Page 2 of 38

8E7362 and 8E7363; 2-(2’-hydroxy-3’, 5’-di-tert-amylphenyl) benzotriazole (CAS Reg. No. 

25973-55-1) and Phenol, 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methyl (CAS Reg. No. 23328-53-

2)). Much of the current document discussion is taken from the Agency’s 14 July 2010 

assessment. 

CAS Reg. No. 25973-55-1 and CAS Reg. No. 23328-53-2 are currently used as packaging 

stabilizers (preventing UV light from yellowing or hardening product packages). They are also 

used in paints and coatings. In addition, the Food and Drug Administration (FDA), under 21 CFR 

175.105, has approved the use of CAS Reg. No. 25973-55-1 as an indirect food additive for use in 

food packaging. 

Phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2) is classified 

among the phenolic benzotriazole (PBTZ) class of chemicals. The PBTZ class of chemicals 

consists of mono and di-substituted phenolic derivatives of 1,2,3-benzotriazole. Data have been 

published regarding a number of PBTZ chemicals regarding chemical properties, mammalian 

toxicity and environmental fate and effects. There are five compounds which are structurally and 

toxicologically similar to phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl-. They are:

1) drometrizole (Tinuvin® P; CAS Reg. No. 2440-22-4); 2-(2’-hydroxy-5’-methylphenyl 

benzotriazole

2) octrizole (UV 329; CAS Reg. No. 3147-75-9); 2-(2’-hydroxy-5’-octylphenyl benzotriazole

3) HDBB (CAS Reg. No. 3846-71-1); phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethyl)- 4) 

4) Tinuvin® 234 (CAS Reg. No. 70321-86-7); 2-(2H-benzotriazole-2-yl-4,6-bis(1-methyl-1-

phenylethyl) phenol and

5) Tinuvin® 328 (CAS reg. No. 25973-55-1); 2-(2’-hydroxy-3’,5’-di-t-amylphenyl)benzotriazole.

Acute studies revealed low acute toxicity with an oral LD50 >2325 mg/kg based on the highest 

dose tested. Acute inhalation, acute dermal toxicity, skin and eye irritation and skin sensitization 

studies have not been conducted on either of the chemicals contained in this petition; however, 

evidence does exist for structurally similar chemicals contained within the High Production 

Volume (HPV) document. Acute inhalation and dermal studies resulted in LC50 >1420 mg/m3and 

LD50 >2000 mg/kg, respectively. Skin irritation studies on rats and mice showed no local irritation 

and no systemic toxicity. The Agency concluded in the HPV document that CAS Reg. No. 2440-

22-4 was slightly irritating to rabbit eyes. The document states that CAS Reg. No. 2440-22-4, in 

skin sensitization studies on guinea pigs, showed skin sensitization; however, studies conducted on 

humans showed no sensitization. 

In a 90-day study Wistar rats were given the test substance via their diet at 100, 200, 400, 800, or 

1600 ppm (approximately 5, 10, 20, 40, or 80 mg/kg/day). Decreased hemoglobin and packed cell 

volume were seen in males administered ≥~20mg/kg/day and increases in glucose-6-phosphatase 

activity was noted at all dietary concentrations; however, these values were within the normal 

range of variability and therefore, are not considered to be of toxicological significance. Liver, 

kidney, spleen, and testes weights were increased in higher exposure groups with an indication of 

increased thyroid weights. Increases in testes weights were seen at ~20, ~40, and ~80 mg/kg/day; 

however, the testes weights were reported as testes weight per 100g body weight. The increase in 

testes weight may be caused by the decreased body weight and not a toxicologically significant 
Page 3 of 38

finding. Reproductive organs were not evaluated microscopically. The primary target organ was 

the liver which showed a greenish-drab discoloration in males and females at higher exposure 

levels. “Microscopic examination revealed foci of necrosis and slight proliferation of bile duct 

epithelia.”(HPV, 2009) Enlargement of the parenchymal cells was also observed. Tubular necrosis 

was reported in the kidney of some males in the higher does groups. A treatment related yellowishbrown pigmentation was seen in the cytoplasm of the proximal tubular cells of females. No 

mortality was observed. The NOAEL of 20 mg/kg/day is based on blood, liver, and kidney effects 

seen at the LOAEL of 40 mg/kg/day. 

In a 90-day dog study male and female Beagles were administered 0, 15, 30, 60, 120, or 240 

mg/kg/day through their diet. Animals in the high-dose group showed decreases in body weight 

and food consumption. Males were more sensitive than females with mortality of one male dog in 

the highest dose group. Anemia and slight changes in blood chemistry parameters including 

increased serum bilirubin levels and gamma glutamyl transpeptidase (GTP), glutamyl oxalacetic 

transaminasae (GOT) and alkaline phosphatase activity were noted in the animals from the two 

highest dose groups. Males from these groups showed decreases in testes, prostrate, and 

epididymal weights and females showed deceases in body weight and uterus weight in the three 

highest dose groups. In higher dose groups, some animals showed atrophy of uterus, abnormal 

spermiogenesis, and atrophy of the prostate. The liver was reported to be the primary target organ 

for toxicity. Although the full study was not available, the submission summary for the HPV 

program states that at treatment levels of 60, 120, and 240 mg/kg/day, reduced food consumption 

and body weights were seen. In addition, histopathologic effects were noted in the liver, kidney, 

and testes of the 3 highest dose groups (details not provided). Increased liver weights associated 

with liver damage including icterus (jaundice) were observed upon gross and histopathological 

examination in a few dogs in the 120 and 240 mg/kg/day dose groups. Microscopically, fatty 

degeneration of hepatocytes, presence of protein globules in the cytoplasm, Kupffer cell 

hyperplasia and centrilobular choleostatis were seen. (HPV) The NOAEL for this study is 30 

mg/kg/day based on body weight, liver, and kidney effects seen at the LOAEL of 60 mg/kg/day.

Developmental studies have been conducted on two structurally similar chemicals. In one study 

rats and mice received the test substance containing CAS Reg. No. 2440-22-4 on days 6-15 of 

gestation. No maternal toxicity was evident and the rates of implantation and embryotoxicity were 

not affected by treatment. No teratogenic effects were observed however, the study did not specify 

what developmental endpoints were examined. The NOAEL for maternal and developmental 

toxicity was 1000 mg/kg/day (highest dose tested).

A second developmental rat study showed no maternal toxicity at any dose tested for CAS Reg. 

No. 70321-86-7 on gestation days 6-15. A significant reduction in fetal body weight and an 

increased delay of skeletal maturation was observed in the 1000 mg/kg dose group. However, there 

were no similar effects in the high dose group indicating that these effects may be “incidental”. An 

omphalocele was seen in one fetus in the high dose group. The maternal toxicity NOAEL was 

3000 mg/kg/day (highest dose tested). A developmental toxicity NOAEL of 1000 mg/kg/day was 

chosen based on the omphalocele seen at the LOAEL of 3000 mg/kg/day.

All genetic toxicity tests (in vitro and in vivo) conducted on the chemicals assessed in the HPV 

document indicated that this group of chemicals are not mutagenic and will not undergo 
Page 4 of 38

chromosomal aberrations. A 104 week feeding study administered up to 142 mg/kg/day to rats did 

not find evidence of carcinogenicity. The Agency does not believe that CAS Reg. No. 25973-55-1 

and CAS Reg. No. 23328-53-2 will be carcinogenic in humans. No clinical signs of neurotoxicity 

were seen in any of the repeat dose studies. After evaluating the available data and the expected 

exposure from the intended use pattern of this inert ingredient, the Agency does not feel that CAS 

Reg. No. 25973-55-1 and CAS Reg. No. 23328-53-2 will cause neurotoxicity.

A combined repeated dose toxicity study with the reproduction/developmental toxicity screening 

test (OECD 422) was conducted using drometrizole (CAS Reg. No. 2440-22-4). Male and female 

Crl:CD(SD) rats (12/sex/group) were administered drometrizole by gavage at dose levels of 0, 30, 

100 or 300 mg/kg/day in olive oil. An additional group of 5 rats/sex were placed on test for the 

control and high dose group as recovery animals (15 days). Males were administered the test 

material for 42 days and females from 14 days prior to mating to d 4 of lactation. Offspring were 

terminated on PND 4. 

