Workers struck by lung diseases - 1 October, 2004
About 70 workers at a car engine factory in Birmingham have been struck down with serious lung illness. The Health and Safety Executive (HSE) said it is investigating cases of extrinsic allergic alveolitis (EEA) and occupational asthma at Powertrain in Longbridge, and expects more cases to be diagnosed. It said 73 people had 'definitely or probably' got one of the two illnesses.

More than 1,000 workers at Powertrain, which is the sister company of MG Rover, are now to be screened. Marcia Davies, the HSE's Midlands director, said it was 'a very unfortunate and worrying outbreak of occupational lung disease. We have required Powertrain to make serious improvements to the cleaning and monitoring regimes for the metalworking machines and fluids. The microbes in the metalworking fluids, which may have caused the diseases, are now being adequately controlled and most people affected are still able to work.'

TGWU regional industrial organiser John Walsh said 'we are keeping in close touch with the company and seeking an urgent meeting with the Health and Safety Executive.'  He said that compensation claims were being prepared on behalf of some affected workers, adding: 'These are difficult and, indeed, worrying times but we need to be calm and measured to make sure the causes of the cases are identified, isolated and eradicated.'

Similar outbreaks of 'hypersensitivity pneumonitis' - another name for chronic EAA - have been reported in car plants in the US and Canada.

Metalworking fluids
Metalworking fluids (MWFs) is the name given to a range of oils and other liquids that are used to cool and lubricate metalwork when being machined. MWFs are classified as either "Straight Oil" or "neat" oils (not meant to be diluted with water, and may contain highly refined petroleum, animal, marine, vegetable or synthetic oils); Soluble Oil (highly refined petroleum oils, and emulsifiers); Semi-synthetic fluids; and Synthetic fluids (which may include detergent-like components). The last three classes are diluted with water before use. All MWF class may contain additives such as stabilizers, biocides, dispersants, dyes, and odorants. When MWFs are used, a primary concern is the presence of contaminants that encourage the growth of bacteria and fungi. Also, there is a potential for oils to be heated high enough where the cutting tool works on metal workpiece to form polynuclear hydrocarbons (PAH's).

While MWFs are used by hundreds of thousands of workers safely, problems can develop when good hygiene practices are not followed or when fluids are not properly managed or maintained. Major health concerns of improperly managed fluids or when good hygiene practices are not followed include skin irritation, allergic contact dermatitis, irritation of the eyes, nose and throat, and, occasionally, breathing difficulties such as bronchitis and asthma. Although rare, some workers have contacted hypersensitivity pneumonitis (HP) from improperly managed fluids. HP is an allergic type reaction in the lungs that may be caused by exposure to certain microbial products. HP is marked by chills, fever, shortness of breath and a deep cough - similar to a cold that will not go away. Prior to 1985, the use of poorly refined mineral oils had been associated with an increase risk of cancers.

Cancers often associated with exposure to metalworking fluids include rectum, pancreas, larynx, skin, scrotum, esophagus, and bladder. The National Institute for Occupational Safety and Health (NIOSH) in the USA reports that studies were not highly consistent regarding the specific types of cancer associated with MWFs. This uncertainty is likely due to the wide variation in the types of MWFs and contaminants and the lack of detailed exposure information.

Also, because the latency period (the time between first exposure and the discovery of disease) for cancer is often 20 years or more, it is likely that the diseases studied recently are associated with older formulations of MWFs (from the mid 1970s and earlier). For example, fluids used before 1985 may have contained nitrites, mildly refined petroleum oils and other chemicals which were removed because of health concerns. Cancer risks have likely been reduced but there is not enough data yet to prove this theory.

Areas of concern for risk of cancer currently include:
     • unrefined mineral oils and contact with exposed skin (including oil soaked clothing and especially oily rags kept in pockets, which caused cancer of scrotum)
     • nitrites or nitrates and amines that cause the formation of nitrosamines when MWFs are heated or under pressure. Certain nitrosamines, such as N-nitrosodiethanolamines (NDELA), are known to be cancer causing agents.
     • some biocides release formaldehyde, a suspected carcinogen. Formaldehyde can also speed up the formation of nitrosamines.
     • chlorinated paraffins are carcinogens (often used when extreme pressure is required). They also form dioxin, another carcinogen.

What Are the Signs That a Fluid May No Longer Be Safe to Use?

There are many signs that a fluid has undergone changes and is no longer safe to use because of emerging health hazards. If one or more of the following changes occur, the fluid should be evaluated to see if it is safe for continued use or if it should be replaced.

