Irritant cutting fluid

Ether carboxylates are a very versatile class of surfactants, used in diverse applications from mild personal care formulations to lubricants and cutting fluids. They are interrupted soaps, with the addition of a number of ethylene oxide groups between the alkyl chain and the carboxylate group. The additional solubility imparted by the EO groups gives much greater resistance to hardness and reduced irritancy compared to soap. 

Jarvholm B, Ljungkivst G. Laventius B, et al. 1995. Acetic aldehyde and formaldehyde in cutting fluids and their relation to irritant symptoms. Ann Occup Hyg 39 591-601. 

The ideal cutting fluid, in achieving the above, should not corrode the work or machine, have a low evaporation rate, be stable and not foam or fume, not injure or irritate the operator. 

Oils and coolants have recently been reported as common irritants in the electronics industry [20]. This problem has not been previously highlighted. In the paper quoted, however, the precise chemical culprits are not given. Historically, exposure to oil-based cutting fluids have been considered to be associated with cutaneous squamous cell carcinomata [42, 43], although no reports of this have as yet emerged among workers in the electronics industry. 

The problems potentially caused by cutting fluids are listed in Table 5. With solvent refining of oils, acne and folliculitis is now seen rarely. Primary irritant and allergic contact dermatitis are the most frequently encountered clinical problems. 

This also applies to cases of sensitisation to sodium mercaptobenzthiazole (a corrosion inhibitor), where sensitisation occurs in spite of working levels between 0.01% and 0.05%. The fact that this can occur suggests that there are particular factors related to cutting-fluid sensitisation that are not found in other situations. Apart from the irritancy of oils, particularly if inappropriate strengths are used, the warmth of the oils, the wetness of the situation, the abrasion from metal fragments and occlusion from protective gloves may all contribute to the high level of sensitisation found. 

Pre-employment screening of individuals should try to exclude those that have a personal history of longstanding atopic dermatitis, particularly if this has affected the hands. Those individuals with a previous history of hand dermatitis from other irritant causes are also at increased risk of recurrence. If they are allowed to work in a cutting-fluid environment, then every effort needs to be made to enable them to maintain meticulous hand care. 

The fluids have also found a number of uses in medicine. Barrier creams based on silicone fluids have been found to be particularly useful against the cutting oils in metal machinery processes which are common industrial irritants. The serious and often fatal frothy bloat suffered by ruminants can be countered by the use of small quantities of silicone fluid acting as an antifoam. 

Water is also used with oil and other additives in the form of an emulsion as a coolant and lubricant in cutting processes. These fluids must be nonflammable, as a spark from the cutting tool or electrical equipment would cause a fire, and they should not cause irritation to the skin or produce harmful vapours. Furthermore, for purposes of protection from corrosion, they should not cause corrosion of the cutting equipment or the material being cut and should give short-term protection from atmospheric corrosion. 

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