Mortality was unaffected by treatment and no clinical signs of toxicity were observed. No 

treatment-related effects were observed on body weights, food consumption, reflex/reaction, grip 

strength, locomoter activity, hematology parameters or reproductive parameters. 

The reproductive/developmental toxicity NOAEL was the highest dose tested at 300 mg/kg/day. 

The NOEL in males was considered to be < 30 mg/kg/day based on increased relative liver 

weights observed in all dose groups and 30 mg/kg/day based on effects on liver and kidney 

weights and kidney histopathology. The NOAEL was concluded to be 300 mg/kg/day for males 

and 30 mg/kg/day for females based on kidney lesions. 

In an extended one-generation oral reproduction study (OECD Test Guideline 443) with the rat 

(MRID 49358004), the no-observed-effect-level (NOAEL) for phenol, 2-(2H-benzotriazol-2-yl)-6-

dodecyl-4-methyl- for parental and reproductive toxicity was 10000 ppm (equal to 618 mg/kg/day, 

the highest dose tested). The NOAEL for offspring toxicity was 5000 ppm (equal to 311 

mg/kg/day) based on decreased body weight, and body weight gain, increased absolute spleen 

weights in males and increased incidence of splenic extramedullary hematopoiesis in males 

observed in pups at the LOAEL of 10000 ppm (equal to 618 mg/kg/day).

The data from the combined repeated dose toxicity study allow the Agency to remove the 

additional 10X uncertainty factor originally applied due to data gaps. Based on the discussion 

summarized above, Margins of Exposure > 100 based upon conservative (protective) assumptions, 

the Agency approves the use of phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl (CAS Reg. 

No. 23328-53-2) as an inert ingredient used in pesticide formulations under 40 CFR § 180.920 on 

agricultural crops at a maximum end-use concentration not to exceed 10 % by weight 

II. BACKGROUND

The U.S. Environmental Protection Agency (EPA or “the Agency”) received a request (Pesticide 

Petition IN-10704; 9 April 2014) from Pyxis Regulatory Consulting, Inc. (4110 136th St., N.W., 

Gig Harbor, WA 98332) on behalf of Loveland Products, Inc. (3005 Rocky Mountain Ave., 

Loveland, CO 80538) to amend the exemption from the requirement of a tolerance of phenol, 2-
Page 5 of 38

(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2) to allow for its use under 

40 CFR § 180.920 at a maximum of 10% (0.10) in final pesticide formulations applied to growing 

crops.. Phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- is used as an ultraviolet (UV) 

stabilizer in pesticide formulations. The current tolerance exemption for 2-(2H-benzotriazol-2-yl)-

6-dodecyl-4-methyl- is for use at a maximum of 0.6% on adzuki beans, canola, chickpeas, cotton, 

fava beans, field peas, lentils, linola, linseed, lucerne, lupins, mung beans, navy beans, pigeon 

peas, safflower, sunflower and vetch.

On 14 July 2010, the Agency previously assessed the use of phenol, 2-(2H-benzotriazol-2-yl)-6-

dodecyl-4-methyl- (Memorandum, D. Sunderland, Decision Document for Petition Numbers 

8E7362 and 8E7363; 2-(2’-hydroxy-3’, 5’-di-tert-amylphenyl) benzotriazole (CAS Reg. No. 

25973-55-1) and Phenol, 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methyl (CAS Reg. No. 23328-53-

2)). Portions of the current document are taken from the Agency’s 14 July 2010 assessment.

Phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- was originally approved for use under 40 

CFR § 180.920 at a maximum of 0.6% on adzuki beans, canola, chickpeas, cotton, fava beans, 

field peas, lentils, linola, linseed, lucerne, lupins, mung beans, navy beans, pigeon peas, safflower, 

sunflower and vetch. 

The Agency’s existing regulatory decision regarding phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl4-methyl- includes use of a 10X uncertainty factor (UF) as required by the Food Quality Protection 

Act (FQPA) due to what was viewed as an incomplete data based on the lack of any reproduction 

toxicity data. In its request to remove the FQPA 10X SF and to increase the maximum permitted 

concentration in formulated pesticide products, the petitioner has submitted an extended onegeneration reproduction study using the rat in addition to other data not previously considered by 

the Agency.

Phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2) is classified 

among the phenolic benzotriazole (PBTZ) class of chemicals. The PBTZ class of chemicals 

consists of mono and di-substituted phenolic derivatives of 1,2,3-benzotriazole. Data have been 

published regarding a number of PBTZ chemicals regarding chemical properties, mammalian 

toxicity and environmental fate and effects. There are five compounds which are structurally and 

toxicologically similar to phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl-. They are:

1) drometrizole (Tinuvin® P; CAS Reg. No. 2440-22-4); 2-(2’-hydroxy-5’-methylphenyl 

benzotriazole

2) octrizole (UV 329; CAS Reg. No. 3147-75-9); 2-(2’-hydroxy-5’-octylphenyl benzotriazole

3) HDBB (CAS Reg. No. 3846-71-1); phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethyl)- 4) 

4) Tinuvin® 234 (CAS Reg. No. 70321-86-7); 2-(2H-benzotriazole-2-yl-4,6-bis(1-methyl-1-

phenylethyl) phenol and

5) Tinuvin® 328 (CAS reg. No. 25973-55-1); 2-(2’-hydroxy-3’,5’-di-t-amylphenyl)benzotriazole.

III. PHYSICAL/CHEMICAL PROPERTIES (Taken from MRID 49358001)

Molecular Weight........................................393.57

Molecular Formula.......................................C24H35N3O

Color........................................................Yellow
Page 6 of 38

Physical State..............................................Liquid

Odor.........................................................Faint Odor

pH............................................................5.4

Melting Point...............................................-54°C

Boiling Point...............................................174°C

Density at 25°C............................................1.003 gm/cm3

Octanol/water partition coefficient (KOW)..............log P = 8.9 @ 20-25°C

Water solubility............................................<0.0003 mg/L @ 20°C

Vapor Pressure.............................................0.1 hPa @ 20°C 

Molecular Structure (Taken from www.chemblink.com)

Also known as:

Tinuvin 571

UV 571

2-(2H-benzotrialzol-2-yl)-6-dodecyl-4-methyl phenol

benzotriazolyl docecyl –cresol (linear)

2-(3’-dodecyl-2’-hydroxy-5’-methylphenyl)benzotriazole

2-(3’-dodecyl-5’-methyl-2’-hydroxyphenyl)benzotriaole

IV. HAZARD CHARACTERIZATION

Much of the discussion of the toxicological profile is taken from MRID 49358002 as well as the 

Agency’s 2010 assessment cited earlier. The EPA has previously considered phenol, 2-(2Hbenzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2) in Petition Numbers 8E7362 

and 8E7363. In addition to the available, previously reviewed data, the petitioner has submitted 

additional, new data/information not reviewed by the Agency as well as an extended, onegeneration reproduction study.

Acute Oral Toxicity (Rat)

An acute oral toxicity study on phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- is not 

available. Acute oral toxicity studies are available on drometrizole, octrizole, Tinuvin 328 and 

Tinuvin 234. The acute oral toxicities of these compounds ranges from an LD50 of 

< 1000mg/kg for octrizole to >10000 mg/kg for drometrizole.

Acute Dermal Toxicity (Rabbit)
Page 7 of 38

An acute dermal toxicity study is not available for phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-

methyl-. However, the acute dermal toxicity of Tinuvin 234 has been studied and the LD50 is 

>2000 mg/kg.

Acute Inhalation Toxicity (Rat)

An acute inhalation toxicity study is not available for phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl4-methyl-. However the acute inhalation LC50 for drometrizole is >1420 mg/cm3

or 1.42 mg/L.

Acute Eye Irritation (Rabbit)

Drometrizole was considered minimally irritating to the eyes of 2/6 rabbits at a dose of 100 

mg/eye.

Acute Dermal Irritation (Rats and Mice)

Drometrizole did not cause any dermal irritation when applied to rats and mice at doses of 5% to 

0.4 cm2(rat) and 0.1 cm2(mouse).

Dermal Sensitization (Guinea pigs)

Thirty per cent drometrizole in Vaseline was used in the induction phase and 20 % in Vaseline was 

used in the challenge phase of the test. At the 48 hr time point, 90% of the animals had positive 

reactions to the challenge. Drometrizole was considered to be a strong dermal sensitizer.

Tinuvin P was tested using the mouse local lymph node assay. Tinuvin P did not cause an increase 

in the stimulation index in any test group and was considered to be negative in the assay.

REPEAT DOSE TOXICITY

In a 28-day oral toxicity study MR Wistar rats (5/sex/group) were administered octrizole (CAS 

Reg. No. 3147-75-9) in the diet at 0, 1.2, 2.5 or 5 % (corresponding to 0, 1.286, 2.594 or 5.658 

mg/kg/day respectively) according to OPPTS Guideline 870.3050; MRID 49358002). Body 

weights and food consumption were recorded. Gross necropsy was performed and apparently 

some histopathology performed on some organs. There were no deaths nor clinical signs of 

toxicity. Body weights and food consumption were not affected by the treatment. Hydronephrosis 

was noted in 3 control and 4 high dose rats – a finding common with this strain. There were no 

treatment related lesions. The no observed adverse effect level (NOAEL) was determined to be 

5658 mg/kg/day.

In a 90-day oral toxicity study (OPPTS 870.3050; MRID 49359002) with Wistar-derived rats, 

animals were administered drometrizole (CAS Reg. No. 2440-22-4) in the diet at levels of 0, 0.2, 

1.0 and 5.0% (equivalent to 0, 100, 500 or 2500 mg/kg/day, respectively) for 14 weeks. Body 

weight was recorded weekly and food consumption was determined weekly during the first 4 

weeks of the study and then in the 11th and 12th week of the study. Blood was collected at week 13 

for hematological evaluation. Rats were sacrificed at 14 weeks and gross necropsy conducted. 
Page 8 of 38

Organ weights were recorded for the liver, kidney, spleen, heart, brain, testes, ovary, adrenal, 

thyroid, pituitary and thymus. There were no significant effects on food consumption. 

Erythrocyte counts were statistically decreased and leucocyte counts statistically increased in 

males at the high dose. Statistical differences in relative organ weights were noted as follows: 

liver weights were increased in both sexes at the mid and high dose; kidney weight was increased 

in both sexes at the high dose; testes weights were decrease at the mid and high dose; spleen 

weights were increase at the high dose in females; and adrenal weights were increase at the mid 

and high dose in females. An increased incidence and severity of nephropathy was observed in 

male rats at the mid and high dose. Two males in the high dose group had liver changes consisting 

of bile duct proliferation, an increase in the number of Kupffer cells, extended sinusoid and often 

enlarged parenchymal cells with irregular nuclei. A slight increase in lymphatic tissue in the 

spleen was observed. No other treatment-related microscopic lesions were observed. The no 

observed adverse effect level (NOAEL) was determined to be at the 0.2% level of the diet or 

approximately 100 mg/kg/day based on the effects on body weights, hematology parameters, liver 

weights and kidney histopathology observed at the mid and high doses. 

In a 90-day oral toxicity study using Tinuvin 328 (CAS Reg. No. 25973-55-1), Wistar-derived 

rats (10/sex/group) were administered dietary dose levels of 0, 100, 200, 400, 800 or 1600 ppm 

(approximately 0, 5, 10, 20, 40 or 80 mg/kg/day respectively) for 90 days. Body weights were 

recorded weekly and food consumption was determined per group in the first four weeks and in the 

11th and 12th weeks. Blood was drawn to evaluate hematological parameters at week 12. The 

following organs were weighed: heart, liver, kidney, spleen, brain, testes/ovary, thymus, pituitary, 

thyroid an adrenal. Glucose-6-phosphatase activity was determined in the liver. Histopathology 

was performed on the liver and kidney. Body weights were statistically decreased in males at 1600 

ppm throughout the study and in females at the 2-week time period. Food consumption and food 

efficiency were decreased in males at 1600 ppm. Percentage packed cell volume was statistically 

decreased at ≥ 200 ppm in males and in females at 800 and 1600 ppm. Hemoglobin levels were 

decreased or statistically decreased at ≥ 400 ppm in males and at 800 and 1600 ppm in females. 

Liver glucose-6-phosphatase activity was increased in males at the lower dose, but not at the high 

dose levels. Statistical significance was not indicated. Liver weights were statistically increased 

in males and females at 100 and 400 ppm and kidney weights were statistically increased in 

females at 1600 ppm in the subgroup of rats treated for 4 weeks. In the rats sacrificed after 90 

days of treatment, liver weights were statistically increased in both sexes at all dose levels tested 

and kidney weight were statistically decreased in both sexes at ≥ 400 ppm. In the 4-week 

subgroup rats, microscopic examination of the liver revealed very enlarged parenchymal cells in 

the 400 ppm group and slightly enlarged parenchymal cells at 100 ppm. No microscopic findings 

were observed in the kidneys. In the rats in the 90-day group, foci of necrosis and extremely 

enlarged parenchymal cells in males and in a smaller number of females in the 800 and 1600 ppm 

groups. There was a slight proliferation of the bile duct. These findings occurred to a lesser extent 

in the lower dose groups. Foci of necrosis were absent in males at doses below 800 ppm and 

occurred incidentally in females. Parenchymal cells were enlarged at the lower dose levels. The 

no observed effect level (NOEL) was considered to be < 100 ppm and the NOAEL was considered 

to be 100 ppm (about 20 mg/kg/day) based on increased liver weights and microscopic findings in 

the liver.
Page 9 of 38

A 90-day oral toxicity study was conducted using Tif:RAif(SPF) rats (20/sex/group). Test 

animals were administered Tinuvin 234 (CAS Reg. No. 70321-86-7) (according to OPPTS 

Guideline 870.3100) in the diet at dose levels of 0, 50, 300, 2000 and 10000 ppm for 92 to 94 days. 

The dose levels correspond to 0, 2.5, 15, 100 and 500 mg/kg/day respectively. Body weights and 

hematology, clinical chemistry and urinalysis parameters were unaffected by treatment. No 

treatment-related ophthalmic or gross macroscopic findings were observed. Mean absolute and 

relative (to body and brain weights) liver weights were statistically increased in both sexes at ≥ 

300 ppm. Slight to moderate hypertrophy and or cytoplasmic vacuolization of hepatocytes were 

observed in both sexes ≥ 300 ppm. Based upon findings in the liver at 300 ppm (about 15 

mg/kg/day), the NOAEL was considered to be 50 ppm or about 2.5 mg/kg/day.

A 17-day oral toxicity study was conducted using HDBB (UV 320) (CAS Reg. No. 3846-71-1) 

administered by gavage in corn oil to preweanling Crl:CD(SD) rats at dose levels of 0, 0.1, 0.5, 2.5 

or 12.5 mg/kg/day from post-natal days (PND) 4 to 21. Dams were observed daily for clinical 

signs of toxicity and body weights were recorded on days 0, 10 and 20 of pregnancy and on days 0, 

10, 20 and 22 after delivery. All pups were observed daily before and three to four hours after 

dosing for clinical signs of toxicity. Body weights were recorded on PBD 0, 4, 6, 8, 10, 12, 16, 18, 

21 and 22. On PND 22 blood was collected from two male and two female pups per litter. Plasma 

was evaluated for clinical chemistry parameters. At necropsy, th4e heart, lung, liver, spleen, 

kidney and adrenals were weighed. The liver and heart were examined microscopically. 

No treatment-related mortality, clinical signs of toxicity or effects on body weight were observed. 

In male and female pups, albumin, aspartate aminotransferase (AST) and alkaline phosphatase 

(ALP) levels were statistically increased at the high dose. Statistically increased blood urea 

nitrogen (BUN) levels in males and lactate dehydrogenase (LDH) in females were observed at the 

high dose. In male and female pups, liver weights (absolute and relative) were statistically 

increased and spleen weights were statistically decreased. The effects on spleen and adrenal 

weights were not correlated to any histopathologic findings. In the liver, an increased incidence of 

nucleolar enlargement in hepatocytes, hepatocellular anisokaryosis, hepatocellular hypertrophy, 

hepatocellular eosinophilic granular change and decrease hepatocellar glycogen were seen. The 

NOEL was 0.5 mg/kg/day based on increase relative liver weights in male and female pups 

observed at 2.5 mg/kg/day. The NOAEL was 2.5mg/kg/day in male and female pups based on 

liver pathology observed at 12.5 mg/kg/day. 

