Stockholm (03.04.1998 - Rolf Ählberg*) Exposure to isocyanates is a more serious health hazard than has previously been realised, according to recent findings by scientists Gunnar Skarping, Marianne Dalene and their colleagues at Lund University Hospital in Sweden.
Nordic Metal (the confederation of metalworker unions in the Nordic countries) is working to fight these problems in a European context by seeking regulations on the use of products containing or discharging isocyanates.
What are isocyanates?
Isocyanates are basic chemicals. They are mainly used in producing polyurethane foam, polyurethane elastomers, polyurethane adhesives and polyurethane varnish.
Where are isocyanates and polyurethane used?
Isocyanates are found in chemical products such as
- PAINTS
- VARNISHES
- SURFACE TREATMENTS
- ADHESIVES
- CAULKING COMPOUNDS
- UNDERBODY COMPOUNDS
- FILLERS
- RAW MATERIALS FOR MAKING FOAM RUBBER AND URETHANE RUBBER
- FOAM RUBBER
- URETHANE RUBBER
When does exposure to isocyanates occur?
The industrial manufacture of polyurethane or any processing of polyurethane products involving heating can cause exposure to isocyanates. Such risks occur in
- HEAT TREATMENT
- WELDING
- SOLDERING
- CUTTING (WITH A BLOWPIPE OR TORCH)
- SAWING
- SECTIONING
- PLANING
- PAINTING
- GLUING
- FILLING
How many people are exposed and to what quantities?
The production and use of isocyanates has been increasing for many years. In Western Europe, polyurethane production increased from 994,000 tons in 1983 to 1,687,000 tons in 1992 and this increase has continued. It is difficult to estimate the number of people whose health is at risk in their workplaces because of isocyanates, but they can be counted by the thousand. Most western European countries apply the same safety limits (0.005 ppm) and this value is also applied in the USA and Canada. Strict regulations apply to the use of isocyanates as such. The problem is that the methods so far used to measure exposure have failed to reveal the true extent of the problem.
What is the problem?
The methods used for many years to measure isocyanates have turned out to be inadequate, untrustworthy and inaccurate. The limitations of the principal methods have meant that symptoms have not been linked to exposure to isocyanates. New measurement methods make it possible to study the decomposition products of polyurethanes. Other constituents of technical isocyanate products can also be determined.
New measuring instruments providing direct readouts have been developed and this has made it possible to trace isocyanate levels over a period of time and also to register short processes, thus enabling us to identify critical manufacturing operations. New methods for analysing urine and blood samples have also been developed.
What symptoms are linked to working with products with a high isocyanate content?
The following are some of the symptoms that can arise. Runny noses, stuffy noses, sneezing and/or itching in the nose, nose bleeds, soreness or dryness in the throat, wheezing, breathlessness and/or a tight feeling in the chest, pain, irritable coughs, breathing problems, asthma and loss of lung capacity, irritation of the eyes and skin problems ranging from redness to eczema-like changes. Isocyanate asthma is the most common form of workplace asthma in contemporary Sweden. These symptoms may appear long after the work has been finished and may also disappear during long periods of absence from work such as holidays.
What kinds of jobs involve working with isocyanates?
Isocyanates are found almost everywhere.
1. THE ELECTRONICS INDUSTRY
- Varnishing printed circuit boards
- Hardening or heat-treatment of printed circuit boards
- Soldering printed circuit boards
- Reconditioning or repairing printed circuit boards
- Cutting and splicing optical cable
- Working with copper wire
2. MANUFACTURING DOMESTIC APPLIANCES
- Production of polyurethane foam
- Using mineral wool, rock wool etc.
- Service staff and operators are also at risk
3. MANUFACTURING PLASTIC GOODS
- Manufacturing e.g. rubber mattresses
- Manufacture of various automobile components
4. ELECTRICAL INDUSTRY
- When spliced, copper wire can release isocyanates
- Cable manufacturers, electricians and service staff are also at risk
5. CAR AND VEHICLE WORKSHOPS
- Paint shops and panel work
- Welding, sanding and cutting painted panels or underseals
- Gluing car windows
- Repair of coachwork, interior trim and bumpers
6. CASTING
- Production of mould cores (coldbox method)
- Casting in which mould cores are heated to high temperatures
7. WELDING INVOLVING
- Painted or varnished material
- Glued material
- Material containing plastic or insulation foam
8. WORK INVOLVING PLASTIC FOAM OR INSULATION FOAM
- Heat treatment
- Repair work
- Welding
- Soldering
- Cutting (with a blowpipe or torch)
- Sawing
- Sectioning
- Planing
9. WORK INVOLVING PAINTING/VARNISHING
- Manufacture of paint and varnishes containing polyurethane or isocyanates
- Painting or varnishing with paints or varnishes of this type
- Heat treatment, soldering, cutting (with a blowpipe or torch), sawing, sectioning, planing or using a blowpipe on material that has been treated with paints or varnishes of this type
10. WORK INVOLVING ADHESIVES OR GLUED COMPONENTS OR PRODUCTS
- Using two-component adhesives
- Heat treatment, soldering, sawing, sectioning or cutting (with a blowpipe or torch), planing glued joints
- Gluing flooring materials
11. WORK INVOLVING MINERAL WOOL (ROCK WOOL, GULL FIBRE ETC.)
- Used instead of asbestos in processes involving heat
- Isocyanates of metal are emitted at temperatures above 150 degrees centigrade
- Insulation material used in industrial facilities, ranging from furnaces and heating equipment to foundries and steelworks
- Compare with the Bophal catastrophe in India
12. WORK INVOLVING BAKELITE AND WOOD GLUE
- Isocyanates are emitted during the heating of Bakelite, laminated board, chipboard etc.
- There are risks in manufacturing processes and when waste products are burnt
What solutions do we propose?
Besides measures at national level, Nordic Metal also proposes European regulations on the use of products containing or capable of discharging isocyanates. Irrespective of the form of European regulations, they should at least cover the following areas:
- Inspection of raw materials
- Documentation
- Handling procedures for isocyanates at work
- Information on health risks and preventive measures
- Training in handling substances based on isocyanates
- Hygienic safety limits
- Measurement techniques adapted to workplace needs
- Medical supervision
- Taking samples, - air samples, - biological samples (blood samples, urine samples)
- Access to competent staff in company health services, industrial hygienists, safety engineers, etc.
- Evaluation, for example of necessary research resources.
(*Rolf Ählberg works as the National Officer in the Health and Safety Department of the Swedish Metalworkers Union)