Arsenic Medical and Biological Effects of Environmental Pollutants (1977) / Chapter Skim
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5 Biologic Effects of Arsenic on Plants and Animals
5 Biologic Effects of Arsenic on Plants and Animals
Pages 117-172
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From page 117... ...
A specific nutritional role for inorganic arsenic has been uncovered only recently, but animal feeds have been supplemented with "growth-promoting" organic arsenical additives for many years. Another curious feature of arsenic biochemistry is the ability of the element partially to counteract the ill effects of yet another toxic substance, selenium.
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From page 118... ...
Adaptation The adaptation of microorganisms to arsenic compounds was of great practical interest during the earlier part of this century, because organic arsenicals were used extensively as trypanocides at that time. The resistance to organic arsenicals was found to depend on the nature of the chemical substituents on the phenyl ring:5 water-attracting groups (such as -OH and -NH2)
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From page 119... ...
This is the location of at least some of the enzymes of the living plant. One of the first symptoms of injury by sodium arsenite is wilting, caused by loss of turgor, and this immediately suggests an alteration in membrane integrity.
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From page 120... ...
It is difficult to visualize a more effective way in which an herbicide might kill a plant. Phytotoxicity of Organic Arsenicals Injury symptoms on crop plants resulting from toxic quantities of arsenic in soils were noted in the 1930's, when it was found that young trees planted in old orchard soils grew slowly and were stunted.748 Young apple trees, in addition to being stunted, had leaf symptoms that indicated water-deficiency stress, which implied injury to the roots; pears showed similar symptoms.785 Peach trees planted on these old orchard soils that have accumulated lead arsenate exhibit by midsummer a red or brown discoloration along the leaf margins and then throughout the leaves.
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From page 121... ...
473) 121 arsenic content varied between 1 and 4 ppm.
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From page 122... ...
The amount of available arsenic in some treatments continued to change throughout the 19-month experimental period; some of the change may have been the result of the addition of phosphate fertilizers, particularly where available arsenic reached a minimum and then increased. Plant growth at any particular degree of available arsenic in the soil may be affected by the amount of available phosphorus in the soil solution.878 The organoarsenical herbicides are not growth-regulators in the way that plant hormones are; they apparently act through or on enzyme systems to inhibit growth.
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From page 123... ...
Biologic Effects of Arsenic on Plants and Animals TABLE 5-1 Effect of Temperature after Treatment on the Degree of Chlorosis Induced by DSMA in Crabgrassa Chlorosis Ratingb DSMA 60 F (16 C)
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From page 124... ...
With sodium arsenite and cacodylic acid, temperature had no effect. Kempen4~7 found that relatively high temperature (35 C)
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From page 125... ...
Everett '39 indicated that phosphorus increased the arsenic content of bluegrass in a turf treated with tricalcium arsenate. However, he found that phosphorus reduced absorption of tricalcium arsenate (measured as arsenic)
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From page 126... ...
Batjer and Benson showed that toxicity in peaches (but not apples) grown in arsenic-contaminated soils could be reduced by foliar applications of zinc or iron chelates or soil applications of zinc or iron sulfates.55 Zinc chelates worked best and reduced the symptoms and the arsenic content of peach leaves.
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From page 127... ...
If such programs are used, occasional application of the organic arsenicals in the particular roles in which they are highly effective may not result in soil residues of any . ·~ slgn~lcance.
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From page 128... ...
The dependence of the toxicity of arsenic trioxide on the physical form in which it is given is probably a result of its rather poor solubility; e.g., Harrison et al.329 commented that heating was required to solubilize arsenic trioxide. The practical consequences of the great variation in toxicity of arsenicals due to their different so'ubilities were recently emphasized by Done and Pear, who criticized government regulations that equated the poison hazard of the highly soluble sodium arsenite with that of the less soluble (and thereby less toxic)
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From page 129... ...
and As(V) on the basis of their different toxicities has been suggested.489 The toxicity of a number of synthetic aromatic organic arsenicals has been the subject of several investigations, because of the value of these compounds for improving weight gain and feed efficiency in swine and poultry.
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From page 130... ...
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From page 131... ...
cat ~ Cat ~ ret ~ ~ ~ ~ ~ ~ ~ ~ ~ O O ~ ~ ~ ~ ~ ~ ~ 0 0 - - ~ O rut ~ cot Do t- ~ ~ ~ ~ ~ ~ do ~ ~ t- t- ~ ~} I, u, us C C ~O ~C _ _ x = ~o 3:~ o ~ x = o pet ~3 ~ ~ 3~ y C |
From page 132... ...
