Published: 01st Apr 2004
Basics, selection and trends
Wearing hiking boots to play soccer, ballet shoes for rugby or golf shoes for tennis would be unthinkable. For every sport there exists a shoe to prevent the musculoskeletal system of the foot from suffering injuries, wearing out or exhaustion. It is natural to wear a safe and proper sports shoe.
The risks of injuries at work can be similar to those in sport. When it comes to parts of the body, the feet are one of the highest at risk to get injured in professional life, beaten into second place only by our hands.
Feet are affected in about 20% of all accidents at work. Typical injuries are sprains, dislocations, fractures, stab wounds from stepping onto pointed objects and local skin damage (corrosion, dermatitis, allergy) from contact with chemicals. Unfortunately too little emphasis is placed on wearing the right footwear that could prevent these injuries (fig. 1).
Design versions of footwear
Shoes for safety, protection and work are called protective footwear. Because of their special design the shoes are able to protect workers against injuries and hazards. Shoes for safety, protection and work require an EC-type testing according to the EC-Directive 89/686/EEC (council directive for personal protective equipment). Some kinds of protective footwear, e.g. shoes used for isolation against high voltage, require additional production control by a notified body. These products are category III-protective equipment.
EN 344, which will be replaced by EN ISO 20344, determines the basic requirements for protective footwear. The basic requirements are the stability and impermeability of the shoe as well as the abrasion resistance and the fuel resistance of the sole. EN 345, EN 346 and EN 347 are constitutive standards to EN 344. These separate the protective footwear into three different types. The determining factor for the subdivision depends on the different requirements for the toe protection. Safety footwear (code designation S) according to EN 345 has protective toe caps against extraordinary burdens. The protective toe caps have to abide 200 J of test energy. Protective footwear (code designation P) according to EN 346 has protective toe caps against medium burdens.
The test energy is 100 J. Working shoes (code designation O) according to EN 347 do not normally have protective toe caps.
The different design versions of protective footwear are divided into classes depending on their manufacture. Class I includes shoes made of leather or other materials which are joined by common methods. Class II includes shoes which are vulcanised or formed on the whole (e.g. rubber boots or synthetic material boots).
Beyond this classification, safety shoes (S) are divided into several categories. The higher the number following the S, the higher the safety and the requirements:
- SB: SB is the code designation for shoes meeting the basic requirements, type of manufacture: class I or II
- S1: as SB, plus closed heel area, antistatic, energy consumption in the heel area, type of manufacture: class I
- S2: as S1, plus suitable for moist areas, class I
- S3: as S2, plus penetration resistance, corrugated sole, class I
- S4: as S1, class II (e.g. rubber boots)
- S5: as S4, plus penetration resistance, corrugated sole, class II
The manufacturer will be asked for further requirements of the different shoe types. The conditions for safety shoes are also valid for protective shoes (P1 to P5) and working shoes (O1 to O5). Safety, protective and working shoes are offered in different types (A to E) as follows (see also fig. 3):
- Type A: low shoe
- Type B: ankle boot
- Type C: mid-height boot
- Type D: high boot
- Type E: femoral-height boot
To inform the user, the shoes require a marking with its protective functions, e.g. S2, Type B. Additionally the marking has to have the name or the logo/trademark of the manufacturer, the date of manufacture, the size of the shoe and the number of the standard according to which the shoe was tested, as well as the CE-mark. The manufacturer confirms with the CE-mark that his shoes are tested by an accredited laboratory and that they meet the directive. Safety, protective and working shoes from category III have to be additionally marked with the number of the notified body that carries out the product monitoring.
Selection of footwear - who is responsible?
According to the EC-Directive 89/656/EEC the employer is responsible for handing out personal protective equipment in a proper form to the employee. This also includes protective footwear. The employer is beholden to ascertain and judge the hazards in working areas before selection and the use of suitable protective footwear. Checklists as shown in Table 1 may help. The hazard judgement determines what kind of shoe is needed. A list with positive tested shoes is published by the BG-Institute for Occupational Safety and Health. If the employer has made a decision on the protective footwear, then it is necessary that the employees try on these shoes. The willingness to wear protective footwear depends, not only on matters of safety, but on comfort and the individual fit of the shoe. The checklist as shown in Table 2 provides important items to support the right choice. It is the employee's duty to wear the protective footwear and to take care of it. The employees are not allowed to wear worn or damaged footwear. The employer should be informed about possible defects.
