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This article examines the reasons why certain groups of workers may be at greater risk of exposure to dangerous substances in the workplace. The article covers new workers, young workers, migrant workers and workers with certain medical conditions. The article gives information on the additional precautions that are necessary to ensure that adequate exposure control is achieved for these groups. Some information on relevant EU legislation is also included. There is also information on the additional risks associated with maintenance activity, reproductive risks and on the potential for secondary exposure of people outside the workplace, including a discussion on how this may be prevented.

Many substances used in the workplace have the potential to cause harm to workers, and to other individuals who may inadvertently exposed to such substances, and it is important to adequately control exposures. European legislation (Council directive 98/24/EC) [1] sets out the basic requirements to achieve adequate exposure control, and this is supported by national legislation in European Union (EU) member states.

Certain exposure control options are more reliable and robust than others; this is often referred to as the hierarchy of control measures. Dangerous substances can enter the body by breathing them in, through the skin and can be swallowed (ingested) if good hygiene practices are not followed. Occupational exposure limits (OELs) define an upper level for inhalation exposure, [2] but for many substances no limits exist. Furthermore, for many substances, including carcinogens, mutagens, reprotoxins and asthmagens, it is often not possible to identify a ‘safe’ level of exposure. Exposure to these substances should be reduced to the lowest possible level, and OELs where set, may represent what is reasonably achievable [3].

In some instances, special conditions need to be applied to protect vulnerable individuals or groups. These include workers who are intrinsically vulnerable such as migrant workers, young workers and those with certain medical conditions. Other workers may also be vulnerable at certain times for different reasons, for example when conducting high risk, non-routine work activity such as maintenance work. Some work activities can lead to secondary (bystander) exposure of especially vulnerable groups who would not normally receive direct occupational exposure. These might include children or elderly people, who can be especially susceptible to chemical exposure.

Dangerous substances

Dangerous substances can be found in many different situations, and may not be immediately obvious to the untrained eye. They are found in paints and glues, cleaning fluids, and even foodstuffs (flour dust can cause asthma, for example). Supplied chemicals come with safety data sheets. These describe the potential harmful effects of the substance, and give some information on how to control exposure [4]. However, many harmful substances are process-generated materials. For example, stone dust contains respirable crystalline silica, which can cause irreversible effects on workers lungs, while wood dust can cause asthma. Both of these types of dust can also cause cancer [5][6] and occupational limit values for both substances are determined within the EU directive 2004/37/EC Carcinogens or mutagens at work[3].

Chemicals can enter workers bodies are by breathing them in (inhalation), through the skin (dermal) or by unintentionally swallowing them (ingestion). Controlling exposure to dangerous substances often needs the skills of an occupational hygienist (also known as an industrial hygienist). Many businesses, especially small and medium-sized enterprises (SMEs), will not have this expertise in house and may need to engage the services of a competent contractor to provide occupational hygiene support.

Vulnerable groups

Certain groups of workers may be at increased risk when working with dangerous substances. This may be due to several reasons:

• Increased susceptibility to the effects of chemicals

• Communication difficulties

• Poor working conditions

• Inexperience (coupled with inadequate supervision)

• Workers conducting high risk, non-routine activities

• Service workers exposed to multiple lower level exposures

• Lack of training or experience

• Lack of access to preventive services.

• Working at client's premises with changing conditions

These issues need to be considered at the risk assessment stage wherever such workers are potentially exposed to dangerous substances. Vulnerable groups covered in this article include:

Migrant workers

Young people

• Newly hired workers

Workers with medical conditions

Maintenance workers (including service workers who work a multiple sites) and other workers with constantly changing workplaces

Pregnant and breastfeeding women (this section also deals with other reproductive risks)

The article also contains a brief discussion on secondary exposure, where people not directly involved in the work activity are exposed as a result of coming into contact with dangerous substances from work activity. This can lead to especially vulnerable individuals, including young children and elderly people, being exposed to dangerous substances generated by work activity.