Again, to put these studies in perspective, it should be emphasized that the recommended concentration of arsanilic acid for feed-additive use is only 50-100 ppm. Perhaps of more direct concern to consumers is the toxicity of arsenic that occurs naturally in seafood, such as shrimp (such arsenic compounds are commonly referred to as "shrimp arsenical.
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From page 133... ...
Thus, a more sensitive indicator of toxicity showed the detrimental effects of a dosage that had previously been regarded as "safe." With sophisticated assessment techniques, such as biochemical and enzyme measurements, even more subtle effects of poisons can be detected. For example, Bencko and Simane66 found that the respiration rate of liver homogenates prepared from mice that had received arsenic at S ppm as arsenic trioxide in their drinking water was only 61% of that of the normal controls.
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From page 134... ...
It should be pointed out, however, that the toxic effects of inorganic trivalent arsenic (arsenite) can often be potentiated by BAL in vitro.
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From page 135... ...
McDonough529 suggested that the sA~-arsenite complex can act as an inhibitor of germination, inasmuch as lettuce seeds soaked in mixed solutions of sodium arsenite and BAL yielded lower germination ratios than did seeds soaked in either compound alone. The mechanism of action of the toxic effects of inorganic pentavalent arsenicals is less clearly understood than that of the trivalent arsenic compounds.
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From page 136... ...
Chan et al.~42 have isolated an arsenylated component of rat liver mitochondria that they feel may represent the arsenic analogue of a low-molecular- weight pho sphorylated mitoch ondrial constituent that plays a role in oxidative phosphorylation. A nonhydrolytic mode of action of arsenate in inhibiting mitochondrial energy-linked functions has recently been proposed.549 Adaptation to Toxicity of Arsenic Compounds Most early investigators reported that animals were unable to adapt to the toxic effects of inorganic arsenic compounds,7~3 although adaptation to some organic arsenicals was readily achieved.44i In spite of the early failures to demonstrate adaptation to inorganic arsenic, Bencko and Symon68 have recently shown that the arm for arsenic as arsenic trioxide administered subcutaneously could be increased from 10.96 to 13.98 mg/kg in hairless mice as a result of giving arsenic at 50 ppm as arsenic trioxide in the drinking water for 3 months.
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From page 137... ...
Studies with t74AsUarsenate revealed that mice previously exposed to arsenic at 50 ppm as arsenite in the water for 64 days displayed a significant decrease in the retention of a later dose of radioarsenate administered parenterally.65 Although the authors interpreted their results as evidence of an increase in capacity of the excretory mechanism for arsenic due to arsenic exposure, this experiment could also perhaps be explained by a saturation of the tissue binding sites for arsenic by previous arsenic intake, which could then cause an "apparent" increase in the excretion of the element. Clearly, more research is needed to determine whether animals are able to adapt to the toxic effects of inorganic arsenicals.
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From page 138... ...
Zharkova890 studied the effect of continuous 24-h exposures to arsenic trioxide at 25-37 ,ug/m3 of air on various physiologic characteristics in rats. He found that such treatment resulted in a lag in weight gain, disordered chronaxy ratios of antagonist muscles, suppression of cholinesterase activity, a reduction in concentration of sulfhydryl groups in blood proteins, an increase in the number of reticulocytes, a decrease in blood hemoglobin, porphyrinuria, a reduction in ascorbic acid in all organs and tissues, and accumulation of arsenic in the organs and tissues.
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From page 139... ...
, mortality was significantly reduced if the mice were given sodium arsenite at the time of inoculation with virus, but mice treated with 3-nitro-4hydroxyphenylarsonic acid in the drinking water after inoculation had higher mortality than did controls. British antilewisite did not inhibit, but appeared to stimulate, the mortality-increasing activity of sodium arsenite in pseudorabies infection.
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From page 140... ...
Indeed, a later paper by Gainer277 showed that the induction of interferon by poly I/poly C in rabbit kidney cell cultures could be inhibited by sodium arsenite. It was found somewhat unexpectedly, however, that, although high concentrations of arsenite inhibited the action of exogenous mouse interferon added to cultures of mouse embryo cells, low concentrations of arsenite increased the antiviral activity of low concentrations of interferon.
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From page 141... ...
Sodium arsenite and sodium arsenate were equally effective against seleniferous grain, but the arsenic sulfides were ineffective. Arsanilic acid and 3-nitro4-hydroxyphenylarsonic acid, two organic arsenicals used as '~growth-promoters" for livestock, also exhibited a beneficial action against selenium poisoning in rats when given in the drinking water.344 There is evidence that it would be practical to use these two agents to protect swine and poultry in high-selenium regions.~30834 Amor and Pringle~3 even suggested the use of an arsenic-containing tonic as a prophylactic agent against selenium poisoning in exposed industrial workers.