In a 28-day oral toxicity study (OPPTS 870.3100) HDBB (CAS Reg. No. 3846-71-1) was 

administered in corn oil by gavage to Crj:CD (SD)IGS rats (10/sex/group for controls and high 

dose and 5/sex in the other groups). Daily dose levels were 0 (corn oil), 0.5, 2.5, 12.5, and 62.6 

mg/kg/day for 28 days. Five rats/sex/group were sacrificed after the last dose for assessment of 

hematology and blood biochemistry parameters, organ weights and macroscopic and microscopic 

pathology. The remaining 5 rats/sex/group were maintained on the control diet for a 14-day 

recovery period. Animals were observed for clinical signs of toxicity at 1 and 4 hours after dosing. 

Body weights and food consumption were recorded weekly. Urine was collected for analysis o 

day 25 of the dosing period and on day 11 of the recovery period. Blood was collected for 

evaluation of hematology and clinical chemistry parameters prior to necropsy. Selected organs 

were weighed and microscopic examination of a full set of tissues/organs were examined in the 
Page 10 of 38

control and high dose groups. The liver, heart, kidneys, spleen and thyroid of the mid and low 

dose groups were also examined microscopically.

No mortality or clinical signs were observed. Body weights, food consumption and urinalysis 

parameters were unaffected by treatment. A significant decrease in red blood cells (RBCs) 

hematocrit and hemoglobin was observed at doses of ≥ 2.5 mg/kg/day in males, but not females. 

Fibrinogen levels were statistically decreased at doses of ≥ 2.5 mg/kg/day in males and at the high 

dose in females. A statistically significant increase in the A/G ratio at ≥ 0.5 mg/kg/day, glucose at 

≥ 2.5 mg/kg/day , albumin, ALT and ALP at ≥ 12.5 mg/kg/day and BUN and AST at the high dose 

in males. In females, a statistically significant increase in glucose, A/G ratio, total cholesterol, 

triglycerides and ALT was observed at the high dose only. Relative liver weights were statistically 

increase in males at all dose levels, while absolute liver weights were statistically increased at ≥ 

12.5 mg/kg/day. Absolute kidney weights were increased in male and females in the high dose 

and relative weight at the high dose in males only. Microscopically, an increased incidence of 

hypertrophy of hepatocytes at ≥ 2.5 mg/kg/day, bile duct proliferation at 12.5 and 62.6 mg/kg/day, 

vacuolar degeneration of hepatocytes at ≥ 2.5 mg/kg/day and of focal necrosis and increased 

mitosis of hepatocytes were seen in males at the high dose. Further, males had an increased 

incidence of cell infiltration in the heart (≥ 2.5 mg/kg/day), degeneration of the myocardium (12.5 

and 62.6 mg/kg/day), hypertrophy of the myocardium (62.6 mg/kg/day) and hypertrophy of tubular 

epithelium (62.6 mg/kg/day). In females, an increased incidence of hypertrophy of hepatocytes 

was observed at 12.5 mg/kg/day and 62.6 mg/kg/day and of degeneration of the myocardium at the 

high dose only. The NOAEL was determined to by <0.5 mg/kg/day in males and 2.5 mg/kg/day

in females based on the increased A/G ratio observed in males at all dose levels and effects on 

liver weights and liver histopathology in females at 12.5 mg/kg/day.

In a 90-day oral toxicity study, HDBB (CAS Reg. No. 3846-71-1) was administered once daily 

in corn oil by oral gavage to Crj:CD(SD)IGS rats (10/sex/group) at doses of 0 (corn oil), 0.1, 0.5 or 

2.5 mg/kg/day (males) and of 0 (corn oil), 0.5, 2.5 or 12.5 mg/kg/day (females). Body weights and 

food consumption were recorded weekly. Prior to necropsy, blood was drawn for the evaluation of 

hematology and clinical chemistry parameters and urine collected for determination of urinalysis 

parameters. Selected organs were weighed and microscopic examination of a full set of 

tissues/organs were examined in the control and high dose groups. The liver, heart, kidneys, 

spleen and thyroid of the mid and low dose groups were also examined microscopically. 

No clinical signs of toxicity were observed. Body weight gain was statistically decreased in males 

in the 2.5 mg/kg/day group from study day 36 until the end of the study. In males, the following 

statistically significant findings were noted on hematology parameters: RBCs were decreased at 

the high dose; hemoglobin levels were decreased at the mid and high dose; and platelet count was 

increased at the high dose. In females, hematocrit and mean corpuscular volume (MCV) were 

statistically decreased and mean cell hemoglobin concentration (MCHC) was statistically 

increased. A/G ratio was statistically increased in males at 0.5 and 2.4 mg/kg/day and in females 

at 12.5 mg/kg/day. In males, additional statistical significance was noted in: decreased α1 and α2-

globulin and β-globulin levels at the mid and high doe; and increased albumin, ALP, glucose and 

BUN at the mid and high dose. In females, total protein and albumin levels were statistically 

increased at the high dose and α2-globulin and β-globulin levels were decreased at the high dose. 

Absolute heart, testes, kidney and brain weights were statistically increased at the high dose males 
Page 11 of 38

and absolute liver weights were increased in the mid and high dose. Absolute liver weights were 

statistically increased at the high dose females. An increased incidence of centrilobular 

hypertrophy of hepatocytes was observed in mid and high dose males and at the high dose in 

females. The NOAEL was determined to be 0.1mg/kg/day in males and 2.5 mg/kg/day if females 

based on hematology and clinical chemistry findings, increased liver weights and liver pathology 

observed in males at 0.5 mg/kg/day and in females at 12.5 mg/kg/day. 

In a 90-day oral toxicity study with the dog, drometrizole (CAS Reg. No. 2440-22-4) was 

administered in the feed to beagle dogs (6/sex/group) at dose levels of 0, 1000, 3000 and 10000 

ppm (~32.9, 98.7 or 329 mg/kg/day respectively) for 13 weeks. One dose/sex/group was fed the 

control diet for a month to test for recovery. No mortality or clinical signs of toxicity were 

observed. Body weight gain and food consumption were decreased at 10000 ppm. There were no 

effects on ophthalmology or auditory perception. Mean levels of alanine aminotransferase at 3000 

and 10000 ppm and γ-glutamyl transpeptidase at 10000 ppm were increased. No treatment-related 

gross or microscopic changes were observed. The NOAEL was determined to be 1000 ppm or 

31.75 mg/kg/day in males and 34.6 mg/kg/day in females based on increased levels of alanine 

aminotransferase at 3000 ppm.

In a 90-day oral toxicity study with the dog, Tinuvin 328 (CAS Reg. No. 25973-55-1) was 

administered daily in the feed to beagle dogs at dose rates of 15, 30, 60, 120 and 240 mg/kg/day

for three months. Controls consisted of 5 dogs/sex/group and were fed untreated diet. Dogs were 

examined daily for mortality and clinical signs of toxicity. Food consumption was monitored daily 

and recorded per week, and body weights were recorded every three days. Ophthalmology 

examinations were conducted on all dogs. Hematology, clinical chemistry and urinalysis 

parameters were evaluated pretest and monthly after the start of test material administration. Gross 

necropsy was performed on all dogs and the following organs weights were recorded: brain heart, 

lung, liver, kidneys, spleen, hypophysis, thyroid, adrenals, testes, epididymis, prostate and thymus. 

Selected organs/tissues from all dogs were examined microscopically.

One male dog in the high dose group died during week 8. Mean body weight was decreased in 

dogs receiving ≥ 60 mg/kg/day. Food consumption was decreased in males at 120 and 240 

mg/kg/day and in females at 240 mg/kg/day. No treatment-related ophthalmic findings were 

observed. A decrease in the number of erythrocytes, a decrease in packed cell volume and 

decreased hemoglobin levels were observed in the 120 and 240 mg/kg/day groups. Slight effects 

were observed in bilirubin levels, and guanosine 5’-triphosphate (GTP) and glutamic-oxaloacetic 

transaminase (GOT) and alkaline phosphatase activities. No effects were observed on urinalysis 

parameters. Enlarged livers were observed with severe liver damage in the 120 and 240 

mg/kg/day groups. Microscopic changes in the liver consisted of fatty degeneration of 

hepatocytes, protein globules in the cytoplasm, Kupffer cell hyperplasia and centrolobular 

choleostatisis. Kidney effects were observed but there was no clear dose response. In some dogs 

in the higher dose groups, atrophy of the uterus (≥ 60 mg/kg/day), abnormal spermiogenesis (240 

mg/kg/day) and atrophy of the prostate (≥ 60 mg/kg/day) were observed. The NOAEL was 

considered to be 30 mg/kg/day based on body weight effects and histopathology observed at 60 

mg/kg/day.
Page 12 of 38

CHRONIC TOXICITY

A chronic toxicity study (OECD Guideline 452) was conducted using Crj: CD (SD) IGS rats. 

