Arsenic Medical and Biological Effects of Environmental Pollutants (1977) / Chapter Skim
Currently Skimming:
4 Metabolism of Arsenic
4 Metabolism of Arsenic
Pages 80-116
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 80... ...
Around smelters, high-arsenic soils may be rendered completely sterile and bare of higher plants. Natural waters are usually low in arsenic, and plants reflect this in their arsenic contents.
|
From page 81... ...
Translocation of Arsenic Compounds The application of dilute sodium arsenite solution to bindweed foliage in 1917 resulted in the killing of root tissues and showed that it was possible for toxic compounds to be translocated in plants.306
|
From page 82... ...
The acidarsenical method might prove useful in eliminating old deep-rooted perennial weeds before the application of a soil sterilization treatment. Sodium arsenite, long used as a general contact herbicide, was not considered to be translocated, probably because, as a contact treatment, it was used at a concentration that rapidly destroyed the foliage.
|
From page 83... ...
turf.483 This result can be explained only by translocation from foliage to tubers, a movement that occurs via the phloem. In a later paper, Long, Allen, and Holt showed that those organic arsenicals kill nutsedge tubers if they are applied several times over a 2-year period.482 Long and Holt483 showed amine methanearsonate to be somewhat superior to DSMA at equivalent rates of application-a result that seems logical in view of the mechanism of herbicide activation described by Crafts and Reiber.~° In further studies on purple nutsedge, Holt et al., 366 using single and repeated applications of amine methanearsonate to shoots of single tubers and shoots of terminal tubers on chains of tubers, found that arsenic was translocated laterally into tubers separated from the treated shoots by up to four tubers.
|
From page 84... ...
The writers concluded that death of tubers after repeated treatments was due to depletion of food reserves, rather than to the concentration of arsenic in the tubers. The variability in arsenic content in killed tubers and the variability in the number of treatments required to kill tubers suggested that failure to sprout is not related to the overall arsenic content of the tuber; some viable tubers contained more arsenic than some dead ones.
|
From page 85... ...
found that actively growing terminal tubers in a chain accumulated arsenic, whereas intermediate and dormant tubers did not.2~6 Thus, the arsenic content of a tuber may not serve as an index of the lethality of a treatment; the effects of the initial impact of arsenic on later growth activity may be the critical factor in lethality and continuing transport of arsenic to growing roots. Other tubers and shoots may mask the effects of the arsenic content, as determined by analysis at any time.
|
From page 86... ...
cotton leaves and in the soil from beneath the plants; MSMA treatment rate was 2.24 kg/ha.86, By using long counting periods, they were able to extend the lower limit of detection to 5 ng of arsenic. Table 4-1 presents the results TABLE 4-1 Arsenic Content of Leaf and Soil Samples Taken from Field-Grown Cotton Treated with MSMA at 2.24 kg/haa Arsenic Content, ,ug/g New Leaves Old Leaves No.
|
From page 87... ...
MsMA was primarily acropetal in the xylem, but small amounts also moved basipetally, proving that this organic arsenical is phloem-mobile. Within a week, the arsenic was transported from a treated mature leaf into the leaf base and sheath, to meristematic regions, and to roots and rhizomes; this indicates symplastic movement.
|
From page 88... ...
With the same three herbicides in studies on purple and yellow nutsedge, Keeley and Thullen found the yellow species to be more susceptible; the yellow species absorbed and translocated more of the ~4C-labeled tracers than did the purple.4~34~5 In chromatography of plant extracts and standards, there was less than 5% variation; nutsedge plants did not readily metabolize these arsenicals in 72 h. Surfactants have been found to increase the penetration and translocation of the organic arsenical herbicides.
|
From page 89... ...
and cacodyl oxide, which have a strong garlic odor, could have been formed and would have the same methyl: arsenic ratio. The recent suggestion796 that such a reaction in stream sediments could be hazardous to fish is without foundation; methylarsine decomposes to methanearsonic acid in the presence of oxygen, 658 and the latter compound is less toxic than sodium arsenite.
|
From page 90... ...
at: no ~ o o ~9 · CL c)
|
From page 91... ...