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From page 142... ...
Sodium arsenite was the most effective form of arsenic in enhancing the biliary excretion of selenium, but arsenate and 3-nitro-4-hydroxyphenylarsonate were also active to some extent. In experiments with radioactive arsenic, it was found that selenium stimulated the biliary excretion of arsenic, just as arsenic stimulated the excretion of selenium.
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From page 143... ...
The rats were fed a specially formulated purified diet that contained arsenic at only 30 ppb. The deficiency signs were most striking in male rats and included rough haircoat, low growth rate, splenomegaly, decreased hematocrit, and increased osmotic fragility of red cells.
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From page 144... ...
None of these deficiency signs were observed in control animals fed the semisynthetic diet supplemented with arsenic at 350 ppb. DOMESTIC ANIMALS Inorganic and Aliphatic Organic Arsenicals Arsenic appears to be second only to lead in importance as a toxicant in farm and household animals.~5335 Toxicoses caused by inorganic and aliphatic organic arsenicals are generally manifested by a syndrome entirely different from that caused by the phenylarsonic feed additives and therapeutic agents; therefore, the phenylarsonic compounds will be discussed separately.
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From page 145... ...
It was concluded that the lethal dose of sodium arsenite via drinking water was 100-200 mg/kg of body weight. Experience with field cases of arsenic poisoning has indicated that animals that are weak, debilitated, and dehydrated are much more susceptible to arsenic poisoning than normal animals, probably because renal excretion is reduced.
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From page 146... ...
Experience with field cases in the Veterinary Diagnostic Laboratory, Iowa State University, has indicated that, if an animal lives several days after consuming a "toxic" amount of arsenic, the liver and kidney tissues may contain less arsenic than is ordinarily considered diagnostic of arsenic poisoning.~0 ii2 Other authors have reported similar findings.564 Signs and Lesions of Toxicosis Peracute and acute episodes of poisoning by inorganic and aliphatic organic arsenicals are usually explosive, with high morbidity and mortality over a 2- to 3-day period. The poisoning produces intense abdominal pain, staggering gait, extreme weakness, trembling, salivation, vomiting (in dogs, cats, pigs, and perhaps even cattle)
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From page 147... ...
A concentration above 10 ppm would, confirm arsenic poisoning.~5 The urine of poisoned animals often contains protein, red blood cells, and casts. The arsenic content of the urine varies with the form of arsenic, the route of exposure, and the species and usually ranges from 2 to 100 mg/liter.~5 Whenever an episode of illness is characterized by rapid onset and gastroenteritis, with only minor signs of central nervous system involvement, and results in weakness, prostration, and rapid death, inorganic or aliphatic organic arsenic poisoning should be considered.
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From page 148... ...
Five-percent BAL iS added to a loo solution of benzylbenzoate in arachis oil and given at 3 mg/kg of body weight.~53 It is important to give supportive therapy, such as electrolytes to replace body fluids, and to provide plenty of drinking water. In small animals, if there is an opportunity for early treatment, the stomach should be emptied before the arsenic can pass into the intestine and be absorbed.
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From page 149... ...
The most widely used compounds are arsanilic acid; its sodium salt, sodium arsanilate; and 3-nitro-4-hydroxyphenylarsonic acid.5l 587 The additives are considered to improve weight gain and feed efficiency and to aid in the prevention and control of some enteric diseases of swine and p 0 u 1 t r y . 7 6 , 1 1 4 , 2 6 8 , 5 5 8 , 5 5 ~ There is still considerable discussion regarding the mode of action of the organic arsenicals.
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From page 150... ...
were excreted unchanged by chickens and that there is no evidence that these compounds are changed to any others or converted to inorganic arsenic.~835556~36~46~6 Similar results were obtained in studies with 3-nitro4-hydroxyphenylarsonic acid and 4-nitrophenylarsonic acid in chickens. Similar experiments by other workers with rats, rabbits, and swine indicated that the phenylarsonic acids for the most part are excreted unchanged by the kidneys, although some apparently undergo a limited amount of biotransformation.556 557 Because pentavalent arsenic compounds do not react readily with sulfhydryl groups and the phenylarsonic acids are apparently excreted unchanged, one must conclude that the mechanism of their action is something other than interaction with sulfhydryl-containing enzymes and proteins.
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From page 151... ...
in swine feed for 5-6 days for the control of dysentery. The margin of safety for arsan~lic acid and its TABLE 5-3 Arsenic Compounds Used as Feed Additivesa Concentration in Compound Complete Feed, Go Species Purpose Arsanilic acid or O.OOS-O.O1 Chickens (broilers)
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From page 152... ...
