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close this bookBuilding Materials and Health (UNCHS/HABITAT; 1997; 74 pages)
View the documentABBREVIATIONS
View the documentFOREWORD
View the documentINTRODUCTION
close this folderI. HEALTH HAZARDS ASSOCIATED WITH BUILDING MATERIALS
View the documentA. Introduction
View the documentB. Health and building materials: An overview
View the documentC. Asbestos
View the documentD. Metals
View the documentE. Solvents
View the documentF. Formaldehyde
View the documentG. Insecticides and fungicides
View the documentH. Timber
View the documentI. Silica dust
View the documentJ. Earthen and traditional materials
View the documentK. Radon and its sources
View the documentL. Wastes
View the documentII. CONTROLLING HEALTH HAZARDS: PROBLEMS AND ISSUES
Open this folder and view contentsIII. A STRATEGY FOR THE CONTROL OF HEALTH HAZARDS ASSOCIATED WITH BUILDING MATERIALS
View the documentANNEX
View the documentREFERENCES
 

E. Solvents

Sources and health implications

Organic solvents are very widely used in construction as key ingredients of adhesives, paints, flooring materials and mastics. The most commonly used solvents include white spirit, toluene, xylene, trichloroethane, styrene and carbon tetrachloride. Paints, glues and lacquers contain toluene, methyl n-butyl ketone, n-hexane and xylene. Paint strippers and solvents contain white spirit and dichloromethane and expanded plastics contain styrene.

If inhaled, solvents dissolve readily in the blood stream. Sufficiently low concentrations will be metabolised quickly with no ill effects by the body, but if exposure is excessive a variety of health effects can occur, including sedation effects ranging from slowed reaction time and decreased vigilance to anaesthesia, irritation to the eyes, nose and throat, liver damage, and damage to the nervous system (26).

The International Federation of Building and Wood Workers has reported major health hazards for painters which include (27):

 

• Occupational cancer - Painters run a high risk of getting cancer from the chemicals with which they work: benzene can cause leukaemia; carbon tetrachloride can cause liver cancer; all chlorinated solvents (those with “Chloro” or “Chloride” in their names) are suspected carcinogens, for example, methylene chloride is a suspect carcinogen because it causes cancer in animals. See also table 6. A complete list of known cancer agents evaluated by IARC is given in the Annex. For the evaluation criteria refer to table 3.

• “Painters’ Syndrome” - is the name given to the effects on health which may arise from long-term exposure to organic solvents. Organic solvents get into the body and brain through the lungs or skin and slowly cause permanent changes in the brain and the central nervous system. Solvents may also damage the peripheral nervous system which is the system of nerves leading from the spinal cord to the arms and legs. The symptoms caused by this damage are numbness and tingling in the hands and feet, weakness and paralysis.

• Occupation skin diseases - all solvents can dissolve the skin’s protective barrier of oils, causing dermatitis. There are two types of contact dermatitis: irritant contact dermatitis, and allergic contact dermatitis. Contact dermatitis is the most common occupational skin disease, caused when the skin comes into contact with certain chemicals which can make the skin red, sore, inflamed, irritated, cracked, dry and itchy, and sometimes rashes and blisters may develop. Anyone working with paints and coatings runs a high risk of contracting irritant contact dermatitis because many paints and coatings contain chemicals which irritate the skin. This is a non-allergic skin reaction from exposure to irritating substances. Exposure to irritants accounts for 80 per cent of the cases of occupational contact dermatitis.

• Allergic contact dermatitis is a type of dermatitis caused by becoming allergic or sensitised to particular chemicals called allergens. Common allergens include epoxy adhesives, chromium and nickel compounds. Once someone has developed an allergy to a chemical (has become “sensitised”), the dermatitis will flare up again, usually within twelve hours after contact with the chemical. Some workers develop allergic contact dermatitis after many years of trouble free working with paints/coatings. Other workers never develop it at all even though they work with the same paint ingredient that gives allergic contact dermatitis to other painters. Allergic contact dermatitis is not easy to treat. Studies show that 25 per cent of people with allergic contact dermatitis will not recover from their allergy and will have to leave their work so as to avoid all contact with the allergens.

• Occupational lung diseases - occupational asthma; lung irritation from paint vapours and mists, lung tumours in painters and chronic bronchitis/emphysema. Occupational asthma is the result of becoming allergic to a chemical or substance. Once the lungs become allergic to a lung allergen, the symptoms of asthma can come back with exposure to a tiny amount of the substance. This means some workers are forced to leave their jobs because the asthma is so serious. It can be very difficult to “lose” an allergy. Common symptoms are wheezing, shortness of breath and coughing but there can also be other symptoms.