~ ,r ~ ~ XID ON UP ~ ~ ~ ~ ~ ~ ~ ~ O ~ 00 ~ -} \0 ~ ~ ~ ~ 00 AN =~ ~ ~ ~ ~ 00 (~\ ~\ \0 ~0 ~ ~ ~ Cut 06 _ ~ ~.O Cut ~Ct C ~ ~ ° ~ ~O a,, O ~ ~ ~' E Amman ~ to A,= ~ u, co t a ~ ~ % Z Z a a ~ >~ z Z Z a a ~ a o ~ ~ ~ ~ ~ a ~ ~ z z zz>> >> z z z z z z a ~ ~ ~ ~ o~ ~o-^ Pa z~X ~ z Zeus ~ z us us us cut cn ~ cut 0 ~ c' c, ~ ~ 0 ~Z>~> >>Z>~> ~z c~ U3 ct oo E ~ ~ e E c c O O ~9 D O E ~0 D ~O O ~ ~O ~ ·- O C¢ ~ ~ O ~ ~ ~ ~, V~ ~ ~ C )
|
From page 92... ...
This difference may be due to the lower concentration of arsenic in fresh water; it was found in New Zealand that algae grown in lakes fed by hot springs with arsenic contents as high as 0.1 ppm had arsenic concentrations between 20 and 1,450 ppm on a dry-matter basis.448 These concentrations prevented the use of the dried algae for animal food, because the arsenic concentrations produced in edible organs were above tolerance. The relationship between the water concentration and the uptake of arsenic by algae has been studied experimentally in aquariums contain
|
From page 93... ...
Algae of both marine and freshwater origin can synthesize both fat-soluble and water-soluble organic arsenic compounds, as shown in Table 4-5. It was suggested that algae TABLE 4-3*
|
From page 94... ...
~ O lo O ~ +1 ,~+1 O{~N _ O~ O 8_ o~-X X ° l_ ~ ~o _ _~ _t_ ', oo _oo o~ o~ o +1 +1+1 +1+I tl o \o~o - o- o- o ooo~ oo c`, o(~! o~ o tl tltl tltl tl ON ~o~C)
|
From page 95... ...
The total arsenic in seaweed collected from the fjords of Norway, where there is minimal pollution, varies with the species from 0.15 to 109 ppm on a dry-matter basis,495 as shown in Tables 4-6 and 4-7. If the oil from seaweed is saponified, the major part of the arsenic is found in the unsaponified lipid, rather than in the fatty-acid fraction, as shown inTable4-8.49~ TABLE 4-6 Arsenic in Seaweed (Reine in Lofotenja Date of Ash, % of Arsenic Sample and Location Collection dry matter Content, ppm Pelvetia canaliculata, Reine March 1951 23.6 22 Pelvetia canaliculata, Reine June 1951 17.6 21 Fucus serrates, Reine March 1951 27.6 47 Fucus serrates, Reine June 1951 23.8 40 Fucus spiralis, Reine March 1951 25.3 34 Fucus spiralis, Reine June l95I 21.6 26 Fucus vesiculosus, ovre Reine March 1951 23.2 65 Fucus vesiculosus, ovre Reine June 1951 20.6 26 Laminaria digitata lamirca, Reine April 1952 36.2 73 aDerived from Lunde.495
|
From page 96... ...
The arsenic in the plankton rose from an initial value of 5.9-10.6 ppm to a peak of 6,955 ppm at 27 days and then fell to 2,172 ppm at 78 days. Ball and Hooper47 used sufficient t74Asisodium arsenite on a pond and in aquariums to be able to follow
|
From page 97... ...
49 21 Fucus vesiculosus 35 5.1 Fucus serrates 27 6.1 Fucus spiralis 5.7 5.0 Pelvetia canaliculata 10.8 7.3 aDer~ved from Lunde.495 Samples collected off the west coast of Norway. 97 its concentration in a complete ecosystem of fish, water plants, plankton, and soil over an extended period.
|
From page 98... ...
