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,, 200 5fcA Wota. &<*<-, fj Coy./y.i tfrerj Pvihd*/,^ Mr 3-A 'WATUR QUALITY CRITERIA H^ //&& ' /i}g Adult blucgills exposed up to four weeks in water con taining 0.25 m;.r/l of lautonitrilo did not pick up any or ganoleptic properties that could be delected'by a taste panel (2058). L l-TO.'HAI'TULI (see also Chapter VIII---Rad'(activity) La This raro-eartli metal occurs in nature chiefly as the oxide in several minerals, frequently associated with cerium. It is used as a weighting agent for silk and rayon, in the niana.factn.ro of glass and or. ramies, and in "flint" lighters (364, 2121). The chloride, hydroxide, and nitrate salts are highly soluble in water; but the carbonate, oxide, and sulfate are insoluble. Hence, lan thanum ions in waste waters are likely to be precipitated and removed by sedimentation or adsorption, as car bonates or sulfates. Lanthanum is not recognized as a toxie element for man or animals. The LPr.o values for rats, in terms of lanthanum were reported (3526, 3527) as 4440 mg/kg for lanthanum acetate, 1450 mg/kg for tlie nitrate, 2450 mg'/kg for the sulfate, and over 8500 mg/kg for the oxide. Using water from the River Havel from which the test organisms were recovered, Brinjrmann arid Kuhn (21.58, 8348) studied the threshold effects of lanthanum acetate on four organisms. For Daphnia exposed for 48 hours at 23C, the median threshold effect occurred at 160 mg./l, expressed ns lanthanum. For Scencdcxmm exposed for 4 days at 240, the median limit was only 0.15 mg/1 of lanthanum; for 17. coli at 27C it was 0.4 mg/1, and for a protozoan QLicroreyma) it was 24 mg/1. LARVIOIDES (see Chapter IX) LAUJIYL BBSSTHYL BSfcHSYL AMKOHIOM CHLORIDE (see Chapter X) LEAD Pb 1. General. Some natural waters contain lead in solu tion, ns much as 0.4-0.8 mg/1, where mountain limestone and galena are found. In tire U.S.A., lead concentrations in surface and ground waters used for domestic supplies range from traces to 0.04 mg/1 averaging- about 0.01 mg/1 (3528). Lead may also be introduced into water as a constituent of various industrial and mining efflu ents, or as a result of the action of the water on lead in pipes. In the examination of waters for various beneficial uses, their action on lead may be of great importance and should always be considered since lead is frequently used for service and domestic pipes and -water-storage elm rubers. The factors that determine the action of pi umbo-solvent wafers are complex and not yet fully understood. Practically all waters have a slight action on new lead pipes, although in most eases it is only transient and insufficient to he harmful. Normally the. internal lead suiTaves quickly acquire a protective coat ing, after winch no further load is dissolved by the water. . With certain types of water, however, no such protec tive covering is developed, or its formation may be so slow tluit the solution of lead can go on for a long time. The characteristics of water, soft or hard, that appear to he conducive to plnnibo-solveney include comparative absence of calcium and magnesium bicarbonate*, low plf, high dissolved oxvgcn, and high nitrate content (36, 1100, 122G). The following material was gathered from references in which the effects of lead were given without details of the entire compound, if any. Where specific lead salts were mentioned, the data were listed under the appro priate salt. Certain lead salts, such as the acetate and chloride, are readily soluble, but owing to the fact that the carbonate and hydroxide are insoluble and the sul fate is only sparingly soluble, lead \pll not remain long in natural waters. 