Migrant workers

The ILO [7] lists several issues that are specifically relevant to migrant workers:

• A tendency to work in higher risk sectors such as farming and construction. By their nature, jobs in these sectors will often involve working with dangerous substances, such as pesticides or silica dust, and hence there is increased potential for exposure. The problems for migrant workers in these industries are exacerbated by the transient nature of work, meaning short-term employment contracts and no trade union representation.

• Language barriers, which can significantly hamper communication of written and verbal occupational safety and health (OSH) information. It is often the case that effective use and maintenance of engineering controls and personal protective equipment (PPE) rely on the understanding of how such controls operate. Migrant workers in countries where the language is not their mother tongue may fail to grasp such detail and hence are likely to receive higher exposure to dangerous substances. Pictorial messages may assist effective communication. Similarly, translation of written instructions and information into the workers mother tongue may be necessary to ensure safety critical messages are understood. Regardless of the way in which the communication of health and safety information is conducted, it is important to check that the relevant workers understand the messages. This can be achieved either by informal discussion or by a more structured system of testing. As in all cases, adequate supervision is required to ensure that the information is being used correctly in the workplace.

Cultural issues. Workers moving into more developed countries may be accustomed to different and/or less structured safety and health standards to those applied in the country into which they have migrated. It is important that such workers adopt the higher standards, as failure to do so may result in higher exposure to dangerous substances for themselves and also for other workers with whom they work.

Longer working hours and a tendency to regularly work overtime. When working with dangerous substances, increasing exposure time increases overall exposure, i.e. the ‘dose’ of the substance received. Exposure limits are based on 8-hour workdays. The limits need to be adjusted downwards on a pro-rata basis when longer shifts are worked. For example to ensure that an 8-hour time weighted average exposure is below 3 mg/m3, an exposure of less than 2 mg/m3 is required if a 12-hour day is worked.

Further information can be found in European Agency for Safety and Health at Work European Risk Observatory - Literature Study on Migrant Workers

Young people

Statistics show that young workers (aged 18 to 25) are more likely to be involved in accidents at work. The situation is less clear for ill health, and this is complicated by the fact that many serious health problems caused by work result from long-term exposure over many years or even decades. Specific EU legislation exists to address the special circumstances relevant to workers under 18 years of age. Directive 94/33/EC on the protection of young people at work[8] obliges employers to adopt measures to protect the safety and health of young people, taking particular account of the specific risks which are a consequence of their lack of experience or of the fact that young people have not yet fully matured. The Directive also provides that Member States shall prohibit the employment of young people in case the work involves specific risks such as work involving harmful exposure to agents which are toxic, carcinogenic, cause heritable genetic damage, or harm to the unborn child or which in any other way chronically affect human health. All member states have transposed the directive into national law.

There are various reasons why young people may be at increased risk when working with dangerous substances. The main issues are discussed below:

• Increased susceptibility - data indicate that the prevalence of allergic reactions (such as asthma) and work-related skin disorders are higher among young workers [9]. Due to the effects on the development of the nervous system, it is acknowledged that lead exposure may be especially harmful to young people, and this is reflected in the legislation of certain countries. In the United Kingdom (UK), action levels based on blood lead concentration are prescribed in legislation and are set at lower levels for workers below the age of 18 years.

• Employment in high-risk sectors - young workers are often employed on farms, where they could be exposed to dangerous substances, including microbiological hazards and pesticides. There is also a tendency for young workers to be employed in low skilled manufacturing jobs or the construction sector, where there is the potential for exposure to a range of dangerous substances.