Toxicoses may occur, however, with any of the phenylarsonics in any of the species. The circumstances usually associated with toxicoses related to the organic arsenicals used as feed additives include: · Purposeful incorporation of excessive amounts in feed or water.458 · Mistaken feed formulation resulting in excessive amounts in feed.
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From page 153... ...
After a few days, swine and poultry may become paralyzed, but will continue to eat and drink (Figure 5-41. Arsanilic acid and sodium arsanilate may produce blindness, but this is rarely seen with 3-nitro4-hydroxyphenylarsonic acid toxicosis.
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From page 154... ...
Poultry usually become incoordinated and ataxic after consuming excessive concentrations of 3-nitro-4-hydroxyphenylarsonic acid, but more commonly exhibit ruffled feathers, anorexia, depression, coma, and death when exposed to excessive concentrations of arsanilic acid or sodium arsanilate. in ~4 539 Postmortem findings in swine and poultry affected by organic arsenicals include no gross changes, except skin erythema in white pigs and muscle atrophy in chronic cases.~2~4326 Harding et al.326 reported abnormal distention of the urinary bladders in pigs poisoned by arsanilic acid.
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From page 155... ...
The results are presented in Table 5-4. Evans and Bandemer237 measured the arsenic content of eggs from hens fed diets containing arsanilic acid at 100 and 200 ppm for 10 weeks and found concentrations below the tolerance, established by the FDA, of 0.5 ppm.
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From page 156... ...
, and that show little or no gross change on postmortem examination should be suspected of having been exposed to excessive concentrations of phenylarsonic compounds.5~ (Figure 5-4 shows the appearance of a pig suffering from arsenic paralysis.) Concentrations of arsenic in tissue are rarely diagnostic, because the organic arsenicals are excreted without being metabolized by the kidneys.
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From page 157... ...
It should be kept in mind, however, that demyelination and gliosis will not be evident in the optic tract earlier than 10 days after the beginning of exposure, nor will these lesions be evident in sciatic and brachial nerves earlier than 2 weeks after the beginning of exposure326 458 (see Figures 5-5-5-71. AQUATIC ORGANISMS Because arsenic compounds are poisonous to microorganisms and lower aquatic organisms, they have been used in wood preservatives and paints and in pesticides.
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From page 158... ...
459 (Pi 447) FIGURE 5-7 Sciatic nerve from pig fed arsanilic acid at 900 g/ton (992 g/tonne)
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From page 159... ...
Effects of long-term exposure to low concentrations of arsenic singly or in combination with other metals are generally unknown. Pollutants are rarely found in the environment in isolation.
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From page 160... ...
Commercial sodium arsenite contains various amounts of other arsenic compounds and impurities and is labeled in terms of equivalent arsenic trioxide. For the control of submerged vegetation in ponds and lakes, applications of 2-5 ppm as arsenic trioxide (1.5-3.8 ppm as arsenic)
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From page 161... ...
> mallard. Earlier reports have shown the mallard to be tolerant to an arsenic dosage of 8 mg/day as sodium arsenite for a period that provided a total dose of 973 mg/kg.
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From page 164... ...
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From page 165... ...
W W W .0 · 3 ._ Cal o o ._ au Cal sit ¢ o A o Cal Cal o Cal o C)
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From page 166... ...
Arsenic trioxide was used to poison western grasshoppers (Melanophis bivittatus, M femus-rubrum, M
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From page 167... ...
In a study to determine the palatability or acceptability of sodium arsenite, potassium arsenite, and ammonium arsenite to deer, the authors recorded the number of licks that the test deer made on trees coated with solutions of these compounds. They observed that sodium arsenite was as palatable as sodium chloride, whereas potassium arsenite was significantly less palatable, and ammonium arsenite was the least acceptable to the deer.
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From page 168... ...
Analyses performed by the EPA Toxicology Laboratory showed that surface soil samples contained arsenic at up to 2.4 ppm, whereas water samples from the area averaged 0.42 ppm. Arsenic concentrations in the dead deer are shown in Table 5-8.
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From page 169... ...
Similarly, tree-canopy insects also had high arsenic contents (10 ppm)
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From page 171... ...
~to ~ ct 'e ct C: c: - ~ ~ ~ ~ o o o o o o -= .= .= ~ ~ ~ ~ By a)
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From page 172... ...
The arsenic content of livers from 36 guillemots ranged from less than 0.1 to 41 ppm (dry basis) , with an average of 7.1 ppm.
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