2. Cross References. Dissolved Oxygen, pH, Lead Acetate, Lead Arsenate, Lead Chloride, Lead Fluoride, Lead Nitrate, Lead Sulfate, Tetraethyl Lead. 3. Effects Upon Beneficial Uses. a. Domestic Water Supplies. Foreign to the human body, lead is a cumulative poison. It tends to be deposited in bone as a cumulative poison. The intake that can be regarded as safe for everyone cannot be stated definitely, bec-iUi.se the sensitivity of individuals to lead differs con siderably. Typical symptoms of advanced lead poisoningare constipation, loss of appetite, anemia, abdominal pain, and tenderness, pain, and gradual paralysis in the muscles, especially of the. arms A. uiildcr and often un diagnosed form of lead poisoning- also occurs in which the only symptoms may be lethargy. morosener-s, consti pation, flatulence, mid occasional abdominal pains (36). Lead poisoning usually results from the cumulative toxic effects of lead after continuous consumption over a long period of time, rather than from occasional small doses. Immunity to load enunot. he acquired, but sensitivity to lead seems to increase (1227). Lead is not among the metals considered essential to the nutrition of animals or human beings (2121). Lead may enter the body through food, air, and to bacco smoke as well as from water and other beverages. Consequently, the total intake of load must be considered in setting; standards for water. The exact level at which the intake of lead by the human body will exceed the amount excreted has not been established, but it. probably lies between 0.3 and 1.0 ms; per (lay (152). The mean daily intake of lead by adults in North America is about 0.33 mg. Of this quantify, 0.01 to 0.08 mg per day are derived from water used for cooking and drinking (8528, 8529). A total intake of lead appreciably in excess of 0.8 mg- per day may result in the aeenm'nluliou of a danger ous quantity of lead during a lifetime. Lead In an amount of 0.1 mg ingested daily-over a period of years has been reported to cause lead poisoning (1228, 122!)). The daily ingestion of 0.8 mar lead is considered excessive by one authority (1230). On the other hand one reference con sidered 0.5 mg per day snfo for human beings, and a daily dose, of 2.0 mg for a one-year period apparently did not alTeet. the health of one adult (353). Lead poisoning- among human beings is reported to have been caused by the drinking of water containing N36885 WATER. QUALITY CRITERIA 207 lead in concentrations varying from 0.042 mg/1 to 1.0 nijr/1 or more (27, 2.0. 22, 86, 620, 997, 1281, 1232, 1233, 1231, 123*, 3236,1237,1238, .1.230, 1240,1241, 3242, 1243, 1244, .124'), 2326, 3530, 3531). Oil the other hand, con ceit I rations of 0.0'J to 0,16 mg/1 have been apparently non-poi.sonons over long periods of time (1077, 1201, 3332). However, there is a feeling that 0.1 mg/1 may cause chronic poisoning if the water is used continuously, especially among hypersensitive persons (29). ];Y/V many years, the mandatory limit for lead in the CSPUS Drinking Water Standards was 0.1 mg/1; hut in the 1962 Standards, the limit for lead was lowered to 0.05 mg/1. In the WHO International Standard and WHO European Standards (see Chapter V) the limit for lead has been set at 0.1 mg/1. In the past, the Nether lands and Germany hare permitted a temporary lead concentration up to 0.3 mg/1 in water that had been in pipes for 24 hours (997, 1229, 3530). Uruguay, on the other hand, .lias used a standard as low as 0.02 mg/1 (1457). Several countries .use 0.1 mg/1 as a standard. Owing to the fact that the total intake of lead from food, inhaled atmosphere, and tobacco smoke in indus trial urban areas appears to be increasing, with little elmnec of regulation and diminution, and inasmuch as tlie concentration of lead in drinking water can be eontrolled without undue hardship on water purveyors, the USPHS Drinking Water Standard for load was low ered to 0.05 mg/1 in 1962 (2062, 2672). It is significant, however, to note that the U.'S. Government has also estab lished a tolerance of lead in food at 7 mg/kg, more than .100 times the limit for drinking- water (3533). b. Industrial Water Supplies. Traces of lead in metal-plating baths will affect the smoothness and bright ness of deposits (214). e. Irrigation. Inorganic lead salts in irrigation wa ter may be toxic to plants and should be investigated further (269, 1014). Klintworth (1493) stated that lead is harmful to plants at all concentrations. On the other hand, the addition of 2.0 mg of lead per kg of dry soil in pot, tests increased the nitrogen content of peas (2926). In the culture of oats and potatoes, lead nitrate in concentrations of 1.5 to 25 mg/1 had a stimulating effect, but at concentrations over 50 mg/1 all plants died in a week's time (2997). See also lead salts. Lead at a concentration of 51.8 mg/1 of nutrient solu tion was slightly injurious to sugar beets grown in sand culture (1.473). Germination of cress and mustard seeds in solution culture was completely inhibited by a 2700 mg/I lend solution, during an exposure period of IS days. Germination was delayed and growth was retarded by 345-1380 mg/1 of load (1479). d. Stock and Wildlife Watering. Farm animals are poisoned by load from various sources, including paint, more frequently than by any oilier metallic poison (1247). It is not unusual for cattle to be poisoned by lead in the water; the lead need not necessarily be in solution, but may be in suspension, as, for example, oxycavbonatc (36). Chronic lead poisoning among ani mals lias been caused by 0.18 mg/1 of lead in soft water (.1252); and by concentrations under 2.4 nig/l (1238). Chronic changes in (lie central nervous system of white eats were observed after an ingestion of 0.005 mg of lead per kg of body weight (3534). Most. authorities agree that 0.5 mg/1 of lead is the maximum safe limit for lead in a potable supply for animals (1238). Aileroft (1589) reported that calves given as much as 2.0 grams ol: lead daily have survived for 3 to 3 years. Calves have tolerated daily doses of 8 mg and G mg of lead per kg of body weight for, respectively, many months and up to three years. Doses of 0.2-0.4 grams of lead per kg body weight caused death within a few days (1599). When a calf was given drinking water contain ing lead nitrate at a concentration of 100 mg/1 of lead, it survived for only four months. It. was suggested that nitrate was partly responsible for the death (1539). Geese have been reported to have contracted lead poison ing from the ingestion of mine tailings (3535). <-. Fish and Other Aquatic Life. The loxie concentra tion of lead for aerobic bacteria is reported to be 1.0 mg/1; for flagellates and infusoria, 0.5 mg/1: The bac terial decomposition of organic matter is inhibited by 0.1 to 0.5 mg/1 of lead (576, 2977, 3324, 3534). Carpenter and others have studied the effects of small concentrations of heavy metals, particularly lead, upon fish. Such studies indicate that in water containing- lead salts, a film of coagulated mucus forms, first over the gills, and then over the whole body of the fish, probably as a result of a reaction between lead and an organic constituent of mucus. The death of the fish is caused by suffocation due to this obstructive layer (346, 991, 1248, 2411). In soft water, lead may be very toxic ; in hard wa ter equivalent concentrations of lead are less toxic (311). Calcium iu a eoucenfration of 50 nig/1 has destroyed the toxic effect of .1.0 mg/1 of lead (353). Wilder found that lobsters died within 20 days when kept in lead-lined tanks; however, in steel-lined and other control tanks they survived for GO days or longer (1530). Small sticklebacks appeared to be slightly more sensitive to lead than the larger fisli (1460). The Water Pollution Research Board (74) in England conducted extensive experiments to determine the effects of lead salts on rainbow trout in hard and soft waters. In water of the lowest hardness used, 14 mg/1 as CaCO;!, all of the lead added as lead nitrate remained in solution and produced a curvilinear relationship of lead concen tration vs time of survival. A similar curve was obtained for a water with a total hardness of 27 mg/1 ns Ca(J03, although some precipitation of PbCO:! occurred with lead concentrations greater than 8.0 mg/1. In solutions with a total hardness of 53 mg/1 as CaCO* the maximum concentration of lead remaining in solution was approxi mately 1.6 mg/1, and the median period of suvvivel of the trout exceeded two days even at lead dosages hi excess of 20 mg/I. It seems probable, therefore, that precipitated lead carbonate is not effective as a lethal agent. For further evidence that insoluble lead is not. highly toxic to fish, see. Lead Oxide. A chart submitted by the Water