HDBB (CAS Reg. No. 3846-71-1) was administered in corn oil once daily for 52 weeks by oral 

gavage at doses of 0 (corn oil), 0.1, 0.5 or 2.5 mg (males) and of 0 (corn oil), 0.5, 2.5 or 12.5 

mg/kg/day(females). Animals were observed daily prior to and after dosing for clinical signs of 

toxicity. Body weight and food consumption were recorded weekly for the first 13 weeks and then 

every four weeks after that. Prior to necropsy, blood was drawn for hematology evaluation and 

clinical chemistry parameters. Urine was collected for urinalysis. Selected organs were weighed 

and microscopic examination of a full set of tissues/organs in the control and high dose groups. 

The liver, heart, kidneys, spleen and thyroid of the mid and low dose groups were also examined 

microscopically. 

Two males in the 0.1 mg/kg/day group were found dead on days 231 or 357 of the dosing period 

and one female was moribund on day 354. No clinical signs of toxicity were observed in males or 

females. Body weight was decreased in males at the high dose from day 36 to the end of the 52 

week study. RBCs were statistically decreased in males at the mid and high dose and hematocrit at 

the high dose. Platelet count was increased at the high dose. In females, platelet count was 

increased at the high dose. A/G ratio, albumin levels and ALP activity were statistically increased 

in males at 0.5 and 2.5 mg/kg/day. The following additional statistically significant findings were 

noted in males: decreased α1 and α2-globulin levels at the mid and high dose; decreased β-globulin 

levels at the high dose; and increased BUN at the mid and high dose. In females, albumin levels 

were statistically increased at the high dose. Absolute pituitary, heart, brain, thyroid, lung, testes, 

kidney and epididymides weights were statistically increased in high dose males and absolute liver 

weighs were increased in the mid and high dose. Absolute liver weights were statistically 

increased in the high dose females. An increased incidence of centrilobular hypertrophy of 

hepatocytes was observed in mid and high dose males and at the high dose in females. An increase 

incidence of lipofuscin deposition in hepatocytes was observed at the high dose; also altered 

hepatocellular foci at the mid and high dose and of cystic degeneration of hepatocytes at the high 

dose in males only. The NOAEL was 0.1 mg/kg/day in males and 2.5 mg/kg/day in females based 

on hematology and clinical chemistry findings, increased liver weights and liver pathology 

observed in males at 0.5 mg/kg/day and of hematology findings, increased liver weights and liver 

pathology in females at 12.5mg/kg/day. 

COMBINED CHRONIC TOXICITY/CARCINOGENICITY (Rat)

A combined chronic toxicity/carginogenicity study was conducted using CFY rats 

(50/sex/group). Drometrizole (CAS Reg. No. 2440-22-4) was administered in the diet for 104 

weeks at dose levels of 0, 100, 300, 1000 and 3000 ppm which corresponds to 0, 4 to 6, 14 to 17, 

47 to 58 and 142 to 169 mg/kg/day, respectively. Mortality, clinical signs of toxicity, body weight 

and food consumption were monitored. Hematology and clinical chemistry were evaluated. Body 

weight gain was statistically decreased in males during the second year of the study and food 

consumption was statistically decreased in females from study week 53 to week 80 at 3000 ppm. 

Mortality was slightly increased in male rats at the high dose; however the increase was not 

statistically significant. A reduction in blood urea nitrogen was observed at study termination in 

males of the high dose group. Relative thyroid/parathyroid weights were statistically increase 
Page 13 of 38

compared to the control group in males at 1000 ppm and females at the 1000 and 3000 ppm 

groups. No correlating histopathology was observed in the thyroid/parathyroid. No microscopic 

non neoplastic or neoplastic lesions attributable to treatment were seen. The NOAEL was 

established at 1000 ppm (47 to 58 mg/kg/day) based on effects on body weights and BUN in males 

at 3000 ppm. Drometrizole was not carcinogenic under the conditions of the study.

CARCINOGENICITY (Mouse)

A carcinogenicity study (OPPTS 870.4200) was conducted using Tif: MAGf(SPF) mice

(50/sex/group). Mice were administered drometrizole (CAS Reg. No. 2440-22-4) for 24 months in 

the diet at dose rates of 0, 5, 50 or 500 ppm which corresponds respectively to 0, 0.8, 6.5 and 64 

mg/kg/day in males and 0, 0.8, 6.7 and 62 mg/kg/day in females. Mice were housed 5/cage. 

Mortality, clinical signs of toxicity, body weight and food consumption were monitored. No 

treatment related effects were observed on mortality, clinical signs of toxicity, body weights or 

food consumption. Liver weight was decreased in males at the 50 ppm group and adrenal weights 

were slightly increased in treated females. Nor correlating histopathology was observed in those 

organs. No treatment-related microscopic non neoplastic or neoplastic lesions were seen. The 

NOAEL was determined to be > 64mg/kg/day in males and 62 mg/kg/day in females. 

Drometrizole was not carcinogenic to mice under the conditions of the study. 

GENOTOXICITY

A dominant lethal assay study was conducted on NMRI-derived mice (20/group) (OPPTS 

870.5450). Male mice were administered a single dose of drometrizole (CAS Reg. No. 2440-22-4) 

in aqueous carboxymethyl cellulose by gavage at dose levels of 0, 1000 or 3000 mg/kg. 

Immediately after treatment each male mouse was placed in a cage with 2 untreated female mice. 

After one week, the female mice were removed and replaces by two additional females. This was 

done for 6 weeks. Females were examined daily for the presence of a vaginal plug. The day a 

plug was observed was designated as gestation day 0. On day 14 of pregnancy, the females were 

necropsied. The number of live embryos and embryonic deaths were recorded. The uteri were 

examined for embryonic resorptions. Drometrizole was tested for its ability to produce dominant 

lethals in NMRI-derived mice. Mating ratio, the number of implantations and embryonic deaths 

were unaffected by treatment. Drometrizole was determined to be negative for producing 

dominant lethals in mice. 

A somatic mutation assay (non-guideline) was conducted on Chinese hamsters (3/sex/group). 

Drometrizole (CAS Reg. No. 2440-22-4) was administered by oral gavage for 2 consecutive days 

at dose levels of 0, 500, 1000 or 2000 mg/kg. Hamsters were sacrificed 24 hours after the last dose 

and one marrow was harvested from the shaft of both femura. Bone marrow cells (1000/animal) 

were scored for chromosomal anomalies. The positive control was cyclophosphamide (128 

mg/kg). The positive control produced the expected response. Drometrizole was negative for 

producing chromosomal anomalies in this test.

A mammalian bone marrow chromosomal aberration test (OPPTS 870.5385) was conducted 

using Chinese hamsters. Drometrizole (CAS Reg. No. 2440-22-4) was administered by gavage 

for 2 consecutive days at dose levels of 0, 500, 1000 or 2000 mg/kg. A control group consisted of 
Page 14 of 38

8 females and 9 males and was administered the vehicle (2.0% sodium carboxymethyl cellulose). 

Groups receiving the test material consisted of 8 females and 4 males/group. A group of hamsters 

(10 females and 9 males) received the positive control, cyclophosphamide (64 mg/kg). Animals 

were injected intraperitoneally (i.p.) with colcemide (10 mg/kg) two hours after administration of 

the second dose. They were sacrificed 4 hours later and bone marrow from 2 females and 2 

males/group was harvested. The bone marrow was analyzed for chromosomal aberrations. No 

chromosomal aberrations were observed in the test groups. The positive control produced the 

expected positive results. Drometrizole was negative for inducing chromosomal aberrations in this 

test.

A bacterial reverse mutation (Ames) test was conducted (OPPTS 870.5100) on Salmonella sp. 

The Salmonella strains were TA98, TA100, TA 1535 and TA1537 with and without metabolic 

activation. Test concentrations were 0, 10, 30, 90, 270 and 810 μg.0.1 ml. No increase in 

mutation frequency was observed. Drometrizole was considered negative for inducing genetic 

mutations.