Although there are wide variations between studies and within the same species in a single series, there is no evidence of a trend in arsenic concentration with time, nor are there significant geographic differences. The arsenic compounds present in mollusks and crustaceans have never been characterized chemically, but studies in which shrimp were fed to rats and humans clearly indicated that the compounds are less toxic than arsenic trioxide and, although absorbed from the gastrointestinal tract, rapidly excreted in the urine in both rats and humans.
|
From page 99... ...
Metabolism of Arsenic TABLE 4-10 99 Arsenic in Mollusks and Crustaceans Arsenic Concentration, Organism ppm (wet wt) Reference and Date Location Gulf shrimp 1.94 171, 1935 Texas Bay shrimp 2.44 171.
|
From page 100... ...
He found liver to have a higher arsenic concentration than muscle, owing to its larger oil content. The oil that had an arsenic content of 3.0~.0 ppm was studied extensively by him, but he was unable to isolate the compound to which the arsenic was bound.
|
From page 101... ...
When freshwater ponds are treated with sodium arsenite to control water weeds, the arsenic concentrations in the water are reflected in the fish. Gilderhus289 compared water and fish concentrations; the results are shown in Table 4-13.
|
From page 102... ...
in lo; 'e v)
|
From page 103... ...
method that determines organic (methanearsonate) and inorganic arsenic simultaneously, Lakso et al.447 found both Johnsongrass and cottonseed to contain methanearsonic acid at 0.05~.10 ppm and only traces of inorganic arsenic.
|
From page 104... ...
at 3,140 ppb. Lane County, Oregon.294 The arsenic compounds present presumably are pentavalent inorganic, but proof has not been reported.
|
From page 105... ...
The mechanism of intestinal absorption of organic arsenicals in rats has been studied.378 Solutions of carbarsone, tryparsamide, and sodium cacodylate were injected into isolated loops of small intestine in anesthetized rats, and the arsenic remaining in the loops was determined periodically. The results indicated that the process was simple diffusion and was not an active transport mechanism.
|
From page 106... ...
i o z - o ~ ~ (, A ~ z ~ ~ z ~ lo o z ~ o co ~ 11 1 .
|
From page 107... ...
gore ~m +- ~ 45~ |
From page 108... ...
Duc off et al. 220 used t76As~sodium arsenite on rats, rabbits, mice, and man, studying their excretion rates and tissue distribution patterns.
|
From page 109... ...
The proportion of pentavalent arsenic in the urine showed a steady increase until the fourth day, when it remained constant at 75%.
|
From page 110... ...
The high content in blood also makes it difficult to get true tissue values in such organs as the spleen and liver. In an attempt to find another small-animal model for man, Peoples625 studied the distribution of arsenic in rats, guinea pigs, rabbits, and hamsters that were fed arsenic trioxide; the results are shown in Table 4-15.
|
From page 111... ...
The distribution of arsenic in the cow has been studied with a variety of compounds in nontoxic doses.625 The feeding of arsenic acid to cows at 0.05-1.25 mg/l~g of body weight for 8 weeks did not increase the arsenic content of the milk, but it did increase the arsenic in the tissues. Urine was the main pathway of excretion, which was very rapid-the urine was free of arsenic 2 days after arsenic administration was 100 10 In o ~5 TO UJ ~ 1.0 at o LL a: c' o.1 x .- L.L.
|
From page 113... ...
The valence of urinary arsenic was determined; pentavalent arsenic was the only form found. A similar study with sodium arsenite and cacodylic acid yielded essentially the same results (Peoples, unpublished data)
|
From page 114... ...
The arsenic content of neoplasms has received scant attention, although arsenic is often listed as a carcinogen, particularly in books on dermatology (see Chapter 6~. Domonkos209 reviewed studies on the arsenic content of normal skin, skin that was pigmented by exposure to arsenic, and keratoses.
|
From page 115... ...
o at c ~ = CD Z m c cut 0 0 ED `ouanba`' 0 0 0 cut m ~ ° 1 L '''- 1 o A: o .
|
From page 116... ...
There were no health problems related to the compounds used. Further studies were made by Wagner and Weswig on forestry workers who were exposed to cacodylic acid over a 2-month period.832 An attempt was made to correlate blood and urinary arsenic concentrations with degree of exposure without much success.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.