Environmental monitoring risk assessment

Abstract

Environmental Monitoring describes the microbiological testing undertaken in order to detect
changing trends of microbial counts and micro-flora growth within cleanroom or controlled
environments. The results obtained provide information about the physical construction of ...

Full text

INTRODUCTION
Environmental Monitoring describes the microbiological testing under-
taken in order to detect changing trends of microbial counts and micro-
flora growth within cleanroom or controlled environments.The results
obtained provide information about the physical construction of the room,
the performance of the Heating, Ventilation, and Air-Conditioning (HVAC)
system, personnel cleanliness, gowning practices, the equipment, and
cleaning operations.
Over the past decade, environmental monitoring has become more
sophisticated in moving from random sampling, using an imaginary grid
over the room and testing in each grid, to the current focus on risk assess-
ment and the use of risk assessment tools to determine the most appro-
priate methods for environmental monitoring.
This paper explores current trends in the application of risk assessment
to the practice of environmental monitoring by examining the following key
areas:
• Determining the Frequency of Monitoring: Using the concept of
risk assessment to decide how often to monitor different types of
cleanrooms
• Risk Assessment Tools: Applying risk assessment tools to estab-
lish methods for environmental monitoring
• Numerical Approaches: Considering a numerical approach to
assess risk data using a case study of an aseptic filling operation
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Institute of Validation Technology
Environmental
Monitoring
Risk Assessment
By Tim Sandle

The examples used are from a sterile drug manufacturing facility and
focus mostly on aseptic filling; however, the concepts and tools are appli-
cable to the environmental monitoring of other types of manufacturing and
packaging operations.
DETERMINING THE FREQUENCY
OF MONITORING
In developing an adequate environmental monitoring programme, there
should be a balance between using resources efficiently and monitoring at
sufficiently frequent intervals so that a meaningful picture can be obtained.
Sources of guidance with respect to monitoring frequencies are very limit-
ed within Europe, and the monitoring frequencies specified within the
United States Pharmacopoeia (USP) <1116> may not be suitable for all
facilities. Some guidance can be obtained from the International
Organization for Standardization’s (ISO) standards: principally ISO 14644
and ISO 14698. However, these do not always fit with regulatory guidance
documents because they apply to controlled environments across a range
of industries other than pharmaceuticals, where standards can be higher
(Jahnke, 2001).
When establishing an environmental control programme, the frequency
of monitoring different controlled areas can be determined based on ‘criti-
cality factors’ relevant to each specific area.
Criticality Factors
The establishment of a criticality scheme on which to base monitoring
frequencies is designed to target monitoring of critical process steps.
Therefore, the final formulation process would receive more monitoring
than an early manufacturing stage with a relatively closed process.
Using a criticality factor is a means of assigning a monitoring frequency
based on the risk assessment of each critical area. The risk assessment
relates to the potential product impact from any risk. For example, an area
of open processing at an ambient temperature, a long exposure time, and
the presence of water, would constitute a high risk and would attract a
higher risk rating. In contrast, an area of closed processing, in a cold area,
would carry a substantially lower risk and associated risk rating.
Using a range of 1 to 6, with ‘1’ being the most critical and ‘6’ the least
critical, a score of 1 would be assigned to an aseptic filling operation; a
score of 2 to final formulation, a score of 3 to open processing, and so on.
Each user must adapt such a scheme to his or her particular area and
defend it by way of supportable rationale. An example of monitoring fre-
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Environmental Monitoring

quencies under such a
scheme can be seen in
Figure 1
, and an exam-
ple of its application is
seen in
Figure 2
.
Each controlled
area would be evaluat-
ed against set criteria
and, with the use of a
series of guiding ques-
tions, the monitoring
frequency would be
determined. Decision criteria include considerations in two category areas:
areas of higher weighting and areas of higher monitoring frequency.
Examples of these categories follow:
➤Giving Higher Weighting to –
✓‘Dirtier’ activity performed in a room adjacent to a clean activity,
even if the clean activity represents later processing
✓Areas that have a higher level of personnel transit (given that peo-
ple are the main microbiological contamination source). This may
include corridors and changing rooms.
✓Routes of transfer
✓Areas that receive in-coming goods
✓Component preparation activities and sites
✓Duration of activity (such as a lower criticality for a 30-minute
process compared to a six-hour operation)
➤Having Higher Monitoring Frequencies for –
✓Warm or ambient areas as opposed to cold rooms
✓Areas with water or sinks as opposed to dry, ambient areas
✓Open processing or open plant assembly compared to processing
that is open momentarily or to closed processing (where product
risk exposure time is examined)
✓Final formulation, purification, secondary packaging, product
filling, etc.
Once the monitoring frequency for each controlled area is determined, it
should be reviewed at regular intervals.This review may invoke changes to a
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Institute of Validation Technology
Figure 1
Criticality Factors of Monitoring Frequencies
Criticality Factor Frequency of Monitoring
1 Daily or Each Batch
2 Weekly
3 Fortnightly or Bi-weekly
4 Monthly
5 Three-monthly or Quarterly
6 Six-monthly or Semi-annually