Trends of development
Manufacturers of protective footwear are trying constantly to improve their products. This means not just design improvements that motivate the workers to wear protective footwear but also that capacity and safety are permanently being developed. The following two examples demonstrate the multiplicity of developments in the shoe sector. Finally, recent activities of health and safety institutes and pre-normative research about a standard for chemical protective footwear are reported.
Improved joint protection
The Elten company, an established manufacturer of shoes, has developed a protection system to provide increased safety for the ankle called BIOMEX Protection©. Less attention has been given to the prevention of joint damage, such as twisted ankles or injuries caused by stumbling, falling or slipping. The after effects may be overexpansion of the tendons or other injuries of the ankle. The protection system from Elten covers the heel area and the ankle and is a moveable asymmetric cuff made of hard-wearing plastic. The advantage of this technology is the benefit of stability to the ankle. Normal shoes with a high shaft may lose part of their stability because they develop a typical wrinkling in the ankle area through wear and tear. The BIOMEX© system keeps its stability on the basis of the hard plastic shaft and decreases the risk of over-expanded tendons. At the same time the moveable construction with pivots and slotted holes provide a high flexibility of the shaft. The additional substitution of the foot characteristics while walking guarantees a high wearing comfort.
The whole concept of the shoe is biomechanical, aligned with the natural movement of walking. This is shown by the asymmetric axis of the shaft (fig. 5).
Profile control system
Safety, protective and working shoes need a slip resistant sole to prevent slips. This can be done with the right choice of sole material and the profile tread.
A recent research project examined the shoes of casualties working in the butcher industry with consideration to anti-slip properties. It was noticeable that all soles were badly worn. The profile tread was too low. All shoes had severe abrasions and yet were still in use. Because of the abrasions the anti-slip properties had degraded. Safe walking through slippery working areas often becomes impossible. The risk of causing accidents increases. The user is supposed to regularly check the profile of the soles. But how can a busy employee keep tabs on whether his shoes need to be repaired or even replaced?
During flexion the knee moves to the sagital plane of the body. The bevelled Biomex© - axis follows the natural movement. Result: more comfort, less counterpoise, less exhaustion
The Lupos shoe factory offers a patented PCS-system (Profile Control System), a simple solution to monitor the profile height of soles. If the sole becomes worn so that anti-slip properties cannot be guaranteed, three red points appear clearly on different parts of the sole (fig. 6). Simple but effective...
Chemical safe footwear - a new approach
No agreed European procedure currently exists for the evaluation of footwear products for personal protection against chemicals and micro-organisms with respect to their conformity to the PPE Directive 89/686/EC. The absence of such a standard represents a problem for notified bodies, as they are not able to access tests based on generally recognised principles for the certification of such products. At the same time, the manufacturers of chemical-resistant footwear are confronted with a distortion of the market conditions. In order to rectify this situation, a European project has been launched in which the essential requirements for chemical-resistant footwear and the corresponding test procedures were to be drawn up. A further step was to improve an existing draft standard, based upon these requirements and procedures, for the competent standardisation committees under CEN. The involved partners in the project were CTC (France, project leadership), BIA (Germany), CIMAC (Italy), CIOP (Poland), INESCOP (Spain) and SATRA (United Kingdom).
