Hämeenkyrö MSWI risk assessment: Dioxin

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See the main page of this assessment: Hämeenkyrö MSWI risk assessment: General

Dioxin emissions in Hämeenkyrö

Scope
Dioxin emissions in Hämeenkyrö. Annual dioxin emissions in the area of Hämeenkyrö municipality from the relevant sectors (involving both current sources, as well as the possible future sources considering the different decisions on the MSWI).

Description

The name dioxin is used for the family of structurally and chemically related polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and certain polychlorinated biphenyls (PCBs). Some 419 types of dioxin-related compounds have been identified, and about 30 of these are considered to have significant toxicity.

Dioxins are produced unintentionally as by-products of many chemical industrial processes and of all combustion processes. Sources include metal industry, power plants, industrial combustion plants, small combustion units (mostly domestic), waste incineration, road transport and mineral products production.

Total dioxin emissions are usually reported in toxic equivalency values (TEQ), which enables comparison of the toxicity of different combinations of dioxins and dioxin-like compounds. A TEQ is calculated by multiplying the actual grams weight of each dioxin and dioxin-like compound by its corresponding toxic equivalency factor (TEF) and then summing the results. The number that results from this calculation is referred to as grams TEQ.

(Comment: The emissions sources of dioxin are known pretty well. Although it is unlikely that these factories have direct dioxin measurements, emission estimates for the sources of this size should be available. You should ask Juhani Ruuskanen (KuY) or Päivi Ruokojärvi (KTL)).

References


Definition

Inputs = Kyro gas power plant, MSWI in Hämeenkyrö, biofuel power plant in Hämeenkyrö, landfills, fires on landfill areas, waste transport

Index = Possible dioxin sources in Hämeenkyrö: R↻

  • Currently:
    • the local gas power plant
    • landfills, traffic
    • domestic combustion
    • (cardboard factory, sawmill)
  • Future:
    • Municipal solid waste incinerator
    • biofuel power plant

Emission factors for different processes (UNEP 1999a):

  • Municipal solid waste incineration (µg TEQ/t MSW burned)
    • Low technology combustion, no APC system: air 3500, fly ash 0, bottom ash 75
    • Controlled combustion, minimal APC: air 350, fly ash 500, bottom ash 75
    • Controlled combustion, good APC: air 30, fly ash 200, bottom ash 7
    • High technology combustion, sophisticated APC system: air 0.5, fly ash 15, bottom ash 1.5
  • Energy production (µg TEQ/TJ)
    • Natural gas fired power boiler: 0.5
    • Mixed biomass fired power boiler: air 500, residue NA
    • Clean wood fired power boiler: air 50, residue 15
    • Domestic energy production (µg TEQ/TJ)
      • Household heating and cooking (contaminated wood/ biomass fired stoves): air 1500, residue 2000
      • Virgin wood/ biomass fired stoves: air 100, residue 20
      • Domestic heating (coal fired stoves): air 70, residue 5000
      • Domestic heating (Oil fired stoves): air 10, residue NA
      • Domestic heating (natural gas fired stoves): air 1.5, residue NA
  • Transport (µg TEQ/t of fuel burned)
    • 4-stroke engines
      • leaded fuel without catalyst: air
      • unleaded fuel without catalyst: air 0.1
      • unleaded fuel with catalyst
    • Diesel engines: air 0.5
  • Production of pulp and paper products
  • Emissions from landfills (pg TEQ/L of leachate released)
    • Hazardous wastes: air 0, water 200
    • Non-hazardous wastes: air 0, water 30
    • Landfill fires (µg TEQ/t of material burned): air 1000

Unit

g I-TEQ/a

Result

Intake fraction for dioxin emissions from Hämeenkyrö

Scope
Intake fraction for dioxin emissions from Hämeenkyrö. Emission from a high stack in Hämeenkyrö, exposed population anywhere in Europe. Long-term exposure, includes accumulation in food chain. 'Dioxin' means TEQs of all 17 toxic congeners, not only TCDD.