Table 6. A list of some of the known cancer agents related to painting as evaluated by IARC (27,28).

Cancer Agent

IARC Group

Likely Sources

Chromates

1

Primers, paints

Cadmium

1

Pigments

Benzene

1

Solvents, some thinners

Methylene Chloride

2B

Paint strippers

Styrene

2B

Organic solvent, e.g. in some polyesters, putties and fillers

Nickel Compounds

1

Pigments

3,3’ - Dichlorobenzidine

2B

Pigments

Lead

2B

Primers, dryers, some pigments

Antimony oxide

2B

Some pigments,

2-Nitropropane

2A

Organic solvent

Tetrachloroethylene

2B

Organic solvent for degreasing

 

Source: IFBWW Series 3 (1992). Solvents and Paint Hazards, International Federation of Building and Wood Workers, Geneva, and IARC (1995). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Lists of IARC Evaluations, Lyon, France.

Factors influencing exposure

An important characteristic of the hazardous substances in forms of gases and vapours which strongly influences their significance as health hazards is their volatility. Highly volatile substances are those with low boiling points, which will give off gases and vapours at a very rapid rate at normal temperatures. A study on the solvent vapour hazards during painting with white - spirit - borne eggshell paints, indicated that when painting was carried out at a lower temperature (12°C instead of 24°C) the rate of solvent vapour release, and consequently the hazard, was reduced by about 25 per cent (29). The same study concluded that the use of such paints in unventilated conditions can constitute significant health hazards: in the trials the short-term exposure limit (STEL) for white-spirit vapour was exceeded approximately 10 minutes from the start of painting, and concentrations approaching 700 ppm for a 10 - minute time weighted average (TWA) were reached before completion of painting. The allowable long-term exposure limit for an eight hour time weighted average (TWA) exposure is 100 parts per million (ppm), and the short-term exposure limit (STEL) for any given 10-minute period is 125 ppm (29). Thus, unless ventilation is good, hazardous concentrations can easily be reached shortly after use or installation; but the rate of emission will decline rapidly, and they are not likely to be a long-term problem, except where, for some reason, emissions are delayed. Substances of low volatility, or semi-volatile substances, conversely, are not emitted rapidly: but they can continue to be emitted for a long period of time; they can be absorbed by dust and furnishing materials, and then later be re-emitted to the environment; and they are metabolised only slowly in the human body, and can therefore tend to accumulate.

Solvents are volatile and therefore can build up in the indoor environment during construction and maintenance work. Moreover, their emission can continue even after occupancy, and thus add to the load of other solvents and organic chemicals in the environment from dry cleaning, aerosol propellants, correction fluid, cigarette smoke and so on.

The World Health Organization classifies organic chemicals as Very Volatile (VVOC), Volatile (VOC), and Semi-Volatile (SVOC). The VVOCs are a fairly small group of which, among building materials, formaldehyde which is a gas is the most important member. The VOCs are a much larger group, of growing size; they include the binders in plastics and other polymeric materials and the large group of solvents used in the manufacture of paints and varnishes. The semi-volatile materials, SVOCs, consist largely of pesticides which are also very numerous. A fourth category of organic compound which has significant hazards is particulate organic matter (POM) in the form of dust. Building materials are, however, not a significant cause of POM in the indoor environment. The classes of substances, their characteristics and uses, based on the World Health Organisation (WHO) data, are summarised in table 7 (5, 30).

Table 7. Classification of organic compounds in the indoor atmosphere and their sources.

Description

Abbreviation

Boiling point range (OC)

Main example

Principal uses

Very volatile organic compounds

VVOC

<100

Formaldehyde (gas)

Pressed board products
Urea formaldehyde foam carpets

Volatile organic compounds

VOC

50-260

Solvents

Paints, varnishes, plastics, mastics

Semi-volatile organic compounds

SVOC

240-400

Pesticides

Timber treatments, paints, wallpaper paste, carpets

Participate organic matter

POM

>380

Dust

Carpets, ventilation ductwork

 

Source: Crowther, D. (1994). Buildings and Health, Ph.D. Thesis, University of Cambridge, UK, and WHO (1990). Indoor Environment: Health Aspects of Air Quality, Thermal Environment, Light and Noise, UNCHS/UNEP/WHO

Acceptable exposure levels

WHO and national authorities, such as American Conference of Government Industrial Hygienists (ACGIH) have set limits for industrial exposure. The Threshold Limit Values (TLV) set by ACGIH for some of the more important solvents are shown in table 8. Guidelines recommended by WHO regarding ambient and indoor air would be appropriate for domestic exposure, because of the increased time of exposure, and the greater susceptibility of some occupants such as small children and the elderly. Table 8 also shows some domestic air levels taken from a variety of studies (31,32). It will be seen that all are far below the Threshold Limit Values prescribed.