A reverse mutation (Ames) test was conducted on Salmonella tester strain TA98 with 

metabolic activation. Five dose levels (not stated) of drometrizole (CAS Reg. No. 2440-22-4) 

were tested with duplicate plates in two independent assays. The S9 was prepared from the livers 

of male Sprague-Dawley rats treated with phenobarbital and 5,6-benzoflavone. The solvent was 

dimethylsulfoxice (DMSO). No increase in mutation frequency was observed and under the 

conditions of this study drometizole was considered negative to induce mutations. 

Drometrizole (CAS Reg. No. 2440-22-4) was used in an unscheduled DNA synthesis in 

mammalian cells in culture test (OPPTS 870.5550). The test material was dissolved in DMSO at 

concentrations of 0, 11.9, 17.8, 26.7, 40 and 60 μg/ml. The concentrations were selected based on 

results from a preliminary toxicity range finding study where the threshold for toxicity was 

determined to be between 6.5 and 65 μg/ml. The positive control was 7,12-

dimethylbenzanthracene. Primary cultures of rat hepatocytes were prepared from a male SpragueDawley rat. Cells were exposed to the test material and incubated with 3H-thymidine. The 

cultures were prepared on coverslip and processed for autoradiography. At least 50 cells from 

each treatment group (25 cells from each coverslip) were scored and mean grain counts 

determined. The test concentrations were 0, 2.3, 3.5, 5.3, 7.9, 11.9, 17.8, 26.7, 40 and 60 μg/ml. 

The 40 and 60 μg/ml concentrations were toxic yielding no cells for evaluation at the highest dose 

tested. The mean net grain count per nuclei as ≤ 5 for dose levels of ≥ 11.9 μg/ml. The response 

was dose related. The positive control produced the expected positive results. Drometrizole was 

considered to be positive for inducing UDS in primary rat hepatocytes.

Octrizole (CAS Reg. No. 3147-75-9) was used in a bacterial reverse mutation test (OPPTS 

870.5100) (OECD Guideline 471). Octrizole was tested in Salmonella typhimurium strains TA 98, 

TA100, TA1535, and TA1537 and in E. coli WP2uvrA at concentrations of 20.5, 61.7, 185.2, 

555.5, 1666.6 and 5000 μg/plate with and without metabolic activation. The solvent was DMSO 

and appropriate positive controls were used. No increase in the mean number of revertant colonies 

was observed with any tester strain in the presence or absence of metabolic activation. Positive 

controls produced the expected results. Octrizole was considered negative in the Ames Salmonella

test.
Page 15 of 38

Tinuvin 328 (CAS Reg. No. 25973-55-1) was used in a Salmonella microsome mutagenicity test

using Salmonella tester strains TA98, TA100, TA1535, and TA 1537 in the presence or absence of 

metabolic activation at concentrations of 25, 75, 225 and 2025 μg/0.1ml. No increase in mutant 

frequency was observed in the presence or absence of metabolic activation. Tinuvin 328 is 

considered negative in this study.

Tinuvin 328 (CAS Reg. No. 25973-55-1) was used in a bacterial reverse mutation assay 

(OPPTS 870.5100) with Salmonella tester strain TA98 with and without metabolic activation. S9 

was prepared from the livers of male Sprague-Dawley treated with phenobarbital and 5,6-

benzoflavone. Five dose levels (not specified) were used and the solvent was DMSO. No increase 

in the frequency of mutations was observed and Tinuvin 328 is considered negative in this study.

Tinuvin 234 (CAS Reg. No. 70321-86-74) was used in a nucleus anomaly test on somatic 

interphase nuclei of Chinese hamster bone marrow cells. Chinese hamsters (6/sex/group) were 

administered the test material for two consecutive days by oral gavage at dose levels of 0, 1250, 

2500 or 5000 mg/kg. The vehicle was 0.5% carboxymethyl cellulose. Animals were sacrificed 24 

hours after the last dose and bone marrow was harvested from the shafts of both femora. Bone 

marrow cells (1000/animal) were examined for nuclear anomalies. The positive control was 

cyclophosphamide (128 mg/kg). The number of single Jolly bodies, fragments of nuclei in 

erythrocytes, micronuclei in erythroblasts, micronuclei in leucopoietic cells, bizarre forms of 

nuclei and polyploidy cells were counted. The results were that the percentage of cells displaying 

nuclear anomalies did not statistically differ from the negative control group. The positive control 

group produced the expected response. Tinuvin 234 was negative in this test. 

An in vivo sister chromatid exchange test was conducted using Tinuvin 234 (CAS Reg. No. 

70321-86-74). Chinese hamsters (4/sex/group) were administered the test substance once by oral 

gavage in 0.5% carboxymethyl cellulose at dose levels of 0, 1250, 2500, or 5000 mg/kg. They 

were injected i.p. with colcemide 22 hours after administration of the test material and were 

sacrificed 2 hours later. The positive control was 7,12-dimethylbenzanthracene (100 mg/kg in 0.5 

% carboxymethyl cellulose). Bone marrow slides were prepared and examined for sister chromatid 

exchange. The results were that there was no increase in the incidence of sister chromatid 

exchanges occurred in the dosed groups compared to the control. Tinuvin 234 was negative for 

inducing sister chromatid exchanges in Chinese hamsters. 

A bacterial reverse mutation test (OPPTS 870.5100) was conducted using Tinuvin 234 (CAS 

Reg. No. 70321-86-74). Salmonella typhimurium strains TA98, TA100, TA1535 and TA 1537 

were tested at concentrations of 25, 75, 225, 675 and 2025 μg/plate with and without metabolic 

activation. The solvent was acetone and positive controls were used. The results were no increase 

in mutant frequency was observed in the presence or absence of metabolic activation. Tinuvin 234 

was negative in this test. 

An autoradiographic DNA repair test was conducted on rat hepatocytes using Tinuvin 234 

(CAS Reg. No. 70321-86-74). The test material was dissolved in acetone at concentrations of 0, 

0.4, 2, 10 and 50 μg/ml for the definitive study. The positive control was DMN (100mM). 

Primary cultures of rat hepatocytes were prepared from a male Tif:Ralf (SPF) rat. Cells were 
Page 16 of 38

exposed to the test material and incubated with 3H-thymidine. The cultures were prepared on 

cover slips and processed for autoradiography. At least 150 cells from each treatment group (50 

cells from each coverslip; total of 3 coverslips) were scored and mean grain counts were 

determined. Mean nuclear counts ≥ were considered a positive response. There was no increase in 

the mean number of silver grans per nucleus seen in the cultures of the treated groups. Tinuvin 

234 was negative for inducing unscheduled DNA synthesis in the primary rat hepatocyte assay.

PRENATAL DEVELOPMENTAL TOXICITY

Drometrizole (CAS Reg. No. 2440-22-4) was the test substance in a prenatal developmental 

toxicity study in the rat. Study methods closely followed OECD Guideline 414 

(“Teratogenicity”). Pregnant Sprague-Dawley rats were administered drometrizole by gavage at 

dose levels of 0 (vehicle; 2% aqueous carboxymethyl cellulose), 150, 500 or 1000 mg/kg/day from 

gestation days 6 to 15. During the treatment period, clinical signs, weight gain, and food 

consumption were monitored and recorded daily. Caesarean sections were conducted on gestation 

day 21. Fetuses were examined for external, visceral and skeletal abnormalities. No maternal 

toxicity was observed and there were no effects of treatment o the number of implantations. No 

embryotoxicity was seen and no teratogenic were observed. The NOAEL for maternal and 

developmental toxicity was determined to be 1000 mg/kg/day which was the limit dose in this 

study.

Drometrizole (CAS Reg. No. 2440-22-4) was used in a prenatal developmental toxicity study 

in the mouse. Study methods follow OECD Guideline 414 “Teratogenicity”. Pregnant NMRIderived mice were administered drometrizole by gavage at dose levels of 0 (vehicle control; 2% 

aqueous carboxymethyl cellulose), 150, 500 and 1000 mg/kg/day from gestation days 6 through 

15. During the treatment time, clinical signs, weight gain and food consumption were monitored. 

Caesarean sections were conducted on gestation day 18. Fetuses were examined for external, 

visceral and skeletal anomalies. No maternal toxicity was observed and there were no treatment 

related effects on number of implantations. No embryotoxicity was observed and no teratogenic 

effects were noted. The NOAEL for maternal and developmental toxicity was determined to be 

1000 mg/kg/day, the limit dose of this study. 