• Lack of awareness of health and safety issues - young people lack practical experience and, in general terms, are acknowledged to take greater risks than older people. This is exacerbated in situations where employers fail in their duty to provide adequate information and training to young workers. It is therefore especially important that young people receive adequate training to allow them to understand the risks associated with their work and how to use the control measures provided by the employer. Key messages may need repeating several times, and a combination of training methods will increase the chances of the information being received and understood. A good safety culture within the organisation, whereby older, more experienced workers set good examples, will greatly support young people in recognising and adopting safe working practices. It is likely that enhanced supervision of young people may be necessary to ensure that the information received is being effectively put into practice [10].

Workers with medical conditions

Certain medical conditions, although not caused by work, mean that individuals with these conditions are more susceptible to the adverse health effects caused by exposure to dangerous substances. The key factors to consider include:

• Pre-existing medical conditions – certain medical conditions render the individual more susceptible to the effects of exposure to dangerous substances. For example, atopic people are more likely to develop respiratory symptoms as a result of inhaling irritant or sensitising materials [11][12][13]. Health surveillance can play a useful part in identifying susceptible individuals and in monitoring whether certain medical conditions are made worse through workplace exposures. Where health surveillance detects a worsening medical condition, it is necessary to review the individual’s occupational exposure patterns and decide on the need for improved exposure control and/or the need to remove the individual from exposure by redeployment.

• Medical conditions resulting from occupational exposure – many substances have the potential to cause sensitisation in exposed individuals. It is most commonly the skin or respiratory system that are affected by such substances. Relevant health conditions include allergic contact dermatitis, asthma and allergic alveolitis. Many naturally occurring substances, containing proteins or microbiological agents, are sensitisers. Sensitisation, which can be irreversible, results in an allergic response, which causes affected individuals to suffer an adverse reaction when exposed to tiny amounts of the sensitising substance. In extreme cases, respiratory sensitisation can be fatal. Accurate diagnosis of sensitisation will require medical expertise. Good exposure control should prevent workers developing sensitisation. However, in situations where workers have become sensitised, it is necessary to prevent further exposure by redeploying the affected individual into a job where there is no potential to encounter the sensitising substance.

• Transient medical conditions – some transient medical conditions, whilst not caused by work, can put affected workers at increased risk whilst they are affected by the condition. For example, workers with damaged skin, including open cuts, are more susceptible to dermal exposure. Chemicals can enter the body through open cuts more quickly than they can through intact skin.

Whilst it is the employers’ duty to control exposure to dangerous substances, individual workers have a responsibility to make their employers aware of any medical conditions which might make them more susceptible to adverse effects resulting from exposure to dangerous substances.

Maintenance workers

Maintenance, of buildings, equipment and machinery, is essential to ensure ongoing safe operation. However, there are health and safety risks associated with maintenance activity and these can include exposure to dangerous substances. This can occur in many situations, for example:

• Chemical industry - breaking into storage tanks, reaction vessels and associated pipe work;

• General manufacturing – working on contaminated plant and machinery;

• Agriculture – working on vehicles which may be heavily contaminated with pesticides or microbiological agents, for example from animal waste or straw/grain dust

• Building maintenance - work can result in the disturbance of dangerous substances, which can include asbestos containing materials [14].

Even in workplaces with a good standard of exposure control, it is usually the case that the engineering controls present are designed to protect workers during routine production activity. Exposure control for maintenance workers is often reliant on safe systems of work. In such situations, as always, workers must be involved in the risk assessment process to ensure that the safe systems of work are practical and usable. Such strategies are highly dependent on effective communication and well-trained workers closely following approved work procedures. PPE should only be considered as the last line of defence for any risk. In terms of maintenance activity, specific consideration should be given to the following points:

• Reliance on PPE - maintenance workers are often highly reliant on PPE for exposure control. Although it is possible to achieve adequate exposure control with these methods, the limitations of PPE must always be considered wherever they are used. Policies should be in place to ensure that PPE is only used within the parameters where it remains effective. Facilities should be provided to decontaminate PPE after maintenance work is complete. Biological monitoring can provide a useful exposure assessment tool to verify the effectiveness of the PPE in these cases.

