«GUIDING PRINCIPLES FOR THE SAFE HANDLING OF ENZYMES IN DETERGENT MANUFACTURE Version 2 - December 2014 -SUMMARY – ENZYMES Safety task force 1. ...»
GUIDING PRINCIPLES FOR THE SAFE
HANDLING OF ENZYMES IN
Version 2 - December 2014
ENZYMES Safety task force
Enzymes are important constituents of modern detergent products. They are proteins
which catalyse chemical reactions. They break down soils and stains and thus achieve
improved washing performance. The major types of enzymes used are proteases (to remove proteinaceous stains), amylases (for starch removal), lipases (for fat removal) and cellulases (for general cleaning and to remove cotton fuzz).
Enzymes were first introduced into detergent washing powders in the mid-1960s.
Unfortunately the potential adverse health effects of enzymes, particularly the induction of respiratory conditions, including asthma, were not recognized at that time and the enzymes used were in a dusty form, resulting in significant exposure to workers handling them. Within a few years, reports were published indicating many workers handling enzymes had developed respiratory disease symptoms and a few sporadic cases in consumers were also reported. Recognition of these adverse effects led the detergent industry and enzyme manufacturers to take steps to reduce exposure. Major reductions in the dustiness of enzymes, achieved by granulation and changes of product form, the introduction of process and equipment control measures and safe-handling procedures to reduce exposure, and improved monitoring methods led to virtual elimination of occupational respiratory disease due to detergent enzymes. At the present time, such effects are only found when process or equipment controls are inadequate or when failure to comply with recommended safe practice occurs.
A.I.S.E. has produced a document which provides detailed guidance on procedures and equipment recommended to achieve safe handling of enzymes. The present document is a shortened version of the guidance which summarizes the principles which guide the safe use of enzymes in detergent manufacture. Both documents are intended for use by detergent manufacturing facilities and by third-party co-packers. They gain even more additional value in the light of REACH regulation (Registration, Evaluation, Authorisation and Restriction of Chemicals, (EC) No 1907/2006). REACH requires demonstration of adequate control of risks for identified uses and exposure scenarios should be communicated to ensure implementation of risk managements through the supply chain.
The guidance documents support both the enzyme manufacturers/importers as well as the detergent manufactures so that they can meet the REACH obligations managing the adequate control of risks of enzymes.
2. Health hazards The main safety concern associated with enzymes is the potential development of respiratory allergies. When allergens such as enzymes are inhaled in the form of dust or aerosols they may give rise to the formation ofspecific antibodies. This process is called sensitisation and is a response of the immune system to the foreign protein. People who are sensitised do not experience any signs of illness and sensitization does not predict the likelihood of respiratory symptoms occurring. A low number of sensitised individuals may be found in all enzyme handling facilities but past experience in facilities which handle enzymes safely shows that these low incidences are not associated with the presence of individuals with clinical symptoms. However some sensitised people may upon a further exposure to the enzyme develop respiratory allergy with symptoms similar to those of asthma and hay fever. These may be itching and redness of the mucous membranes, watery eyes/nose, sneezing, nasal or sinus congestion, hoarseness or shortness of breath, coughing and tightness of the chest. The symptoms may develop during or after working hours, and will normally disappear within hours or a few days after exposure ceases.
There is no clear scientific evidence that enzymes are skin sensitisers or cause sensitisation by ingestion.
Enzyme preparations containing proteolysis enzymes are capable of causing eye and skin irritation. Other enzymes such as lipases, cellulases and amylases are not likely to cause irritation. Other components of a liquid or encapsulated enzyme may also contribute to skin and eye irritation.
3. Occupational Exposure Guidelines Under new EU legislation (REACH), there is a requirement to define safe conditions of use for a substance for which human exposure is expected. This is based on setting a derived no-effect level (DNEL) for the substance. Where a DNEL cannot be established, e.g. for respiratory sensitizing substances, then a derived minimal effect level (DMEL) is recommended. For the bacterial and fungal enzymes a DMEL of 60 ng/m3 has been proposed and is used in the detergent industry but applies to all industries handling enzymes.
Decades of experience demonstrates that enzymes can be used safely by ensuring that the exposure is strictly limited. Occupationally, a DMEL of 60 ng/m3 provides an excellent starting point for safety assessment, with experience showing that downward adjustment of this value may be necessary to take account of particular circumstances to ensure safe working practice. In the detergent industry it is recognized that co-exposure with surfactants may enhance the allergenic effect of the enzyme.
Occupational Exposure Guidelines (OEGs) for enzymes are established in order to provide guidance on exposure levels which are not associated with clinical symptoms (although a limited degree of sensitisation may occur at these levels). In well-controlled facilities an incidence of 3% new sensitisations amongst its workforce per annum represents a pragmatically acceptable upper limit, and one which is not associated with the generation of clinical symptoms, either in newly sensitized workers or in those that have been sensitized for some time.
There is only one occupational exposure limit established by regulatory agencies for enzymes. This is for Subtilisins (proteolytic enzymes derived from Bacillus subtillis or related species). A limit of 60ng/m³, based on at least one-hour sampling, was set by the ACGIH. This limit has been adopted by several countries.
In addition to the levels set for enzymes, an industry guidance value for the overall detergent dust levels is recommended as 1 mg/m³ to avoid respiratory irritation from the detergent formulation.
