The use of hazardous chemicals in the tannery

In this paper the principles of chemical control and risk assessment are discussed. The interaction between industrial activities and the environment has become something of a social and political issue of our time. The information provided is intended to help the tannery plant manager to understand the basis of legislation, to take the necessary measures, and to show him that the application process does not present an unjustifiable risk.

Although this paper contains mostly references to European Union chemical legislation, as laid down in various EU Directives, it is recognized that suppliers and manufacturers must conform primarily to the local equivalent legislation. It is, however, known that the EU Guidelines on classification, packaging, labelling and material safety data sheets are often identical or very similar to national requirements outside Europe.

Introduction

The first systematic description of health hazards associated with workplace exposure to chemicals was given by B Ramazzini¹ at the beginning of the 18th century. He described adverse health effects associated with mining, printing, potting and other industries.

The history and determination of potential worker risks associated with chemicals are very well documented for synthetic dyes because dye fabrication was the starting point of the chemical industry as we know it today. Manufacturing was concentrated in large firms, and these kept excellent records of workers safety.

Synthetic colorants represent a relatively large group of organic chemicals which are used in practically all spheres of our daily life. The aniline dye industry started with Perkin’s² ‘mauveine’ in 1856. It was later shown to be the impurities in aniline that created the desired colour, which was used for many years for textile, paper and leather.

The induction of bladder cancer by certain aromatic amines was first observed in the workplace. Rehn³, a German surgeon, reported bladder cancer arising in workers involved in the manufacture of aromatic amines like benzidine. It was often not so clear if the hazard arose from the substances as such or from their impurities. In the 1950s there was clear evidence that dyestuff workers exposed to benzidine and beta-naphtylamine⁴ showed an increased incidence of bladder cancer. Dye manufacturers immediately started research and replaced benzine dyes within 25 years⁵. Today, only a minority of commercially available dyes need to be classified as harmful according to European Guidelines⁶.

In tanneries we had a similar situation with chromium VI and III. As soon as it was realized that chrome VI entails a high potential risk of cancer it was completely replaced with the less dangerous chrome III. However, there are still hazardous chemicals such as alkalis, acids, or solvents, which must be used in a tannery. Therefore, workers protection must still be considered.

The impact of chemicals on human safety and the environment can only be fully assessed by considering all relevant data. Ensuring the safe use of chemicals involves three steps:

* Hazard assessment

* Risk assessment

* Risk management

A crucial consideration in supporting the workforce, end-users and authorities including the emergency services, is the availability of all relevant data in a readily understandable form, ie material safety data sheets (MSDS). The data supplied must be sufficient for the user to protect human beings and the environment, and include emergency and first aid measures.

Work hazards

A work hazard is something that has the potential to harm the health and safety of people at work.

Examples of hazards are:

* Noise

* Some chemicals (hazardous substances)

* Unguarded machinery

* Working at heights

* Stressful working conditions etc

The employer or the tannery manager is responsible for his workers’ safety. He has the obligation to communicate potentialhazard information to the workers in such a way that they can understand and are able to avoid the hazards in question.

How safe is a tannery? To answer this question it is instructive to consult workplace accident statistics.

It can be concluded that a worker in a tannery is three times safer than in public transport. In addition, the risk to tannery workers of an accident is below the average for the other work places. Nevertheless, the tannery manager must be committed to support a continuing effort to protect human health and the environment.

Principles of chemical control and risk assessment

Where chemicals are concerned, the possibility of risk is ascertained by means of a risk assessment, which is based on knowledge of the potential hazards posed by a chemical. It can be deduced from the basic information given by the suppliers in the MSDS, the literature and own experience regarding:

* Type of hazards – nature of hazards

* Type of work – work of organisation

* Type of workplace – layout and workplace condition

* Type of injury – type of injuries or accident likely to arise

* Frequency and durations – exposure time

* Impact (severity) – effect of an accident

* People’s knowledge – ways to cope with the hazard

Hazard identification:

A risk assessment starts with the identification of potential sources of injury or disease.

Risk assessment:

Anticipation, recognition and evaluation are the basic elements in assessing the risk posed by each hazard in a risk assessment.

Risk management/control:

When hazards have been identified and the risks assessed appropriate control measures should be developed and implemented. Risk management (control) is not an element of a risk assessment. Risk management is the process of preventing and controlling exposure by introduction of safety measures to protect workers and the environment.

There are several ways of risk management and these are often presented as a hierarchy of measures:

Elimination means completely removing the hazard or risk of exposure to the hazard. This is the ideal control solution. An example of elimination is redesigning a work area so that hazardous processes are no longer involved.

Substitution means replacing the hazard by a non-hazardous alternative such as using a non-flammable solvent finishing agent in place of a flammable one.

