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1 Risk assessment: main definitions and concepts

Lead-in. Fill in the spidergram with the words associated with the word «risk». Explain your associations.

Exercise 1. Read and remember the pronunciation

[3] decision, exposure, measure, measurement

[j] insurance, social, financial, potential, spatial

[tj] feature, conceptual, manufacture

[u:] include, prove, pollutant

[ju:] value, evaluate, human, therapeutic, duration

[ai] provide, analyze, hypothesize, minimize, paramertize

[aio] require, environment, desirable, variety, entire

Risk assessment and risk management

Ecological risk assessment (ERA) is a process for collecting, organizing, and analyzing information to estimate the likelihood of undesired effects on nonhuman organisms, populations, and ecosystems. It was developed in the early to mid-1980’s to provide a basis for environmental decision making equivalent to human health risk assessment. It was derived from practices in human health risk assessment, environmental hazard assessment, and environmental impact assessment. However, the concept of estimating risk as a means of managing financial hazards through insurance, options, and other instruments dates at least to the late 17th century. All varieties of risk assessment are based on the recognition that decisions must be made under conditions of uncertainty and that the desirability of alternative outcomes depends on their likelihood as well as their utility.

The primary purpose for conducting ecological risk assessment of contaminated sites is to provide information needed to make decisions concerning site remediation.

Risk assessment is the process of determining potential health effect on people exposed to environmental pollutants and potentially toxic materials. One of the defining features of ecological risk assessment is the standard framework which has evolved from the National Research Council for human risk assessment (USA, 1983). Such an assessment generally includes four steps:

  • 1. Identification of the hazard (or Problem formulation phase). Is the planning and problem definition phase. It includes:
    • • Integrate available information assembling and summarizing data concerning sources, contaminants, effects, and the receiving environment.
    • • Assessment endpoint - definition of the environmental values to be protected in operational terms.
    • • Conceptual model - development of description for the hypothesized relationships between the wastes and the endpoint receptors.
    • • Analysis plan - development of a plan for obtaining the needed data and performing the assessment.
  • 2. Dose-response assessment (or Analysis). This is a phase in which technical evaluation of the data concerning exposure and effect is performed. This involves figuring out whether and how the dose of a chemical (therapeutic drug, pollutant, or toxin) affects people’s health and environment.
  • 3. Exposure assessment. In this step we evaluate the intensity, duration, and frequency of human exposure to a particular chemical pollutant or toxin. This phase consists of:
    • • Measures of exposure - results of measurements indicating the nature, distribution, and amount of the waste and its components at points of potential contact with receptors.
    • • Exposure analysis - a process of estimating the spatial and temporal distribution of exposure to the contaminants.
    • • Exposure profile - a summary of the results of the exposure analysis.
  • 4. Risk characterization. Using what we learned in the first three steps, we attempt to determine the percentage of the population at risk and the probability of individual suffering ill effects. In this phase the results of analysis are integrated to estimate and describe risks. It consists of:
    • • Risk estimation - the process of using the results of the analysis of exposure to parameterize and implement the exposure-response model and estimate risk and of analyzing the associated uncertainty.
  • • Risk description - the process of describing and interpreting the results of the risk estimation for communication to the risk manager. Risk management requires us to make scientific judgments and decide what actions we should take to help minimize health problems related to exposure to pollutants and toxins. Risk management takes into account our risk assessment plus technical, legal, political, social, and economic issues. It appears at two points in the framework.
  • • at the beginning of assessment, the risk manager provides policy input to the problem formulation;
  • • at the end of the assessment, the risk manager learns the results of the risk analysis and makes decision.

Risk assessment and risk management can lead to arguments. Scientific opinions about toxicity of a substance are often to debate, and so are opinions about what actions to take. The appropriate action may be to apply the Precautionary Principle, that is to take cost-effective measures to protect ourselves even when we are not entirely certain about the risk. For example, although we cannot be absolutely certain how hormonally active substances such as the weed killer atrazine may affect us, that should not keep us from taking cost-effective steps to protect ourselves and the environment from the pesticide. The precautionary principle is emerging as a powerful ideology that is shifting the burden of proof from those who claim a substance is dangerous to those who manufacture, distribute, and use it. In short, it is not up to you to prove it’s harmful, it’s up to them to prove it’s not - before they use it.

Exercise 2. Match the synonyms from A to В

A

В

1. to determine

a), to indicate

2. to estimate

b). probability

3. to show

c). debate

4. framework

d). danger

5. likelihood

e). to evaluate

6. argument

f). to affect

7. pollutant

g). to define

8. to influence

h). scheme

9. hazard

i). contaminant

Exercise 3. Fill in the necessary preposition

1. The purpose of exposure assessment is to estimate spatial and temporal

distribution of exposure ... the contaminants.

  • 2. Ecological risk assessment was derived ... the experience in human health risk assessment.
  • 3. Risk assessment and risk management may lead ... great arguments.
  • 4. Site remediation is much ... to us!
  • 5. Risk management takes ... account legal, technological, and financial issues in addition to risk assessment.
  • 6. Usually the environmental decisions are made ... conditions of uncertainty and likelihood.
  • 7. Exposure assessment phase consists ... measures of exposure, exposure analysis, and exposure profile.
  • 8. The aim of exposure measures is to determine the nature, distribution, and the amount of waste components ... the point of potential contact with receptors.

Exercise 4. Complete the sentences translating the Russian words

  • 1. Assessment endpoint means determination of the environmental values to be protected (в оперативные сроки).
  • 2. We cannot be (совершенно уверены) how biologically modified substances may affect us.
  • 3. It (зависит от) manufactures to prove that the goods they produce are not harmful.
  • 4. The risk manager learns the results of risk analysis and (принимает решение).
  • 5. Using risk characterization we try to determine the percentage of people (подвергающихся риску).
  • 6. In the stage of exposure assessment specialists evaluate the intensity, duration, and frequency of people’s (воздействие) a particular chemical pollutant.
  • 7. Developing the conceptual model ecologists describe (гипотетическое соотношение) between the wastes and the endpoint receptors.

Exercise 5. Match the collocations, compose your own sentences with one of them.

A

В

1. To take

a), decision

2. to make

b). account

3. to take into

c). environment

4. to perform

d). pollutant

5. to protect

e). measures

6. to expose to

f). analysis

Exercise 6. Match the stages and the appropriate actions of risk assessment

Stages

Actions

Problem formulation

a), technical evaluation of data on exposure and effect, figuring out whether and how the dose of a contaminant will affect human health and environment.

Dose-response analysis

b). determination of the percentage of population at risk and probability of an individual suffering ill effects.

Exposure assessment

c). Making scientific conclusion and decision on actions for minimizing health problems related to exposure to pollutants or toxins.

Risk characterization

d). assembling and summarizing data, definition of the environmental values to be protected, description of hypothesized relationships between the wastes and the receptor, development of plan

Risk management

e). evaluation of intensity, duration, and frequency of human exposure to pollutants or toxins.

Exercise 7. Draw a framework of risk assessment on the basis of information from the text.

Compare it to the model Appendix 1. Describe it.

Texts for self-study

Read the texts and answer the question.

Text 1. Main definitions. Risk and hazard classification

During last years the term “RISK” became very popular in different areas: engineering, economics, environment, management, biology & medicine, etc. and different authors use this term in different senses. Below we consider some definitions of risk in different sources.

Definitions of risk

There are many definitions of risk that vary by specific application and situational context.

One is that risk is an issue, which can be avoided or mitigated (where an issue is a potential problem that has to be fixed now.)

Risk is described both qualitatively and quantitatively.

Qualitatively, risk is proportional to both the expected losses which may be caused by an event and to the probability of this event. Greater loss and greater event likelihood result in a greater overall risk.

In engineering, the definition risk often simply is:

Risk = (probability of an accident) x (losses per accident).

Or in more general terms:

Risk = (probability of event occurring) x (impact of event occuring).

In common risk is the chance that something undesirable will happen. Risk is described as a situation which would lead to negative consequences. Risk is considered as an indicator of threat, or depends on threats, vulnerability, impact and uncertainty.

1. What is risk? Give all possible definitions.

Text 2. Risk and hazard classification

There are a lot of classifications of hazards and risks. Scientists distinguish types, categories, and indexes of risk. Below the classification of hazards and risks in the sphere of natural resource use is presented.

Individual risk is a frequency of the affections of a single individual as a result of the danger factors investigated.

where N0 - number of lethal outcomes in a group of a number N which is subjected to an influence.

Collective (integral) risk determines the scale of expected consequences of potential accidents for people

where NR - number of people subjected to a risk

  • Social (mean individual) risk (set of numbers or functional relation) is the relation of a number of events, in which the number of injured persons is higher than a certain number, to this certain number of people.
  • Potential territorial risk (set of numbers or functional relation) is the space distribution of the frequency of a negative influence of a certain level

Distribution of potential risk on territory near to object on which failures with large emission of toxic substances are possible. By figures at isolines value of frequency of destruction the person (1/year), A - zone border of the people defeat calculated for scenarios of failure with identical weight of emission in all directions of a wind, Б - a zone of defeat for the separate scenario with the given wind direction.

• Compulsory - for example, habitation near to a dangerous oil refinery enterprise

Constrained are connected with dangerous occupation (for example, working in coal mine)

Voluntary - extreme sports and tourism

Economical damage is a financial cost estimation of a negative impact on the economy

Or is loss of material assets or loss of profit as a result of nature management

  • Social damage is a damage or loss of the profit because of the deterioration of life quality, disease growth, mortality, decrease of the quality of recreation zones. It can be expresses as the number of sick, injured or died persons as a result of negative effects or in terms of money.
  • Ecological damage is a damage for the environment as a result of the negative impact of both natural and anthropogenic processes which can be expressed in terms of money, as the amount of polluted area and as quantitative characteristics of damaged ecosystems
  • Catastrophic risks are sudden accidents at industry or natural disasters which have mainly destructive effect and are characterized with substantial force
  • Emergency risks appear as a result of accident (breakage, crash, emergency)
  • Persistent risks are “creeping”, slow processes which have a paralyzing or exhausting effect (radiation effect, destruction of flora and fauna, the consequences of which could be seen foe a long time)

Episodic risks suddenly appear, they are unpredictable in force and form of influence.

  • Negligible level is the level of the individual risk which does not lead to the deterioration of the life quality and economical activity, and does not cause a trouble of an individual
  • Acceptable level is the level of a risk which the society is ready to accept for the sake of certain welfare or benefits in their activity

Or it is the risk, the level of which is acceptable and reasonable in terms of economical and social considerations.

  • Unacceptable level is the level of a risk determined by administrative or regulating authorities as the maximum, measures for its elimination are necessary in case it is higher.
  • Excessive level is the level of the individual risk conditioned by economical activity, which exceeds the maximum permissible level.

They differ in the space distribution, extent of material damage, number of victims and cause of origin.

Over to you:

  • 1. The annual number of victims in road accidents all over the world amounts to 1.2 million a year. Estimate an individual risk of loss of life in road accidents in the world. Assume the population number is 6.5 billion according to 2006.
  • 2. Estimate the probability of dearth (Personal risk, year-1) caused by the events listed below.
  • • Calculate the number of expected fatal outcomes for 1 million human beings.
  • • Arrange the causes listed below in column 1 in the sequence according to descent of the degree of danger.

Estimation of the number of sudden death events in USA in 1973

The cause of an accident

Total number of deaths

Personal risk, year-1

Number of expected fatal outcomes for 1 million human beings

Background (natural) radiation e.g.solar radiation

7200

Medicine radiodiagnosis and radiotherapy

330

nuclear industry

3

Other causes isn’t connected with radiation

398500

Air pollution

20000

aviation accident

1778

rail disaster, train crash

798

Do the following tasks:

  • 1. Give all possible definitions of risk. In what spheres could they be used?
  • 2. Complete the chart of risk classification without looking into the text.
  • 3. Give definitions of individual risk, collective risk, mean individual risk, potential territorial risk.
  • 3. Point out the difference among the economical, social, ecological damages.
  • 4. Complete the chart of risk classification according to its activity. Describe each type.

5. Complete the chart of risk classification according to its hazard level. Describe each type.

6. Point out the difference among the local, regional, and global risks.

Text 3. The concept of acceptable risk

The nature itself from one side and the human activity from the other side are sources of risks. The avoidances on large chemical enterprises, breaks in oil- and gas- pipelines etc. represent significant hazard and lead to high damage for population and environment. Since these risks are connected with reliability of appropriate equipment, their study directed to excuse the payment for the providing and support of the necessary level of reliability equipment

Over the years the risk concept has been introduced into the structures of government to provide safety and sustainable development of the country. The “risk” concept is used in a number of federal laws.

For a long period another concept - the so called concept of “absolute safety” or “zero risk” has been the bases of industrial enterprise operation.

The concept of “zero risk” implies such an organization of industrial plant that would exclude any probability of accident completely. Not long ago, 10-15 years ago it seemed that nearly all natural and technogenic hazards could be brought to naught due to improvements in engineering protection, increase in reliability of technical equipment. But after Spitak (07.12.88) and Neftegorsk (28.05.95) earthquakes, subsinking of atomic submarine “Kursk” (9.08.99), a number of accidents at oil- and gas pipelines (Komi republic, 17.08.94, Bashkiria, 03.06.89), leading to severe consequences, the inefficiency of zero risk concept or absolute safety was realized.

“Zero risk” concept does not meet the regulations of technosphere. The regulations of technosphere are of probabilistic nature. There is always a probability of emergencies and accidents. Zero accident probability could be achieved only in the systems without energy storage of chemically or biologically active components.

Besides, the presence of potentially harmful substances in the environment always produces some risk extent, different from zero.

The disadvantages of the concept are:

Firstly, its principal inaccessibility;

Secondly, very high cost of its implementation;

Thirdly, unpreparedness of the staff for efficient actions in case of emergency.

On the basis of assumption of complete accident exception, a lot of nuclear plants were built where efficient safety precautions were provided. Nevertheless, there a number accidents at those plants, the consequences of which were calamitous.

The concept of “zero risk” was replaced by the so-called concept of “acceptable risk”, the basis of which was formed by the principle “to foresee and to prevent”. This concept implies the probability of accident and, hence, the measures for prevention from accident occurrence and development.

Acceptable risk is an acceptable level of risk, justified from the point of view of economic, social, and ecological factors, which society could bear for the sake of gaining some positive outcomes of its activity.

Quantitative characteristic of risk level is the numeric value of individual risk. Individual risk is characterized by one numeric magnitude, i.e. probability of deaths per one person a year. It is a universal feature of hazard for human being that constitutes the foundation of acceptable risk level standardization.

The analysis of domestic and foreign documentation concerned with standardization of safety and risks indicates the fact that acceptable magnitude of one person death probability during a year (acceptable individual risk) ranges 10-5 ^ 10-6. In this case the probability value 10-6 is sometimes called desirable (upper) level of individual risk, but the probability value 10-5 is acceptable (lower) level of individual risk.

Feasibility evaluation of risk levels (unacceptable, acceptable, negligible) requires careful consideration as a large complex of technical, economical, social, and psychological problems taking into account the local factor.

  • 1. What could be the cause of risk?
  • 2. What concepts are the bases of industrial enterprise operation over the long period?
  • 3. What is zero risk?
  • 4. Why was the inefficiency of zero risk concept realized?
  • 5. In what conditions can zero risk be achieved?
  • 6. What are the disadvantages of zero risk concept?
  • 7. What is acceptable risk? What does it imply?
  • 8. What is individual risk characterized by?
  • 9. What does feasibility evaluation of risk levels include?

Text 4. Read the text, give the title, do the tasks given below

Ecological risk assessment is more complex than human health risk assessment and is fundamentally different in their approaches. The greater complexity is mainly due to the large number of species and diversity of routes of exposure that must be considered in ecological risk assessment. However, the differences in approaches and part of the greater complexity are due to the fact that ecological risk assessments for waste sites may be based on epidemiological approaches while human health risk assessment for the waste sites are nearly always based on modeling. This discrepancy (отличие) raises the question, why not just model ecological risk as well? The reasons are as follows:

  • • Epidemiological approaches, when they are feasible (возможный, выполнимый), are fundamentally more reliable than modeling, because they address real observed responses of real receptors. Human health risk assessments are based on epidemiology when possible, but epidemiology is not feasible for most sites because there are no observable effects in human populations.
  • • Ecological epidemiology is feasible in practice, because nonhuman organisms reside (проживать) on most sites and are, in some cases, experiencing observable exposures and effects.
  • • Ecological epidemiology is feasible in principle, because the levels of effects that are considered to be significant by most regulatory agencies are observable in many populations and communities.
  • • Because of the assumption (предположение) that must be made to model risks, the uncertainties in model-generated risk estimates are large. These uncertainties can be accepted in practice by human health assessors because the effects are not observable. However, it is common for modeled ecological risks to be manifestly incorrect because the predicted effects are not occurring or effects are observed where they are not predicted. Therefore, it is incumbent to use an epidemiological approach to avoid mistakes.
  • • Because of the great value placed on human life, remedial actions may be taken on the basis of highly uncertain estimates of hypothetical risks. Therefore, if ecological risk assessments are to be useful, they must be compelling.
  • • Biological surveys and ecological toxicity tests are highly cost-effective, because they are inexpensive relative to chemical analyses and provide more direct evidence concerning ecological risks.

Even in those cases when ecological epidemiology is not feasible, the process of determining that to be the case is instructive (поучительный) and assists in the interpretation of modeled risks. For example, if contaminants on a site would cause reproductive failure (спад) in robins feeding on that site, counting robins would not indicate the effect, because the number of breeding pairs is limited by habitat availability relative to territory size, and loss of production on the site would easily replaced by birds produced elsewhere. This example also suggests that the potential effect (i.e. reduced reproduction on the site) would not be significant at the population level for a species that is not limited by production.

Tasks:

  • 1. Name 3-4 differences between human health assessment and ecological risk assessment.
  • 2. Name some reasons for using both these assessment in practice.
  • 3. Give an example of inefficiency in using only ecological risk modeling.

Text 5. Methodology of Human Health Risk Assessment of Environmental Chemicals

The methods of human health risk assessment have been intensively developed lately in some European countries, Great Britain, USA, and Russia. The modern science testifies the absence of a threshold impact for a lot of chemical contaminants. Risk is the likelihood that a harmful consequence will occur as a result of an action. Human health risk assessment evaluates the probability of health effects as a result of potentially hazardous behaviors.

Traditionally, such assessments have focused on the probability of increased disease in human populations. The approach follows the four steps recommended by the United States National Academy of Sciences:

  • 1. Hazard identification;
  • 2. Dose-response assessment;
  • 3. Exposure assessment;
  • 4. Risk characterisation.

According to Environmental Protection Agency USA Approach and Guideline of the State Committee for Sanitary and Epidemiological Oversight under the Russian Ministry of Public Health, one mathematical formula that determines an individual cancerogeneous risk from chemical exposures is

Rind - individual cancerogeneous risk,

SF - Slope Factor, or Unit Risk, (mg/kg x day)-1, reference date are used; LADD - Living Average Daily Dose, mg/kg x day,

C - the average concentration of the chemical substances, affecting during the exposure, mg/m3;

CR - Contact Rate, for inhalation affect - inspiratory rate, m7day;

ED - Exposure Duration, years;

EF - Exposure Frequency, day/year;

BW - Body Weight, kg;

AT - Average Time, or average life expectancy, years

The noncancerogeneous risk, or Index Damage (HQ) is calculated by the

equation

HQ - Index Damage

LADD - Living Average Daily Dose, mg/kg x day,

RfD - Referent (harmless) Dose, mg/kg x day, reference date are used.

Risk level

R-ind

HQ

Extremely

high

104

More than 5

Unacceptable neither for the population, nor for professionals. Other actions for risk decrease

Carrying out of emergency improving and other actions for risk decrease is necessary

High

кг'-кг3

Average

КГ3-1(Г4

1-5

Acceptable for professionals and unacceptable for the population as a whole; occurrence of such risk demands planned improving actions in the conditions of the inhabited sites

Low

КГ4-КГ6

0,1-1

Corresponds to a zone of conditionally (admissible) risk; at this level the majority of hygienic standards recommended by the international organizations for the population as a whole is established

Minimum

Less

than 10-6

Less than 0,1

Corresponds to one additional case of serious disease or death per 1 million persons suffered from the effect. Such risks are perceived by people as negligibly small, do not differ from usual, daily ones. Do not demand for additional measures in their decrease, are subject to only the periodic control

Fig. 1 The screenshot of the soft ware “Risk Assistant”

Software package “RISK ASSISTANT” is commercial software to assess health risk from toxic contamination at local sites, used for the risk evaluation for health, caused by the chemical substances in drinking, surface, underground water, soil and atmospheric air. It is necessary to determine the chemical substances concentrations in water, soil and atmospheric air and know the impact conditions for using RA. Conceptual models, ecological effects, and other factors are incorporated into this software for the definition of assessments.

  • 1. Answer the questions:
  • 1. What does human health risk assessment evaluate?
  • 2. What are the steps in risk assessment?
  • 3. What risk levels do you know?
  • 4. What software package is used to assess health risk from toxic contamination at local sites?
  • 5. What is necessary to know for risk evaluation?
  • 2. Decipher the abbreviations:

SF, ED, RfD, LADD, BW, AT, HQ, EF, CR.

Text 6. Devide the text into parts with your groupmates.

Translate the text from Russian into English paying special attention to the use of terms

ОЦЕНКА РИСКА ДЛЯ ЗДОРОВЬЯ НАСЕЛЕНИЯ г. ТОМСКА ПРИ ВОЗДЕЙСТВИИ ХИМИЧЕСКИХ ВЕЩЕСТВ, ЗАГРЯЗНЯЮЩИХ АТМОСФЕРУ

Химическое загрязнение окружающей среды создает опасность для здоровья человека. Ведутся специальные научные исследования, направленные на количественное определение связи между загрязнением окружающей среды и его влиянием на организм человека. На настоящий момент приходится констатировать, что использование традиционных подходов, основанных на сопоставлении существующих уровней химического загрязнения с гигиеническими нормативами, не всегда является эффективным. Это касается оценки качества окружающей среды и попытки увязать его со здоровьем путем соотнесения реального загрязнения с величинами ПДК.

В научном отношении оценка риска - это последовательное, системное рассмотрение всех аспектов воздействия анализируемого фактора на здоровье человека, включая обоснование допустимых уровней воздействия. В научно-практическом приложении основная задача оценки риска состоит в получении и обобщении информации о возможном влиянии факторов среды обитания человека на состояние его здоровья.

В суммарном объеме общегородских выбросов доля автотранспорта составляет около 78 % (77.9 тыс. т в год). Причинами высокой степени загрязнения автотранспортом является высокая плотность потока автотранспорта, повышенное содержание загрязняющих веществ в выхлопных газах, плохое качество дорожного покрытия.

Предприятиями города и автотранспортом в атмосферный воздух выбрасывается более 250-ти загрязняющих веществ. В городе имеется 5,5 тыс. стационарных источников загрязнения атмосферы, принадлежащих 194-м промышленным предприятиям. Основными отраслями промышленности являются электроэнергетика (21,5 %), машиностроение и металлообработка (18%), а также топливная (17,4%), пищевая (9,7 %), химическая и нефтехимическая промышленность (7 %).

Оценка канцерогенного риска проводилась в соответствии с нормативным документом [5] Центра Госсанэпиднадзора Минздрава РФ, в соответствии с подходом ЕРА US [6] (Агенство по охране окружающей среды США, этот подход официально используется в РФ, рекомендован Всемирной Организацией Здравоохранения и Программой ООН по окружающей среде,), с помощью комплекса программных средств «RISK ASSISTANT» [7]. В данной работе рассматривалось лишь поступление в организм вредных веществ через дыхательные пути (ингаляционная экспозиция). Была выбрана группа населения, подвергшаяся воздействию (в настоящей работе выбран «средний житель» весом 70 кг, продолжительная длина жизни которого 70 лет и воздействие на которого длится 30 лет). Предполагается, что это его постоянное место жительства, кроме 2-х недель в году, а воздействие продолжается 3 часа в неделю.

Расчет канцерогенного риска проводится по формуле:

Эти оценки представляют теоретический дополнительный канцерогенный риск (то есть риск сверх фоновой заболеваемости) получения рака. Например, если расчетный риск есть 1 на 1000 000, это буквально означает, что человек имеет шанс на миллион получить рак из-за указанного химического воздействия, в дополнение к его шансам получить рак по другим причинам.