room’s status, and hence, its monitoring frequency, or to changes for different
sample types within the room. For example, it may be that after reviewing
data for one year, surface samples produce higher results than air samples
for a series of rooms. In this event, the microbiologist may opt to vary the fre-
quency of monitoring and take surface samples more often than air samples.
There would also be an increased focus on cleaning and disinfection prac-
tices, and their frequencies, based on such data (Sandle, 2004b).
When both types of monitoring are producing low level counts, the bal-
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Environmental Monitoring
Environmental
Criticality Factor
1
2
3
4
5
6
Likelihood of
Environmental
Impact on
Finished Product
Highly Likely
Likely
Moderately Likely
Unlikely
Very Unlikely
High Unlikely
Definition
Aseptic filling where no further
processing takes place. Here the
risk of contamination would have
a considerable product impact
because contaminants could not
be reduced or removed by
further processing.
Area of final formulation. This
may apply to an area where the
final process is a sterilizing
grade filter.
Direct or indirect exposure of
the product to the environment
is somewhat likely to introduce
contaminants.
This may also apply to an area
that is at ambient temperature
and where there is a high water
presence.
This may apply to cold areas
where little or no open processing
takes place.
Indirect exposure to the environment
is highly unlikely to introduce
contaminates that could affect the
finished product. If a contaminant
were to be introduced, sufficient
downstream controls and/or the use
of preservative agents are highly
likely to remove and significantly
reduce contaminants.
An area that is uncontrolled or
where microbial contamination is
very unlikely, such as a freezer.
Monitoring Frequency
Daily or Each Batch
Weekly
Fortnightly or Bi-Weekly
Monthly
Every 3 Months or Quarterly
Every 6 Months
or Semi-annually
Figure 2
Application of Criticality Factors

ance of risk would be toward air samples. This is because air samples are
direct indicators of the quality of the process and assign a level of control to
the process, whereas surface samples are indicators of cleaning and disin-
fection. If the results of surface samples are generally satisfactory, as indi-
cated by trend analysis, then either the number of samples or the frequen-
cy at which they are taken can be reduced. If subsequent data showed an
increase in counts, the monitoring frequency could easily be restored.
Indeed, all types of monitoring frequencies may increase as part of an
investigation, as appropriate. Therefore, the criticality factor approach not
only sets the requirement for a room, it can also be used to vary the sam-
ple types within a room (Ljungqvist and Reinmuller, 1996).
RISK ASSESSMENT TOOLS
Once the status for each room has been selected, a risk assessment
procedure is required to determine locations for environmental monitoring.
Such risk-based approaches are recommended in ISO 14698 and regulato-
ry authorities are increasingly asking drug manufacturers about this subject.
Risk-based approaches include Failure Mode and Effects Analysis
(FMEA), Fault Tree Analysis (FTA), and Hazard Analysis and Critical
Control Points (HACCP), all of which employ a scoring approach. (Other
approaches include: Failure Mode, Effects, and Criticality Analysis
(FMECA); Hazard Operability Analysis (HAZOP); Quantitative
Microbiological Risk Assessment (QMRA); Modular Process Risk Model
(MPRM); System Risk Analysis (SRA); Method for Limitation of Risks; and
Risk Profiling.)
At present, no definitive method exists, and the various approaches dif-
fer in their process and in the degree of complexity involved. However, the
two most commonly used methods appear to be HACCP, which originated
in the food industry, and FMEA, which was developed for the engineering
industry (Whyte and Eaton, 2004a).
These various analytical tools are similar in that they involve:
• Constructing diagrams of work flows
• Pin-pointing areas of greatest risk
• Examining potential sources of contamination
• Deciding on the most appropriate sample methods
• Helping to establish alert and action levels
• Taking into account changes to the work process and seasonal
activities
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These risk assessment approaches are not only concerned with
selecting environmental monitoring locations. They integrate the environ-
mental monitoring system with a complete review of operations within the
cleanroom to ensure those facilities, operations, and practices are also
satisfactory. The approaches recognise a risk, rate the level of the risk,
and then set out a plan to minimise, control, and monitor the risk. The
monitoring of the risk will help to determine the frequency, locations for,
and level of environmental monitoring (for example, refer to an article by
Sandle [2003a], for a more detailed example).
This paper explores an example from three different techniques:
• A simple conceptualisation of risk using a table
• HACCP
• FMEA
Tabular Approach
An example using a simple table for analyzing risk in environmental
monitoring situations appears in
Figure 3
.
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Environmental Monitoring
Area or Equipment: Sterility Testing Isolator
Risk: Contamination due to build-up of microbial counts in the isolator environment
Failure or Situation: Failure to adequately clean after use
Effect
• When isolators are not
cleaned regularly, there
is a possibility of
micro-organisms
remaining in the
environment.
Minimising the Risk
(Mitigations to Reduce Risk)
• Cleaning surfaces using water to
remove dirt or spillages prior to the
application of a suitable disinfectant.
• The disinfectant used must have
a wide spectrum of efficacy, but
not be aggressive to the isolator
material.
• The isolator should be designed
so that it is easy to clean.
Monitoring
• An environmental monitoring
programme (using settle plates,
air samples, contact plates, swabs,
or finger plates) will show the areas
of greatest risk. This data should be
examined for trends.
• For out-of-limits environmental
monitoring results, appropriate
Corrective and Preventive Actions
(CAPA) should be put in place.
Figure 3
Tabular Approach to Risk Assessment

HACCP
➤The seven principles behind constructing an HACCP analysis consist of:
1. Identifying hazards or contamination risks and assessing their
severity
2. Determining Critical Control Points (CCPs)
3. Establishing critical limits
4. Establishing a system to monitor and control CCPs
5. Establishing corrective action when a CCP is not under control
6. Establishing procedures for verification to confirm that the
HACCP system is working effectively
7. Establishing documentation and reporting systems for all proce-
dures
Each of these seven key points is a vital step in developing the risk
assessment.
➤
The seven points include:
1. Construct a risk diagram, or diagrams, to identify sources of contami-
nation. Diagrams should show sources and routes of contamination.
Examples include:
✓Areas adjacent to Cleanroom or Isolator (e.g.: airlocks, chang-
ing rooms)
✓Air supply and Room air
✓Surfaces
✓People
✓Machines and Equipment
2. Assess the importance of these sources and determine whether
or not they are hazards that should be controlled.
Examples include:
✓Amounts of contamination on, or in, the source that is avail-
able for transfer
✓Ease by which the contamination is dispersed or transferred
✓Proximity of the source to the critical point where the product
is exposed
✓Ease with which the contamination can pass through the
control method
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The use of a scoring method can greatly help in assessing the
relative importance of these contamination sources.
3. Identify the methods that can be used to control these hazards.
For example:
✓Air Supply: High Efficiency Particulate Air (HEPA) filters
✓Dirty Areas adjacent to Cleanroom or
Isolator: differential pressures, airflow movement
✓Room Air: air change rates, use of barriers
✓Surfaces: sterilisation, effectiveness of cleaning and
disinfection procedures
✓People: cleanroom clothing and gloves, room ventilation,
training
✓Machines and Equipment: sterilisation, effectiveness of
cleaning, exhaust systems
4. Determine valid sampling methods to monitor either the hazards
or their control methods or both.
For example:
✓HEPA filter integrity tests
✓Air supply velocity, air change rates
✓Room pressure differentials
✓Particle counts
✓Air samplers, settle plates, contact plates, etc.
5. Establish a monitoring schedule with ‘alert’ and ‘action’ levels
and the corrective measures to be taken when these levels
are exceeded.
For example:
✓The greater the hazard, the greater the amount of monitoring
required
✓Trend analysis for alert and action levels, in or out of control
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6. Verify that the contamination control system is working effectively
by reviewing key targets like product rejection rate, sampling
results, control methods, and so on. These may require modifica-
tion over time.
For example:
✓System for data review
✓Examine filling trials
✓Audits
✓Reassess - hazards, effectiveness of control systems, frequency
of monitoring, appropriateness of alert and action levels
7. Establish and maintain documentation.
For example:
✓Describe the steps being taken
✓Describe the monitoring procedures
✓Describe the reporting and review procedures
Before implementing HACCP, it is important to train all staff involved in
the process and to use a multi-disciplinary team. For example, the team
may be comprised of personnel from Production, Engineering, Quality
Control (QC), Quality Assurance (QA), Validation, and so on.
FMEA
FMEA schemes vary in their approach, scoring, and categorisation. All
methods share a numerical approach. The example presented here,
based on a sterility testing isolator, assigns a score (from 1 to 5) to each
of the following categories:
➤Severity
➤Occurrence
➤Detection
Where:
✓Severity is the consequence of a failure
✓Occurrence is the likelihood of the failure happening based on
past experience
✓Detection is based on the monitoring systems in place and on
how likely a failure can be detected
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By asking a series of questions, each main part of the cleanroom or
isolator system can be grouped or classified into key parts.
Such questions include:
✓What is the function of the equipment? What are its perform-
ance requirements?
✓How can it fail to fulfil these functions?
✓What can cause each failure?
✓What happens when each failure occurs?
✓How much does each failure matter? What are its conse-
quences?
✓What can be done to predict or prevent each failure?
✓What should be done if a suitable proactive task cannot be
found?
The scoring is 1 (very good) to 5 (very bad). Therefore, a likelihood of
high severity would be rated 5; high occurrence rated 5; but a good detec-
tion system would be rated 1.
Using these criteria, a final FMEA score is produced from:
Severity score
x
Occurrence score
x
Detection score
Decisions on further action will depend upon the score produced.
There is no published guidance on what the score that dictates some form
of action should be. However, 27 is the suggested score for the cut-off
value at which action is required. This is based on 27 being the score
derived when the mid-score is applied to all three categories (i.e., the
numerical value '3' for severity 3 x occurrence 3 x detection 3) and the
supposition that if the mid-rating (or a higher number) is scored for all
three categories, then at a minimum, the system should be examined in
greater detail.
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Environmental Monitoring