Engineering control includes modifying tools used and guarding machinery.

Administrative controls entail introducing work practices which reduce risk such as special procedures for dealing with hazardous materials.

Last but not least personal protective equipment such as helmets, safety glasses and hearing protection should be used if necessary. These items, even if fitted properly, may be uncomfortable. Employers must ensure that personal protective equipment:

* Is appropriate for the job

* Fits the operator correctly

* Is cleaned and maintained regularly

Finally, employees must be trained in the proper use of personal protective equipment

Risk management measures can often be most effective when used in combination, rather than separately. For example engineering control of a dosing facility for hazardous chemicals like alkalis or acids, is most effective when used in combination with the administrative controls of specific training and safe operating procedures. The control measures from the top of the hierarchy give better results. Those from the bottom of the list are more difficult to maintain and usually are less effective.

Risk calculation

There are two types of risk assessment

* Pure risk assessment

* Practical value evaluation

Considering that pure risk assessment is not truly feasible today, practical risk evaluation is not an elegant science. Best estimates are used as well as subjective judgment. It is important that those who will be affected by the decisions about risk should be involved in the assessment.

A risk is a function of impact (severity) and degree of probability. A risk-ranking, table 2, is one way of prioritising risks.

When hazards have been identified and the risks assessed an appropriate control procedure should be developed and implemented. The higher the risk-ranking number, the greater the risk. In political and social discussion, impact and probability are justified differently. Impact often receives more attention than probability (see table 28). Hazards with the greatest risk must be controlled first. The aim is to eliminate or minimise risk.

Concept of risk minimisation

This concept is illustrated with reference to toxic substances. Paracelsus (1493-1541)9 made the first risk calculation for poisonous substances by saying: ‘the dose alone makes a substance poisonous.’

As discussed before, the risk of becoming poisoned is an equal function of toxicity (impact) and dose (probability), where the dose is operationally defined as exposure (see figure 1).

The minimal risks are those risks judged to be too small to be of social concern, or too small to justify the use of risk management resources for control. The minimal risk level frequently used by government agencies such as the US Environmental Protection Agency (EPA)¹⁰ is 1 in 1,000,000 or ‘1 in a million’ increased risk of an adverse effect occurring over a 70 year lifetime in a large population. This is often used as exposure limit.

The target minimal risk must be smaller than 1¹¹ (see figure 2).

There are different types of exposure limits as limit values in the ambient air at the workplace. The German MAK Values¹², literally ‘maximum workplace concentrations’, are defined as the maximum concentrations of a chemical substance (gas, vapour, particulate matter) in the workplace air which generally will not cause adverse effects on employees even when repeatedly exposed. As a rule, MAK values are average concentrations for one working shift. The exposure limits are often concluded from animal tests and may differ from country to country as different tests are used.

Another example is the German Consumer Goods Regulation. The second amendment to the 1992 original introduced a prohibition on the production, import and sale of garments and fabrics in Germany dyed with certain azo colorants. The amendment bans the use of certain azo dyes, which cleave carcinogenic amines. There are 20 prohibited amines in total. A detection limit of 30 milligrams per kilogram leather has been established as the acceptable level for the 20 prohibited amines¹³. The limit is ascertained by analytical accuracy and not by a risk limit.

Practical implementation

The European Directives 67/548/EEC (Dangerous Substances Directive) and 88/379/EEC (Dangerous Preparations Directive) including all amendments and adaptations place several obligations upon the suppliers of chemicals. The Council Directive 67/548/EEC includes a list of classified dangerous substances in Annex I. When the European Union issues its periodic adaptations, these adaptations must be implemented¹⁴.

All manufacturers and suppliers within the European Union are obligated to:

* Assess known hazards associated with any chemicals supplied

* Communicate any hazards and appropriate safety advice to the user

* Package and label products suitable for safe usage and transport

* Consider storage, transport and disposal related risks

The object of classification is to identify all the toxicological, physico-chemical and ecotoxicological properties of substances which may constitute a risk during normal handling or use. EU Commission Directive 93/67/EEC of July 20, 1993, has laid down the principles for assessment of risks to humans and the environment of substances notified in accordance with Council Directive 67/548/EEC Product safety information. If the supplier has identified any hazardous properties, the substance or preparation must be labelled to indicate the hazard(s) in order to protect the user, the general public and the environment. The label identifies the hazards which are likely to be faced in the normal handling and use of dangerous substances and preparations.

The most severe hazards are highlighted by symbols taking into account the main potential hazards. In addition, the main hazardous and the other dangerous properties are specified in standard risk phrases, and safety phrases give advice on necessary precautions. Less harmful chemicals are not applied as hazards according EU Guidelines.

