Pesticides 



A general description of the use and the effects 

 of pesticides on aquatic life is given in the marine 

 section. Basically, their effects are similar in both 

 the marine and fresh water environments. 



The addition of any persistent chlorinated 

 hydrocarbon pesticides is likely to result in dam- 

 age to aquatic life. Therefore, as concentrations 

 of these chemicals increase in the aquatic environ- 

 ment, progressive damage will result. The acute 

 effects usually will be recognized, but the chronic 

 consequences may not be observed for some time. 



The use of other kinds of chemical pesticides in 

 or around fresh waters may produce a variety of 

 acute and chronic effects on fish and the other 

 components of the biota. Because these other 

 chemicals are usually not as persistent as the 

 chlorinated hydrocarbons, the Subcommittee feels 

 some of them can be used around water, but only 

 in amounts below those that produce chronic dam- 

 age to desirable species. 



Recommendation: (1) Chlorinated hydrocarbons. — 

 Since any addition of persistent chlorinated hydro- 

 carbon insecticides in likely to result in permanent 

 damage to aquatic populations, their use should be 

 avoided. 



(2) Other chemical pesticides. — Addition of other 

 kinds of chemicals used as insecticides, herbicides, 

 fungicides, defoliants, acaracides, algicides, etc., can 

 result in damage to some organisms. Table III-5 lists 

 the 48-hour TL,,, values for a number of pesticides for 

 various types of fresh water organisms. To provide 

 reasonably safe concentrations of these materials in 

 receiving waters, application factors ranging from Mo 

 to Vioo should be used with these values depending on 

 the characteristic of the pesticide in question and used 

 as specified earlier in the section on application factors. 

 Concentrations thus derived tentatively may be con- 

 sidered safe under the environmental conditions rec- 

 ommended. 



Other Toxic Substances 



Detergents and Surfactants: The toxicity of 

 ABS has been reported by many workers. A wide 

 range of endpoints have been used as criteria and 

 while comparison is difficult, a reasonable conclu- 

 sion is possible. There is no agreement on the 

 effect of calcium and magnesium concentration. 

 Recommendations are based on the data from 

 table III-6. 



Recommendation: With continuous exposure, the con- 

 centration of ABS should not exceed Vt of the 48- 

 hour TL„, concentration. Concentrations as high as 

 1 mg/1 may be tolerated infrequently for periods not 

 exceeding 24 hours. ABS may increase the toxicity 

 of other materials. 



Much less work has been done on LAS, a 

 newer, degradable detergent, than on ABS. Bar- 

 dach, Fujiya, and Holl (1965) report that 10 mg/1 

 is lethal to bullheads and 0.5 mg/1 will erode 50 

 percent of the taste buds within 24 days. For fat- 

 head minnow fry, Pickering (1966) reports a 

 9-day TL„, of 2.3 mg/1. Thatcher and Santner 

 (1967) report 96-hour TL„, values from 3.3 to 

 6.4 mg/1 for five fish species. Swisher, O'Rourke, 

 and Tomlinson (1954), testing bluegills, found 

 TL,u values of 3 mg/1 for LAS and 12 carbon 

 homologs and 0.6 mg/1 for 14 other carbon homo- 

 logs. An intermediate degradation product had a 

 TLn, of 75 mg/1. Dugan (1967) found that sensi- 

 tivity to chlorinated pesticides possibly increased 

 after exposure to detergent. Other studies as yet 

 unpublished indicate a surprising increase in tox- 

 icity at low dissolved oxygen concentrations. 



Pickering and Thatcher (in press), in the only 

 reported study on reproduction, found that 0.6 

 mg/1 had no measurable effect on reproduction or 

 growth but 1.1 mg/1 had an effect. In tests with 

 five species of fishes. Thatcher and Santner 

 (1967) found two species which were more sensi- 

 tive to LAS than fathead minnows. 



With both ABS and LAS detergents, the more 

 readily degradable components are the more toxic. 

 As a result, the components remaining will be less 

 toxic than the original product. 



Recommendation: The concentration of LAS should 

 not exceed 0.2 mg/1 of V^ of the 48-hour TL,,, con- 

 centration, whichever is the lower. 



Cyanide: Although it has been studied exten- 

 sively, cyanide is not well understood as a hazard 

 to aquatic life. Certain unique and peculiar char- 

 acteristics necessitate special treatment of this 

 chemical even though acceptable concentrations 

 cannot be given. 



Recent work on fish by Doudoroff et al. ( 1966), 

 has demonstrated that HCN rather than CN is the 

 toxic component. Except for certain extremely 

 toxic heavy metals (silver, for example) the tox- 

 icity of metallo-cyanide complexes can also be 

 attributed to the HCN. This then makes the effect 

 of pH on cyanide toxicity of great importance. 

 Doudoroff (1956) demonstrated a thousandfold 

 increase in the toxicity of a nickelo-cyanide com- 

 plex associated with a drop in pH from 8.0 to 6.5. 

 A change in pH from 7.8 to 7.5 increases the tox- 

 icity ten times. The data reported by Cairns and 

 Scheier (1963b) indicate that the calcium-mag- 

 nesium concentrations (hardness) do not mate- 

 rially affect cyanide toxicity. It should be noted 

 that in their test solutions while the calcium- 

 magnesium concentration of their soft and hard 



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