In a past STLE article on dermatitis among machinists, I covered a variety of broad topics dealing with causes of dermatitis among machinists and some prudent measures to reduce incidences of this common disease(1). Dermatitis is the most prevalent occupational disease among machinists and many preventive strategies have been studied and tested extensively(2). Data from a widely cited epidemiological study of 286 machinists exposed to metalworking fluids showed that the prevalence of contact dermatitis was 27%, due mostly to irritant reactions(3). This article recaps the most obvious but frequently overlooked strategy for reducing dermatitis among machinists, i.e., timely and prudent removal of fluids from skin surfaces.
MWF formulations, especially water-soluble types (soluble oils, semi-synthetics, synthetics), may be tested for acceptable skin mildness prior to being commercially available to customers. Fresh (unused) fluids are commonly alkaline products (~pH 8-9) that contain various additives such as inhibitors, biocides, amines, stabilizers, etc. These constituents and others may contribute to the propensity of a given formulation to contribute to clinical diagnoses of irritant or allergic dermatitis, if not removed from exposed skin in a timely manner. During machining activities, particulate matter such as dirt, grit, swarf, and exogenous fluids from mechanical systems (tramp oils, way oils, hydraulic fluids, etc.) that migrate into MWF systems may increase the probability that a MWF fluid will cause or exacerbate dermatitis symptoms. Good fluid management practices advise that active fluids should be filtered and conditioned during circulation through central systems and sumps. Also, scheduled disposal, cleaning, and recharging (DCR) regimens provide fluids that foster worker health, and acceptable parts quality and tool life.
Ideally, avoidance of any kind of dermal exposure to MWFs would preclude dermatitis. However, on a practical basis, this is not possible, even in machining operations that have fully enclosed machines, since inevitably there will be skin exposures among workers during various stages of manually handling fluid-drenched tools and workpieces, machine set-ups, moving parts for additional processing, and during packaging, storage, and transport operations. Wearing personal protective equipment (PPE) (gloves, aprons, arm and face shields, etc.) can be very effective in reducing exposures. However, in some high-speed machining operations, some PPE may actually pose safety hazards to workers (machine entanglement) and, therefore, if there is ever any doubt, supervisory personnel should be immediately notified to assess the situation.
The epidermis of skin (outermost layer) is made up of 5 layers of cells called the stratum corneum which is important for the protection, health, and general appearance of skin(4). This natural barrier is normally very effective in protecting skin from daily environmental insults. However, any compromise of the epidermis by chemical or physical agents can lead to a variety of dermatological disorders(1,2,3). Industrial hygienists have long-recognized that an effective strategy to minimize dermal problems is the removal of MWFs residues from the epidermis in a manner that does not damage it. In this regard, frequent washing of exposed areas with mild soaps is an effective yet frequently neglected step in prudent skin care. However, excessive hand washing may deplete natural skin oils and lead to skin dryness, subsequent cracking, and the development of opportunistic bacterial infections. Also, metal fines in MWFs can act as abrasives on skin and foster a variety of dermal problems. Therefore, shop cloths saturated with MWFs should not be used to wipe skin surfaces, and workers should be encouraged to change clothing soiled with fluids. Again, the basic strategy is to reduce the time that MWFs reside on exposed skin.
Periodic training about MWF skin exposures and protective measures can reinforce simple yet effective practises of good skin care among workers. Many companies have instituted Skin Care Programs that can be very effective in reducing dermatitis among the workforce(5).
Other articles in this issue: