PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
Principles and Guidelines for the Conduct of Microbiological Risk Assessment  
 
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 Introduction  1 
 2 
Risks from microbiological hazards are of immediate and serious concern to human 3 
health. Microbiological Risk Analysis is a scien ce-based structured process consisting 4 
of three components: Risk Assessment, Risk Management, and Risk Communication, 5 
which has the overall objective to ensure public health protection. This document deals 6 
with Risk Assessment which is a key element in assuring that sound sci ence is used to 7 
establish standards, guidelines and other recommendations for food safety to enhance 8 
consumer protection and facilitate international trade. The Microbiological Risk 9 
Assessment process should include quantitative information to the greatest  extent 10 
possible in the estimation of risk. A Microbiological Risk Assessment should be 11 
conducted using a structured approach such as that described in this document. This 12 
document will be of primary interest to responsible competent authorities although 13 
other organizations, companies, and other interested parties who need to prepare a 14 
Microbiological Risk Assessment will find it valuable. Since Microbiological Risk 15 
Assessment is a developing science, implementation of these guidelines may require a 16 
period of time and may also require specialized training in our country.  Although 17 
Microbiological Risk Assessment is the primary focus of this document, the method can 18 
also be applied to certain other classes of biological hazards.  19 PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
Principles and Guidelines for the Conduct of Microbiological Risk Assessment  
 
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 1 Scope  20 
 21 
The scope of this document applies to Risk Assessment of microbiological hazards in 22 
food.1 23 
 24 
2 Normative references  25 
 26 
The following referenced documents are indispensable for the application of this 27 
document. For dated references, only the edition cited applies. For undated references, 28 
the latest edition of the referenced document (including any ame ndments) applies.  29 
 30 
CAC/GL 30 -1999, Principles and Guidelines for the Conduct of Microbiological Risk 31 
Assessment  32 
 33 
3 Terms and definitions  34 
 35 
The definitions cited here are to facilitate the understanding of certain words or phrases 36 
used in this document.  37 
 38 
3.1  39 
dose -response assessment  40 
determination of the relationship between the magnitude of exposure (dose) to a 41 
chemical, biological or physical agent and the severity and/or frequency of associated 42 
adverse health effects (response)  43 
 44 
3.2  45 
exposure assessment  46 
qualita tive and/or quantitative evaluation of the likely intake of biological, chemical, 47 
and physical agents via food as well as exposures from other sources if relevant  48 
 49 
3.3  50 
hazard  51 
biological, chemical or physical agent in, or condition of, food with the potential to cause 52 
an adverse health effect  53 
 54 
3.4  55 
hazard characterization  56 
qualitative and/or quantitative evaluation of the nature of the adverse health  effects 57 
associated with biological, chemical and physical agents, which may be present in food  58 
 59 
 60 
 61 
 62 
3.5  63 
                                                      
1 These principles for risk assessment also apply to feed and feed ingredients for food -producing animals 
in cases where it could impact food safety.  PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
Principles and Guidelines for the Conduct of Microbiological Risk Assessment  
 
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 hazard  identification  64 
identification of biological, chemical, and physical agents capable of causing  adverse 65 
health effects and which may be present in a particular food or group of foods  66 
 67 
3.6  68 
quantitative risk assessment  69 
Risk Assessment that provides numerical exp ressions of risk and  indication of the 70 
attendant uncertainties (stated in the 1995 Expert Consultation definition on Risk 71 
Analysis)  72 
 73 
3.7  74 
qualitative risk assessmen t 75 
Risk Assessment based on data which, while forming an inadequate  basis for numerical 76 
risk esti mations, nonetheless, when conditioned by prior expert knowledge and 77 
identification of attendant uncertainties permits risk ranking or separation into 78 
descriptive categories of risk  79 
 80 
3.8 81 
responsible competent authority  82 
refers  to the regulatory agency responsible for the implementation of official food 83 
control system to ensure public health and safety across the food supply chain  84 
 85 
3.9 86 
risk  87 
function  of the probability of an adverse health effect and the severity of that effect, 88 
consequential to  a hazard(s) in food  89 
 90 
3.10  91 
risk analysis  92 
science -based structured process consisting of three components: risk assessment, risk 93 
management and risk  communication  94 
 95 
3.11  96 
risk assessment  97 
scientifically based process consisting of the following steps: (i) hazard identification,  98 
(ii) hazard characterization, (iii) exposure assessment, and (iv) risk characterization  99 
 100 
3.12  101 
risk characterization  102 
process of de termining the qualitative and/or quantitative estimation, including  103 
attendant uncertainties, of the probability of occurrence and severity of known or 104 
potential adverse health effects in a given population based on hazard identification, 105 
hazard characteriz ation and exposure assessment  106 
 107 
 108 
 109 
 110 
3.13  111 
risk communication  112 PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
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 interactive exchange of information and opinions throughout the risk analysis  process 113 
concerning risk, risk -related factors and risk perceptions, among risk assessors, risk 114 
managers, consumers, indu stry, the academic community and other interested parties, 115 
including the explanation of risk assessment findings and the basis of risk management 116 
decisions  117 
 118 
3.14  119 
risk estimate  120 
qualitative  and/or quantitative estimation of risk resulting from risk characterization  121 
 122 
3.15  123 
risk management   124 
process, distinct from risk assessment of weighing policy alternatives, in  consultation 125 
with all interested parties, considering risk assessment and other factors relevant for 126 
the health protection of consumers and for the promotion of fair trade practices, and, if 127 
needed, selecting appropriate prevention and control options  128 
 129 
3.16  130 
sensitivity analysis  131 
method used to examine the behavior ` of a model by measuring the variation in its  132 
outputs resulting from changes to its inputs  133 
 134 
3.17  135 
transparent  136 
characteristics of a process where the rationale, the logic of development, constraints,  137 
assumptions, value judgements, decisions, limitations and uncertainties of the 138 
expressed determination are fully and systematically stated, documented, and 139 
accessible for review  140 
 141 
3.18  142 
uncertainty analysis  143 
method used to estimate the uncertainty associated with model inputs,  assumptions 144 
and structure/form  145 
 146 
4 General principles of microbiological risk assessment  147 
 148 
4.1 Microbiological Risk Assessment should be soundly based upon science.  149 
4.2 There should be a functional separation between Risk Assessment and Risk 150 
Management.  151 
4.3 Microbiological Risk Assessment should be cond ucted according to a structured 152 
approach that includes Hazard Identification, Hazard Characteri zation, Exposure 153 
Assessment, and Risk Characterization.  154 
4.4 A Microbiological Risk Assessment should clearly state the purpose of the 155 
exercise, including the form of  Risk Estimate that will be the output.  156 
4.5 The conduct of a Microbiological Risk Assessment should be transparent.  157 PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
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 4.6 Any constraints that impact on the Risk Assessment such as cost, resources or 158 
time, should be identified and their possible consequences described.  159 
4.7 The Risk Estimate should contain a description of uncertainty and where the 160 
uncertainty arose during the Risk Assessment process.  161 
4.8 Data should be such that uncertainty in the Risk Estimate can be determined; 162 
data and data collection systems shoul d, as far as possible, be of sufficient quality 163 
and precision that uncertainty in the Risk Estimate is minimized.  164 
4.9 A Microbiological Risk Assessment should explicitly consider the dynamics of 165 
microbiological growth, survival, and death in foods and the comp lexity of the 166 
interaction (including sequelae) between human and agent following 167 
consumption as well as the potential for further spread.  168 
4.10 Wherever possible, Risk Estimates should be reassessed over time by 169 
comparison with independent human illness data.  170 
4.11 A Microbiological Risk Assessment may need reevaluation, as new relevant 171 
information becomes available.  172 
5 Guidelines for application  173 
 174 
These Guidelines provide an outline of the  elements of a Microbiological R isk 175 
