CPM LCA Database - Impact assessment method

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Characterisation Method Information

Characterisation Method Name:

Ozone layer depletion impact on DALYs

Version:

2000

Date Completed:

2000

Principal Method Name:

ECO-indicator: skin cancer pathway

Method Description:

DALY (Disability Adjusted Life Years)

Description of the problem

Stratospheric ozone levels are near their lowest point since measurements began in 1970. The most important reason is the increase of the chlorine and bromine levels, due to the release of substances such as CFCs with a long atmospheric residence time. This low level has resulted in increased UV
radiation levels:
• about 4 to 7 % at mid latitudes in the Northern and Southern hemisphere
• about 130% in the Antarctic Spring
• about 22% in the Arctic Spring
Since the Montreal Protocol and the Copenhagen and London Amendments have been accepted by many industrial and developing countries, the production and release of chlorine and bromine compounds with a long atmospheric residence time such as CFCs have been significantly reduced, and are still decreasing. Only in some, mainly developing countries, production and releases are continuing.
According to the most important producers of ozone-depleting substances the AFEAS (Alternative fluorocarbons environmental acceptability study) [www.afeas.com], their industries represent about 40% of global CFC production and 90% of HCFCs. The remaining 60% of CFC production takes place in China, Russia and Argentina.

the protection of the ozone layer is clearly a good example of how international
co-operation averted a potentially big problem. Without the Montreal Protocol the number of excess death because of skin cancer would have increased rapidly to 10 or more deaths per 100.000 inhabitants in mid-latitude areas, this would have made the ozone layer depletion problem by far the most
important environmental problem [UNEP 1998].
With the apparent success of the abatement, one could argue that ozone layer depletion is no longer an issue. However, this is not true; any emission of CFCs or to a lesser extent HCFCs is still contributing to the damages to human health.
The modelling of damages has some specific difficulties:
• Most studies are analysing the effect of the Montreal, Copenhagen and London Protocol. No studies have been found analysing the marginal effect of releasing an additional kg of CFCs.
• Knowledge on a number of endpoints is not sufficient. It is unclear to what extent the ozone layer depletion contributes to the damage to the human immune system and the damage to ecosystems.
• It is relatively easy for humans to avoid exposure to higher UV levels by behavioural changes.
• The UV increases are dependent on the latitude. In the tropics the increases are negligible, near the poles they are at a maximum.
• Only fair skinned persons are sensitive for skin damages due to increased UV levels, while cataract can occur with every skin type.

Fate and exposure model

Chlorine containing substances are diluted in the troposphere. In an average of 4 years they also drift into the stratosphere, where they contribute to chemical processes that result in the depletion of the ozone layer. Clearly the atmospheric residence time (which spans a range of about 1 to 1000 years) is an important factor. Substances that have a significantly lower residence time than 4 years do not reach the stratosphere in substantial amounts. This means the damage created by a substance is depending on the time horizon. If the time horizon is just 100 years, part of the damage created by substances with a residence time of more than 100 year will be neglected. (see also under “Equivalency factors”).

No real fate factors or fate models have been found in this research. However, [SLAPER ET AL 1992] present some useful data for CFC11. Unfortunately they do not provide a fate factor. However, for CFC11 Slaper presents two graphs, displaying the CFC11 production rates under the London amendments, and the expected CFC11 concentration for this scenario. As a temporary solution the fate for CFC11 will be calculated. For other substances equivalency factors will be used.
As a first estimate the surface area under these graphs was assessed. The left-hand picture of figure ...
displays the flow (Mkg/yr) as a function of time. The surface under these graphs is a mass. For the London amendments, the expected cumulative emission is 9.8 Megatonnes. In the right hand picture the
expected concentration is plotted. The surface under this curve has the dimension of concentration times years. The London amendments will result an average concentration of 27.5 ppbv * yr.

Apparently the relation between an emission and a change in concentration for CFC11 is 2.8 ppbv*yr/Mton.

The concentration of CFC11 is not equivalent with the ultimate concentration of chlorine, as each CFC molecule has three chlorine atoms. Per ppb CFC, there will be 3 ppbs chlorine. Finally, the relation between chlorine concentration and ozone depletion must be established. This relation is dependent on the geographic latitude.

It is clear that the ozone depletion will occur mostly at the higher latitudes. [SLAPER ET AL 1992] gives higher k factors (4,9% per ppb at 50 N and 4.3%/ppb at 40N) but this is based on older measurements from the TOMS system. We have not been able to perform a population density weighted average calculation, but it is clear that
most people live between 30 South and 55 North. As an average value we take a value for k as 2%/ppb.