Pollution Research Board (74) indicates that the median period of survival of rainbow trout in soft water containing dissolved lead, at 1S.5C, was 18 to 24 hours at 1.6 nig/I and only .10 to .12 horn's at 4.0 mg/1. The Water Pollution Research Board has also shown that the toxicity of lead toward rainbow trout increases with a reduction of the dissolvod-oxvgen concentration <>f the wafer (74, 88, 3321, 3322). The following table DUP050311851 4 SOS WATER QUALITY CRITERIA shows factors by which the .threshold concentration of lead must bo multiplied to determine concentrations of equal toxicity at lower dissolvcd-ox-ygen tensions: Dissolved oxygen (piTtvnt of .saturation) Factor 100 SO 00 40 1.0 0.95 0.S5 0.71 The following concentrations of lead have been re ported toxic or lethal to fell in the time specified (see also the various lead salts) : Coisvenirnt.jon of Ic .k I, iu sig/l Type of water Time of exposure Species of fish Reference 0.1 0.1 0.1-0.2 0.2 0.21 0.25 0.33 0.34 0.4 0.41 0.53 0.75 1.0 x.o 1.4 1.4 2.0 2.413 2.7 2.3 4.0 4.0 5.5 5.5 0.3 10.0 17 27 40 63 75E very soft soO, _ fresh - 1000-3000 mg/1 ofdissolvcd solids distiller! 1000-3000 ms/! of dissolved 4S-hour TL 2G-4S hours 24-hour TLm fish.............................. 353, 573, 1249 Sticklebacks. ......... 14G0, 2920, 2944 Sticklebacks_________ 1459 Fish........ ..................... 3319 Gappy.......................... 2921 Fish.............................. 593 Minnows, brown trout and sticklebacks___ 311,313.353,2920 Stickk*lcl:s and coho 3536 salmon Minnows......... Coho sAlmon.......... 1459 3536 1000-3000 ma/l of dissolved solids soft tap tap SOlfc distilled fresh stream witter distilled tap tap hard 24-hour TLm long-term 8.5 days 1S-24 hours 48-hour TLm 24-hour TLm 90-hour TL,,, 4-10 hours [6-12 hours 24 it 48-hour TLm i(M$3 days SO hours 80 hours O'.i-hour TL[,, Sticklebacks.............. .. 3536 Minnows.....--_____ Carp............................. Sticklebacks...... Rainbow trout........ . Llbn.Td1161uift>;h__ .... ninegill sunfish........ Fathead minnows......... Minnows____________ PVh.............................. 363 3327 H44,1480 74 2093 2093 2154, 2125 313 8631 Fish.............................. 313 Trout............................ 313. 5113, 609 313 Illuccillsunfisli_______ Goldfish........................ Goldfish........................ Catfish.......................... Goldfish........ Goldfish.............. Fathead minnows 2093 1439,2320 1459 1459 H6G 1406 2151, 2125 E = exploratory test only The following concentrations of lead have not visibly harmed fell within the time specified: Concentration of lead, in rog/1 Type <it water Time of exposure 0.02 0.7 1.0 4.0 soft tap water very soft 3 weeks indefinitely Species of fish Minnows and StickleCol .fish ...................... Reference 1459 M59 1459 1469 Toward the giant kelp, Macrocystis pyrifera, North and Clcndenuing (2107) found that lead was less toxic than mercury, copper, liexavalcnt chromium, zinc, and nickel. Lead nitrate produced no deleterious effect on tho rate of photosynthesis of kelp in sea water during a four-day exposure at 4.1 iug/1 of lead. The Mersey and Severn River Boards in England have established "working standards" for several streams whereby the total concentration of all heavy metals, including lead, cannot exceed 1.0 mg/1. 4. Summary. In view of the 19G2 Drinking Water Standards of the TJSPHS, setting a mandatory limit of 0.05 mg/1 on lead in water delivered to the consumer, and in light of the fact that lead concentrations as low as 0.1 mg/1 have been deleterious to fishlifc, especially in soft waters, it is evident that the dissolved lead content of surface waters should be restricted to 0.1 iug/I where these two beneficial uses arc involved. LEAD ACETATE rb(<^H302)2-3H20 1. General. Known also as "sugar of lead", this freely soluble lead salt is used in printing and dyeing opera tions, in the weighting- of silk, and in the manufacture of other lead salts. 2. Cross References. Acetate, Lead, and other load salts. 