Assessment indicating the types of decisions t hat need to be considered at each step.  176 
 177 
5.1 General considerations  178 
 179 
5.1.1 The elements of Risk Analysis are: Risk Assessment, Risk Management, and Risk 180 
Communication. The functional separation of Risk Assessment from Risk 181 
Management helps assure that the Risk A ssessment process is unbiased. 182 
However, certain interactions are needed for a comprehensive and systematic 183 
Risk Assessment process. These may include ranking of hazards and risk 184 
assessment policy decisions. Where Risk Management issues are taken into 185 
accou nt in Risk Assessment, the decision -making process should be transparent. 186 
It is the transparent unbiased nature of the process that is important, not who is 187 
the assessor or who is the manager.  188 
5.1.2 Whenever practical, efforts should be made to provide a Risk As sessment 189 
process that allows contributions by interested parties. Contributions by 190 
interested parties in the Risk Assessment process can improve the transparency 191 
of the Risk Assessment, increase the quality of Risk Assessments through 192 
additional expertise and information, and facilitate risk communication by 193 
increasing the credibility and acceptance of the results of the Risk Assessment.  194 
5.1.3 Scientific evidence may be limited, incomplete or conflicting. In such cases, 195 
transparent informed decisions will have to  be made on how to complete the 196 
Risk Assessment process. The importance of using high quality information 197 
when conducting a Risk Assessment is to reduce uncertainty and to increase the 198 
reliability of the Risk Estimate. The use of quantitative information i s encouraged 199 PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
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 to the extent possible, but the value and utility of qualitative information should 200 
not be discounted.  201 
5.1.4 It should be recognized that sufficient resources will not always be available and 202 
constraints are likely to be imposed on the Risk Assessme nt that will influence 203 
the quality of the Risk Estimate. Where such resource constraints apply , it is 204 
important for transparency purposes that these constraints be described in the 205 
formal record. Where appropriate, the record should include an evaluation of the 206 
impact of the resource constraints on the Risk Assessment.  207 
5.2 Statement of purpose of risk assessment  208 
5.2.1 At the beginning of the work the specific purpose of the particular Risk 209 
Assessment being carried out should be clearly stated.  The output form an d possible 210 
output alternatives of the Risk Assessment should be defined. Output might, for 211 
example, take the form of an estimate of the prevalence of illness, or an estimate of 212 
annual rate (incidence of human illness per 100,000) or an estimate of the rate  of 213 
human illness and severity per eating occurrence.  214 
5.2.2 The microbiological risk assessment may require a preliminary investigation 215 
phase. In this phase, evidence to support farm -to-table modelling of risk might be 216 
structure d or mapped into the framework of risk assessment.  217 
5.3 Hazard identification  218 
For microbial agents, the purpose of hazard identification is to identify the 219 
microorganisms or the microbial toxins of concern with food.  Hazard identification will 220 
predominately be a qualitative process. Hazards can be identified from relevant data 221 
sources. Information on hazards can be obtained from scientific literature, from 222 
databases such as those in the food industry, government agencies, and relevant 223 
international organizati ons and through solicitation of opinions of experts. Relevant 224 
information includes data in areas such as: clinical studies, epidemiological studies and 225 
surveillance, laboratory animal studies, investigations of the characteristics of 226 
microorganisms, the in teraction between microorganisms and their environment 227 
through the food chain from primary production up to and including consumption, and 228 
studies on analogous microorganisms and situations.  229 
5.4 Exposure assessment  230 
5.4.1 Exposure Assessment includes an assessmen t of the extent of actual or 231 
anticipated human exposure. For microbiological agents, Exposure Assessments might 232 
be based on the potential extent of food contamination by a  particular agent or its 233 
toxins, and on dietary information. Exposure assessment shou ld specify the unit of food 234 
that is of interest, i.e., the portion size in most/all cases of acute illness.  235 
5.4.2 Factors that must be considered for Exposure Assessment include the frequency 236 
