Tests of DDT on pinfish, Lagodon 

 rhomboides in 40-liter volunne s 



POLYETHYLENE 



showing that toxicity was reduced 

 by use of polyethylene bags for con- 

 tainers over use of glass vessels. 



25 50 



TECHNICAL DOT ( ppb) 



Experiments to determine methods for studying the long-term ef- 

 fects of sublethal levels of pesticides were initiated. In the first trial 25 sail- 

 fin mollies, Mollienisia latipinna, 16 to 17 days old were exposed to a continu- 

 ous flow of technical grade DDT (2 p.p.b. ) The glass tanks hold approximately 

 40 liters, and new medium is added at the rate of approximately 1 liter per hour. 

 Every 2 weeks animals are removed, counted, measured, and returned to the 

 tanks. After 14 weeks, animals in 

 the test and control tanks show no dif- - 

 ference between groups in either 

 growth or survival. 



Showing similarity at end of 14 weeks 

 in growth and survival of sailfin mol- 

 lies, Mollienisia latipinna, exposed 

 to a sublethal concentration of 2 

 p.p.b. of technical grade DDT. 



«^8 



TIME (WEEKS) 



54 



