| collaboration between monitoring authorities, regulatory authorities and test facilities on glp principles provides confidence in data quality with an emphasis on sound science. glp: an example of a focused effort that paid off. | the herbicide atrazine has been the subject of numerous studies investigating its potential effects on amphibians. the united states environmental protection agency (epa) required the atrazine registrant to conduct a tiered study approach. tier i of the studies involved laboratory studies to determine whether atrazine affects amphibian gonadal development. several good laboratory practice (glp) inspections were conducted during the tier 1 atrazine amphibian study entitled "response of larval xen ... | 2008 | 19351996 |