As its production and use increased, public response was mixed. At the same time that DDT was hailed as part of the "world of tomorrow," concerns were expressed about its potential to kill harmless and beneficial insects (particularly pollinators ), birds, fish, and eventually humans. The issue of toxicity was complicated, partly because DDT's effects varied from species to species, and partly because consecutive exposures could accumulate, causing damage comparable to large doses. A number of states attempted to regulate DDT.   In the 1950s the federal government began tightening regulations governing its use.  These events received little attention. Women like Dorothy Colson and Mamie Ella Plyler of Claxton, Georgia gathered evidence about DDT's effects and wrote to the Georgia Department of Public Health, the National Health Council in New York City, and other organizations. 
1. Antibiotics in food and as medicine . A recent article in the New York Times confirms suspicions that the antibiotics routinely given to livestock to make them fat do the same thing to people. Antibiotics are thought to fatten by changing gut bacteria to make absorption of nutrients more efficient. In 1974, an experiment was done on several hundred Navy recruits to see if they would gain weight on antibiotics and, after only seven weeks, they did. An experiment was also done, unethically it sounds, on "mentally deficient spastic" children in Guatemala in the 1950s, reports the Times. The children gained an extra five pounds over a year compared with children who were not given antibiotics. Denmark researchers found babies given antibiotics within six months of birth were more likely to be overweight by age seven.