July 29, 2014

Diethylmethylbenzene diamine (DEDTA) Developmental Toxicity Study in Rats, TNOTriskelion Study Report No. V20193, Project No. 093.20418, 

Summary

A developmental toxicity study was conducted with Diethylmethylbenzene diamine (DEDTA) 

accoring to OECD TG 414 (2001) and Council Regulation EC No. 440/2008 B.31 (2008). Groups 

of 24 pregnant rats received DEDTA by continuous oral administration in the diet from gestation 

day (GD) 0 until GD 20. The test substance was given at constant dietary nominal concentrations 

of 0 (control), 50 (low-dose), 150 (mid-dose) and 500 mg/kg diet (high-dose). These doses 

corresponded to 0, 2.63, 7.83 and 20.45 mg/kg bw per day interpolated actual test substance 

intake. The doses were chosen on the basis of two dose range finding studies. During the in-life 

phase clinical signs, maternal body weight and food consumption were recorded. 

Ophthalmoscopic examination was performed pre-treatment and at gestation day 20. At 

Caesarean section, females and fetuses of all groups were macroscopically examined and blood 

was collected for haematology and clinical chemistry. Fetuses, placentas and reproductive 

organs were weighed. Histopathology of the pancreas as the primary target organ for DEDTA 

toxicity was performed in the dams. Fetuses were further processed for fetopathological 

examination.

Upon analysis of the experimental diets, DETDA was found to be homogeneously distributed at 

all dose levels and stable in diets after storage in a freezer (≤ - 18oC). However, the initial 

measured content of DETDA was 10-16% lower than intended, and storage in the animal room 

for 5 days (in an open container) resulted in 32-41% loss. Although the measured concentrations 

were lower than the intended nominal concentrations in diets, the achieved exposure levels did 

result in maternal toxicity at the high dose level. Therefore the guideline requirements of maternal 

toxicity at the high dose level were met and the study was considered valid at relevant dose 

levels.

Feed was removed and completely replaced by feed from the freezer twice weekly at three or 

four day intervals. The actual test substance intake was assessed taking into account the 

measured initial levels and the (interpolated) loss during storage for 3 or 4 days in the animal 

room. 

In the high dose group maternal toxicity was observed as represented by a body weight loss 

during the first three days of gestation, followed by a decreased mean body weight gain and 

decreased food consumption during gestation, reduced ovary weight and induction of acinar cell 

apoptosis and mononuclear cell inflammation in the pancreas in most of the animals of the high 

dose group (13 animals with minimal to moderate apoptosis of the pancreatic acinar cells, 15 

animals with minimal to mild mononuclear cell inflammation). In the mid dose group minimal 

induction of acinar cell apoptosis was observed in two animals and minimal mononuclear cell 

inflammation in one animal. Although this finding was of low incidence and severity in this group, 

it could be regarded as a first indication of an effect on the target organ. Consequently, the low 

dose level was considered a No Observed Effect Level (NOEL) for maternal toxicity..

Developmental toxicity was observed in the high dose group, as evidenced by a decreased 

number of implantation sites and live fetuses. In addition mean placenta weight and mean fetus 

weight were decreased, which was confirmed by an increase in incidence of small fetuses. A 

Dr. Sylvia Jacobi

Corporate Toxicology Director

Parc Scientifique Einstein Rue de Bosquet 

9B-1348 Louvain-la Neuve Sud

Belgium

Phone: +3210481768

Fax: +3210481768

e-mail: Sylvia.jacobi@albemarle.com
2

slight retardation in ossification in the fetuses of the high dose group was related to the lower 

fetus weight.

Fetal observations with single incidences including one foetus showing a hernia ventralis, one 

fetus being too small and one fetus showing dilated ventricles of the brain were considered not 

treatement related based on the low (single) incidence and the absence of dose relationship.

In absence of developmental effects in the mid-dose group, the NOAEL for developmental toxicity

was placed at the mid-dose level of 7.83 mg/kg bw/day

Effects on fetus weight, placenta weight and ossification are considered to be related to maternal 

toxicity as outlined in Waalkens-Berendsen et al., 2002 and 2004, Wolterbeek et al., 2004 and 

Meiling et al., 2004. In this study overt maternal toxicity was observed at the high dose level. An 

onset of the target organ effects in the dams was already observed in some animals of the mid 

dose group, but not accompanied by fetal toxicity. Consquently, the effects on embryo-fetal 

development that were observed at the high dose level were considered to be secondary to 

maternal toxicity

References: 

Waalkens-Berendsen D.H., Kuilman-Wahls M.E.M., Wolterbeek A.P.M. Maternal toxicity and fetal 

development: effects of decreased food intake.

Reproductive Toxicology 16, 425, 2002.

Wolterbeek APM, Tegelenbosch-Schouten MM, Waalkens-Berendsen DH and Dijkstra A.

Impact of maternal toxicity on pre- and postnatal development of rats.

Reproductive Toxicology 18, 753, 2004.

Meiling J, Wolterbeek APM, Waalkens-Berendsen DH, Tegelenbosch-Schouten MM and Dijkstra 

A. Impact of maternal toxicity on pre- and postnatal development of rats.

Toxicology and Applied Pharmacology 197, 211, 2004.

Waalkens-Berendsen ID, Tegelenbosch-Schouten MM, Dijkstra A and Wolterbeek APM.

Impact of maternal toxicity on pre- and postnatal development of rats.

The Toxicologist 78, Suppl. 1, 221, 2004