Оценка канцерогенного риска была выполнена для всех веществ, за содержанием которых ведутся постоянные наблюдения на ПНЗ: пыль, оксид серы (IV), оксид азота (IV), оксид углерода (II), сероводород, фенол, формальдегид, аммиак, хлористый водород. В соответствии с [5-8] канцерогенный риск рассчитывается по каждому загрязняющему веществу в отдельности. Индивидуальные канцерогенные риски от всех этих веществ, за исключением формальдегида, составили менее 1x10 6. Согласно классификации уровней риска, представленной в [5-8], индивидуальный риск в течение всей жизни, равный или меньший lxlO-6, соответствует 1 дополнительному случаю серьезного заболевания или смерти на 1 млн экспонированных лиц; характеризует такие уровни риска, которые воспринимаются всеми людьми как пренебрежимо малые, не отличающиеся от обычных, повседневных. Подобные риски не требуют никаких дополнительных мероприятий по их снижению и их уровни подлежат только периодическому контролю.

Таким образом, индивидуальный канцерогенный риск для здоровья при вдыхании атмосферного воздуха для жителей г. Томска формируется под воздействием формальдегида. Анализ данных наблюдений показал, что атмосферный воздух загрязнен формальдегидом, его содержание неоднократно превышало среднесуточную предельно допустимую концентрацию в 4-6 раза за весь период наблюдений.

На рисунке представлено изменение индивидуального канцерогенного риска на ПНЗ г. Томска в период с 1993-2002 гг. (вставка с рукописного текста, *).

Ранжирование уровней индивидуального канцерогенного риска за 2002 год приведено в таблице.

Таблица

Ранжирование уровней индивидуального канцерогенного риска за 2002 год

№ поста

Адрес

Индивидуальный пожизненный канцерогенный риск

Уровень риска

ПНЗ-2

площадь Ленина

2е-004

Низкий

ПНЗ-5

ул. Герцена, 68;

8е-005

Низкий

ПНЗ-11

перекресток ул. Пролетарской и пер. Баранчуковского

1е-004

Средний

ПНЗ-12

поселок Светлый

2е-004

Низкий

ПНЗ-13

ул. Вершинина

1е-004

Средний

ПНЗ-14

ул. Лазо

9е-005

Низкий

Минимальный уровень риска наблюдается на ПНЗ-2 (площадь Ленина), ПНЗ-5 (ул. Герцена, 68), ПНЗ-12 (поселок Светлый) и ПНЗ-14 (ул. Лазо). В соответствии с классификацией риска такой риск характеризуется как низкий. Индивидуальный риск в течение всей жизни находится в пределах более lxKT6, но менее 1x10-4 и соответствует зоне условно приемлемого (допустимого) риска; именно на этом уровне установлено большинство зарубежных и рекомендуемых международными организациями гигиенических нормативов для населения в целом.

Максимальный уровень риска наблюдается на ПНЗ-11 (перекресток ул. Пролетарской и пер. Баранчуковского) и на ПНЗ-13 (ул. Вершинина). Такой индивидуальный риск характеризуется как средний и приемлем для профессионалов и неприемлем для населения в целом; появление такого риска требует разработки и проведения плановых оздоровительных мероприятий в условиях населенных мест.

Средний уровень риска по городу составляет 7,7><1 о-5, что признает вероятным, что в течение 70 лет возможно возникновение 7 дополнительных случаев рака в популяции населения, равной 100000 человек, подвергающейся ингаляционному воздействию формальдегидом.

Результаты исследования показывают, что полученная величина индивидуального риска 2x10-4 признает вероятным, что в течение 70 лет возможно возникновение 2 дополнительных случаев рака в популяции населения, равной 10000 человек, подвергающейся ингаляционному воздействию формальдегида. Такой риск наблюдается в центре города на площади Ленина, а также на улицах Пролетарской и Вершинина, переулке Баранчуковского. В соответствии с классификацией такой индивидуальный пожизненный канцерогенный риск имеет средний уровень и является неприемлемым для населения в целом. Появление такого риска требует разработки и проведения плановых оздоровительных мероприятий.

 
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