Tinuvin 234 (CAS Reg. No. 70321-86-74) was the test substance in a prenatal developmental 

toxicity study in the rat (OPPTS 870.3700). Pregnant Tif: RAIF (SPF) rats were administered 

the test substance from gestation day 6 to 15 by oral gavage at dose levels of 0, 300, 1000 and 

3000 mg/kg/day. The number of pregnant rats/group and vehicle was not specified. During 

treatment, general condition, weight gain, food consumption and clinical signs of toxicity were 

checked daily. Just prior to parturition, the females were sacrificed and the uteri examined. Live 

fetuses were weighed, sexed and evaluated for external, visceral and/or skeletal abnormalities. 

Maternal body and food consumption were comparable to the controls. No embryo or fetal 

mortality was observed at necropsy. Neither were observed at the high dose. The maternal 

NOAEL was set at 3000 mg/kg/day and the developmental NOAEL at 1000 mg/kg/day based on 

the findings at 3000 mg/kg/day. 
Page 17 of 38

REPRODUCTIVE TOXICITY

A recently submitted extended one-generation reproduction study with the rat (OECD 443) 

was conducted using Tinuvin 571 (CAS Reg. No. 23328-53-2). Wistar rats (25/sex/group) were 

administered Tinuvin 571 in the diet at dose levels of 0, 2500, 5000 or 10000 ppm. Parental male 

rats were administered the diets four weeks prior to mating, during mating and during the postmating period until F1 animals were weaned. Parental females were administered the diets for four 

weeks prior to mating, during mating and throughout the gestation and lactation periods up to the 

day of termination after weaning of offspring. After weaning, F1 rats were maintained on the diets 

until termination on post-natal day (PND) 56. Rats were examined once daily for clinical signs 

and twice daily for mortality and morbidity. Body weights of males were determined weekly 

during the treatment period. Females were weighed weekly prior to mating, on gestation day 0, 7, 

14 and 20 and during lactation on day 0, 4, 7, 14 and 21. Food consumption was monitored with 

the body weight determinations. Estrus cyclicity was evaluated over a two week period. Parental 

animals were observed for neurobehavioral parameters once weekly. Blood was collected for 

evaluation of hematology and clinical chemistry parameters and for analysis of thyroxine (T4) and

thyroid stimulating hormone (TSH). A vaginal smear was taken at termination for estrus staging. 

The number of corpora lutea and implantation sites was recorded. At termination, sperm was 

collected for evaluation of motility and morphology and homogenization-resistant testicular 

spermatids and cauda epididymal sperm were counted. Selected organ weights were recorded and 

selected tissues/organs were examine microscopically. On PND 4 litters were culled to five males 

and five females per litter. On PND 0 and 4 body temperature was recorded and reaction to 

handling was evaluated. Ano-genital distance was measured on PND0 for all pups. Pup body 

weights were recorded on PND 0, 4, 7, 14 and 21. Blood was collected on PND 4 for 

determination of T4 and on PND 22 and 56 for determination of T4 and TSH and evaluation of 

clinical chemistry and hematology parameters. Urinalysis was conducted. Body weights of 

selected F1 animals were recorded weekly until termination on PND 56. Sexual developmental 

landmarks were evaluated. F1 rats were examined for neurobehavioral effects weekly after 

weaning. Selected organ weighs were recorded at termination on PND 56. A vaginal smear was 

taken from all F1 females after attaining vaginal patency until day of sacrifice. 

The results were no effects on body weight, food consumption, neurobehavioral parameters, 

hematology or clinical chemistry parameters, organ weighs, reproductive parameters, T4 or TSH 

levels, sperm evaluations, estrus cyclicity or upon microscopic examination of tissues/organs. In 

pups at 10000 ppm, statistically significant lower body weight and body weight gain were 

observed in both sexes when compared to the controls. However, on PND 4, body temperature of 

male and female pups was statistically significantly decreased at 5000 and 10000 ppm compared to 

the concurrent control groups. However, the changes in body temperature was slight without 

significant systemic toxicity and therefore, not considered adverse. On PND 4 serum levels of T4 

were comparable with concurrent control group. T4 levels were unaffected by treatment on PND 

22 and PND56 pups. However, TSH levels were statistically increased in PND 22 females at 5000 

and 10000 ppm without a clear dose response and in males at 10000 ppm. The changes in T4 and 

TSH were not consistent, changes were small in magnitude, and not collaborated with 

histopathology, therefore, they were not considered as adverse. There were no treatment-related 

effects on body weight, body weight change, feed consumption, clinical pathology, or sexual 

development in F1 animals. Absolute liver weight in males was significantly increased at the mid 
Page 18 of 38

and high doses in F1 animals. In females, absolute liver weight was significantly increased at the 

mid-dose only, while relative liver weights at the mid and high dose were also significantly 

increased. In the absence of correlating findings in clinical chemistry parameters and 

histopathology, the liver effects were considered treatment-related but non-adverse. Absolute 

spleen weight was significantly increased in males of the high dose and associated with an 

increased incidence of splenic extramedullary hematopoiesis (17/20). The incidence was 

significantly increased (p < 0.05; calculated by the reviewer) compared to the incidence in the 

males of the control group (9/20). Therefore, under the conditions of this study, the offspring 

toxicity LOAEL for Tinuvin 571 in rats is 10,000 ppm (equal to 618 mg/kg bw/day in males, and 

870 mg/kg bw/day in females), based on increased spleen weight associated with increased 

incidence of splenic extramedullary hematopoiesis, body weights and body weight gain from 

PNDs 4-21 were significantly decreased in males and females. The offspring systemic NOAEL is 

5000 ppm (equal to 311 mg/kg bw/day in males and 432 mg/kg bw/day in females) (MRID 

49358004). 

A combined repeated dose toxicity study with the reproduction/developmental toxicity 

screening test (OECD 422) was conducted using drometrizole (CAS Reg. No. 2440-22-4). Male 

and female Crl:CD(SD) rats (12/sex/group) were administered drometrizole by gavage at dose 

levels of 0, 30, 100 or 300 mg/kg/day in olive oil. An additional group of 5 rats/sex were placed on 

test for the control and high dose group as recovery animals (15 days). Males were administered 

the test material for 42 days and females from 14 days prior to mating to d 4 of lactation. 

Offspring were terminated on PND 4. Animals were examined for mortality and clinical signs of 

toxicity. Body weights and food consumption were recorded. A functional observation battery 

(FOB) was conducted and motor activity was evaluated. The length of estrous cycles were 

recorded as were the number of mated pairs, pregnant females and pairing days until copulation. 

The copulation index and fertility indices were calculated and parturition and lactation were 

monitored for abnormalities. Hematology, clinical chemistry parameters were evaluated at 

termination for parental males and females. The thymus, adrenals, heart, kidneys, spleen, liver, 

brain, testes and epididymides were weighed. Selected organs/tissues were examined 

microscopically. 

Mortality was unaffected by treatment and no clinical signs of toxicity were observed. No 

treatment-related effects were observed on body weights, food consumption, reflex/reaction, grip 

strength, locomoter activity, hematology parameters or reproductive parameters. Increased protein 

was observed in the urine of males at ≥ 100 mg/kg/day which returned to normal during the 

recovery period in the high dose group. Plasma levels of phospholipid were statistically increased 

in males and females at the high dose as were cholesterol levels in females. The values of both of 

these parameters returned to control levels during the recovery period. Relative liver weight was 

statistically increased in males at ≥ 30 mg/kg/day and absolute liver weight at the high dose. In 

females, absolute and relative liver and kidney weights were statistically increase at 100 and 300 

mg/kg/day. The incidence of hepatocellular hypertrophy was statistically increased in male and 

female rats at 300 mg/kg/day. The presence of eosinophilic bodies in the kidney was statistically 

increased in males at 300 mg/kg/day. One female in the 100 mg/kg/day group and 2 in the 300 

mg/kg/day group had hydropic changes in the proximal tubule compared to none in the control 

group. The reproductive/developmental toxicity NOAEL was the highest dose tested at 300 

mg/kg/day. The NOEL in males was considered to be < 30 mg/kg/day based on increased relative 
Page 19 of 38

liver weights observed in all dose groups and 30 mg/kg/day based on effects on liver and kidney 

weights and kidney histopathology. The NOAEL was concluded to be 300 mg/kg/day for males 

and 30 mg/kg/day for females based on kidney lesions. 

