Magazine article Occupational Hazards

Controlling Exposure to Metalworking Fluids: That Smoky Haze in Machining Shops Carries the Potential for a Variety of Serious Health Problems. A Veteran Safety and Health Expert Examines the Use of Metalworking Fluids and What Can Be Done to Eliminate or Minimize Workplace Exposures

Magazine article Occupational Hazards

Controlling Exposure to Metalworking Fluids: That Smoky Haze in Machining Shops Carries the Potential for a Variety of Serious Health Problems. A Veteran Safety and Health Expert Examines the Use of Metalworking Fluids and What Can Be Done to Eliminate or Minimize Workplace Exposures

Article excerpt

Anyone who has worked in a shop where machining of metal parts is the primary business knows that these operations tend to be noisy and "smoky." During my 21 years of industrial hygiene consulting practice, I've been in many machine shops where a visible, smoky haze is present (usually it can be seen by looking at lighting fixtures near the ceiling). This smoky haze generally consists of metalworking fluid mists and vapors.

[ILLUSTRATION OMITTED]

Metalworking fluids (MWFs) are used during machining and grinding of metal parts to prolong the life of the tool, carry away metal chips and other machining debris and to protect the surface of the work piece. These fluids reduce friction between the cutting tool and the work piece, reduce wear and dissipate heat generated by the machining process.

The first generation of MWFs included sperm whale oil, mineral oils and various types of petroleum oils. These products were in use from the beginning of the Industrial Revolution up until the early 1940s.

With the changes in manufacturing brought about by World War II (and the declining availability of sperm whales), the second generation of MWFs began to appear, including the first water-soluble and semi-synthetic MWFs. By the 1970s, water-soluble and semi-synthetic MWFs were in common use throughout the metalworking industry.

The advent of high-speed machining operations, new metal alloys and closer tolerances for machined parts brought about the current generation of MWFs, which began about 1985 with the introduction of amine-based, reduced-hydrocarbon, synthetic MWFs.

Today, health and safety professionals may encounter all three generations of MWFs, even within a single shop. MWFs in common use today are classified into four general types:

1. Straight Oils/Neat Oils. These MWFs are severely solvent refined petroleum (lubricant-based) oils, or other animal, marine, vegetable or synthetic oils, used alone or in combination, and with or without additives. These MWFs are not designed to be used with water.

2. Soluble Oils. These MWFs are combinations of severely refined straight oils and emulsifiers. Other additives may be included. Soluble oils are intended to be mixed with water before use.

3. Semi-Synthetics. These MWFs contain from 30 percent to 50 percent water (they also have lower amounts of straight oils and higher amounts of emulsifiers). Semi-synthetic oils may also contain other organic compounds, such as amines (i.e., triethanolamine).

4. Synthetics. These MWFs contains no petroleum oils (they are generally designed to be mixed with water before use).

Occupational exposure to MWFs occurs from the inhalation of the fine mists/aerosols that often are generated in machining processes and from direct skin contact. It is estimated that more than 1.2 million workers are currently exposed to MWFs in the United States.

HEALTH CONCERNS

There are several heath concerns that have been associated with exposure to MWFs, including:

* Dermatological (skin) disorders, including contact dermatitis.

* Carcinogenisis (of various types, including cancer of the larynx, rectum, pancreas, skin, scrotum and bladder).

* Pulmonary (lung) disorders, including hypersensitivity pneumonitis, and MWF-induced asthma.

It is not unusual to see dermatitis in workers exposed to MWFs. Workers who handle metal parts after machining often experience skin irritation and/or dermatitis on their forearms, chests and abdomens (when metal parts are in direct contact with the body during handling/loading). The cause of the irritation/dermatitis may be chemical, biological or mechanical (used MWFs also contain very fine metal particles).

Other factors that play a role in the development of contact dermatitis and other skin diseases include (1) the type of MWF used, (2) the amount of skin contact (including the use/reuse of MWF-soaked clothing), (3) individual susceptibility to irritants or allergens present in MWFs, (4) personal hygiene/inadequate cleansing of the skin after contact, and (5) the use of impervious personal protective equipment. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.