Figure 4
Isolator Operation Example
An example of one area of an isolator operation, and the risks associated with the
room in which the isolator is housed, is examined below.
Description of the Critical Area:
The isolator is situated in an unclassified
room. There is no requirement to place a sterility testing isolator in a classified room.
FMEA Schematic:
FMEA score: 3 x 1 x 1 = 3
Analysis:
There is no problem to be considered from the room environment
described. Entry to the room is controlled; the sanitisation cycle has been challenged
with a level of micro-organisms far greater than would ever be found in the environ-
ment (spores of Geobacillus stearothermophilus); all items entering the isolator are
sanitised (using a chlorine dioxide-based sporicidal disinfectant); and the isolator itself
is an effective, positive pressure barrier to the outside (at >15 pascals).
As detailed earlier, environmental monitoring is performed inside the isolator during
testing. This monitoring, which has an action level of 1 CFU (Colony Forming Unit), is
designed to detect any potential contamination inside the isolator environment.
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Process Step
Loading isolators
pre-sanitisation,
performing sterility
testing
Failure Mode
That contamination from the
room could enter transfer or
main isolators
Significance
of Failure
Reduced efficiency of
transfer isolator
sanitisation, contamination
inside main isolator
Severity of
Consequence
(score)
3
Measures to
Detect Failure
Would be shown from
reduced evaporation rate
for isolator sanitisation,
poor environmental
monitoring results in
main isolator, potential
sterility test failures.
Sanitisation cycle has
been validated using
biological indicators
of 106 spores.
Occurrence (score)
1
Detection Systems
Isolator room is monitored
monthly for viables
and particles, staff wear
over-shoes on entry, Dycem
mat in place, entry to room
has controlled
access, environmental
monitoring performed
inside main isolator.
Isolators are at positive
pressure to the
room, and air is
HEPA filtered.
Detection
(score)
1

NUMERICAL APPROACHES
A third component of the risk assessment approach is to evaluate a
risk once an activity has taken place. Then, by using a largely numerically-
driven set of tools, repeatability and reproducibility can be ensured.
Examples of individual out-of-limits results and data-sets relating to an
operation are examined below using examples from an aseptic filling
process. Following this, an example of an overall assessment of different
processes over time is explored. Numerical approaches are useful in
applying a level of consistency between one decision and another.
Individual Assessments
The section below details some methods that can be used to quantify
the risk of contamination in pharmaceutical cleanrooms. The models out-
lined are based on the work performed by Whyte and Eaton (2003a and b).
➤
Estimating the Risk to Product Using Settle Plate Counts
The method applies to the assessment of settle plates at the point-
of-fill, under the Grade A zone. It allows an estimate of the proba-
ble contamination rate to the product as derived from the following
equation:
Contamination rate (%) =
Settle plate count x
Area of product x
Area of petri dish
Time product exposed x 100
Time settle plates exposed
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The fixed value is the area of the petri dish, which for a 90mm plate,
is 64 cm2.
➤Settle Plate Count Worked Example:
✓Area of petri dish = 64 cm2
✓Settle plate count = 1 cfu
✓Neck area of product = 1 cm2
✓Exposure time of product = 1 minute
✓Exposure time of settle plate = 240 minutes
By inserting these example values into the equation:
1 x 1 x 1 = 0.000065 x 100 = 0.0065%
64 240
The formula can also be applied to the monitoring of product filtration
activities when ‘1’ is entered as a constant for neck area of product.
There is no available guide as to what percentage constitutes which
level of risk. The 0.03% figure has been used by some practitioners. This
is based on the Parenteral Drug Association Survey of Aseptic Filling
Practices (2002), where it is common in the pharmaceutical industry to
allow 0.03% of broth bottles in a media simulation trial to exhibit growth at
a ‘warning level’ (where 0.03% = 1/3,000, with 3,000 being the average
size of a media fill). An ‘action level’ is often set as 3/3,000 bottles or 0.1%.
This would constitute a high risk. Logically, the range between 0.03 and
0.1 would be a medium risk (Whyte and Eaton, 2004c).
Therefore, where the ‘risk’ is that of micro-organisms detected on a set-
tle plate, with a probability of <0.1% depositing in the neck of a bottle
when bottles are exposed in a unidirectional air flow, risk categories would
be as shown in
Figure 5
.
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Figure 5
Micro-Organism Risk Categories
Percentage Risk
<0.03% Low
>0.03 – 0.09% Medium
≥0.1% High

➤Finger Plate Assessment
The formula can readily be applied to operations that relate to Grade A
operations, for example: filtration connection, vessel to filling machine con-
nection, the filling activity, and loading a freeze-dryer. Where the operator
is only present in the Grade B room and has no impact on the Grade A
operation, this is automatically considered to be low risk if there are no
other special factors. (Low risk does not imply lack of action or assess-
ment. However, it aims conceptualisation of the result in terms of probable
risk to the batch.)
The following formula can be used:
Microbial count x Location x Method of intervention x Duration of operation
Where:
In this example of a finger plate assessment, the location, activities,
and duration require weighting. Examples of logic that apply to the rating
of the location, activities, and duration categories can be seen in
Figures
6, 7, and 8
, respectively
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Environmental Monitoring
Microbial Count = Count in cfu for the plate
Location = Area of the filling machine, or
other location to which the
plate relates
Activity = Whether the hand directly
touched part of the filling
machine or if utensils were
used
Duration = Length of the activity
in seconds