The classification is normally presented in the form of an abbreviation representing the category of danger together with the appropriate risk phrase or phrases. However, in some cases (ie substances classified as flammable, sensitising and some substances classified as dangerous for the environment) the risk phrase alone is used. The abbreviation for each of the categories of danger is shown in figure 3.

In addition in countries with legislation governing hazard labelling the local regulation must be followed. Outside Europe they are mostly similar local regulations, and in countries without specific regulations it is highly recommended to use the EU Guidelines or an adequate alternative as a basis for implementing a customary ethic for dealing with chemicals.

(Material) Safety Data Sheets (MSDS)

MSDS are designed to communicate hazard information to the user and public avoiding any risk to the worker and the environment. EU Commission Directive 93/112/EC of December 10, 1993 defines and lays down detailed arrangements for the system of specific information relating to dangerous substances. The MSDS is divided into 16 sections:

1. Chemical product & company infor- mation

2. Composition/information on ingredients

3. Hazards identification

4. First aid measures

5. Fire fighting measures

6. Accidental release measures

7. Handling and storage

8. Exposure controls/personal protection

9. Physical and chemical properties

10. Stability and reactivity

11. Toxicological information

12. Ecological information

13. Disposal considerations

14. Transport information

15. Regulatory information

16. Other information

The information on the MSDS is the summarization of facts from many sources. Training, knowledge, and understanding of the technical data enable the supervisor good judgement to safely deal with occupational exposure to hazards.

The MSDS takes account of all potential hazards which are likely to be faced in the normal handling and use of a dangerous substances or preparation. It is valid for the form in which the product is placed on the market, but not necessarily for any different form in which it may finally be used, eg diluted. Alkaline or acidic substances, for example, are neutralized before discharge, and this changes their properties. A dye can exhaust to 99% but will leave uncoloured standardization agents in the waste float. For these reasons a MSDS cannot be used for calculation of wastewater loads.

Transport information

Alongside the EU Regulations the United Nations has issued guidance on the transport of hazardous goods. Many countries are signatories to these agreements:

* ADR Accord Dangereux Routiers (carriage of dangerous goods by road)

* RID Règlement International concernant le transport des merchandises Dangereuse par chemin de fer (carriage of dangerous goods by train)

* IMO International Maritime Organization

* IATA International Air Transport Authority

For correct transport of dangerous goods by road, train, sea or air the following information must be given:

* UN number (the United Nations substance identification number, according to the lists published by the UN Commission of Experts)

* Proper shipping name

* The correct hazard class

* Packing group, which determines the United Nations packing group

* Susidiary risk

If a product, following the UN classification¹⁵, has been assigned as hazardous or dangerous goods, there is a requirement that the product must be labelled to indicate the hazard(s)or danger. When preparing each package of dangerous goods the shipper must comply with the set of packing requirements appropriate to the type of packaging. The nine classes relate to the type of hazard whereas the packing groups relate to the applicable degree of danger within the class. The nine hazard classes without their divisions are listed below:

1. Explosive

2. Gas

3. Flammable liquid

4. Flammable solid

5. Organic peroxide

6. Toxic

7. Radioactive

8. Corrosive

9. Miscellaneous

Unfortunately the UN label (focus on transport, short exposure time) has a different thrust from that of the EU label (focus use, longer exposure time). For tannery substances the following labels are the most common:

For packing purposes, packing group numbers I, II, or III are assigned to dangerous goods according to the relative degree of danger presented by the substances.

Group I indicates a great degree of danger

Group II indicates a medium degree of danger

Group III indicates a minor degree of danger

The UN specification packing detailed in the packing instruction must meet the performance test requirements of the relevant packing group. If those hazardous products are delivered to the tannery, it is recommended not to change the packing, to keep it in one safe place and to instruct the workers how to deal with it.

Conclusion

This paper presents only a short overview of the important and complex topic: ‘Safe operating procedures with chemicals’. Not all subject matter can be covered in a short paper. Still statistics show that it is safe to work in a tannery. Nevertheless our aim is to prevent accidents before they happen. The main way to achieve this is to reduce and manage the hazards in the workplace. This is one of our most important roles as a supervisor: it is easy to jump to conclusions about the cause of an accident. But a more thorough investigation is likely to be more helpful in preventing future accidents. An understanding of how to interpret a MSDS is the best defence against accidents and injury involving chemicals. It provides information, which helps to minimize a chemical accident. Labels make it easier to understand hazards and to instruct workers. Some MSDS may be more explicit with the information than others, depending on the hazards, knowledge about the substances and suppliers’ policies. However, if you feel that some information is incomplete or is not fully understandable, contact your suppliers for further assistance.