3. Effects Upon Beneficial Uses. a. Irrigation. When lead acetate was tested, 1000 to 10,000 mg/1 of lead severely stunted the growth of water hyacinths in water culture; and 1 to 100 mg/1 retarded growth (1525). In nutrient solution containing lead ace tate, 1500 to 20,000 ing-/l of lead inhibited tlie germina tion of cress and mustard seeds; however, even after 18 days of exposure to lead, the seeds germinated when they were transferred to water cultures (1479). b. Eisli and Other Aquatic Life. Dawson (1459) found evidence of injury to blood cells of catfish exposed for 16 to 183 days to a 50 mg/I solution of lead acetate (27 mg/1 of Pb) in tap water, renewed at 48-hour inter vals. Minnows were killed in 26 to 4.8 hours by 0.4 mg/1 of lead in a solution of lead acetate in non-toxic distilled water, renewed at regular intervals during the observa tion period. It lias been reported that lead acetate concentrations of 10 mg/1 in stream water killed trout (313, 59S, 609). In distilled water, 5.0 mg/1 of lead acetate killed min nows in 4 to 16 hours; and. 10 mg/1 in distilled water rc` newed every second day, killed goldfish in 12 days (313). The Washington Department of Fisheries (2931) re ported that lead acetate at a concentration of 2.8 mg/1 of lead killed fish in fresh water; but Fujiya (3327) maintained that long-term exposure of carp to a much lower concentration of lead acetate (1.0 mg/1 as Pb) resulted in a harmful effect to their serum. LEAD ABSEFAT3 PbHAsO* 1. General. Lead arsenate sprays are used for insect control on crop lauds, especially for the gypsy moth and boll weevil; but it is believed that such use has not re sulted in the contamination of water supplies derived from treated watershed areas (15?,). Fortunately, lead arsenate is highly insoluble in water. 2. Gross References. See Lead, Arsenic, other' arsenic compounds. 3. Effects on Beneficial Uses. a. Domestic Water Supplies. Lead arsenate is more toxic to humans than lead carbon ate. A total of 100 mg of lead arsenate ingested by two individuals over a period of 1.0 days caused no apparent harm (353). b. Stock and Wildlife "Watering.- In doses of 1.3 to 56.7 grams per day, lead arsenate killed 18 out of 3.1 chickens, but the survivors showed ho symptoms of poi soning'. Drinking water containing- about 1800 mg/1 ol: lead arsenate caused no harm to 10 birds after a GO-ihty DUP050311852 WATER QUALITY CRITERIA 209 period (1013). Toward male rats, the LD5o value of lead arsenate has been reported as 1050 mg/kg. TIic daily consumption by one cow of 6.48 grams of lead arsenate for an unspecified period was not harmful (1014). e. Fish and Other Aquatic Life. A concentration of 25 mg/1 of lead arsenate has killed trout within 24 hours (359), but a concentration of 17.1 mg/1 in stabi lized tap water did not harm minnows during a one-hour oxposuro(362). Li!AD GHLGEID3S PbCl2 (sec also Chlorides, Lead and other lead salts) This relatively soluble lead salt is used in the manufastute of certain lend paints and as a solder and flux. The following concentrations of lead chloride have been reported as deleterious toward aquatic life: Concentration of Loud CWcrido, mg/1 Typo of water Tima of exposure Type of organism Reference sF" many Vanda gsss Luke ISrie 10 days jm-ltr. Tlim 9G-Ur. TLn. MHfc::::: SEE Cucbjtt wrmlU............ Va 2tM5Sa5 K = exploratory lest only It was also reported (654) that Daphnia magna with stood 10 mg-/l of lead chloride for 5 hours, but succumbed in 24 hours. LEAD OXIDE PbO This insoluble whitepowderis used extensively in paints. Wallen et til.(2940)tested Itstoxicity toward the mosquito fish (Gamlmsia afflnis) in water having a turbidity from soil suspension of 315 mg/1, a pH range of 7.1 to 7.2, and a temperature range of 18 to 20G. He fouud that the 96-hour TLm was greater than 56,000 mg/1 and there was no significant decrease in turbidity as a result of the addition of lead oxide. Apparently insoluble load is not toxic to fish. LHAD 3TSTEATS ' (see also Lead, Nitrates) Pb(N03)2 Used in the manufacture of matches and special explo sives, as a mordant in dyeing and planting of textiles, as an oxydizer in the dye industry, and in photography and engraving, this lead salt is highly soluble in water (364). For