Description

Intake fraction (iF) means the fraction of an emission that is finally inhaled or ingested by a target population. The exposure to dioxins occur after a multistep process. First, dioxins are emitted into the atmosphere often due to a combustion process. Dioxins are persistent molecules and can transfer hundreds or thousands of kilometres before depositing to water, vegetation, or soil. It absorbs tightly onto surfaces, and therefore it is rather inert if adsorbed to soil. However, when dioxins deposit to water, they enter the aquatic food chain and end up to fish. When they deposit on grass fields or crop, they typically enter the cattle feed and then milk or meat. Because of this long process including accumulation in food chain, the dioxin exposure of a population is mostly derived from other than local sources.

Margni and coworkers have estimated an iF for Western European sources. The iF is approximately 3.5*10-3 for emissions of dioxin in Western Europe. This iF compares well to the traditional non-spatial multi-media/-pathway model predictions of 3.9*10-3 for the same region and to 2*10-3 for the USA. Approximately 95% of the intake from Western European emissions occurs within the same region, 5% being transferred out of the region in terms of food contaminants and atmospheric advective transport. (Margni et al., 2004) However, when the emission source is in the North-Eastern corner of Europe like Hämeenkyrö is, the population exposed is likely smaller than on average, especially because the predominant wind direction is from southwest and away from densely populated areas. Therefore, the published value is likely an overestimate.

References

  • Margni M, Pennington DW, Amman C, Jolliet O. Evaluating multimedia/multipathway model intake fraction estimates using POP emission and monitoring data. Environ Pollut. 2004;128(1-2):263-77.
  • Bennett DH, Margni MD, McKone TE, Jolliet O. Intake fraction for multimedia pollutants: a tool for life cycle analysis and comparative risk assessment. Risk Anal. 2002 Oct;22(5):905-18.

Definition

Comes from literature (Margni et al., 2004).

Unit

- (dimensionless)

Result

3.5*10-3

Baseline dioxin exposure in Hämeenkyrö

Scope
Baseline dioxin exposure in Hämeenkyrö inhabitants. The daily intake and the adipose tissue concentration of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and biphenyls (PCBs) in Hämeenkyrö population.

Description

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, "dioxins") are ubiquitously present, stable and persistent environmental contaminants. They are fat soluble and thus tend to bioaccumulate in tissue lipid and in the food chain. More than 90 % of the average human intake of dioxins originates from food, especially food of animal origin. In Finland the main source is fish, whose contribution is 72-94 % of the total PCDD/F intake via food.

Here we will use the daily PCDD/F intake estimated for the Finnish population in average as a starting point. In addition, the other variable in this model, "Dioxin emissions in Hämeenkyrö", may affect the estimate of baseline dioxin exposure in Hämeenkyrö.

For the adipose tissue PCDD/F concentration the value estimated for the general population living in Finnish inland is used.

It is noteworthy, that some subgroups within society, such as nursing babies and people consuming lot of fish may be more highly exposed to dioxins than the average people.

PCBs, another group of persistent environmental contaminants, were included as they behave similarly in the food chain and have partly similar health effects as dioxins.R↻

References

  • Holtta P, Kiviranta H, Leppaniemi A, Vartiainen T, Lukinmaa PL, Alaluusua S. Developmental dental defects in children who reside by a river polluted by dioxins and furans. Arch Environ Health. 2001 Nov-Dec;56(6):522-8.
  • Kiviranta H, Ovaskainen ML, Vartiainen T. Market basket study on dietary intake of PCDD/Fs, PCBs, and PBDEs in Finland. Environ Int. 2004 Sep;30(7):923-32.
  • Kiviranta H, Tuomisto JT, Tuomisto J, Tukiainen E, Vartiainen T. Polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in the general population in Finland. Chemosphere. 2005 Aug;60(7):854-69.
  • Tuomisto et al. 1999. Synopsis on dioxins and PCBs. Publications of the National Public Health Institute B17/1999.

Definition

Comes from literature.

