4 HRA Food 7 March 2012

8/2/2019 4 HRA Food 7 March 2012

1/99

1

Health Risk Assessment of Contaminants in Food

MSc in Environmental and Public Health Management, HKBU

EPHM 7330 Food Protection and Safety Management

AOW Leung (Dept of Biology, HKBU)E-mail: [email protected]

8/2/2019 4 HRA Food 7 March 2012

2/99

8/2/2019 4 HRA Food 7 March 2012

3/99

Food Safety

Protection of the food supply from harmfulcontamination

Prevention of the development and spread of harmful contamination

Effective removal of contamination andcontaminants

3

8/2/2019 4 HRA Food 7 March 2012

4/99

Food Safety Hazards

Food safety hazard: Any factor present in foodthat has the potential to cause harm to theconsumer, either by causing illness or injury. Biological hazards Chemical hazards Physical hazards

4

8/2/2019 4 HRA Food 7 March 2012

5/99

Biological Hazards

Bacteria Salmonella, Listeria moncytogenes, Vibrio

parahaemolyticus

Parasites and protozoa Entamoeba histolytica, Cyclospora cayetanensis

Viruses Hepatitis A

Microtoxins

5

8/2/2019 4 HRA Food 7 March 2012

6/99

Chemical Hazards

Toxic metals (i.e. lead, mercury, cadmium) Environmental pollutants (i.e. PCDD/Fs, PCBs) Pesticide residues (i.e. DDT, HCH)

Additives (i.e. preservatives) Contaminants produced during food processing

(i.e. PAHs, acrylmide) Veterinary drug residues (i.e. antibiotics, growth

stimulants) Plasticisers and packaging migrants (i.e. Bisphenol

A)

6

8/2/2019 4 HRA Food 7 March 2012

7/99

Industrial andenvironmental

Source Associatedfood

PCBs Transformers Fish, animal fat

Dioxins By-product Fish, animalfat

Mercury Chlor-alkali FishLead Vehicle emission,

paintCanned food,acidic foods

Cadmium Sludge, smelting Grains, molluscs

Radionuclides Accidentalrelease

Fish,mushrooms

Nitrate/nitrite Fertilizers Vegetables

Chemical Hazards

7

8/2/2019 4 HRA Food 7 March 2012

8/99

Physical Hazards

Glass Hair Metal

Pebbles Wood Plastic Parts of pests Bone Fruit pits

8

8/2/2019 4 HRA Food 7 March 2012

9/99

The hazards associated with an agent will beaffected by: the structure and associated physicochemical

properties the metabolism and toxicokinetics of the

substance

the results of a series of toxicity tests conductedboth in animal models and/or in in vitro systems

9

8/2/2019 4 HRA Food 7 March 2012

10/99

When can these hazards arise in thefood supply?

Before the raw material enters foodprocessingDuring storage of raw materialsDuring food processing (i.e. PAHs)During packagingDuring storage of the end-productDuring cookingDuring eating

10

8/2/2019 4 HRA Food 7 March 2012

11/99

Health Risk Assessment (HRA) Health Risk Assessment A method used to characterize

the magnitude and probability of an adverse effect fromexposure to a substance i.e. a chemical, physical ormicrobiological agent in food.

Risk Assessment - A scientifically based process consistingof the following steps: (i) hazard identification, (ii) dose-response assessment (hazard characterization), (iii)exposure assessment, and (iv) risk characterization

Aim: To evaluate whether the chemical, physical ormicrobiological agent has the potential to cause adverseeffects in humans based upon review of all available dataon toxicity and the biological mechanism that leads totoxicity

Risk = Hazard X Exposure 11

8/2/2019 4 HRA Food 7 March 2012

12/99

Definition: Adverse effect is defined as "...anybiochemical, physiological, anatomical,pathological, and/or behavioral change thatresults in functional impairment that mayaffect the performance of the whole organismor reduce the ability of the organism to

respond to an additional challenge . (USEPA)

12

8/2/2019 4 HRA Food 7 March 2012

13/99

Why do we need risk assessment?

Develop standards for levels of toxic chemicals orpathogenic microorganisms in food

Construct what -if scenarios to set priorities forcorrective action.