tadpoles in tap water, 1.6 mg/1 of lead nitrate is deleterious to growth and 3.3 iug/1 is lethal (313). Pish appeared to try to avoid, i.e., react negatively, to solu tions of lead nitrate varying in strength from 0.33 to 61:4 mg/1, but reacted positively to a 6610 mg/1 solution after a temporary initial negative reaction (1046). Westfall found that concentration of dissolved oxygen lias a significant effect on the response of goldfish to lead nitrate, for example, all the fish tested survived a 2-hour exposure to 5 mg/1 of lead nitrate in the presence of 6.2 mg/1 of oxygen, but all the fish tested died within 2 hours in tire presence of only 1.4 mg/1 of dissolved oxy gen (1459). In fresh water, 3 mg/1 lead nitrate lias been fatal to Fnndulus within 12 hours (145!)). Using lead nitrate, Jones found the lethal concentration limit of lead for sticklebacks to be 0.1 mg/1. At dliferent concentrations of lead, the average survival times of the fish were as' follows: one day at 1.0 mg/1, two days at 0.7 mg/1, four days at 0.3 mg/1, and one week at 0.2"mg/1 (1460). How ever, goldfish died only after an 80-hour exposure to 63 mg/l of lead (1466). Minnows died within -48 hours when exposed to 0.4 nig/i of lead in a solution of lead nitrate in non-toxic distilled water (1459). Tile following concentrations of lead nitrate have been reported to have killed fish: Conoen- tration of Lead Ni irate,in Type of mg/l water 0.16 0.53 tap tap 10 natural 10 tap 10 16 16.6 100 1G5 240 250 250 830 3320 8300 10(500 -1 `1000 53000 hard tap hard distilled turbid distilled dimmed --_ -- .... Time of Exposure ~ 2.5 hours 2 1 and *1S-Ur 4 clajs _ 20 hours SO hours ___ 90-hr T.t/m 4-5 clays 2-3 hours 3 hours 3.2 hours 1.5 hours 1.4 hours 4 4 minutes 40 minutes ls. Pis7i Reference stieklobacfc 2020, 593 minnows, sticklebacks, and bvowrt trout 2920 trout 313, r>98 bincgill sunftsli 2093 miwnowa goldfish fish gmooldsfqisuhito-fish minnows minnows minnows minnows minnows mmiinnnnooww'ss On the other band, 10 mg/I of lead nitrate in hard water has not harmed fish during a 96-hour exposure period (313). Bringmann and Kulin (2158, 3343) tested the effects of lead nitrate in River Havel water at pH 7.5 and a temperature of 240 against several organisms during an exposure of 4 days. The threshold concentrations for deleterious action were as follows: Test Organism Daphnut magna Seenedeamus Escherichia coll Microregma, Threshold Concentration in mgfl of Lead 5.0 2.5 1.3 1.25 Cleland (3328) found that lend nitrate i i a concen tration of about 200 rng/l in sea water produced abnor malities in the eggs of sea urchins. LEAD BTJLFATE (see also Lend, Sulfates) PbSCL Sparingly soluble in water, this salt is used as a paint pigment, for weighting fabrics, in lithography, and in galvanic batteries. In distilled water 25 mg/1 of lead sulfate killed goldfish iu 4 days and killed minnows in 2 to 3 hours (313). Jones (2920) reports the lethal con centration for goldfish ns 26 mg/1. LEAD TETRAETHYL PMCH-I-.U Used as an additive in motor fuels to prevent knocking, this lead compound might occur in the effluents from re- DUP050311853 210 WATER QUALITY CRITERIA fineries. Tn'imbull ct al. (2093) conducted bioassays with ibis subsliiucq hi -Philadelphia taptvat.er, using blucgill s i in fish 1is > macrochirna) as the test fish. They found a'S-llliour.TL,,, of 2.0 mg/1 as lead and a 18-hour TL,,, of l.sllmg/l. They estimated the safe concentration at 0.20 mg/l.., LIGHASAHT(sec Mcr<mro-Orgauie Compounds) hmohwp)^mp >&im l h io l e at e s (see Fatty Acids) l is s a roii11 (isrq n y l p h h n o l e t h y l e n e OXIDE 1 CONDENSATE) (see Chapter X) . LIME (see Calcitfm Hydroxide) ij n d a n e ;,',. . (see Chajojer IX-.