How to estimate the health impact for restriction process with a special focus on estimation of the number of exposed people

Transcription

1 How to estimate the health impact for restriction process with a special focus on estimation of the number of exposed people SEAC Training Helsinki, 29-30/06/2009 Kimmo Louekari Unit B4, Evaluation Disclaimer: This presentation does not represent ECHA s position on the issues covered nor is it based on expert consultation within ECHA. The presentation includes an introduction to some of the basic concepts of toxicology and risk assessment. It is also a preliminary suggestion of the author on how results of risk assessment process could be used for the Human Impact Assessment under the restriction processes of REACH.

2 History of restrictions It seems that so far the justification of the restriction of chemicals has come from Severity of the health effects; e.g. asbestos, lead, brominated biphenyl Public perception of the risks; lead, mercury, organotin compounds, endocrine disrupters, PCBs Availability of substitutes; solvents, cadmium -- Rather than from a formalized Health Impact Assessment (HIA)

3 HIA in view of economists A human life is worth $200,000 if it is saved using the 1979 safety requirements on trihalomethanes in drinking water but worth $6.3 trillion if saved using 1990 rules for handling the hazardous waste of woodpreserving chemicals. Re: Nobelist Kenneth Arrow and co-authors (Science April 1996)

4 Why HIA has not developed more? People working in health care are usually not too keen to consider/estimate the price of human life; it might even be regarded as unethical Saving lives, i.e. minimization of obvious risks (asbestos, passive smoking) is probably thought to be worthwhile even if the costs exceed the benefits - but not in any cost Btw, many toxicologists are medical doctors

5 Aim of the health impact assessment (HIA) To be able to conclude e.g. that with an estimate of risk, e.g. that 5 people of million will get cancer at a specific exposure level and with an estimate of the size of population e.g. 50 million, an impact assessment can be generated, i.e. 250 people will get cancer. Estimates like this include several layers of uncertainty! Cancer and most other health impacts can be monetized, if necessary: e.g. WTP, loss of (working) years, health care costs. What is needed to provide the estimates of impact?

6 Starting point of HIA Types of the risk assessment outcomes Statistical risk, e.g. cancer risk 5 cases/1million exposed Risk characterization ratio, i.e. exposure/dnel: e.g. RCR is above one in a specific scenario Qualitative assessment: e.g. skin exposure may case sensitisation Each risk assessment result has uncertainties and limitations Recommendation: Uncertainties should be expressed, even quantified when possible. This should be applied to the exposure modelling tools as well.

7 Structure Concepts Examples of risk assessment How to estimate the number exposed people HIA depends on the RA type Conclusions

8 How to identify toxicity In hazard assessment the aim is to describe the intrinsic properties, i.e. toxicity of chemicals. Understanding the intrinsic hazardous properties can be based on animal or in vitro tests, on human data, e.g. clinical cases or epidemiological studies, and on nontesting methods to estimate how much of the chemical is necessary to produce the toxic response in human (or to obtain DNEL. i.e. a safe level) It is necessary to understand the toxic properties of a chemical to ensure that it can be used safely.

9 Distinction of hazard and risk Hazard refers to the intrinsic toxic properties of the substance/chemical Risk refers to the likelihood that there will be toxic effects in the human population Risk can not be assessed without data on the exposure of the relevant populations In REACH, toxicity data and exposure data are combined in Exposure Scenarios

10 From risk assessment (RA) to impact assessment (HIA) (1) The outcome of the RA can be An estimate of the likelihood or/and severity of the effect e.g. 5 cases of specific cancer may occur in 1 million exposed persons Risk Characterization Ratio i.e. Exposure divided by DNEL/DMEL Dose response curve with respective NOAEL and LOAEL, or Qualitative effects, e.g. sensitisation or skin corrosion may occur in a specific use scenario

11 From RA to HIA (2) In HIA we ask, e.g. How many people are exposed/affected How much will the effect (cancer, skin corrosion) reduce their quality of life (NB. reversibility of an effect should be addressed) What would be the societal and economic costs of the overall effect How should the health impact be valued