• Decontamination - the hierarchy of exposure control should be applied to maintenance activity as it is to any work. Machinery and equipment should be decontaminated as far as possible before maintenance work begins. Decontamination methods should not increase exposure potential, for example wet cleaning or filtered vacuum cleaners should be used to remove dust contamination, rather than dry brushing.

• Service workers - workers conducting peripatetic work on several different customer sites can encounter a range of dangerous substances. In these instances, a co-ordinated approach is needed between the employer of the maintenance worker, and the managers of the premises being maintained. Adequate communication of relevant information between these parties, to also include the workers themselves, is of great importance. It may be necessary to support this with supervision of the maintenance activity, to ensure that safe systems of work are followed and that exposure controls are being used correctly.

New workers

There are various issues that make new workers especially susceptible to the risks associated with exposure to dangerous substances. These include:

• Lack of training – new workers should be provided with adequate information on the health risks associated with the substances with which they work. This information should also extend to clear instruction as to what exposure controls are provided, and should provide enough detail to ensure that the controls can be used properly. New workers should be subject to a high level of supervision until it is clear that they understand the requirement of the job including the need to protect themselves from exposure to dangerous substances.

• Increased susceptibility – there is a great deal of variation in individual responses to exposure to dangerous substances. It is possible that new workers may experience symptoms at levels of exposure, which do not cause more established workers any difficulties. Pre-employment medical surveillance, taking into account the substances to which the new worker may be exposed, should reduce the potential for this. Where ongoing health surveillance is identified as necessary by risk assessment, more frequent testing may be necessary for new starters.

Pregnancy, breastfeeding and other reproductive risks

Women who are pregnant and/or breastfeeding may be exposed to dangerous substances in the workplace and special consideration, such as the need to prevent exposure to certain types of substance, is needed for these groups. Women who work with dangerous substances should consider informing employers of their pregnancy at an early stage. Directive 92/85/EEC[15] provides measures to protect the safety and health at work of pregnant workers and workers who have recently given birth or are breastfeeding. The directive obliges employers to assess the risks of chemical, physical and biological agents and industrial processes considered dangerous for the health and safety of pregnant and breastfeeding women.

There are other reproductive risks, including loss of fertility and the potential for genetic damage, which may pass to workers offspring. Some of these apply to males, which may render any worker of reproductive capacity as vulnerable. As with other vulnerable workers, these issues should be considered in the risk assessment for the work.

Pregnancy – some substances carry specific risks to pregnant women or their unborn child. They may cause irreversible harm to the foetus, resulting in birth defects, or they may increase the risk of spontaneous abortion. Studies have shown that exposure to perchloroethylene, a solvent commonly used in dry cleaning, carries an increased risk of spontaneous abortion [16]. Other commonly encountered substances, which can cause harm to the unborn child, include toluene a common solvent, certain anaesthetic gases used in healthcare, and lead compounds.

Breastfeeding mothers - other health hazard phrases are assigned to chemicals, which carry a specific risk to breast fed children. Chlorinated paraffins, used as plasticisers and flame retardants, are examples of such substances.

Other reproductive risks – a number of commonly occurring substances can affect male fertility. These include lead chromate, which is used as a pigment in industrial paints and pthalates, which are in widespread use as plasticisers.

CLP Pictogram Serious Health Hazard
CLP Pictogram Serious Health Hazard

For supplied chemicals, reproductive hazards should be identified on the safety data sheet and on the label (danger, pictogram Serious Health Hazard, H360: May damage fertility or the unborn child). However, for natural substances, and process-generated contaminants, this is not necessarily the case. Again, a comprehensive risk assessment of the process is needed to identify the potential for such substances to be present. See also EU-OSHA’s publication on risks and trends in the safety and health of women at work) [17].

