Arsenic carcinogenicity: numbers

[Guest guest]

Thanks . I noticed the very low chronic-exposure

carcinogenicity threshholds the other night, but your document has a

good-looking ref for that info, which spurred me to nail down the

numbers.

The apparant carcinogenicity threshhold for lifetime exposure in

drinking water is disturbingly low at ~3-10 ppb. Ten ppb is only 0.01

mg /day, by my claculation, if you drink 1L of water. (I am assuming

ppb indicates a mass ratio as implied by my second URL below; the term

is ambiguous, as wikipedia discusses.) Whereas Tarello's

self-treatment delivered 7 mg /day of arsenic atoms, and the

anti-cancer arsenical Trisenox delivers around 5. Of course, the human

lifespan is ~20,000 days, so Tarello's self-treatment at 10 days was

1000x briefer than a lifetime exposure via drinking water. The

anti-cancer treatment can be quite a bit longer, sometimes up to 85

days in total:

http://www.rxlist.com/cgi/generic/arsenic_ids.htm

So that's 75 mg grand total for the Tarello self-treatment, 425 mg

(*maximum*) for use of Trisenox against cancer, and 200 mg for a

54-year lifetime of 10 ppb in your 1L of water every day. Obviously, a

concentrated exposure could well be much more or less harmful than a

very weak exposure spread out over your lifetime. Also, the activities

of various arsenical compounds may of course vary.

While it'd be better to read the actual papers on the cancer risk,

here's from the press release from the highly respected Nat'l Academy

of Sciences:

" The committee found that men and women who daily consume water

containing 3 parts per billion of arsenic have about a 1 in 1,000

increased risk [ie excess risk, I guess] of developing bladder or lung

cancer during their lifetime. At 5 parts per billion, the risk is

about 1.5 in 1,000; at 10 parts per billion, it is greater than 3 in

1,000; and at 20 parts per billion, it is close to 7 in 1,000. "

http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=10194

Since those cancers are pretty likely to kill you rapidly, that's

basically an extra 1/1000 to 7/1000 risk of early(er) death. For

scale, I always like to compare these things to one of our largest

voluntary risks, the lifetime risk of dying in a car wreck, which is

about 1/230 in the USA (obviously quite a lot higher or lower

depending on your driving and whether you drive in trafficky and/or

deer-infested areas). 7/1000 ~= 1/142.

>

> Dear

> You might like to look at

http://www.thepoultrysite.com/articles/567/playing-chicken-avoiding-arsenic-in-y\

our-meat.

> Regards

> R