Articulate community public health concerns

Developing consistent public health expectationsamong different localities

13

8/2/2019 4 HRA Food 7 March 2012

14/99

Health Risk Assessment

ExposureAssessment

RiskCharacterization

Dose-Response

Assessment

HazardIdentification

14

8/2/2019 4 HRA Food 7 March 2012

15/99

15 of 27

Four Stages of a Health RiskAssessment

Stage 1: Hazard Identification Determine whether there is an actual threat to

our health from a contaminant by identifying thesubstance of concern and evaluating its inherenttoxicity

Stage 2: Dose-Response Assessment

Assess the response of living organisms at variousdoses of the substance

At what dose will we see effects? At what dosewill we see no effects?

8/2/2019 4 HRA Food 7 March 2012

16/99

Four Stages of a Health RiskAssessment

Stage 3: Exposure Assessment Determine the levels of exposure that are actually

occurring within the population of concern

Various routes of exposure How much is actually getting into the body

Stage 4: Risk Characterization

Information obtained from Stages 1-3 arecompiled to characterize the magnitude andprobability of an adverse health effect on thepopulation being exposed

16

8/2/2019 4 HRA Food 7 March 2012

17/99

17

8/2/2019 4 HRA Food 7 March 2012

18/99

Risk Analysis

Risk assessment How big is the risk? What factors control the risk?

Scientific process Risk Communication

How can we talk about the risk with affected individuals? Social and psychological process

Risk Management What can we do about the risk? Political process

18

8/2/2019 4 HRA Food 7 March 2012

19/99

Stage 1: Hazard Identification

Hazard Identification - The identification of biological, chemical, and physical agentscapable of causing adverse health effects andwhich may be present in a particular food orgroup of foods.

HAZARD: biological, chemical or physicalagent with the potential to cause an adversehealth effect (CODEX)

19

8/2/2019 4 HRA Food 7 March 2012

20/99

Hazard Identification What kinds of contaminants and foods are

involved? Contaminants of concern

Toxicity Persistence Mobility What are the health effects that this agent can

cause?

20

8/2/2019 4 HRA Food 7 March 2012

21/99

Hazard Identification

Determine the potential of an agent to causeadverse health effects Types of injury Conditions of exposure

These characterize the ' inherent toxicity ' of the substance /agent

21

8/2/2019 4 HRA Food 7 March 2012

22/99


Types of injury Systemic: liver and kidney damage, reproductive

toxicity, developmental toxicity affecting the fetus,

cancer Contact: skin irritation, rash, blisters or other

injury at the site of contact with the agent

22

8/2/2019 4 HRA Food 7 March 2012

23/99


Conditions of Exposure Conditions under which the various types of injury

occur and are based on duration of exposure

Acute : one or a few doses over a few days Subchronic : repeated exposures from 14-90

days duration Chronic : repeated exposures beyond one yearand up to a lifetime

23

8/2/2019 4 HRA Food 7 March 2012

24/99

Sources of Data

Human studies (epidemiology, case reports orvolunteer studies)

Toxicity studies conducted in laboratoryanimals

Alternative approaches, including use of invitro models such as cells cultures or tissueslices, and comparisons with structurally-related chemical substances

24

8/2/2019 4 HRA Food 7 March 2012

25/99

Evaluating the Inherit Toxicity of a Substance

Gather information from databases and scientific literature Epidemiological Studies : Frequency, distribution, and cause of

disease within a human population Best source of information because they are based on human

exposures and provide a clear and direct link between exposureand adverse effects

Limited , no data for new substances Accidents and Case Studies : Poisoning incidents Animal Studies : Used to predict the effects of substances on

humans based on their effects on animals because some animalsexhibit a response similar to humans (i.e. development al studies onrats and rabbits)

Cell Culture Studies : Short term tests used to observe the effects of substances on specific cell types and are often used to determinethe potential for genotoxicity.

Structure-Activity Relationship Analysis : Study the toxicity of substances with similar molecular structures

25

8/2/2019 4 HRA Food 7 March 2012

26/99

8/2/2019 4 HRA Food 7 March 2012

27/99

Stage 2: Dose-Response Assessment

Dose-Response Assessment - The determinationof the relationship between the magnitude of exposure (dose) to a biological, chemical orphysical agent and the severity and/or frequencyof associated adverse health effects (response) .

Qualitative and/or quantitative evaluation of thenature of the adverse health effects associated

with biological, chemical and physical agents Also referred to as Toxicity Assessment or Hazard

Characterization

27

8/2/2019 4 HRA Food 7 March 2012

28/99

Dose-Response Assessment To determine the capacity of an agent to cause harm, it is necessary to

quantify the toxicity (adverse effects) from exposure Aim: Obtain a mathematical relationship between the amount of a

toxicant involved in an exposure to the risk of an adverse outcome

Dose = amount of chemical/body weight

Possible responses

-no response-temporary response-permanent response-chronic functional impairment-death

28

8/2/2019 4 HRA Food 7 March 2012

29/99

8/2/2019 4 HRA Food 7 March 2012

30/99

Dose-Response Assessment Identify chemicals of concern To estimate the nature, severity and duration of the adverse effects

resulting from ingestion of a particular substance, need information on: fate and distribution of the chemical agent in the body The action of the chemical agent on tissues or functions in the body

Toxicokinetic studies Data on absorption, distribution, metabolism and elimination of

chemicals and major metabolites Effects of dose level and duration on the metabolism Comparative studies in human volunteers to support extrapolation of

animal toxicity data Rates of movement are determined by measuring the amount of chemical

in various body fluids and tissues, such as blood and urine at timedintervals after a controlled exposure

30

8/2/2019 4 HRA Food 7 March 2012

31/99

Dose-Response Assessment

Gather toxicity information for chemicals of concern Determine toxicity values for non-carcinogenic

effects Determine toxicity values for carcinogenic effects

31

8/2/2019 4 HRA Food 7 March 2012

32/99

8/2/2019 4 HRA Food 7 March 2012

33/99

8/2/2019 4 HRA Food 7 March 2012

34/99

8/2/2019 4 HRA Food 7 March 2012

35/99

Dose-Response Relationships

Definition : Endpoint is defined as an effect observedin a toxicity study

Definition : LD50 is the lethal dose for 50% of the testpopulation Used to rank the acute toxicity of a substance

among all other known substances.

Choose the study that displays the most sensitivespecies at the most sensitive endpoint

35

8/2/2019 4 HRA Food 7 March 2012

36/99

NOAEL/LOAEL

Definition : NOAEL (No-observed-adverse-effect level) is anexperimentally determined dose at which there was no statisticallyor biologically significant indication of the toxic effect of concern -the highest dose level at which there was no statistically or

biologically significant indication of the toxic effect of concern

Definition : LOAEL (Lowest-observed-adverse-effect-level ) is thelowest observed adverse effect level (in case that effects were seenat all dose level used in the key toxicity study)

NOEL for the most sensitive endpoint: is referred to as the 'criticalNOEL Used to determine safe exposure levels for humans If the dose range in a study does not the display a NOEL, it may

give a dose where there is a Lowest Observed Effects Level(LOEL). In this case the estimated NOEL is calculated by dividingthe LOEL by an ' uncertainty factor ' of 10

36

8/2/2019 4 HRA Food 7 March 2012

37/99


Animal tests are acute exposures at high doses dueto time constraints

Results are extrapolated down to environmentallevels

Typical dose-responsecurve

Response is usuallydeath

37

8/2/2019 4 HRA Food 7 March 2012

38/99


Effects at the low end cannot be seen clearlyon a linear scale

Typicallogarithmicdose-responsecurve

NOEL no observableeffects level

38

8/2/2019 4 HRA Food 7 March 2012

39/99


The dose of the substanceadministered in toxicitytests is usually expressedas the mass of thechemical usually inmilligrams per unit of testanimals body weight(usually kg)

LD50 dose that is lethal to50 % of the population

The smaller the LD 50 value,the more potent thechemical

39

8/2/2019 4 HRA Food 7 March 2012

40/99

Threshold effects (dose-response)

A threshold is levelbelow which noeffect occurs on the

population (curve B) Toxin A has nothreshold; even thesmallest amount has

some measurableeffect on thepopulation

40

8/2/2019 4 HRA Food 7 March 2012

41/99

Non-Carcinogenic Effects

Allowable Daily Intake - The US Food and DrugAdministration, the World Health Organization, andthe Consumer Product Safety Commission use the Allowable Daily Intake (ADI) to calculate permissiblechronic exposure levels. The ADI is determined by applying safety factors to the

highest dose in chronic human or animal studies that hasbeen demonstrated not to cause toxicity.

41

8/2/2019 4 HRA Food 7 March 2012

42/99

Acceptable daily intake (ADI)

- Acceptable Daily Intake (ADI): the amount of achemical to which a person can be exposed on adaily basis over an extended period of time(usually a lifetime) without appreciable risk(deleterious effect) on the basis of all knownfactors at the time

- ADI concept has often been used as a tool in

reaching risk management decisions (e.g.establishing allowable levels of contaminants infoodstuffs and water.)

42

8/2/2019 4 HRA Food 7 March 2012

43/99

Acceptable daily intake (ADI)

- ADI is derived from an experimentallydetermined "no-observed-adverse-effect level(NOAEL)

- ADI (human dose) = NOAEL (experimentaldose)/safety factor

43

8/2/2019 4 HRA Food 7 March 2012

44/99

Non-Carcinogenic Effects ( cont )

Minimum Risk Levels (MRLs), used by ATSDR,are similar to the EPA's Reference Dose (RfD)and Reference Concentration (RfC).

An MRL is an estimate of the daily humanexposure to a hazardous substance that is likely tobe without appreciable risk of adverse noncancerhealth effects over a specified duration of

exposure.

44

8/2/2019 4 HRA Food 7 March 2012

45/99


Reference Dose - The US Environmental ProtectionAgency has slightly modified the ADI. For the EPA,the acceptable safety level is known as the Reference

Dose (RfD) an estimate of a daily exposure level for humanpopulations, including sensitive subpopulations, that islikely to be without an appreciable risk of deleterioushealth effects during a lifetime

45

8/2/2019 4 HRA Food 7 March 2012

46/99


The position of the EPA is that humansare as sensitive as the most sensitivetest species unless other data are

available.

RfD = NOAEL or LOAELUF1 x UF2 x Ufx

46

8/2/2019 4 HRA Food 7 March 2012

47/99

8/2/2019 4 HRA Food 7 March 2012

48/99

Non-Carcinogenic Effects

Safety Factors (SF)/Uncertainty Factors (UF) x10 Human variability x10 Extrapolation from animals to humans x10 Use of less than chronic data x10 Use of LOAEL instead of NOAEL x10 Incomplete database

48

8/2/2019 4 HRA Food 7 March 2012

49/99

Margin of safety (MS) MS = NOEL/ estimated daily dose

Margin of safety must be greater than 100 or1000 to be acceptable because NOELestimation is inadequate

49

8/2/2019 4 HRA Food 7 March 2012

50/99

RfDs for the Chronic (Non-carcinogenic)Effects of Various Chemicals

Chemical Most Sensitive Organor Effect

RfD (mg/Kg/day)

Aldrin Liver 0.00003

DDT Liver 0.0005

Paraquat Chronic pneumonitis 0.0045

Fluoride Objectionable dentalfluorosis, cosmeticeffects

0.06

Styrene Red blood cell, liver 0.2Ethylene Glycol Kidney 2

50Source: Elements of Toxicology and Chemical Risk Assessment. Revised Ed. July 1988. ENVIRON Corporation. Washington DC

8/2/2019 4 HRA Food 7 March 2012

51/99

Carcinogenic Substances

Dose/Response Assessment for carcinogens isdifferent from non-carcinogen substances

No threshold whereby small doses elicit noresponse (i.e. carcinogens have an effect atany dose)

It is assumed that as the dosage of acarcinogen increases , the risk or probability of getting cancer also increases

51

8/2/2019 4 HRA Food 7 March 2012

52/99

Carcinogenic Effects

Mathematical models are used to extrapolatefrom the high doses used in animalexperiments to the low doses to which

humans are normally exposed in a chronicsetting.

52

8/2/2019 4 HRA Food 7 March 2012

53/99

53Source: ExtoxNet FAQs

8/2/2019 4 HRA Food 7 March 2012

54/99

8/2/2019 4 HRA Food 7 March 2012

55/99

C Ri k Sl F (P i

8/2/2019 4 HRA Food 7 March 2012

56/99

Cancer Risk Slope Factors (Potenciesfor Various Chemicals)

Chemical Carcinogen Slope Factor(mg/kg/day) -1

Aldrin 17

Carbon tetrachloride 0.13

Chromium IV 41

Dimethyl nitrosamine 51

nickel refinery dust 0.84Trichlorethylene 0.11

56

Source: Elements of Toxicology and Chemical Risk Assessment. Revised Ed. July 1988. ENVIRON Corporation. Washington DC., Asreported in EPA's Integrated Risk Information System (IRIS) as of November 1987

Slope Factors and RfDs

8/2/2019 4 HRA Food 7 March 2012

57/99

Slope Factors and RfDs

57

8/2/2019 4 HRA Food 7 March 2012

58/99

IRIS Database (Methylmercury)

