Contamination in the pharmaceutical industry - How technical solutions minimize the risk on dedusting systems

In the pharmaceutical industry, the ongoing occurrence of hazardous dusts is inevitable. Containment measures are implemented to reduce the risk of contamination and also ensure increased employee protection. Their objective is to create a protected area for employees and the environment. Dedusting systems that extract, filter and reliably separate the dust, as it is generated, are deployed here. As the extracted dust, however, has not been transported away, but merely from the collection point into the system, the dedusting systems should also be equipped with containment measures.

This article will inform you about the technical measures that can be implemented in the pharmaceutical industry to reduce the risk of contamination and thus ensure greater employee protection.

Technical measures

Operators of production plants have the duty to protect employees from hazards during their daily work. This obligation can be fulfilled by considering technical containment solutions when planning a system.

According to Directive 98/24/EC, the so-called "STOP" principle must be taken into account when selecting possible containment measures:

• Substitution of hazardous substances - Checking if there are substances that are less toxicologic
• Technical measures - Upgrading systems with appropriate safety solutions
• Organizational measures - Planning to ensure that employees are not exposed to dangerous substances for too long
• Personal protective equipment - Using these if all other measures are not applicable

The measures being applied in the pharmaceutical industry are divided into two groups:

Primary containment measures and secondary containment measures.

While primary containment measures directly ensure that no hazardous dusts can escape from the production systems, secondary measures serve to collect particles that nonetheless occur in the production systems or respectively to prevent their spreading.
However, it must be examined individually for each case which containment measures are reasonable. The decisive factor here always is the exposure respectively the hazard caused by the dust being created, as well as the (statutory) regulations that must be observed (such as GMP, HSE).

To determine the risk and thus define the scope of the measures, a risk assessment is mandatory. In it, the hazard level of the respective substance is brought into relation with the exposure (duration of the exposure).

The main target is to identify technical measures by which the employees are optimally protected. Here, useful solutions adapted to each phase of the product life cycle should be aimed for. It is therefore not only necessary to make the production of the product safe, but also to protect the employees during assembly and dismantling or disposal of the production system.

Primary containment - Preventing particles from escaping

The development of hazardous dusts during the production of medication is unavoidable. It is safest for humans and the environment when occurring dusts and released particles of the hazardous substances do not escape from where they develop: Directly at the production system.

To achieve this, there are a variety of technical possibilities, of which some are listed below. Through combination of various options, employee protection can be increased as best possible and user-friendliness improved.

Glove Box, RABS and Isolator

To prevent the spreading of particles, it is possible to encapsulate and enclose the exposure area. Depending on the hazard potential, this can be achieved with the following measures:

• Glove Box - Box with Plexiglas panel and worked-in gloves
• RABS housing (Restricted Access Barrier System) - Housing with integrated air flow
• Isolator - device, where a defined vacuum and extreme high tightness against leakage is possible

Extraction and filter systems

By means of extraction systems, the air with the substances in it is drawn off directly at the point of occurrence and removed from the employee's working area. The extracted air is then filtered and thus cleaned of the hazardous substances. The so-called dedusters have filter inserts that bind the particles to themselves and in this way remove them from the air. The result is clean, uncontaminated air. The occurring substances as well as the quantity of air to be filtered determine the number of filter elements and their filter class (which particle quantities of a certain size are separated from the air).

Secondary containment - Prevention of particle spreading

During maintenance and repair measures or in the event of malfunctions in the production process, it is possible that the containment is broken and hazardous substances can escape.

For such cases, production areas are designed to minimize the risk of further spreading as well as the contamination of employees and adjacent production areas.The choice of options results from the analysis of the workplaces (e.g. material flow, staff routes, etc.) and the risk considerations of the substances that occur.

The following exemplary solutions are available for secondary containment:

Workareas with airlocks

The workplaces can only be reached via decontamination airlocks. Depending on version, separate entrances and exits can be used or the material flow can be separated from the passenger routes. On the one hand, persons and material are cleaned of contaminants that are carried in from outside and thus represent a danger to the production process or product. On the other hand, however, the use of airlocks also prevents substances getting from the inside to the outside and contaminating the adjacent areas.

Workareas with pressure cascades

This involves different air pressures in the individual areas, through which the movement of the particles suspended in the air is controlled.

• Overpressure - is used when no substances may enter the area
• Vacuum - is used when no substances may leave the area.

Clean room solutions

With the clean room concept, the focus is on ensuring that the amount of particles in the air remains limited. Different regulations are applied, all of which aim to reduce contamination or facilitate the cleaning. Regulations apply e.g. for:

• The material properties of the surfaces - As large as possible to keep the number of compounds as low as possible and to simplify cleaning
• The choice of materials - Smooth surfaces
• The design of the ceilings - Tight against leakage, with recessed lighting and ventilation
• The material flow - Contaminated material may not leave the area unless appropriate decontamination or safe packaging takes place.
• The cleaning of the room air - In this case, filtration takes place via intake and exhaust air filters, which are equipped with appropriate filter cells. Similar measures apply as with the technical measures under primary containment:
  • Filter changing must be carried out under certain protective measures.
  • Ventilation and A/C equipment must be checked and maintained regularly with regard to performance. This applies, for example, to the performance of the filter when installed.
  • By means of so-called DEHS tests, the filters are checked for their separation efficiency before being put into operation.

By using the protection bags, it is ensured throughout the entire process that the system remains sealed off and no substances can escape.
To ensure greater safety, the contaminated filter cell can be moistened with water immediately before removal to bind dust and cause adherence to the filter cells. This once more considerably reduces a possible exposure during the filter changing.

Continuous Liner systems

A safe method for changing the dust discharge on a dedusting system is the continuous liner. It consists of a foil hose cartridge. The length of the foil hose is to be dimensioned in such a manner that the discharge can be emptied several times without having to also change the foil hose each time.
The foil hose is closed off at the bottom end so that the material can fall in. After a certain filling height has been reached, the foil hose is securely closed off above the material and then separated. The important thing is that the sealing-off takes place at two locations, and that the foil hose is separated between the closing locations.

Closure systems

The choice of closure systems is determined by the occurring substances. There are simple systems, such as cable ties, which are sufficient for use with less hazardous substances. Since residues of the substances may still be present in the closing locations, the use of special closure systems is recommended for more hazardous substances. These consist of clips that firmly close off or crimp the protection bag and special tools to separate the clips so that no dust can escape.

Cleaning the filter system from the inside

Apart from the already mentioned measures that are applied during operation, there are also various possibilities used in system maintenance and repair. For example, the areas within systems can be washed out or wetted with water prior to opening, in order to bind the dust:

Wash-In-Place (WIP): 

Before opening the system, the surfaces are wetted with water to bind the dust. For a complete cleaning effect, subsequent manual cleaning is required.

Clean-In-Place (CIP): 

With this method, the system's interior is completely cleaned before maintenance or repair work is carried out. For all processes with product contact, the cleaning must be qualified and validated.