Secondary exposure

There are situations where work activities cause other people not directly employed to be exposed to dangerous substances. This may be a result of airborne releases to the general atmosphere, spills and other leaks, or by individual workers inadvertently transferring contamination outside their workplace. This is undesirable since it unnecessarily increases the number of exposed individuals. Of particular relevance here is the fact that such situations can cause vulnerable individuals to be exposed to dangerous substances.

The wearing of contaminated PPE and other clothing away from the workplace has the potential to spread contamination. If contaminated work clothing is taken home for laundering, there is the potential for exposure of other people living in the home. This may include young children, pregnant women and other vulnerable individuals. This practice should be forbidden. The employer should launder contaminated work wear according to the manufacturer's instructions or provide disposable PPE that should be disposed of appropriately at the end of the working day.

There have been numerous cases of fatal asbestos related cancers in wives and partners of workers who came into regular contact with asbestos, and hence brought contaminated overalls home for washing. Other cases have involved serious illness of worker’s family members due to exposure to highly toxic metals, including beryllium and lead. It is also documented that farm workers regularly transfer pesticide contamination into their homes [18][19][20][21].

In rural areas, people living on or adjacent to farms may be exposed to pesticides. This can occur through a number of mechanisms, including spillages, overspray or spray drift. Again, this can lead to exposure of children, elderly people and other vulnerable individuals [22]. Guidelines exist to prevent such occurrences and those applying pesticides should be aware of these guidelines, and should work within them [23].


The worker groups considered in this article are at increased risk of harm through exposure to dangerous substances as a result of communication difficulties, increased medical susceptibility, or the unusual and infrequent nature of the work they conduct. The considerations outlined in this article should allow the relevant issues to be addressed and should result in reduced risk for workers in these groups.



[1] Directive 98/24/EC of 7 April 1998 on the protection of the health and safety of workers from the risks related to chemical agents at work. Available at:

[2] Directive 2019/1831of 24 October 2019 establishing a fifth list of indicative occupational exposure limit values pursuant to Council Directive 98/24/EC and amending Commission Directive 2000/39/EC. Available at:

[3] Directive 2004/37/EC of 29 April 2004 on the protection of workers from the risks related to exposure to carcinogens or mutagens at work (sixth individual Directive within the meaning of Article 16(1) Directive 89/391/EEC). Available at: [3]

[4] ECHA - European Chemals Agency. Understanding CLP. Available at:

[5] WHO - World Health Organization - International Agency For Research On Cancer, ‘IARC Monographs on the Evaluation of Carcinogenic Risks to Humans’, Vol. 68, Silica. Summary of Data Reported and Evaluation, 1997. Available at:

[6] WHO - World Health Organization - IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 62, Wood Dust and Formaldehyde. Summary of Data Reported and Evaluation, 1997. Available at:

[7] ILO - International Labour Conference, 92nd Session, Report VI. Towards a fair deal for migrant workers in the global economy, Geneva, 2004. Available at:

[8] Directive 94/33/EC of 22 June 1994 on the protection of young people at work. Available at:

[9] EU-OSHA - European Agency for Safety and Health at Work. OSH in figures: Young workers -Facts and figures, 2007. Available at:

[10] EU-OSHA - European Agency for Safety and Health at Work. Young people and safety and health at work. Available at:

[11] Sjostedt, L. & Willers, S., ‘Predisposing factors in laboratory animal allergy: a study of atopy and environmental factors’, American Journal of Industrial Medicine, Vol. 16, 1989, pp. 199-208.

[12] Droste, J., Myny, K. & Van Sprundel, M., Kusters, E., Bulat, P., Braeckman, L., Vermeire, P. & Vanhoorne M., ‘Allergic sensitisation, symptoms, and lung function among bakery workers as compared with a nonexposed work population, Journal of Occupational Environmental Medicine, Vol. 45, 2003, pp. 648-655.

[13] Weill, H, Waddell, L. C. & Ziskind, M., ‘A study of workers exposed to detergent enzymes’, JAMA – The Journal of the American Medical Association, Vol. 26, 1971, pp. 425-433.