Unit

  • Daily intake: WHO-TEQ pg/kg body weight
  • Adipose tissue concentration: WHO-TEQ pg/g fat

Result

  • Average daily intake of PCDD/Fs 0.79 pg/kg bw
  • Average daily intake of PCBs 0.74 pg/kg bw
  • Average adipose tissue PCDD/F concentration 26.4 pg/g
  • Average adipose tissue PCB concentration 18.1 pg/g

Note: During the nursing period, the PCDD/F intake of a child can be 1-2 orders of magnitude higher than that of an adult.


Dioxin exposure-response function on population level

Scope
Dioxin exposure-response function on population level. R↻ . General population average.

Description

Dioxins are a group of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). They are persistent environmental contaminants that accumulate in the human body. Their elimination half-life is quite high (~7 years). 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most toxic PCDD/Fs congener, and it is classified as a known human carcinogen by the International Agency for Research on Cancer (IARC).

  • Health effects related to long-term exposure
    • impairment of the immune system
    • impairment of the developing nervous system
    • impairment of the endocrine system
    • impairment of reproductive functions
    • increased cancer risk

Evidence concerning cancer risk is mainly from animal studies, and dioxins are probably quite weak carcinogens in humans. Hormesis type of dose-response is suspected. Evidence concerning other health effects is inconsistent.

In this specific case

  • MSWI is likely to increase background dioxin exposure (additional low exposure)
  • the risk of accidental exposure is low (dioxin emissions will increase only if burning process is working improperly)
  • health effects of long-term exposure are relevant
  • effects on development and endocrine functions are more relevant than the risk of cancer
  • The health effects of low doses should be modelled from animal and human data. Eg. Alaluusua et al. (1996) have studied tooth development. In a study by Miettinen et al. (2005), exposure to 0.5 μg TCDD/kg body weight on GD 15 resulted in maternal adipose tissue concentration of 2185 pg/g fat. In that study, linear extrapolation of the data predicts a maternal adipose tissue concentration of 100-120 pg/g fat after exposure to 0.03 μg TCDD/kg body weight. This estimated maternal adipose tissue concentration is sufficient to induce developmental dental defects in rat offspring, and is similar to the highest values measured in the Finnish average population (PCDD/F 145.5 pg WHO-TEQ/g fat (Kiviranta et al. 2005).

Sensitive subgroups: foetuses, newborns, young females (women below or at childbearing age), individuals with high fish consumption (e.g. fishermen), individuals working in incineration plants etc. (For health effects related to short-term exposure R↻ )

Tolerable daily intake (TDI): 1-4 pg/kg body weight

References

  • Alaluusua et al. Eur J Oral Sci. 1996 Oct-Dec;104(5-6):493-7.
  • Crump et al. 2003. Meta-analysis of dioxin-cancer dose-response for three occupational cohorts. Environmental Health Perspectives 111 (5), 681-687.
  • Kiviranta et al. Chemosphere. 2005 Aug;60(7):854-69.
  • Kogevinas 2001. Human health effects of dioxins: cancer, reproductive and endochrine system effects. Human Reproduction Update 7 (3), 331-339.
  • Miettinen HM et al. Toxicol Sci. 2005 Jun;85(2):1003-12.
  • Tuomisto JT et al. Int J Cancer. 2004 Mar 1;108(6):893-900.
  • Tuomisto et al. 1999. Synopsis on dioxins and PCBs. Publications of the National Public Health Institute B17/1999.
  • van Leeuwen FX et.al. Chemosphere. 2000 May-Jun;40(9-11):1095-101.

Definition

Effective dose resulting in a 0.01 increase in lifetime risk of cancer mortality (ED01): 45 pg/kg body weight (95% CI 21-324 pg/kg body weight). Comment: This must be in units ng/kg body weight, otherwise the value is way too high.

= 0.01/(45 pg/(kg body weight * 200 g body fat/kg body weight))

= 0.044 /(pg/g body fat)

Unit

Increased incidence/(pg/g body fat)

Result

For cancer risk: 0.044

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