• Low sump level. Check the sump level at the start of the shift. A low sump level (30% below the full mark) shows metalworking fluid loss or water evaporation (increasing the concentration of chemicals present in the MWF). Check the concentration! If too strong, add water to reach the proper concentration. If the concentration is correct then fluid was lost due to dragout. You should add fluid at an appropriate dilution, or if pre-diluted fluid is not available, water and concentrate can be added. All systems should be monitored carefully and metalworking fluid additions should be made on a regular basis to maintain a constant working concentration. The correct concentration should be verified when finished.
  
• Abnormal fluid appearance. Determine if the fluid colour looks normal. When in good condition many synthetic fluids are clear, semi-synthetics are often transparent to milky, and soluble oil usually looks milky white with no free oil layer. If the fluid turns grey or black, then bacteria are often present. If the fluid picks up a yellow or brown tint then tramp oil may be present. Dye fading may indicate that a fluid is ageing.
  
• Foul smell (rancidity). When fluids smell bad, it usually means that there is uncontrolled microbial growth. Although it may be possible to cover up the odour, it's best to address the cause because micro-organisms present in the fluid can be aerosolised into the air as part of the mist. Exposure to micro-organisms in the air may cause adverse health effects to exposed employees. If the fluid has a strong and "locker room" odour, it likely has biological growth and should be treated with biocide and evaluated. If need be, the fluid should then be discarded, the sump properly cleaned, and the fluid replaced.
  
• Floating matter on the fluid. If the fluid has floating chips, swarf, or mold growth, this is not normal. Try to remove as much as possible with a skimmer or have it pumped off. The level of dirt (total suspended solids) in the fluid is a measure of the efficiency of the filtering system. Periodic checks and maintenance of the filtration system and oil skimmer are necessary to assure that they are functioning as designed.
  
• Tramp oil floating on the surface. With water-diluted fluids, if the sump is completely covered with oil and the machinist cannot swish the oil out of the way for more than 5 to 8 seconds before the sump is covered again, there is too much tramp oil present. Skim or pump the surface oil to remove it. Tramp oil is one of the main causes of dermatitis. These oils are not developed with repeated skin contact in mind, and some components of these machine lubricants are highly irritating to the skin. Un-emulsified (tramp) oils can be a significant carrier of metallic fines, which can be deposited on the skin and cause mechanical irritation. These fines, suspended by tramp oil, are a major cause of dermatitis.
  
• Excessive foam. A lot of foam may be caused by soft water with some products. The fluid may also be too highly concentrated, or it may be contaminated by cleaners, or there may be an imbalance in the fluid surfactants. Another possibility is that you could have an undersized system, excessive flow rates, or the fluid may not be at rest long enough to allow air to escape. In addition, the level of cutting fluid in the reservoir may be low, causing air to be drawn into the pump.
  
• Dirty machines or trenches. This could mean that the emulsion is becoming unstable, the cleaners in the fluid have been depleted, the contaminants are being deposited from the fluid, there is filter failure, or there is poor housekeeping.
  
• Employees have skin irritation. If employees have skin irritation, it could mean that the fluid has one or more of the following properties: too high a concentration, high alkalinity, metal contamination, an unstable emulsion, or contamination from workpiece coatings. Of course, skin irritation can also be due to causes not directly related to metalworking fluids, such as changes in the weather, poor personal hygiene, poor work habits, the use of harsh hand soaps, wearing contaminated clothing, or prolonged exposure to the fluid.
  
• Employees have respiratory irritation. Exposure to MWF aerosols can lead to complaints of irritation and tightness in the chest. Factors that can contribute to irritation could be the improper delivery of fluid to the cutting zone; improper use of additives; a high coolant concentration; a heavy concentration of machines in a small area; inadequate or poorly designed enclosures and mist collectors; loss of microbial control; poor general ventilation of the shop; insufficient fresh air make-up rates; and high mist concentrations (even in the absence of machining operations) may be present in areas where coolant flumes make sharp turns.
  

• rust or corrosion of the machine tool or of the part produced;
  
• staining of the metal machined or ma chine tool;
  
• tool failure due to the loss of performance additives;
  
• growth of fungi that block fluid flow;
  
• change of fluid viscosity (thinner or thicker);
  
• accumulation of water at the bottom of the oil sump drain, in straight oils;
  
• dirt and grit suspended in the fluid; and
  
• failure at the workpiece-tool interface (for example, burning of a ground part due to excessive heat build-up).