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Figure 6
Weighting Location Example
Location
General part of machine
not close to filling zone
Off-load
On-load
Stopper bowl
Freeze-dryer loading
Point-of-fill: air sample
placement
Filtration transfer
Machine connection
Point-of-fill:
intervention
Rating*
0.5
0.5
1.0
1.5
1.5
2.0
2.0
2.5
2.5
Reason
Data from air flow patterns suggests very low risk of contamination
movement into the unidirectional air stream over the filling zone
Off-load areas are present for all filling machines. The bottles and
vials are partially stoppered and utensils are normally used. The
likelihood of contamination is considered to be low.
On-load areas are present for all filling machines. The bottles and
vials are not stoppered, although utensils are normally used. The
likelihood of contamination is higher than for off-load.
Stopper bowls are present for filling machines. A direct intervention
into the bowl could result in micro-organisms being deposited onto
stoppers. The risk of this is considered higher than the risk with
on-load or off-load activities, although such an intervention is rare.
This is a direct intervention Grade A activity. However, vials and
bottles are partially stoppered and are contained with cassettes.
The placement of an air sampler does not involve the touching of
any filling equipment (such as needles, balances etc.). However, as
a direct intervention into the Grade A zone, it is a higher risk than
those parts of the filling machine previously examined.
The connection of a vessel for the purpose of transferring a product
into the Aseptic Filling Suite requires human intervention and aseptic
technique. If this process becomes contaminated, this could affect the
product. The time taken to perform the connection is normally very
short (under 30 seconds), which reduces the risk.
The connection of a vessel to the filling machine requires human
intervention and aseptic technique. If the transfer line is contaminated,
this could cause contamination to the product.
A direct intervention, where for example, filling needles are re-adjusted,
is the highest risk rating. Counts associated with such activities require
detailed examination.
Figure 7
Weighting Activities Example
Activity Method
Using forceps
Hand
Rating
0.5
1.0
Reason
The operative does not directly touch the machine and the
utensils used are sterile.
The operative directly touches the machine, thereby creating
a greater risk. However, it is procedure to sanitise hands prior
to undertaking the operation.
* Based on the average time taken for media simulation trials, based on data from a
UK pharmaceutical facility.

➤ Finger Plate Assessment Worked Example
A finger plate with a count of 1 cfu for an activity at point-of-fill, using
forceps, that lasts for one minute.
Microbial count x Location x Method of intervention x Duration of operation
1 x 2.5 x 0.5 x 1 = 1.25
The score produced would be rated
according to standard risk assessment
categories:
These risk ratings are based, in part, on
the worked example. Based on historical data
over the past six-months, the highest record
example of a Grade A intervention finger plate is a count of 2 cfu: using
forceps to retrieve a fallen vial and lasting for more than 120 seconds. This
would have given a score of 7.5, which falls within the medium risk cate-
gory.The user should develop a scheme that fits his or her facility (Whyte
and Eaton, 2004b).
➤Surface Sample Assessment
The following formula can be applied to filling and filtration activities:
Microbial count x Risk Factor A x Risk Factor B x Risk Factor C
Where:
Risk Factor A = Proximity to critical area
Risk Factor B = Ease of dispersion of micro-organisms
Risk Factor C = Effectiveness of control measure
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Environmental Monitoring
Score
1 - 3
4 - 8
9+
Risk
Low
Medium
High
Figure 8
Weighting Duration Example
Duration
Less than 30 seconds
30 seconds - 120 seconds
Plus 120 seconds
Rating
0.5
1.0
1.5
Reason
The length of the intervention is considered minimal.
The intervention is at the average* time taken.
The intervention has taken longer than average*.

Samples are taken using contact plates and swabs and are all
post-operation.
✓The following approach can be used in setting the risk factors:
» The first step is to assign the risk (A) factor based on proximity of
location to the critical area (filled product). The logic demonstrated
in
Figure 9
may be used to determine risk factor A.
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Manufacturing
Stage/ Location
Filtration room
product contact
General filling room
or filtration room area
(Grade B)
Machine general
(non-product contact)
Machine product
contact site
Risk Factor
(A)
2.0
0.5
1.0
2.5
Reason
Samples of the transfer line may indicate potential for
contamination to affect product.
The samples reflect room cleanliness and general trends only.
The impact upon the Grade A activity is low - unless the same
micro-organism has been detected from a Grade B action level
sample. In this event, the risk factor increases to 1.
Samples indicate state of general machine cleanliness but,
the risk of exposure of product to contaminant is low - unless
the same micro-organism has been detected from a Grade B
action level sample. In this event, the risk factor increases to 2.5.
Sites include utensils, filling needles, and stopper bowls.
Direct contact with product: highest risk.
Figure 9
Determining Risk Factor A
» The second step is to assign a risk factor (B) based on ease of
dispersion or transfer of micro-organisms. See
Figure 10
for an
example of the reasoning that would support Risk Factor B.