USEPA Integrated Risk Information System (IRIS)Reference dose for chronic oral exposure of methylmercury: 1 x 10 -4 mg/kg-day

Critical effect : Developmentalneuropsychological impairment

Most extensive data available are onneurotoxicity, particularly in developingorganisms

The nervous system is considered to be the mostsensitive target organ for which there are datasuitable for derivation of an RfD

58

8/2/2019 4 HRA Food 7 March 2012

59/99

IRIS Database (Methylmercury)

Studies to determine whether there were dose-related effects on anumber of neuropsychological endpoints:

Seychelles Island study: 779 mother-infant pairs from a fish-eatingpopulation (Myers et al., 1995a-c, 1997; Davidson et al., 1995,

1998) neuropsychological endpoints, maternal-hair mercury levels

Faroe Island study: 900 mother-infant pairs (Grandjean et al., 1997) Cord-blood mercury, maternal-hair mercury, specific behaviours

Identified methylmercury-related developmental neurotoxicity New Zealand study (Kjellstrom et al., 1989, 1986)

Children were assessed on a number of neuropsychologicalendpoints

59

8/2/2019 4 HRA Food 7 March 2012

60/99

ATSDR Database

Agency for Toxic Substances and Disease Registry (ATSDR), based inAtlanta, Georgia, is a federal public health agency of the U.S. Departmentof Health and Human Services.

Public health statement on chemicals Physical and chemical properties Fate of the chemical when it enters the environment Possible exposure routes Distribution and elimination from the body Health effects (acute and chronic exposure)

Effect on sensitive populations (i.e. children, pregnant women) Medical tests to determine exposure Toxicological information Guidelines and regulations limits on the concentrations in air, water,

food, workplace environment, body loadings60

8/2/2019 4 HRA Food 7 March 2012

61/99

Stage 3: Exposure Assessment

Exposure Assessment - The qualitative and/orquantitative evaluation of the likely intake of biological,chemical, and physical agents via food as well asexposures from other sources if relevant.

Determine actual levels of exposure and absorption of a contaminant among the population of exposedindividuals Concentration of the contaminant

Frequency and duration of exposure Actual absorption is determined by toxicological studies

61

8/2/2019 4 HRA Food 7 March 2012

62/99

Exposure Assessment

Exposure assessment involves describing thenature and size of various populationsexposed to a chemical agent, and the

magnitude and duration of their exposures .

Without exposure there can be no toxicity (i.e.likelihood of exposure through consumptionof food)

62

8/2/2019 4 HRA Food 7 March 2012

63/99

Steps In Exposure Assessment

Characterization of exposure setting Identification of exposure pathways Quantification of exposure

63

8/2/2019 4 HRA Food 7 March 2012

64/99

Characterize The Exposure Setting

What are the situations which could lead toexposure?

What would lead to high exposure, mediumexposure, and low exposure?

Describe the situations for the variousexposure scenarios.

What is the population exposed?

64

8/2/2019 4 HRA Food 7 March 2012

65/99

8/2/2019 4 HRA Food 7 March 2012

66/99

Exposure Pathways

Oral exposure Dermal exposure Inhalation exposure Uptake from these routes of exposure differ based

upon the chemical and physical properties of thetoxicant as well as the permeability of the surface atthe site of absorption (i.e. lung vs. skin vs. GI tract)

The absorbed dose is an average of the daily intakevalue for one route

The absorbed dose for all three routes of exposure areadded together for a total average absorbed dailydose (AADD)

66

8/2/2019 4 HRA Food 7 March 2012

67/99

Exposure Pathways

Contaminated food ingestion of contaminated fishtissue, vegetables and fruit grown in contaminatedsoil or covered with contaminated dust, meat, anddairy products

Contaminated breast milk nursing infants whosemothers were exposed to highly toxic lipophiliccontaminants

Contaminated groundwater ingestion (drinkingwater), dermal contact (bathing), and inhalation of volatile organic compounds (showering)

67

8/2/2019 4 HRA Food 7 March 2012

68/99

Exposure Pathways ( cont )

All potential exposure pathways areconsidered with an analysis of the contaminants released the fate and transport of the contaminants the population exposed to the contaminants

68

8/2/2019 4 HRA Food 7 March 2012

69/99

Sensitive Populations

Some sections of the population are at greaterrisk due to exposure of the chemical hazardthan others: Elderly Infants and children (exposure for children is

higher under the same conditions as adults due to

differences in body weight) Immunocompromised Pregnant women

69

Exposure:

8/2/2019 4 HRA Food 7 March 2012

70/99

where ADD = average daily dose or intake (mg/kg/day)

C = concentration of the contaminant in a specifiedmedia (mg/kg) IngR = ingestion rate (mg/day) EF = exposure frequency (days/yr)

ED = exposure duration (years) BW = average body weight (kg) AT = averaging time (days) CF = conversion factor (1x10 -6 kg/mg)

C x IngR x EF x ED

BW x AT

x CFADD =

pAverage dailydose byingestion

70

8/2/2019 4 HRA Food 7 March 2012

71/99

where SA = surface area of the skin that contacts the

contaminant (cm2

) AF = skin adherence factor soil (mg/cm 2) ABS = dermal absorption factor (chemical specific)

(unitless)

C x SA x AF x ABS x EF x ED

BW x ATx CFADD =

Average daily dose by dermal absorption

71

Exposure factors for a child and an

8/2/2019 4 HRA Food 7 March 2012

72/99

Exposure factors for a child and anadult (US EPA, 1997a)

Exposure factors Child Adult Ingestion rate, IngR (mg/day) 200 50

Inhalation rate, InhR (m3 /day) 7.6 20

Exposed skin area, SA (cm 2) 2800 a 5700 a

(face, forearms, hands, lower legs, 50th percentile)

Skin adherence factor, AF soil (mg/cm 2 /day) 0.2 0.07

Body weight, BW (kg) 15 70Exposure frequency, EF (days/yr) 350 350Exposure duration, ED (yr) 6 6

Averaging timeFor noncarcinogens, AT (days) = (ED x 365 days/yr)For carcinogens, AT (days) = (70 yr x 365 days/yr)

219025550

219025550

a EPA, 2001

72

8/2/2019 4 HRA Food 7 March 2012

73/99

Quantification of Exposure

General statement Concentration of the chemical x Intake x Retention

Factor x Length of Exposure

For Noncarcinogens Maximum Daily Dose (MDD) or ADD

For Carcinogens Lifetime Average Daily Dose (LADD)

73

8/2/2019 4 HRA Food 7 March 2012

74/99

Lifetime Average Daily Dose

= Concentration of a Chemical Chemical xContact Rate x Contact Fraction x ExposureDuration

________________________________Body Weight x Lifetime

74

LADD Calculation Example

8/2/2019 4 HRA Food 7 March 2012

75/99

LADD Calculation Example

75

8/2/2019 4 HRA Food 7 March 2012

76/99

LADD Calculation Example ( cont )

76

8/2/2019 4 HRA Food 7 March 2012

77/99

Important Note to Calculation of LADD

Be aware of the units used for consumption of the chemical (How often the chemical isobtained).

You may need to back calculate the number tomg/kg/day averaged over 70 years (a lifetime) If the units are already in mg/kg/day, then no back

calculation is needed, if units are mg/kg/month, thenyou only need to calculate back from months to days.

77

8/2/2019 4 HRA Food 7 March 2012

78/99

8/2/2019 4 HRA Food 7 March 2012

79/99

8/2/2019 4 HRA Food 7 March 2012

80/99

Stage 4: Risk Characterization

Final phase of the heath risk assessmentprocess Combines the information from

Hazard identification Dose-response assessment Exposure assessment

Determines the probability of an adverseeffect to a human population by a toxicsubstance and outlines permissible exposurelevels from which standards of exposure areset.

80

Risk Characterization

8/2/2019 4 HRA Food 7 March 2012

81/99


Quantify risks from individual chemicals

Quantify risks from multiple chemicals

Combine risks across pathways

Assess and present uncertainty

81


8/2/2019 4 HRA Food 7 March 2012

82/99


Exposure Assessments and Dose-response Assessments are integrated togive a probability of a negative effect. Risk characterization is conducted for

individual chemicals and then summed formixtures of chemicals Additivity is assumed.

82

8/2/2019 4 HRA Food 7 March 2012

83/99

Characterizing Risk for Non-carcinogens

For Non-carcinogenic chemicals: A hazard quotient (or noncancer toxic risk) , HQ , is

determined by dividing the average daily dose for a givenexposure pathway by the reference dose, RfD:

Average daily doses < RfD (i.e. HQ 1) may result inincreasing probability that adverse health effects will occur(US EPA, 1993).