4. Management and Supervision
4.1 Responsibilities As with any other workplace activity, employers of those handling detergent enzymes have a responsibility to ensure that the health and safety of their employees is protected. This duty necessitates a full understanding of the potential risks that are present in the workplace and requires arrangements to be put into place to mitigate those risks. The duty of care of employers extends not only to direct employees (line operatives, maintenance staff, engineers, laboratory staff etc) but also to contractors, agency staff, cleaners, visitors and others who may be affected by the activity in question. Each individual employee is also under a legal duty to safeguard their own health, and that of others, by complying fully with safe working practices prescribed by the employer.
Management is responsible for ensuring risk assessments are performed, appropriate risk management procedures are put in place and risks communicated to the workforce (see below). Additionally, they should ensure that suitable equipment is available for safe-handling of enzymes, procedures are in place to minimize exposure of employees and that monitoring and audit systems are in place to check compliance with these procedures.
4.2 Risk assessment Accepted best practice is to conduct a risk assessment on every activity in order to determine what safeguards need to be put in place to ensure safety. This is also a legal requirement for Manufacturers/Importers under the REACH regulation which demands that adequate control of risks be demonstrated and exposure scenarios be communicated to downstream users for all identified uses of substances, if the tonnage is equal to or more than 10 tons per year. Each operation in which an employee (contractor, visitor etc) can potentially come into contact with enzymes should be identified and evaluated for potential exposure (this is often done by a task analysis, i.e. breaking down the process into individual actions). Similarly, the consequences of exposure should be considered in terms of their severity. Exposure to high levels of airborne enzyme may be considered to involve severe consequences (occupational asthma), while skin contact to proteases would result in mild consequences (possible skin irritation) and ingestion would carry negligible consequences.
Combining the probability of exposure to the hazard and the health consequences of exposure to that hazard allows prioritisation of activities into high, medium, low and negligible risks.
4.3 Risk management Having characterised and prioritised the risk involved in a given activity, it is then necessary to use the information generated to manage or control that risk. Those risks identified as high obviously require immediate attention and the greatest degree of control. Risks can be controlled using a well-accepted hierarchy of approaches.
• Eliminate the hazard
• Substitute the hazard by a less hazardous substance Control of exposure
• Isolate the hazard to prevent exposure
• Reduce exposure by engineering means partial enclosure and exhaust ventilation o local exhaust ventilation o general and forced air ventilation o
• Reduce exposure by use of safe procedures and working practices
• Reduce exposure by personal protection (only if other approaches not feasible).
Risk management also involves ensuring that the controls put in place to manage the risk are effective. This will involve inspection of engineering controls, monitoring of airborne levels of enzymes to confirm efficiency, auditing of procedural controls and observation of the behaviour of operatives involved in enzyme handling, but also the health surveillance of potentially exposed employees. The risk assessment will determine the frequency and extent of monitoring and procedures in the event of monitoring results exceeding predetermined action levels.
4.4 Risk Communication Having completed a risk assessment, and established risk management measures, those potentially affected must be informed of the risks and measures taken to control them.
4.5 Training All potentially exposed employees, contractors and other visitors to the site should have appropriate training in the safe handling of enzymes and the risks involved so that the need for compliance with control measures is fully understood. Employees should also be trained in the use of contingency measures so that they know immediately what to do in the event of spills or other incidents. All employees need to be trained for the tasks and responsibilities they undertake.
5. Control of exposure during the handling of enzymes and the manufacture of enzymatic detergents
5.1 Introduction To prevent the exposure of employees to enzymes during the manufacture of detergent products, there is a series of well-established engineering controls and operational procedures that have been developed over many years by the industry.
The key strategies are:
The prevention of dust or aerosol formation by using plant and equipment designed o to minimise damage to enzyme encapsulates, and to minimise the formation of airborne dust or aerosol within the process.
The containment of dust or liquid aerosols at source using closed process o equipment maintained under negative pressure.
The avoidance of routine or uncontrolled spillages.
In broader terms, control of airborne enzyme centres around the following aspects:
General Building/ plant and equipment design via hygienic design principles o Enzyme quality and form (use of low dust encapsulates) o Enzyme supply units (ensuring direct connection of packaging with the process and o safe disposal) Engineering controls for manufacture and packing (isolating, enclosing and o ventilating potential sources of enzyme exposure) Operational, maintenance and emergency procedures o Personal and respiratory protection o
5.2 Enzyme Quality & Form Encapsulated enzyme must be used for the manufacture of detergent powders or tablets.
Encapsulated enzyme must meet a suitable quality specification with respect to the level of free enzyme dust present in the encapsulate or that remains associated with the encapsulated enzyme after the manufacturing process.
5.3 General Building / Plant and Equipment Design Buildings, plant and equipment should be designed as far as is possible to provide an environment that is easy to maintain in terms of hygiene and which minimizes damage to encapsulates in powder plants or which minimizes the generation of aerosols in liquid plants by avoiding splashing.
The interface of employees with the manufacturing plant, and in particular with packing machinery, is a great potential source of personal exposure to dust and enzyme. The design intent should be to eliminate or reduce spillage and to facilitate cleaning with the use of a vacuum tool.
Process and packing equipment design should eliminate external spillage and reduce liquid
• Designing efficient enclosures to contain spillage and liquid splashes within the equipment
• Using internal spill pans/trays to collect and maintain spillage within the equipment
• Designing access doors that can be opened without causing spillage to the floor
• Incorporating product reject positions within the enclosure
• Incorporating proper quality assurance sampling points into plant and equipment.
In addition, process and packing equipment design should minimise the need for internal