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Environmental Monitoring
Figure 10
Determining Risk Factor B
Manufacturing
Stage/ Location
Filtration room
product contact
General filling room or
filtration room area
(Grade B)
Machine general
(non-product contact)
Machine product
contact site
Risk Factor
(B)
0.5
1.0
1.5
2.5
Reason
Connection is a short activity (less than thirty seconds)
performed under Grade A Uni-Directional Air Flow (UDAF)
protection; operator wears sanitised gloves.
Periphery to the Grade A zone. Risk of transfer is low.
Risk rating would increase to 1.5 if a Grade A and a Grade B
sample exceeded action level and was characterised as the
same microbial species.
Location is within the critical area, but not directly in product
contact area. Some risk of transfer exists, but protective
measures should prevent this.
Sites include utensils, filling needles, and stopper bowls that
are directly within the critical zone. Direct contact with
product: highest risk.
» The third step is to weight the risk factor ‘C’ by assessing the
effectiveness of the control measure. See
Figure 11
for an
example of this assessment.
Figure 11
Determining Risk Factor C
Manufacturing
Stage/ Location
Filtration room
product contact
General filling room
or filtration room area
(Grade B)
Machine general
(non-product contact)
Machine product
contact site
Risk Factor
(C)
0.5
0.5
1.0
1.5
Reason
Grade A UDAF and sterilised components;
operator wears two pairs of gloves and sanitises hands.
Floor is sanitised. Barrier exists by way of filling
machine doors and UDAF.
Sterilised machine components; lines are wiped with
disinfectants; UDAF protection.
Sterilised machine components; no direct intervention; UDAF
protection; however, site is in direct contact with product.

➤ Surface Sample Worked Example:
Where a count of 2 is detected from a conveyor belt (a filling
machine non-product contact location)
Using the formula:
Microbial count x Risk Factor A x Risk Factor B x Risk Factor C
2 x 1 x 1.5 x 1 = 3
Risks can be scored
against standard risk
assessment categories:
This scoring scheme is based on contamination of a product contact
site being high risk by virtue of its direct proximity to the critical area or the
product.
A count of 1 cfu on one of these product contact site locations would
give a score of 9.4. In most filling zones and clean zones, sample results
from product contact sites would be expected to record zero counts for
999 samples out of every 1000. Whereas, a count of 3 from a non-product
contact site would result in a medium risk category.
➤Air Sample Assessment
Approaches are available for the risk assessment of active air samples
that use a numerical system. However, the formulae associated with these
are difficult to calculate in practice because often all information is not
available and assessment of variables, such as impaction speed, are not
readily calculable. Therefore, a qualitative assessment, such as the one
included in the example of the numerical approach, may be more suitable.
An example of the numerical approach:
Airborne microbial count (cfu /m3) x deposition velocity of micro-
organisms from air (cm/s) x area of product exposed (cm2) x time
of exposure (s)
Alternatively, non-numerical risk assessment can be used based on
the proximity and the operation. See
Figure 12
for this example.
Tim Sandle
22
Institute of Validation Technology
Score
1 - 3
4 - 8
9+
Risk
Low
Medium
High

➤Assigning a Risk Factor to Areas of the Filling Room
The location where a high bio-burden is isolated within the filling area
is arguably of greater consequence than the actual count. The location
can be given a risk rating in relation to its proximity to the critical zone,
ease of dispersion or transfer, and effectiveness of control methods.
The table shown in
Figure 13
is proposed as a tool for risk assess-
ment and to aid investigations. It supplements the risk assessment tools
that have been previously examined.
Tim Sandle
23
Environmental Monitoring
Figure 12
Non-Numerical Risk Assessment Example
Activity, Area,
Proximity
General room
environment during
filling or filtration,
away from Grade A zone
Grade A, near critical
zone
Grade A point-of-fill at
critical zone
Risk
Low
Medium
High
Reason
Provided there are no Grade A interventions and there are
no counts recorded at Grade A, where counts are recorded
at Grade A and there is a micro-organism match, then the
category is re-defined as medium risk
Close, but not at the point-of-fill
At point-of-fill
Note:
Where growth is detected on the operator who placed the
air sampler at Grade A, and this is shown to be the same
micro-organism, the category of risk is increased by one
(i.e.: low becomes medium and medium becomes high).
Figure 13
Filling Room Risk Assessment Example
Ease of Dispersion
or Transfer of
Micro-organisms
None
Very low, e.g.: fixed place
on sterilised area
Medium, e.g.: product
contact device
High, e.g.: gloved hands
of operators with direct
contact with product
Proximity or Location
of Source from
Critical Area
None
Low, e.g.: at extreme limit
of room away from filling zone
Medium, e.g.: general
area of cleanroom near
filling machine or at edges
of Grade A zone
High, e.g.: within the critical area
Effectiveness of
Control Method
None
Low, e.g.: barrier control; UDAF
Medium, e.g.: sanitisation
High, e.g.: no effective controls

The type of product and whether further processing occurs can also
influence the risk factors. See Figure 14 for an example. In considering
batches with a high risk rating, further processing of the product can be
considered and ranked (1 = lowest risk, 4 = highest risk).
An Overall Assessment
The approach taken for an overall assessment involves the historical
examination of a number of operations and assigning a value above which
the operation is considered to be atypical. A 95% cut-off is considered to
be the most suitable cut-off point.
CRITICALITY SCORING
Criticality scoring is a way of assessing the totality of results from an
environmental monitoring session. This may be, for example, a batch fill.
The data from the session is examined and points are awarded for each
result above a pre-set warning or action level. The total score is then
summed and the results obtained are compared to a set level at which
atypical sessions are indicated.
The pre-set level would be assessed from historical data over a
reasonable time period (such as one year). An example of such a
scheme follows:
For Grade A
The results from a filling operation are examined (for individual viable
counts and for the mean particle counts taken during the fill). Each result,
which equals or exceeds a warning or action level, is scored according to
Tim Sandle
24
Institute of Validation Technology
Figure 14
Product-related Risk Assessment Factors
Product
Freeze-dried
Liquid product, heat treated
Intra-muscular product
Intravenous product,
no further treatment
Rank
1
2
3
4
Reason
Freeze-drying will destroy most micro-organisms
Undergoes pasteurisation - effective against most non spore-forming
micro-organisms
Small volume; intra-muscular route
Intravenous route; no further processing