RfD ADD HQ

83

8/2/2019 4 HRA Food 7 March 2012

84/99


Permissible concentrations for chemicals inthe environment are calculated based on bodyweight, intake, frequency and duration of

exposure, and the RfD Permissible concentration =

RfD x Body Weight______

Intake x Duration x Frequency

84

f

8/2/2019 4 HRA Food 7 March 2012

85/99


The Risk of exposure for non-carcinogenic effectsis expressed as a Margin of Exposure (MOE).

MOE = __ NOEL___

EXPOSURE A MOE over 10, after extrapolation to humans, is

considered low risk. There the No Effects Level

(NOEL) is a lot higher than the actual exposureoccurring among the most exposed individualswithin the target population.

85

h k f

8/2/2019 4 HRA Food 7 March 2012

86/99


It is also assumed that the toxic risks due to potentiallyhazardous substances are additive, therefore the HQ for each of contaminant for a given exposure route can be added togenerate the hazard index (HI) , as follows:

where i represents the different contaminants HI can also be calculated for a certain contaminant by summing

the HQs of the contaminant for different exposure pathways. If HI>1, this indicates the probability of a noncarcinogenic

adverse effect, otherwise, it is assumed to be negligible.

HI = HQ i

86

Qualitative descriptions for noncancer

8/2/2019 4 HRA Food 7 March 2012

87/99

Qualitative descriptions for noncancertoxic health risks (ATSDR, 1995b)

HazardQuotient

(HQ)

Qualitativedescriptor

Lifetime cancer risk (Risk)

1 minimal 1/1,000,000

>1-5 low> 1/1,000,000 to

< 1/10,000

>5-10 moderate 1/10,000 to 1/1,000>10 high 1/1,000 - < 1/10

1/10

87

Ch i i Ri k f C i

8/2/2019 4 HRA Food 7 March 2012

88/99

Characterizing Risk for Carcinogens

Carcinogens pose a risk at any dose and the probabilityof developing cancer increases with dose thus cancer risk can range from being negligibly low at low

dose ranges or unacceptably high at high dose ranges

Virtually Safe Dose This was initially defined (1961) as 1 extra cancer death

per 100 million people exposed Found unenforceable by FDA in 1977 Currently the EPA uses 1 extra cancer death per 1 million

people exposed . California uses 1 extra death per 100,000 people exposed

88

Ch i i Ri k f C i

8/2/2019 4 HRA Food 7 March 2012

89/99

Characterizing Risk for Carcinogens

For Carcinogenic Chemicals

Risk = Lifetime Average Daily Dose (LADD) x Slope Factor

Units for LADD are mg/kg/day Units for Slope Factor are (mg/kg/day) -1

Therefore units cancel and you get a unit-less number This unit-less number represents the increase in the number

of cancer cases per year due to chemical

89

Qualitative descriptions for lifetime

8/2/2019 4 HRA Food 7 March 2012

90/99

Qualitative descriptions for lifetimecancer risk (ATSDR, 1995b)

Lifetime cancer risk

(Risk) Qualitative descriptor

1/1,000,000 very low and acceptable

> 1/1,000,000 to < 1/10,000 low

1/10,000 to 1/1,000 moderate1/1,000 to < 1/10 high

1/10 very high

90

E l

8/2/2019 4 HRA Food 7 March 2012

91/99

Example

Calculate the risk assuming an LADD of 0.002 mg/kg bodyweight/day and a Slope factor (potency) of Aldrin at 17 (mg/kgbody weight/day) -1

= LADD x Slope factor= 0.002 x 17= 0.034= one in 29

This is a very high value, statistically, one in 29 people exposed willget cancer from the lifetime average daily dose of 0.002 mg/kg/day.Since we can't change the potency of Aldrin we must determinewhat daily dose over a lifetime would give us a maximum of one ina million risk:

= one in 1,000,000 / Slope factor= 0.000001 / 17= 0.00000006 LADD

91

Ri k A t

8/2/2019 4 HRA Food 7 March 2012

92/99

Risk Assessment Provides an effective framework for determining the relative urgency of problems and the

allocation of resources to reduce risks

Risk assessment is used routinely to make decisions by:

FDA (Food and Drug Administration)

OSHA (Occupational Safety and Health Administration)

EPA (Environmental Protection Agency)

These agencies use risk assessment in a variety of situations:

Setting standards for chemical or pathogens in water/food

Assessing risk from GEMS (genetically engineered microbes)