12 Example: Health effects and RC of benzene an average exposure of 1 ppm over a working lifetime of 45 years resulted in estimations which span several orders of magnitude. From cases per thousand exposed individuals to a range of cases per thousand. Re: Two meta-analysis based on epidemiological data

13 Example: HIA on cadmium, indirect and other exposures Main sources of exposure are the diet and smoking Phosphate fertilizers are the major input to the human food chain Increased absorption has a major impact on the exposure There are groups in the general population, for whom the margin of safety is relatively small The main health effects are decreased bone density (fractures) and proteinuria The starting points of the assessment were known concentration of cadmium in many important food items and epidemiological studies and WoE, i.e. exceptionally large data base

14 Exposure to cadmium in Finland, corresponding urinary levels of cadmium and size of population groups. Sources of exposure and risk factors Average dietary intake 7.9 µg/day Predicted average dietary intake (10.0 µg/day) + heavy smoking ( 20 cigarettes daily) High dietary intake + increased absorption + heavy smoking Urinary Cd concentration (µg/l) Size of subpopulation in Fin-land ?

15 Health effects of cadmium and the respective urinary level of cadmium (U-Cd) HEALTH EFFECTS Increased urinary excretion of RBP, NAG, β2-m, AA and creatinine Prevalence of tubular proteinuria increases by 10% Increased urinary excretion of calcium Decreased bone density and increased risk of fractures in women Critical urinary level of Cd µg/l 2 µg/l µg/l 1.16 µg/l RBP=retinol binding protein; NAG=N-acetyl-b-glucosamidase; β2 -M = urinaryβ2 -microglobulin; AA= urinary aminoacids; AAP= alanine aminopeptidase

16 Example of exposure data - benzene Exposure scenario Duration and Inhalation Dermal Freq. of Shift average Shift average activities [mg/m3] [mg/person/d ay] 3) Production of perfumes, use of benzene shift length (assumed), daily 84 (1) (90th percentile) 420 (EASE) 26 ppm 4) Distribution of gasoline, marine, road, rail 1% benzene shift length (assumed), daily 6.8 (90th percentile) 4.2 (EASE) 2.1 ppm

17 Health effects and RC of benzene an average exposure of 1 ppm over a working lifetime of 45 years resulted in estimations which span several orders of magnitude. From cases per thousand exposed individuals to a range of cases per thousand. (Two meta-analysis based on epi data)

18 To assess the impact, both the type of risk and size of the exposed population have to be known Type of risk=adversity/severity of the effect and likelihood of the effect at certain level of exposure

19 Size of exposed populations: main sources of data Workers: Job-Exposure Matrices Consumers: Product type, Market information, Professional associations Indirect exposure via the environment: Dietary surveys, environmental monitoring data

20 JEM What is it Matrix that associates exposure or certain level of exposure to a job title Number of exposure workers can be retrieved from JEMs, however, only for a limited number of chemicals

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22 How a JEM is created, an example FINJEM was designed by a team of scientists experienced in assessing physical, chemical, ergonomic, and psychosocial exposures. Agents and agent-specific minimum criteria of exposure were first determined to improve the consistency of assessment work. Summarized data on Finnish industrial hygiene measurements, interview surveys and workforce surveys were next entered in the database. Fourteen experts from Finnish Occupational Health Institute, then assessed prevalences and levels of exposure based on the data and their own experience. Premises of estimates and bibliographic references were documented in the same database.

23 FINJEM: Sources of Data Number of workers per sector/job title Register of exposure measurements Statistical analysis (mean, GM, GSD etc) Surveys, interviews Statistical analysis (prevalence, index) Expert judgement Finnish Job Exposure Matrix (FINJEM) Lea Aalto FIOH

24 FINJEM has three dimensions: occupations (N 311), agents (N 74) and time periods (N 4) FINJEM can produce information on the numbers of exposed workers by agent, occupation and level of exposure for national hazard surveillance purposes FINJEM has also been used as a job-exposure matrix to generate exposure assignments for large epidemiologic studies in which the data do not allow exposure assessment at individual level. FIOH is planning to update FINJEM every three years.