The project consisted of six tasks. Firstly, suitable chemicals and footwear materials had to be selected for testing of chemical resistance of materials (degradation) and chemical permeation resistance as shown in Tables 3 and 4. The second task entailed development of a test method for determining the degradation of materials used in industrial footwear, in terms of effects on their key physical properties. The third task consisted of the development of a test method for assessment of the shoe materials' resistance to chemical permeation (fig. 8A), and the formulation of the test requirements into a standard. The requirements for footwear providing protection against microorganisms were then assessed in the forth task. Standardised information for the use of this PPE was drawn up in the fifth task. The final part of the project involved preparation of a draft presented in CEN/TC 161 "Foot and leg protectors", considering the modifications made to the document currently in progress.
|Acids||Sulphuric Acid (96 ± 2) % Nitric Acid (65 ± 3) % Acetic Acid (99 ± 1) %|
|Basis||Diethylamine Sodium Hydroxide (40 ± 1) % Ammonia Solution (25 ± 1) %|
|Organic Solvents||Dichloromethane Ethyl Acetate Tetrahydrofurane|
|Hydrocarbons||Acetone n-Heptane Toluene|
|Other||Oleic Acid Hydrogen Peroxide (30 ± 1) % V/V Sodium Hypochloride (20 ± 1) %|
Table 3: Tested chemicals and corresponding categories
|Hypalon (Viton)||Neoprene||Split coated leather (Natural rubber)||Polyurethane||Nitrile rubber||PVC|
Table 4: Tested materials
In the course of the project, a procedure was developed for the degradation of shoe materials by chemicals (fig. 7). This encompassed criteria based upon mechanical tests for assessment of degradation. A cell specially developed and optimised for the purpose was employed. A permeation method was successfully adapted from a glove test. All necessary roundrobin tests were performed with selected combinations of materials and chemicals, and enabled the materials to be classified according to their performance. General test conditions for the resistance to sterilisation were laid down, in order to provide an indication of the suitability of protective footwear for protection against micro-organisms.
Following the conclusion of the project, a revised draft standard for "Footwear protecting against chemicals and microorganisms" was presented to the relevant CEN standards committee (CEN/TC 161) with the aid of the results gained. The standard will consist of a set of four different parts:- Part 1: Terminology and test methods Part 2: Footwear protecting against chemical spraying - requirements Part 3: Footwear highly protective against chemicals - requirements Part 4: Footwear protecting against micro-organisms - requirements
References EN 344: Safety, protective and occupational footwear for professional use EN 345: Safety footwear for professional use EN 346: Protective footwear for professional use EN 347: Occupational footwear for professional use PrEN ISO 20344: Personal protective equipment - Test methods for footwear Directive 89/686/EEC Directive 89/656/EEC
Personal Protective Equipment (PPE) - Useful facts in Relation to Directive 89/686/EEC. European Commission - DG III/Industry. Office for Official Publications of the European Communities, Luxembourg (1999)
D. Mewes, N. von der Bank, H. Unger and R. Fendel: Safety, protective and occupational footwear - List of approved products. Sicherheitstechnisches Informations- und Arbeitsblatt 460 210, 44th suppl. XII/03. In: BIA-Handbuch Sicherheit und Gesundheitsschutz am Arbeitsplatz. Published by: Berufsgenossenschaftliches Institut für Arbeitsschutz-BIA. Erich Schmidt Verlag, Bielefeld, loose-leaf edition (in German). Free download from www.sicherer-auftritt.de
J. C. Cannot: Definition of a standard for footwear protecting against chemicals and micro-organisms. Final Technical Report "CHEM SAFE FOOTWEAR", Project N° GRD1-1999-20011, 2003/03/31
Dr. Detlef Mewes has been working for the BIA for 18 years. He is head of the sub-division 'Working Equipment, Tools, Construction Elements', part of the 'Accident Prevention, Product Safety' division. He holds a doctor's degree in mechanical engineering.
Dr. Peter Paszkiewicz has been working for the BIA for 8 years. He is head of the sub-division 'Personal Protective Equipment against Chemical and Biological Hazards', part of the 'Hazardous Substances: Handling - Protective Measures' division. He holds a doctor's degree in physical chemistry. The Berufsgenossenschaftliches Institut für Arbeitsschutz (BIA) is an institute for research and testing of the German Berufsgenossenschaften (BG), the institutions for statutory accident insurance and prevention in Germany. BIA's activities focus primarily on chemical, biological and physical hazards, ergonomics, epidemiology and accident prevention and product safety.
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Published: 01st Apr 2004 in Health and Safety International