Table 8. Threshold Limit Values (ACGIH) and recorded domestic air levels for some solvents used in construction.

Solvent

Threshold limit value (ACGIH) (mg/m3)

Typical domestic air level (mg/m3)

Aromatic hydrocarbons:

   
 

Styrene

213

0.0027

 

Toluene

188

0.01 - 0.6

 

Xylene

434

0.01 - 0.14

Aliphatic hydrocarbons:

   
 

n-hexane

176

 
 

Methyl n-butyl ketone

20

 

Chlorinated hydrocarbons:

   
 

Dichloromethane

174

5

 

Carbon tetrachloride

31

0.014

 

Source: Ray, D.E, (1992). Hazards from Solvents, Pesticides and PCBs in Leslie, C.B. and Lunau, F.W., Indoor Air Pollution: Problems and Priorities, Cambridge University Press, Cambridge, UK, and ACGIH (1994). 1994-1995 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices.

During occupancy, the key consideration is not the exposure or limit value of any one organic chemical but the exposure to all volatile chemicals. While exposure to individual organic chemicals in the indoor atmosphere may be acceptably low, the combination of numerous gases and vapours at low concentrations can have irritant effects. Measurements by Molhave (26) of the emissions of solvent gases and vapours from 42 building materials showed that about 80 per cent of the compounds identified in the air around the materials were known or suspected mucous membrane irritants. When combined with other gases in an indoor environment, and combined with other environmental factors such as sound, temperature, humidity, these organic chemicals are regarded as being largely responsible for the condition known as sick building syndrome. Molhave (26), based on experiments on people exposed to different levels of exposure, suggests that concentrations of total volatile organic compounds less than 0.16 mg/m3 may be expected to cause no mucous membrane irritation, while concentrations above 5 mg/m3 are found to cause irritation. In the intermediate range, irritation may occur if promoted by other environmental exposures. Molhave (24) has subsequently proposed an approximate dose-response table for airborne VOCs (Table 9).

Table 9. Draft dose response table for airborne VOCs.

Total VOCs (mg/m3)

Possible reactions

Exposure class

<0.2

No irritation or discomfort

Comfort range

0.2-3.0

Irritation and discomfort

Multifactorial exposure range

3.0-25.0

Headache and other weak neurotoxic effects

Discomfort range

>25.0

Additional neurotoxic effects

Toxic range

 

Source: Molhave, L. (1990). Volatile Organic Compounds - Indoor Air Quality and Health, Indoor Air ‘90, Vol. 5, pp. 447-452

At present there are no national or international indoor air criteria for new buildings but in some areas, they are beginning to be developed. In the state of Washington, United States of America, for example, emission rates for office furniture workstations must be such that the resulting air concentrations in the building are less than those shown in table 10 (34).

Table 10. Emission limits for office furniture workstations set by the State of Washington, United States of America.

Substance

Air concentration limit

Formaldehyde

0.05 ppm (0.06 mg/m3)

Total VOCs

0.50 mg/m3

Total particulates

0.050 mg/m3

 

Source: Tucker, W. (1990). Building with Law-emitting Materials and Products: Where Do We Stand?”, Indoor Air ‘90, Vol. 3, pp. 251-256.

Mitigation strategies

While the solvents are in use, during construction activity, levels will clearly reach much higher values over a short period of time. Where solvent - borne paints, have been specified, measures must be taken to ensure ventilation or solvent extraction sufficient to reduce solvent - vapour levels below the occupational exposure limits. Where this is not practicable the operators must be provided with suitable respiratory protection. Protective clothing should also be provided to workers. Workers too need to be provided with health and safety information about the hazards of the solvents including the minimum requirements for safe use and exposure control to protect their health, the chemical ingredients, the short and long-term health effects, first-aid information, and storage and transport requirements.

Substitute materials

There are limited options at present for the substitution of volatile organic chemicals in paints and other finishes. Alternative water-based paints are available which reduce the quantity of organic chemical solvents, but although advertised as environmentally friendly, they do contain significant quantities of organic solvents and a range of other hazardous chemicals. Solvents based purely on natural products do exist (35) but are not manufactured yet in large quantities and paints based on them are not commercially available.

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