25 Chemical agent Number of exposed % of the employed Mean level of exposure Detergents (dermal exposure) 400, Carbon monoxide (CO) 160, ppm Environmental tobacco smoke (ETS) 150,000 7 Iron fume or dust 100, mg/m3 Volatile sulfur compounds 80, ppm Herbicides 60, mg/m3 Lead fume or dust 50, mol/l Polycyclic aromatic hydrocarbons (PAH) 45, µg/m3

26 Consumers how to estimate the size of exposed populations Product type may determine the approximate number of exposure people: chemicals in textiles, paints, furniture and building materials would cause some level of exposure in most part of the population Specialty chemicals with limited uses normally expose small group of the population

27 What is indirect exposure via the environment It refers to residues or contaminants of chemicals in our, food, drinking water or in ambient air. To a large extent releases and environmental fate determines the level of exposure. Often the whole population is exposed via this route, especially when the substance is persistent and (bio)accumulative. Methyl mercury, DDT, cadmium, brominated flame retardant several pesticides etc. In case the fate and distribution of the substance is such a that only local or regional contamination is foreseen, the exposed population is also limited and much smaller.

28 Types of RA 1. Statistical risk or risk ratio 2. RCR based on DNEL 3. Qualitative data

29 How to proceed from RA to HIA depending on the effect 1. Statistical risk or risk ratio Risk ratio (5 cases/1 million) obtained from an epidemiological study is relatively reliable, but the exposure data may be poor. i.e expo categories only Current exposure levels should be compared with the levels prevailing when the epidemiological data was generated JEM may give an estimate of exposed population, special surveys are made in particular cases, e.g. passive smoking in general population, radon in ground water, arsenic in drinking water In case JEM data is not available for that substance (exposure read-across could be examined In conclusion, it might be possible to obtained order of magnitude type HIA, but there are a probably less than 100 carcinogens with sufficient data

30 How to proceed from AR to HIA depending on the effect 2. RCR based on DNEL (1) RCR uses DNEL, which incorporates several assessment factors. AFs are indications/measures of uncertainty, aiming at conservative/precautionary estimate. Replacing AFs with more realistic data would be necessary RCRs are scenario-specific and each scenario concerns a limited number of people: job title and sector specific information can be used, e.g. there might be about 500 workers using a special paint containing solvents toxic to central nervous system (CNS)

31 2. RCR based on DNEL (2) In conclusion: after reconsideration of the AFs and obtaining an estimate of the number of people within a specific ES, it is possible to prepare the HIA For the future development: How to cooperate wth the national maintainers JEM to obtain relevant data

32 3. Qualitative data Effect assessment is qualitative e.g. for irritant, corrosive and sensitising substances and some carcinogens with limited data hairdressers might be exposure to a respiratory sensitizer. (In case they get sensitizer, they normally have to change their job.) Quantitative HIA is difficult because only a number of potential cases of disease can be assessed.

33 Hazard categories in the Qualitative assessment, in Part E of the ctgd Hazard category High hazard: cat 1 and 2 carcinogenic and mutagens, strong corrosives and sensitizers Moderate hazard: cat 3 carcinogens, corrosives, serious damage in the eyes Low hazard: irritant Example of RMMs Very high level of containment, closed system, negative pressure in equipment, control staff entry Containment, segregation of the emitting process, good general ventilation Minimisation of manual phases/work tasks

34 Carry over of the HH risk management RMMs made for human health may have environmental consequences, which in many cases would be difficult to quantify E.g. dry cleaning chemicals: from toxic solvents (perchloroethylene) to fluorocarbons (ozone depletion) and then to less toxic solvents Reduction of uses and releases of cadmium, both health and environmental benefits

35 The applicant of authorization may claim that production/trade/uses of a substance are worth of 100 million How can we/ca respond and build the case? Toxic effect, exposure levels and number of people exposure need to be known to assess the impact Plus valuation of the health effects in question

36 Conclusions There has been no systematic approach or explicit need to perform HIA for chemicals REACH starts a new era Different types of RA outcomes require different approach/methodology of HIA SEAC could recognise these RA starting points in its work and take into account their limitations There are sources of data to estimate the number of people exposure to a chemical; collaboration is necessary to make the use to these data sources operational