Health risks


Isocyanates is a family name of a large amount of substances with an extensive use in the work life. There is a large number of different isocyanates with different characteristics but common for all these is that they cause health problems, especially when inhaling. The largest area of use for isocyanates is when manufacturing polyurethane plastics (PUR). PUR appears as compact and soft foam, and is found in coating and other chemical products. The usage of PUR is increasing and makes up approx. 5 % of all plastics used in Europe. When polymerising and heating of PUR a number of isocyanate combinations are formed. When heating fenylformaldehyd resin methyl isocyanates are formed.

Danger of isocyanates
Isocyanates cause health hazards especially when inhaled in form of gas, steam, dust or aerosol. Inhaling can cause irritation in eyes, mucous membranes and respiratory systems with symptoms resembling asthma or bronchitis and decreased lung function. The risk of hypersensitiveness is big.

Isocyanates can also cause skin irritation. Repeated contact can cause eczema and in some cases skin allergy. Isocyanates have a very low limit value. An allergic person can develop problems even when exposed to concentrations below the hygienic limit value. Isocyanates have such a low limit value that you may be exposed to dangerous proportions without noticing it as the isocyanates do not show nor smell at such low contents.

Isocyanates in the electronics industry
Recently new health hazards have been discovered with certain coatings, so called PUR coatings and some PUR glues used in manufacturing and repairing printed circuit cards. The same risks occur when working with coated optical cables that contain small amounts of PUR and coated wire. When these materials are heated isocyanates are formed in such high concentrates that it can cause asthma. It is believed that the thermal segregation starts at 150-200°C. There is also strong reasons to suspect that isocyanates can be formed when heating resin products like fluxing materials.

Filtronic´s products are tested by IVL (Swedish Environmental Research Institute) for isocyanates.

Occupational asthma

Fumes and gases in industrial areas are very often dangerous to the people working in the same area where the fumes and gases appear. Some of these material are very well visible, other are not visible and even not noticeable. Many of these fumes and gases are toxic and lead to Occupational Asthma and allergic reactions.

Occupational asthma is a major issue in electronics manufacturing because when a person has developed occupational asthma he/she has to be removed from the working area. In some countries occupational asthma due to flux fumes/isocyanates have already lead to legal claims from employees.

FAQ & Facts on solvents

Everybody who is working in industrial environments gets in contact with chemicals which contain a solvent. Chemical processes of one sort or another are occurring either as an essential requirement for, or as a consequence of, many seemingly physical working activities.

How dangerous the chemical is, containing the solvent, depends on the properties of the substance and the precautions taken when handling the chemical.

Not many employees do understand the risks of exposure to hazardous substances due to the fact that it takes a very special knowledge of occupational health risks. And they often fear to loose their jobs when complaining about the situations in their company.

We have made this leaflet for those who want to get extra information about solvents.

Organic solvents are absorbed mainly through the mucuous membranes (resporatory system appr. 80-200 m²) but some can also be absorbed through the skin (2 m²) and digestion (food and drinks) (area appr. 10 m²).

Gases have an ability to mix with the air in a room (from Latin di = pull apart & fusion = spread). Diffusion means that the particles spread in a room and form other molecules till all have the same equal position towards each other.

Additional we see that in western society more persons become sensitive to allergic materials (airborne particles, pets, solvents) which implicates the need for adequate extraction equipment and precautions.

Why are solvents dangerous?
Solvents dissolve fat. The easier they dissolve fat, the easier it is absorbed by the body and the greater is its capacity for affecting the nervous system. The ability to dissolve fat is partly the reason why they are used and that is one of the main reasons why they are so dangerous if they get into your body.

Especially the cells of the brain contain quite a lot of fat. And as the brain nearly works in the same way as a sponge, absorbing solvents, this makes solvents dangerous.

But can't the body break down solvents?
Yes it can. The liver can break down many of the solvents. But unfortunately the chemicals formed when these substances are broken down can be even more dangerous than the original solvents.

It can take a long time, so long that the body cannot get rid of everything during the night or the weekend. And it is very serious because it means that solvents can continue to wreak their effects on the body. The amount of solvents in the organs (of the body) can then accumulate step by step during the week as the break for the weekend is not long enough to have all the absorbed chemicals removed from the body.

Are all solvents equally dangerous?
No, and some are absorbed by the body by greater difficulty than others. If you have to use a solvent, try to use one that causes as little harm as possible.

There are many kinds of solvents which can harm the body. Some of these solvents are used in manufacturing processes to form other products, some are used with heat and other humidities and can transform themselves in other more dangerous materials.

What in the body is harmed by solvents?
That depends on the solvent in question. The brain, bone marrow, liver and kidneys are in the danger zone. The most common thing is damage to the nervous system.

What happens straight away is that your nervous system gets affected. Just as with alcohol (which is a solvent) if you consume a lot. Your reactions are slower, you get clumsy. Your judgement gets worse which, in turn, leads to other risks in many jobs beside the risk of health.

This does not mean that you are harmed for a short period. It has been proven that occupational symptoms appear over a longer period and that solvents can cause lasting damage such as damage to the nervous system, respiratory ways, eyes, brain, liver and kidneys.

Solvents and their properties

TDI (toluene-2,4-diisocyanate), MDI (diphenyl-methane diisocyanate), HDI (hexa-methylene diisocyanate). Isocyanates can easily be absorbed through the skin and through the mucuous membranes. In contact with water they form amines which will stay in the blood for a long time. Isocyanates are found in polyurethane materials (coatings), glues and varnishes.

Methanol, ethanol, isopropanol Inhalation, or contact with the skin can cause diziness, headache, disturbed vision and fainting. Absorption over a longer period can reduce the eyesight of the victom.
Formaldehyde, acetaldehyde These solvents are transformated products when heat is applicated to i.e. rosin. The fumes have an irritating effect on the eyes and the respiratory organs. Inhalation can induce headache, diziness and fainting in severe cases.

Esters (acetate)
Ethyl acetate, dioctyl pthalate. Materials often used as a solvent and dissolvent in paints, plastic industries and synthetic fibres. As all solvents it causes irritation of the respiratory passages but in long- term absorption it will cause damage to kidneys and liver. There are many other solvents present on the market such as ketones, mercaptans, organic acids, ethers which all have their reaction to the human body. Mainly the respiratory ways are involved or with contact to the skin (splashes) they will cause eczema.

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