In most analysis, so called ozone depletion factors are used, that express the relative harmfulness compared to CFC11. These factors are based on a time frame of 500 years or more. For the individualist perspective, we are also interested in the damage when the timeframe is only 100 years. [SOLOMON AND ALBRITTON 1992] calculate the polar ozone depletion potentials for some substances
and a function of the time horizon. This calculation shows that the difference between a time horizon of 100 and 500 years time perspective is not very big. The ODP value for a long living species, such as
CFC113 is 28% lower, while the ODP for HCFCs can be approximately 50% higher. As Solomon
makes her calculation only for a few substances, and as her calulations are only valid for polar regions, it is difficult to use this data. For the time being this difference will be ignored and we will use the standard ODP values.

Effect analysis

UV radiation can cause both beneficial and adverse effects on humans. A direct beneficial effect of exposure is the formation of vitamin D. Adverse effects are among others: sunburn, “ageing” of the
skin, and snow blindness. Health risks associated with ozone depletion are increased damage to skin, eyes, and immune system [UNEP 1994]. In light-skinned populations, exposure to solar UVR appears to be the most important environmental
risk factor for skin cancer (basal and squamous cell carcinomas and cutaneous melanoma). From experimental data and epidemiology, it can be inferred that chronic accumulation of UV exposures is
important throughout the development of SCC [AUTIER AND DORÉ, 1998][UNEP 1998]. In the cases of both basal cell carcinoma (BCC) and melanoma (MSC), increases in risk are tied to early exposures (before about age 15), particularly those leading to severe sunburns. There is reasonably good evidence
that such immuno-suppression plays a role in human carcinogenesis. However, the amplications of such immuno-suppression for human infectious diseases are still unknown [UNEP 1998].
Ocular damage from UV exposures includes chronic eye conditions like cataract [UNEP 1998]. Cataracts may be a more widespread health effect than skin cancers, because all populations are affected [UNEP 1994].
Quantitative risk estimates are available for some of the UV-B-associated effects, e.g., cataract and skin cancer; however the data are insufficient to develop similar estimates for immuno-suppression.

The impact of increases in ambient UV-B on these diseases has been quantified in terms of the biological amplification factor (BAF): the percentage increase in incidence that would result from a 1% increase in ambient UV radiation. The other step in calculating overall increase in incidence per percent ozone depletion is represented by the radiation amplification factor, RAF: the percentage increase in effective UV per percent decrease in ozone. The overall percentage increased incidence per percentage
ozone depletion is then represented by the amplification factor: AF = RAF x BAF [UNEP
1998][ARMSTRONG 1994].

The AF for SCC (Squamous Cell Carcinoma) has a greater degree of certainty than that for BCC because of uncertainties in its action spectrum. For MSC, the AF is probably even more uncertain [UNEP 1998]. Experimental studies for melanomas in fish indicate an RAF of 0.1 [SETLOW ET AL 1993] whereas for DNA damage in skin a RAF of 1.6 is more likely [KELKENS 1990]. In this assessment, the assumption is made that skin cancers depend on cumulative UV-B exposure, following
the assumptions made by [MARTENS 1998]. Data for the AF of cataracts show a high degree of
uncertainty and are based on [UNEP 1994].

Damage assessment

Based on the AF and the world-wide incidence of skin cancer and cataract in 1990 [Murray, 1996], the excess incidence as a result of 1% ozone depletion during 1 year is calculated. Mortality is calculated on base of lethal fraction of the disease and the incidence. Incidences and mortality are translated to DALYs using the approach of [HOFSTETTER 1998] and data from [MURRAY ET AL 1996] for age at onset of the disease, average duration of the disease and disability weighting.

Three-quarters of all DALYs per percentage of ozone layer decrease are caused by disabled years as a result of cataracts. Most DALYs caused by early death (years of life lost) result from increased mortality due to SCC and MSC.

Literature Reference:

1. [UNEP, 1998] UNEP (1998): Environmental Effects of Ozone Depletion: 1998 Assessment. United Nations Environment Programme. see also http://sedac.ciesin.org 2. [Slaper et al 1992] Slaper, H.; Elzen, M.G.J. den; Woerd, H.J.v.d.;Greef, J. de; Ozone depletion and cancer incidence: an integrated modelling approach. 3. [UNEP, 1994] UNEP (1994): Environmental Effects of Ozone Depletion: 1994 Assessment. United Nations Environment Programme. see also http://sedac.ciesin.org 4. [Autier and Doré, 1998] Autier P., Doré P. (1998): Influence of sun exposures during childhood and during adulthodd on melanoma risk. International Journal of Cancer 77:533- 537. 5. [Armstrong, 1994] Armstrong B.K. (1994): Stratosheric ozone and health. International Journal of Epidemiology, 23 (1994) 873-85. 6. [Murray 1996] Murray, Christopher; Lopez, Alan; The Global Burden of Disease, WHO, World Bank and Harvard School of Public Health. Boston, 1996.

Methodological Range:

Geographical range is Europe Data are based on hierarchist perspective

Notes:

Existing Characterisation Factors of Ozone layer depletion impact on DALYs

Characterisation Parameter

Category Indicator

Impact Indication Principle

Aspect

Substance

Quantity

Unit

Notes

CFactor

DALYs