[14] Mlynarek, S., Corn, M. & Blake, C., ‘Asbestos exposure of building maintenance personnel’, Regulatory Toxicology and Pharmacology, Vol. 23, Issue 3, 1996, pp. 213–224

[15] Directive 92/85/EEC of 19 October 1992 on the introduction of measures to encourage improvements in the safety and health at work of pregnant workers and workers who have recently given birth or are breastfeeding. Available at:

[16] Doyle, P., Roman, E., Beral, V. & Brookes, M., ‘Spontaneous abortion in dry cleaning workers potentially exposed to perchloroethylene’, Journal of Occupational Environmental Medicine, Vol. 54, No 12, 1997, pp. 848–853

[17] EU-OSHA - European Agency for Safety and Health at Work, Risks and Trends in the Safety and Health of Women at Work, European Risk Observatory. A summary of an Agency report, 2011. Available at:

[18] Knishkowy, B. & Baker, E. L., ‘Transmission of occupational disease to family contacts’, American Journal of Industrial Medicine, Vol. 9, Issue 6, 1986, pp. 543-550

[19] Czachur, M., Stanbury, M., Gerwel, B., Gochfeld, M., Rhoads, G. G. & Wartenberg, D., ‘A pilot study of take-home lead exposure in New Jersey’, American Journal of Industrial Medicine, Vol. 28, Issue 2, 1995, pp. 289-293

[20] Thompson, B., Coronado, G. D., Grossman, J. E., Puschel, K., Solomon, C. C., Islas, I., Curl, C. L., Shirai, J. H., Kissel, J. C. & Fenske, R. A., ‘Pesticide take-home pathway among children of agricultural workers: Study design, methods, and baseline findings’, Journal of Occupational and Environmental Medicine, Vol. 45, No 1, 2003, pp. 42-53

[21] Curl, C. L., Fenske, R. A., Kissel, J. C., Shirai, J. H., Moate, T. F., Griffith, W., Coronado, G. & Thompson, B., ‘Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children’, Environmental Health Perspectives, Vol. 110, No 12, 2002, pp. 787-792

[22] [22] Gladen, B. C., Sandler, D. P., Zahm, S. H., Kamel, F., Rowland, A. S. & Alavanja, M. C., ‘Exposure opportunities of families of farmer pesticide applicators’, American Journal of Industrial Medicine, Vol. 34, Issue 6, 1998, pp. 581-587

[23] FAO - Food and Agriculture Organization of the United Nations, International code of conduct on the distribution and use of pesticides, Rome, 2015. Available at:

Further reading

EU-OSHA - European Agency for Safety and Health at Work, Info sheet: vulnerable workers and dangerous substances.

EU-OSHA - European Agency for Safety and Health at Work, Practical tools and guidance on dangerous substances.

EU-OSHA - European Agency for Safety and Health at Work, Dangerous Substances e-tool.

Roadmap on carcinogens, good practices and fact sheets.

EU-OSHA - European Agency for Safety and Health at Work, Infosheet: Carcinogens at Work.

EU-OSHA - European Agency for Safety and Health at Work European Risk Observatory Literature Study on Migrant Workers.

EU-OSHA - Safe Maintenance – Asbestos in Building Maintenance

EU-OSHA – European Agency for Safety and Health at Work, Protection for young people in the workplace, Facts No 64, 2006.

EU-OSHA – European Agency for Safety and Health at Work, Preventing risks to young workers: policy, programmes and workplace practices

EU-OSHA – European Agency for Safety and Health at Work, ‘Safe maintenance in practice – success factors. Summary of an agency report’, Facts No 96, 2010.

EU-OSHA – European Agency for Safety and Health at Work, New risks and trends in the safety and health of women at work, 2013.

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Karla Van den Broek

Prevent, Belgium
Chris Keen
Health & Safety Laboratory, UK

Richard Graveling