--Benzene Hexaehloride) LITHIUM L;.',.' . Li (see also Lithium Chloride) As one of the alkali metals, related to sodium and potassium, lithium is not widely distributed in nature, being- found in a few minerals and in certain spring waters. Being very active, the metal does not occur in [he elemental state and when purified as such it must be protected from water or oxygon. It is used in metallurgy, in medicinal waters^ in some types of glass, and as lith ium hydroxide in storage batteries. Hibbard (250) rec ommends,- without references, that lithium in water for drinking and cooking purposes should not exceed 5 mg/1. Lithium toxicity in citrus has been identified in Santa Barbara County, California. In green-house experiments, 2 and 5 mg/l of lithium sulfate, (in air-dried soil) caused the appearance of toxic symptoms in orange seedlings within 6 months. In the field, 1, 2, and 4 mg/l of lithium chloride in-the soil have caused symptoms of: lithium toxicity. Various irrigation waters in the area were found to contain 0.0-13-0.080 'mg/l of lithium. Possibly lithium poisoning has resulted from the accumulation in ground of toxic concentrations over a long period of time. Al drich (.1591) mid his collaborators are making further studies of the effects of 0.05-0.1 mg/l of lithium in ir rigation water. LITHIUM CARBONATE LisC03 This light white alkaline powder, quite soluble in water, is used in the production of glazes on ceramic and electrical porcelain (364). It was reported in 1923 that concentrations of 295-516 mg/l of lithium carbonate re tarded larval and pupal development of Drosophila me- lanogaster (.11592), LITHIUM CHLORIDE LiCl (see also Lithium) A white deliquescent crystalline solid, lithium chloride is highly soluble in water. It is used in pyrotechnics and in the soldering of aluminum. It is also used in the manu facture of mineral waters and it may be found in some natural mineral springs (364). In a concentration of 3750 mg/l, lithium chloride in distilled water killed goldfish in 22 to 27 hours (313). For mature small l`resh-wrdcr fish, the lethal concentra tion in 24 hours of exposure was found to be 2600 mg/l. The data gathered by Powers and by Iwao indicate that lithium chloride at concentrations between 1950 and 3770 mg/l can kill fresh-water fish in about one day, or sooner at warmer temperatures (.1459). In contrast with these high concentrations required for lethal effect, one German publication (2977) reports that 100 mg-/I of LiCl is toxic but 33 mg/l is harmless to fish. The threshold concentration for immobilization of Daphnia r.mgna in Lake Eric water was found to be less than 7.2 mg/l (598) ; but in RiveFThivol water at 23C the threshold of poisonous effect was observed at 16 mg/l during 48 hours contact (2.1.58). With the protozoan Microrcgma as tlio test organism, food intake was inhib ited at 66 mg/I (3343). Toward Seenedcsunts and Esche richia coli, no toxicity was evident at concentrations less than 1000 mg/l (2158). In order to evoke stimulation and movement of the water beetle, T.accophilus maculosis, a LiG1 concentration of .19,500 mg/l was.required (2956). It has been reported that dilute concentrations of LiCl are deleterious to the eggs of various aquatic organisms, retarding their development and producing monstrosities (1467). King demonstrated that concentrations of 848 mg/l were highly toxic to fiy larvae, preventing emerg ence of offspring and retarding development of both larvae mul pupae (15.92). LITHIUM FLUORIDE LiF This moderately soluble salt is used as a flux for solder ing and welding aluminum and in the manufacture of vitreous enamels and glazes (3611. The oral Ll).-0 for guinea pigs is 200 mg/kg of body weight (3271). The lethal dose in 48 hours for the fish, Tinea vulgaris, is reported as 20,000 mg/l (3271). LITHIUM SULFATE (see Lithium) LOROL TOETASODXUM fjULFOBEKZ OATS (see Chapter X) MAGNESIUM Jig 1. General. As one of the most common elements in the crust of the earth, constituting about 2.1. percent of it, magnesium is widely distributed in ores and minerals (364). Because it is very active chemically, it is not found in the elemental state in nature. With the exception of the hydroxide at high pl.t values, its salts are very soluble; even the carbonate will dissolve to the extent of 100 (o 300 mg/l at normal temperatures (364, 911). The solubility of .magnesium hydroxide is governed by the equation: [Mar] [Oft-]2 1.2 x :io-u at I.30 Thus, at pH 7, magnesium ions theoretically can be present to the extent of 1200 tools per liter or 23,800 DUP050311854