the criteria in
Figure 15
and
Figure 16
. Using the criteria presented in
Figures 15
and
16
produces the Grade A score.
For Grade B
The results from a filling operation are examined (for the individual
viable counts and the mean particle counts taken during the fill). Each
result that equals or exceeds a warning level is scored according to the
criteria in Figure 17 and Figure 18.
Tim Sandle
25
Environmental Monitoring
Figure 15
Viable Counts Criteria for Grade A
Sample
Active Air Sample
Settle Plate
Contact Plate
Swab
Finger Plate
Warning Level
5 points
5 points
5 points
5 points
5 points
Action Level
10 points
10 points
10 points
10 points
10 points
Count (cfu)
Figure 16
Particle Count Criteria for Grade A
Particle Size
0.5 µm
5.0 µm
Mean Counts from fill
at Warning Level
5 points
5 points
Mean Counts from fill
at Action Level
10 points
10 points
Count (cfu)
Figure 17
Viable Counts Criteria for Grade B
Sample
Active Air Sample
Settle Plate
Contact Plate
Swab
Finger Plate
1 cfu
1 point
1 point
1 point
1 point
1 point
Count
2-3 cfu
2 points
2 points
2 points
2 points
2 points
4-5 cfu
3 points
3 points
3 points
3 points
3 points
Warning Level
3 points
3 points
3 points
3 points
3 points
Action Level
5 points
5 points
5 points
5 points
5 points

If a warning level or action level is of the same count (cfu) as a value in
the count (cfu) column, the warning or action level score should be select-
ed. This produces the Grade B score. To produce the total criticality score,
the two scores are added together (Grade A + Grade B).
Once the data has been generated, the score at which approximately
95% of the fills would be below (and 5% would be above) can be calculat-
ed. That figure would then be used as the cut-off value with which to
assess the ‘atypical’ filling operations.
Figure 19
displays a simple representation of this assessment. For the
data set, the criticality score was calculated at 25, which corresponded
with the 95th percentile for a set of data from the filling of an example
drug.
The graph in
Figure 19
indicates that some fills exceeded the cut-off
criticality value during a particular time period (see fill numbers 12 through
15). After some corrective action, the scores for the fills were reduced (see
fill numbers 16 through 29) and the situation returned to a state of control.
CONCLUSION
The use of risk assessment approaches is an important current Good
Manufacturing Practice (cGMP) topic in microbiological environmental
monitoring. This paper has outlined some possible tools for such a risk
assessment approach; however, each suite of cleanrooms or isolator will
be subtly different. The microbiologist must consider each aspect of the
environment and decide what level of monitoring best suits his or her sys-
tem, and then must justify the techniques used and the locations selected.
The approach adopted should be detailed in a written rationale and
approved by senior management. After this, a rigorous and defensible sys-
tem will be in place to satisfy regulatory expectations, and to aid the user
in assessing the risk of problematic environmental monitoring situations or
results. ❏
Tim Sandle
26
Institute of Validation Technology
Figure 18
Particle Count Criteria for Grade B
Particle Size
0.5 µm
5.0 µm
Mean Counts from fill
at Warning Level
4 points
4 points
Mean Counts from fill
at Action Level
5 points
5 points
Count (c/cf)

REFERENCES
• BS EN ISO 14698 – 1:2003: ‘Cleanrooms and Associated Controlled Environments –
Bio-Contamination Control – Part 1: General Principles and Methods.’
• Code of Federal Regulations, 1998, Title 21, Part 210, Current Good Manufacturing
Practice in Manufacturing, Processing, Packaging, or Holding of Drugs – General, 210:3.
• 'Guidelines on Sterile Drug Products Produced by Aseptic Processing,' FDA, 1987 (draft
produced for review in August 2003).
• ISO 14644-1 Cleanrooms and Associated Controlled Environments – Classification of
Air Cleanliness.
• ISO 14644-2 Cleanrooms and Associated Controlled Environments – Specifications for
Testing and Monitoring to prove continued compliance with ISO 14644-1.
• ISO 14698-1 Cleanrooms and Associated Controlled Environments Biocontamination
Control – Part 1: General Principles.
• Jahnke, M.‘Introduction to Environmental Monitoring in Pharmaceutical Areas,’ PDA, 2001.
• Ljungqvist, B. and Reinmuller, B. ‘Some Observations on Environmental Monitoring of
Cleanrooms,’ European Journal of Parenteral Science, 1996 1: 9 –13.
• PDA Technical Report No. 13 (revised): 'Fundamentals of an Environmental Monitoring
Programme,' September/October 2001.
• Sandle, T. ‘The Use of a Risk Assessment in the Pharmaceutical Industry – the
Application of FMEA to a Sterility Testing Isolator: a Case Study,’ European Journal of
Parenteral and Pharmaceutical Sciences, 2003 8(2): 43-49.
• Sandle, T. ‘Selection and Use of Cleaning and Disinfection Agents in Pharmaceutical
Manufacturing’ in Hodges, N and Hanlon, G. (2003): ‘Industrial Pharmaceutical
Microbiology Standards and Controls,’ Euromed Communications, England.
• Sandle, T. ‘General Considerations for the Risk Assessment of Isolators Used for Aseptic
Processes,’ Pharmaceutical Manufacturing and Packaging Sourcer, Samedan Ltd,
Winter 2004, pp: 43-47.
Tim Sandle
27
Environmental Monitoring
Figure 19
Graph of Criticality Scores
0
5
10
15
20
25
30
35
40
45
Criticality Scoring
Criticality cut-off
value = 25
Fill Number
3 5 7 9 1113151719 2123252729
1

