Hello,
In EF 3.1 method, which uses USEtox, I try to understand the 1,000 factor between :
- [ World Population in 2010 ] x [ NF_Human toxicity, cancer in 2010 ] = 6,895,889,018 persons x 1.73 10^-5 CTUh/person = 1.19 10^5 CTUh
- approx number of new cancers in 2010 = 10^7 to 10^9 (sources: ourworldindata.com and others.)
Reasons I guess :
- CTUh is an estimation of risk over a normed population, while the observed new cancers are observed things.
- all cancers do not come from pollution (e.g. stress, alcohol, background, etc.)
- USEtox may be missing the "cocktail effect" and in some way, the "tipping point" effect
- co-morbidity with other factors
- USEtox is a fantastic tool but of course still many chemicals and other are not yet implemented (e.g. many pfas / pfas, for example)
- ... would EF 3.1 be totally unaccurate here in trying to compute this Normalisation Factor ? and.or uncomplete (for example, could not find Cr (VI), but only chromium and chromium (III).
But, still, I wonder why such a one thousand factor difference. Isn't it huge, even considering above limits ?
Many thanks, it will help alot understanding the correct use of this indicator.
Nice day to all
Dominique
USEtox and EF3.1
USEtox is used in various LCIA methods, including EF3.1. The decision on how to use the model is up to the LCIA method developers, and the USEtox Team was not involved in how USEtox was implemented in EF3.1. In the official USEtox version (see https://usetox.org/model/download), both trivalent and hexavalent chromium are included and have human toxicity characterization factors available. PFAS substances are currently not implemented in the official USEtox version as they require a more extensive adaptation of the model to account for differences in fate and exposure as compared to other organic substances (see Owsianiak et al. 2023, Table 3, for details). For cancer effects, USEtox provides an estimate of poptential 'population-level incidence risk' and not actual deaths linked to substance emissions.
Global statistics
According to the United Nations population statistics (link), the world population in 2010 was 7.02 billion capita. According to the Global Burden of Disease health statistics (link), the global health burden due to all types of cancers in 2010 was 7.95 million deaths (lower: 7.42 million, upper: 8.23 million). There are many risk factors contributing to these cancers and chemical pollution is only one out of many contributing factors. With that, total global estimated potential deaths due to cancer effects in USEtox should be well below overall global deaths due to to cancer.
Many thanks for your answer. I see I made a mistake in my above calculation of cancers statistics : I computed the number of new cases, whereas I should compute the number of casualties. So, according to your bibliography above, it's now only a factor 10.
(well, to be exact, I guess we should ponderate the population of 2010 by the actual population to when those cancers were rooted : if I am exposed today to Cr(VI), I may have my cancer in (?) next xx years. Cancers of year Y may have been caused in Y minus offset.)