The oral administration of Ametryn Technical at the dose of 100 ppm had no effects on general health, growth, food consumption, pre-terminal deaths and life expectancy, differential leukocyte count values, and changes in organ weights. No gross or histopathological changes seen were attributable to the test substance.
No effect on general health, body weights, net weight gains, food consumption, organ weights and organ weight ratios in both the sexes except an incidental decrease in mean body weights on week 3 and decreased body weight gains in males at the 675 ppm dose level.  NOEL of Ametryn Technical in Swiss albino mice was 225 ppm in the food which is equivalent to 44.8, 51 .8 and 48.3 mg/kg Bwt/day for males, females and combined sex respectively under the testing conditions described in the material and method section and the doses employed.
No effect on general health status, growth, hematological and clinical chemistry parameters, organ weights, and histopathological changes at the low-dose (150 ppm) group.  Adverse effects reported in mid-dose (600 ppm) and high-dose (2400 ppm) groups.
Mortality was significantly increased.  A statistically significant decrease in body weight, increase in urinary pH and presence of occult blood in the urine was also noted.  There was also a significant increase in non-neoplastic and neoplastic lesions of the bladder and urinary system.
In view of the results it is inferred that the oral administration of Ametryn Technical for a period of 24 months at the dose of 75 ppm had no adverse effects on general health, growth, survival and food consumption. There were no treatment related changes in haematology, clinical chemistry and urinalysis. No gross or histopathological changes were attributable to the test substance. Hence this dose, which is equivalent to 3.8, 5.0 and 4.4 mg/kg Bwt/day for males, females and combined sex, respectively was considered as No Observed Effect Level (NOEL) for chronic effects of Ametryn Technical in Wistar rats.
No effect on general health status, body weights and growth and organ weights (excepting for the reduced weights of thymus in males and heart in females).  NOEL is 750 ppm in feed which is equivalent to 86.9, 101.7 and 94.3 mg/kg Bwt/day of the test compound for males, females and combined sex, respectively under the test condition and doses employed.
On the basis of usual observations (i.e. body weight and food consumption), haematological and blood chemical determinations  and autopsy, liver and kidney weights and the histological examination observations on: liver, kidneys, stomach, small and large intestines, spleen, pancreas, heart, lungs, bone marrow, muscle, brain, spinal cord, bladder, adrenals, thyroid, pituitary, gonads, salivary glands, and lymph nodes.
Reduced  final body weight of 10%  together with reduction body weight gain of 12% observed in male rats administered 12,500 ppm eugenol (equivalent to 1250 mg/kg bw/d) compared to control males were considered as slight treatment-related effect since no chemically-related gross or histopathologic effects were observed among the rats. Expert judgment.
There was a significant decrease in the number of total implantation sites per litter, however the lack of associated effects on other reproductive parameters do not allow  for a direct conclusion that this observation has a direct effect on reproduction.
Treatment-related multinucleated hepatocytes of varying numbers were detected in the livers from the mid-dose (T2 = 37.5 mg/kg/day and T3 = 75 mg/kg/day) and high­dose (T4 = 150 mg/kg/day) rats.The "no-toxic-effect" level was considered to be 15 mg/kg/day.
One male and one female at 1000 mg/kg/day were sacrificed for ethical reasons on Day 14 and 24 respectively, showing several clinical signs indicative of ill health. Microscopic examination revealed minimal/slight erosions in the stomach, correlating to the irregular surface recorded at necropsy, slight red pulp atrophy of the spleen and slight/moderate lymphoid atrophy of the thymus, correlating to the reduced size recorded at necropsy. Since these deaths occurred in the highest dose group, and based on clinical signs in the surviving animals at 1000 mg/kg,  a relation to treatment with the test substance cannot be excluded.