of contamination of foods by the pathogenic agent and its level in those foods over time. 237 
For example, these factors are influenced by the characteristics of the pathogenic agent, 238 
the microbiological ecology of the food, the initial contamination of the raw material 239 
including considerations of regional differences and sea sonality of production, the level 240 PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
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 of sanitation and process controls, the methods of processing, packaging, distribution 241 
and storage of the foods, as well as any preparation steps such as cooking and holding. 242 
Another factor that must b e considered in the a ssessment is patterns of consumption. 243 
This relates to socio -economic and cultural backgrounds, ethnicity , seasonality, age 244 
differences (population demographics), regional differences, and consumer preferences 245 
and behavior. Other factors to be considered in clude: the role of the food handler as a 246 
source of contamination, the amount of hand contact with the product, and the potential 247 
impact of abusive environmental time/temperature relationships.  248 
5.4.3 Microbial pathogen levels can be dynamic and while they may be kept low, for 249 
example, by proper time/temperature controls during food processing, they can 250 
substantially increase with abuse conditions (for example, improper food storage 251 
temperatures or cross contamination from other foods). Therefore, the Exposure 252 
Asse ssment should describe the pathway from production to consumption. Scenarios 253 
can be constructed to predict the range of possible exposures. The scenarios might 254 
reflect effects of processing, such as hygienic design, cleaning and disinfection, as well as 255 
the time/temperature and other conditions of the food history, food handling and 256 
consumption patterns, regulatory controls, and surveillance systems.  257 
5.4.4 Exposure Assessment estimates the level, within various levels of uncertainty, of 258 
microbiological pathogens or microbiological toxins, and the likelihood of their 259 
occurrence in foods at the time of consumption. Qualitatively foods can be categorized 260 
according to the likelihood that the foodstuff will or will not be contaminated at its 261 
source; whether or not the food can support the growth of the pathogen of concern; 262 
whether there is substantial potential for abusive handling of the food; or whether the 263 
food will be subjected to a heat process. The presence, growth, survival, or death of 264 
microorganisms, including pathogens in foods, are influenced by processing and 265 
packaging, the storage environment, including the temperature of storage, the relative 266 
humidity of the environment, and the gaseous composition of the atmosphere. Other 267 
relevant factors include pH, moist ure content or water activity (aw), nutrient content, 268 
the presence of antimicrobial substances, and competing microflora. Predictive 269 
microbiology can be a useful tool in an Exposure Assessment.  270 
5.5 Hazard characterization  271 
5.5.1 This step provides a qualitative o r quantitative description of the severity and 272 
duration of adverse effects that may result from the ingestion of a microorganism or its 273 
toxin in food. A dose -response assessment should be performed if the data are 274 
obtainable.  275 
5.5.2 There are several important fa ctors that need to be considered in Hazard 276 
Characterization. These are related to both the microorganism, and the human host. In 277 
relation to the microorganism the following are important: microorganisms are capable 278 
of replicating; the virulence and infecti vity of microorganisms can change depending on 279 
their interaction with the host and the environment; genetic material can be transferred 280 
between microorganisms leading to the transfer of characteristics such as antibiotic 281 
resistance and virulence factors; m icroorganisms can be spread through secondary and 282 
tertiary transmission; the onset of clinical symptoms can be substantially delayed 283 
following exposure; microorganisms can persist in certain individuals leading to 284 PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
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 continued excretion of the microorganism a nd continued risk of spread of infection; low 285 
doses of some microorganisms can in some cases cause a severe effect; and the 286 
attributes of a food that may alter the microbial pathogenicity, e.g., high fat content of a 287 
food vehicle.  288 
5.5.3 In relation to the host t he following may be important: genetic factors such as 289 
Human Leucocyte Antigen (HLA) type; increased susceptibility due to breakdowns of 290 
