglycidyl ether of bisphenol A epoxy resin may be the first indication of such sensitivity. The antioxidant tertiary-butylhydroquinone (TBHQ), more familiar as a sensitizer in cosmetics, has been identified as a cause of allergic contact dermatitis from a vegetable-oil-based cutting fluid.* Other sensitizing antioxidants (BHA and BHT), more familiar in cosmetics, may be similarly used.
References 1. Alomar A. Occupational skin diseasefrom cutting fluids. Dermatol Clin 1994;12:537-46. 2. Goh CL. Cutting fluid dermatitis-epidemiology and an appraisal of somepreventive measures.Environ Dermato1 1994;1:3-11. 3. Shah M, Lewis FM, Gawkrodger DJ. Prognosisof occupational hand dermatitis in metalworkers. Contact Dermatitis 1995;34:27-30. 4. Meding B. Occupational contact dermatitis from tertiarybutylhydroquinone (TBHQ) in a cutting fluid. Contact Dermatitis 1996;34:224. 5. Scerri L, Dalziel KL. Occupational contact sensitizationsto
the stabilized chlorinated paraffin fraction in neat cutting oil. Am J Contact Dermat 1996;7:35-7. 6. Pinola A, EstlanderT, Jolanki R, et al. Occupational ailergic contact dermatitis due to coconut diethanolamide (cc+ camide DEA). Contact Dermatitis 1993;29:262-5. 7. Itschner I, Hinnen H, Elsner P. Skin risk assessmentot metalworking fluids: a survey among Swiss supphers. Dermatology 1996;193:33-5. 8. Wigger-Alberti W, Hinnen U, ElsnerI’. Predictive testmg of metalworking fluids: a comparison of 2 cumuIative human irritation models and correlation to epidemiological data. Contact Dermatitis 1997;36:14-20. 9. Huner A, Fartasch M, Hornstein OP, et al. The irritant effect of different metalworking fluids. Contact Dermatitis 1994;31:220-5. 10. Bahmer FA. In vivo assessmentof irritants made simpic and user-friendly. Contact Dermatitis 1995$3:210-11. 11. Jarvholm B, Ljungkvist G, Lavenius B, et al. Acetic aldehyde and formaldehyde in cutting fluids and their r&tion to irritant symptoms. Ann Occ Hyg 1995;39:591-601. 12. Bruze M, Hradil E, Eriksohn I-L, et a1.Occupational aliergic contact dermatitis from alkanolamineborates in metalworking fluids. Contact Dermatitis 1995;32:24--7. 13. Gruvberger B, Rruze M. Contact aflergy to 4-(2-nitrobu tyl)-morpholine and 4,4’-(2-ethyl-2-nitrotrimethylene)-dimorpholine asactive ingredients of a preservative recommended for metalworking fluids in the guinea pig. Dermatosen1995;43:126-8. 14. Gruvberger B, Bruze M, Zimerson E. Contact allergy tc-1 the active ingredients of BiobanP1487.Contact Dermatitis 1996;35:141-5. 15. Koch P. Occupational allergic contact dermatitis front
oleyl alcohol and monoethanolaminein a metalworking fluid. Contact Dermatitis 1995;33:273.