Conducting baseline analysis of contaminated sites to determine need for cleanup

Cost/benefit analysis

Development of cleanup goals

Constructing what if scenarios

Evaluation of existing and new technologies for pollution prevention and control

Articulation of public health concerns

92

P bl ith Ri k A t

8/2/2019 4 HRA Food 7 March 2012

93/99

Problems with Risk Assessment

A basic problem with human health risk assessment is the sparseness anduncertainty of the scientific data

Variability within dose-response curves There is uncertainty associated with each step of the assessment. The

various sources of uncertainty include:

-Extrapolation from high to low doses

-Extrapolation from animal to human responses

-Extrapolation from one route of exposure to another limitations of

analytical methods-Estimates of exposure

-Vulnerable populations that may be impacted differently than the

general population by the outcome of a risk analysis

93

8/2/2019 4 HRA Food 7 March 2012

94/99

94

Risk Communication and Management

8/2/2019 4 HRA Food 7 March 2012

95/99

g

Identify decisions and immediate actions Define goals

Remediation Management

Address considerations Social Economic Political Technical

95

F d S

8/2/2019 4 HRA Food 7 March 2012

96/99

Food Surveys

Dietary surveys: estimate actual food intakes invarious subgroups of the population Takes into account such factors as age and ethnic

background

Market basket surveys: measure the amount of achemical (i.e. pesticide residues) and otherselected contaminants in freshly prepared andready-to-eat foodstuffs

Detailed theoretical daily intake calculations arecarried out when there is a potential for highexposure levels in humans

96

Risk Assessment Studies (Centre for

8/2/2019 4 HRA Food 7 March 2012

97/99

(Food Safety)

Risk Assessment Studies DateThe first Hong Kong Total Diet Study: Inorganic Arsenic Feb 2012

The first Hong Kong Total Diet Study: Dioxins and Dioxin-likePolychlorinated Biphenyls (PCBs)

Dec 2011

Polybrominated Diphenyl Ethers in Foods of Animal Origin April 2009

Mercury in Fish and Food Safety April 2008

Dietary Exposure to DDT of Secondary School Students July 2006

Polycyclic Aromatic Hydrocarbons (PAHs) in Barbecued Met July 2004

Dietary Exposure to Heavy Metals of Secondary School Students Oct 2002

Dietary Exposure to Dioxins of Secondary School Students Oct 2002

Source: http://www.cfs.gov.hk/english/programme/programme_rafs/programme_rafs_fc_01.html97

Food Safety Management Systems

8/2/2019 4 HRA Food 7 March 2012

98/99

Food Safety Management Systems

Health risk assessment Hazard-Analysis Critical Control Point (HACCP)

a risk management methodology used by the food andrelated industries for the control of food safety hazards toacceptable risk levels

ISO 22000 a generic food safety management system standard that

defines a set of general food safety requirements thatapply to all organizations in the food chain

Codex Alimentarius WHO and FAO have developed risk-based approachesfor the management of public health hazards in food

98

Useful Websites

8/2/2019 4 HRA Food 7 March 2012

99/99

Useful Websites

United States Environmental Protection Agency(USEPA)http://epa.gov/riskassessment/basicinformation.htm#risk

USEPA Integrated Risk Information System (IRIS)http://www.epa.gov/ncea/iris/help_ques.htm#whatiris

Agency for Toxic Substances & Disease Registry (ATSDR)http://www.atsdr.cdc.gov/

ExtoxNet FAQshttp://extoxnet.orst.edu/faqs/risk/riskhome.htm
http://epa.gov/riskassessment/basicinformation.htmhttp://epa.gov/riskassessment/basicinformation.htmhttp://www.epa.gov/ncea/iris/help_ques.htmhttp://www.atsdr.cdc.gov/http://extoxnet.orst.edu/faqs/risk/riskhome.htmhttp://extoxnet.orst.edu/faqs/risk/riskhome.htmhttp://extoxnet.orst.edu/faqs/risk/riskhome.htmhttp://www.atsdr.cdc.gov/http://www.atsdr.cdc.gov/http://www.atsdr.cdc.gov/http://www.epa.gov/ncea/iris/help_ques.htmhttp://www.epa.gov/ncea/iris/help_ques.htmhttp://epa.gov/riskassessment/basicinformation.htmhttp://epa.gov/riskassessment/basicinformation.htmhttp://epa.gov/riskassessment/basicinformation.htm

4 HRA Food 7 March 2012

Documents

Transcript of 4 HRA Food 7 March 2012