physiological barriers; individual host susceptibility characteristics such as age, 291 
pregnancy, nutrition, health and me dication status, concurrent infections, immune 292 
status and previous exposure history; population characteristics such as population 293 
immunity, access to and use of medical care, and persistence of the organism in the 294 
population.  295 
5.5.4 A desirable feature of Hazard  Characterization is ideally establishing a dose - 296 
response relationship. When establishing a dose -response relationship, the different 297 
end points, such as infection or illness, should be taken into consideration. In the 298 
absence of a known dose -response rela tionship, risk assessment tools such as expert 299 
elicitations could be used to consider various factors, such as infectivity, necessary to 300 
describe Hazard Characterizations. Additionally, experts may be able to devise ranking 301 
systems so that they can be used  to characterize severity and/or duration of disease.  302 
5.6 Risk characterization  303 
5.6.1 Risk Characterization represents the integration of the Hazard Identification, 304 
Hazard Characterization, and Exposure Assessment determinations to obtain a Risk 305 
Estimate; provid ing a qualitative or quantitative estimate of the likelihood and severity 306 
of the adverse effects which could occur in a given population, including a description of 307 
the uncertainties associated with these estimates. These estimates can be assessed by 308 
compa rison with independent epidemiological data that relate hazards to disease 309 
prevalence.  310 
5.6.2 Risk Characterization brings together all of the qualitative or quantitative 311 
information of the previous steps to provide a soundly based estimate of risk for a given 312 
population. Risk Characterization depends on available data and expert judgements. 313 
The weight of evidence integrating quantitative and qualitative data may permit only a 314 
qualitative estimate of risk.  315 
5.6.3 The degree of confidence in the final estimation of risk w ill depend on the 316 
variability, uncertainty, and assumptions identified in all previous steps. Differentiation 317 
of uncertainty and variability is important in subsequent selections of risk management 318 
options. Uncertainty is associated with the data themselve s, and with the choice of 319 
model. Data uncertainties include those that might arise in the evaluation and 320 
extrapolation of information obtained from epidemiological, microbiological, and 321 
laboratory animal studies. Uncertainties arise whenever attempts are m ade to use data 322 
concerning the occurrence of certain phenomena obtained under one set of conditions 323 
to make estimations or predictions about phenomena likely to occur under other sets of 324 
conditions for which data are not available. Biological variation inc ludes the differences 325 
in virulence that exist in microbiological populations and variability in susceptibility 326 
within the human population and particular subpopulations.  327 PHILIPPINE NATIONAL STANDARD  PNS/BAFS xxx:2017  
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 5.6.4 It is important to demonstrate the influence of the estimates and assumptions 328 
used in Risk Assessment; for quantitative Risk Assessment this can be done using 329 
sensitivity and uncertainty analyses.  330 
5.7 Documentation  331 
The Risk Assessment should be fully and systematically documented and communicated 332 
to the risk manager. Understanding any limit ations that influenced a Risk Assessment is 333 
essential for transparency of the process that is important in decision making. For 334 
example, expert judgements should be identified and their rationale explained. To 335 
ensure a transparent Risk Assessment a formal record, including a summary, should be 336 
prepared and made available to interested independent parties so that other risk 337 
assessors can repeat and critique the work. The formal record and summary should 338 
indicate any constraints, uncertainties, and assumption s and their impact on the Risk 339 
Assessment.  340 
5.8 Reassessment  341 
Surveillance programs can provide an ongoing opportunity to reassess the public health 342 
risks associated with pathogens in foods as new relevant information and data become 343 
available. Microbiologic al Risk Assessors may have the opportunity to compare the 344 
predicted Risk Estimate from Microbiological Risk Assessment models with reported 345 
human illness data for the purpose of gauging the reliability of the predicted estimate. 346 
This comparison emphasizes the iterative nature of modelling. When new data become 347 
available, a Microbiological Risk Assessment may need to be revisited.  348