• USPNF#25 <1116>
• Whyte, W. ‘Cleanroom Technology: Fundamentals of Design, Testing and Operation,
2001.’
• Whyte, W. and Eaton, T.‘Microbiological Contamination Models for Use in Risk
Assessment during Pharmaceutical Production,’ European Journal of Parenteral and
Pharmaceutical Sciences, 2004 Vol. 9, No.1, pp: 11-15.
• Whyte, W. and Eaton, T.‘Microbiological Risk Assessment in Pharmaceutical
Cleanrooms,’ European Journal of Parenteral and Pharmaceutical Sciences, 2004, Vol. 9,
No.1, pp: 16-23.
• Whyte, W. and Eaton, T.‘Assessing Microbial Risk to Patients from Aseptically
Manufactured Pharmaceuticals,’ European Journal of Parenteral and Pharmaceutical
Sciences, 2004, Vol. 9, No.3, pp: 71-79.
Tim Sandle
28
Institute of Validation Technology
Article Acronym Listing
CAPA Corrective and Preventive Action
CCPCritical Control Point
CFU Colony Forming Unit
cGMP Current Good Manufacturing
Practice
FMEA Failure Mode and Effects Analysis
FMECA Failure Mode, Effects, and Criticality Analysis
FTA Fault Tree Analysis
HACCP Hazard Analysis and Critical
Control Point
HAZOP Hazard Operability Analysis
HEPA High Efficiency Particulate Air
HVAC Heating, Ventilation, and
Air-Conditioning
ISO International Organization for
Standardization
MPRM Modular Process Risk Model
QA Quality Assurance
QC Quality Control
QMRA Quantitative Microbiological Risk Assessment
SRA System Risk Analysis
UDAF Uni-Directional Air Flow
USP United States Pharmacopoeia

SUGGESTED READING
• Anon. (1998), The Gold Sheet, Vol. 32, No.10, October 1998.
• De Abreu, C., Pinto, T. and Oliveira, D.‘Environmental Monitoring: A Correlation Study
between Viable and Nonviable Particles in Cleanrooms,’ Journal of Pharmaceutical
Science and Technology, Vol. 58, No.1, January-February 2004, pp: 45-53.
• Kaye, S.‘Efficiency of Biotest RCS as a Sampler of Airborne Bacteria,’ Journal of
Parenteral Science and Technology, Vol. 42, No.5, September-October 1986, pp: 147-
152.
• Meir, R. and Zingre, H. ‘Qualification of Air Sampler Systems: MAS-100,’ Swiss Pharma,
22 (2000), pp: 15 – 21.
• Ohresser, S., Griveau, S. and Schann, C. ‘Validation of Microbial Recovery from
Hydrogen Peroxide-Sterilised Air,’ Journal of Pharmaceutical Science and Technology,
Vol. 58, No. 2, March-April 2004, pp: 75-80.
• PhRMA Environmental Monitoring Work Group ‘Microbiological Monitoring of
Environmental Conditions for Nonsterile Pharmaceutical Manufacturing,’ Pharm.
Technol., March 1997, pp: 58-74.
• Reich, et al. ‘Developing a Viable Microbiological Environmental Monitoring Program for
Nonsterile Pharmaceutical Operations.’ Pharm. Technol., March 2003, pp: 92-100.
• 'Rules and Guidance for Pharmaceutical Manufacturers and Distributors' ('EU GMP
Guide'), MHRA, 2002.
• Sandle, T. ‘Environmental Monitoring in a Sterility Testing Isolator,’ PharMIG News No. 1,
March 2000.
• Sandle, T. ‘Microbiological Culture Media: Designing a Testing Scheme,’ PharMIG News
No. 2, August 2000.
ABOUT THE AUTHOR
Tim Sandle is the company Microbiologist at Bio Products Laboratory (BPL).
BPL is the manufacturing unit of the UK National Health Service - Blood and
Transplant.
Prior to his current role, Tim has worked on a number of different microbiological
projects within the Pharmaceutical Industry, including: developments in the test-
ing of endotoxins and pyrogens for protein-based products, establishing the
environmental monitoring regime for a network of over two-hundred cleanrooms,
and validating a sterility testing isolator system.
Tim has written more than forty articles relating to microbiology and pharmaceu-
tical operations, including: LAL testing, operation of isolators,
cleanrooms, and environmental monitoring. Tim may be contacted by email at
his BPL address, tim.sandle@bpl.co.uk or at his home address of:
timsandle@aol.com
Tim Sandle
29
Environmental Monitoring
Originally published in the January 2006 issue of the Journal of GXP Compliance