NEUROTOXICITY

There are no neurotoxicity studies available on CAS Reg. NO. 23328-53-2 or its surrogates. 

However, there were no indications of toxicity observed in any of the repeated dose studies 

discussed above. Further, FOB parameters and motor activity was evaluated in an extended onegeneration rat reproduction study and no effects were observed up to a dose of 10000 ppm (~500 

mg/kg/day). 

METABOLISM

In an OPPTS 870.7485 metabolism study (MRID 49358002), four male albino rats (strain not 

specified) were administered 14C-drometrizole (5.07 μgCi/mg) as a single oral dose of 10 mg/kg 

dissolved in polyethylene glycol 400. Urine and feces were collected in 24 hour periods until 168 

hours post-treatment. The test material was labelled in the benzene ring and in the 5’-methyl 

group. The radioactive purity was determined to be >99%. By 168 hours post-treatment, 73% of 

the radioactivity was excreted in the urine and 27% in the feces. Residual radioactivity in tissues 

was below the blood level of 0.017 μg/g except in the kidney, aorta and liver (0.10 – 0.22 μg/g). 

The highest level of radioactivity was in the liver at 0.1% of the initial dose.

V. TOXICITY ENDPOINT SELECTION

In this 2014 review, the Agency relies upon its original selection of toxicological endpoint as was 

discussed in the Agency’s 2010 assessment. The point of departure for the risk assessment for all 

durations and routes of exposure was from the 90-day toxicity study in rats. The NOAEL was 20 

mg/kg/day and the LOAEL was 40 mg/kg/day based on increases in liver, kidney, spleen, and 

testes weights. Although the chronic point of departure was selected from a subchronic study, 

longer-term studies are available that shows the lack of toxicity even at higher doses (NOAEL 

higher than 60 mg/kg/day in carcinogenicity studies). No additional uncertainty factor is needed 

for extrapolating from subchronic to chronic exposure. In this assessment a 100 fold uncertainty 

factor is used for the chronic exposure (10X interspecies extrapolation, 10X for intraspecies 

variability). The need for a 10X FQPA factor used in previous risk assessment is no longer 

necessary in light of the findings in the recently submitted “Extended One-Generation 

Reproduction Toxicity Study of Tinuvin 571 in Wistar Rats” (MRID 49358004).

The NOAEL of 20 mg/kg/day was used for all exposure duration via dermal and inhalation routes 

of exposure. The residential, occupational, and aggregate level of concern (LOC) is for MOEs that 

are less than 100 and is based on 10X interspecies extrapolation and 10X for intraspecies 

variability. 

Dermal absorption is estimated to be 10% based on SAR analysis. A 100% inhalation is assumed.

Special Consideration for Infants and Children (FQPA Safety Factor)
Page 20 of 38

Section 408(b)(2)(c) of the FFDCA provides that EPA shall apply an additional margin of 

safety for infants and children in the case of threshold effects to account for prenatal and 

post natal toxicity and the completeness of the database on toxicity and exposure unless 

EPA determines that a different margin of safety will be safe for infants and children. EPA 

concludes that the10X FQPA safety factor can be reduced to 1X is not necessary due to the 

recently submitted reproductive toxicity study data that fills the original “data gap”. 

VI. EXPOSURE

Dietary Exposure/Risk Characterization

The proposed use of this chemical as an inert ingredient in pesticide products under the current 

petition is restricted to a maximum concentration of 10.0% in the final formulation when applied 

to all agricultural crops. Using the I-DEEM dietary exposure model to estimate the exposure to all 

subpopulations (see the attachment), it was determined that the exposure from the use of this inert 

ingredient at the proposed concentration (including exposure through drinking water) and crop use 

pattern would result in nominal exposure to all subpopulations. 

All subpopulations showed a % RfD of 70% or less. The subpopulation with the greatest % RfD is 

for children 1-2 years old 70.6 % of cPAD. It is important to note that the I-DEEM Model 

assumes a default value of 100 ppb for the concentration of the inert in all sources of drinking 

water. Based on the physical and chemical properties of this chemical and the intended use pattern, 

exposure through drinking water is unlikely; therefore, these results are highly conservative in 

regards to the exposure through drinking water. 

Table 1: Summary of Dietary (Food and Drinking Water) Exposure and Risk for CAS 25973-55-1 and 

23328-53-2 Results Taken from I-DEEM Model

Population Subgroup

Acute Dietary

(95th Percentile)

Chronic Dietary

Dietary Exposure 

(mg/kg/day) % aPAD Dietary Exposure(mg/kg/day) % cPAD

General U.S. Population

No acute endpoint selected

0.037869 18.9

All Infants (< 1 year old) 0.078886 39.4

Children 1-2 years old 0.141248 70.6

Children 3-5 years old 0.097327 48.6

Children 6-12 years old 0.050111 25.1

Youth 13-19 years old 0.026960 13.5

Adults 20-49 years old 0.028948 14.5

Adults 50+ years old 0.030358 15.2
Page 21 of 38

Table 1: Summary of Dietary (Food and Drinking Water) Exposure and Risk for CAS 25973-55-1 and 

23328-53-2 Results Taken from I-DEEM Model

Population Subgroup

Acute Dietary

(95th Percentile)

Chronic Dietary

Dietary Exposure 

(mg/kg/day) % aPAD Dietary Exposure(mg/kg/day) % cPAD

Females 13-49 years old 0.029267 14.6

The most highly exposed subgroup is bolded. 

Residential (Non-Occupational) Exposure/Risk Characterization

The Agency’s 2010 assessment contained estimates of non-occupational (“residential”) exposures 

from “handling” (i.e., applying) pesticides and from post-application exposures. For purposes of 

comparison and characterization, non-occupational “handler” exposures are revised and presented. 

The revisions reflect current Agency policy regarding “Unit Exposures” and “body weight” and 

are explained along with the exposure estimates. The methodology used to estimate exposure and 

risk are the same as were presented in the 2010 assessment. The backpack sprayer method of 

application was substituted for the trigger pump ready to use sprayer as that is not a practical 

method of application to lawns and turf. In addition, the backpack method is considered a high 

exposure situation thus provides a conservative, screening measure of safety or risk. The 

assessment methodology was developed by the Health Effects Division Science Advisory Council 

on Exposure (EXPOSAC) and is standard Agency operating procedure. The basic algorithm is:

ADD = UE x Amount/Day x AF ÷ BW where:

ADD = Average Daily Dose

UE = Unit Exposure expressed as mg of inert per pound of product handled. UE is activity 

specific. UE are taken from: “Standard Operating Procedures for Residential Pesticide 

Exposure Assessment”. Health Effects Division/Office of Pesticide 

Programs/OCSPP/EPA, January 2012.

Amount/day = from 2010 EPA assessment (see below).

AF = absorption factor; 10% dermal absorption and 100 % inhalation absorption from 2010 EPA 

assessment

BW = body weight; 80 kg; HED Hot Sheet # 31 Use of New Human Body Weight Data as 

Presented in the EPA’s Exposure Factors Handbook: 2011 edit.

The 2010 assessment used the assumption that five (5) gallons of formulated pesticide product are 

used per day. A product density of 9.0 lb/gallon was assumed to be a typical product density. The 

product was assumed to be diluted at a 1 to 10 ratio with water. Thus:

5 gal. formulated product * 9 lb/gal * (1part product/10 parts water) = 4.5 lb product per day. The 

amount of product per day is adjusted according to the per cent inert ingredient, in the case of this 

request, 10 % (0.10).

Therefore 4.5 lb product/day * 10% inert = 0.45 lb inert handled/applied per day.
Page 22 of 38

 Table 2. Residential Pesticide Handler/Applicator Estimated Exposure and Risk

Exposure 

Scenario 

(Formulation/ 

Application)

Quantity 

Handled/ 

per day

Dermal 

Unit 

Exposure 

(mg/lb 

inert3

Inhalation 

Unit 

Exposure 

(mg/ lb 

inert)

Dermal Dose 

(mg/kg /day)

Inhalation 

Dose (mg/kg/ 

day)

Baseline 

Dermal 

MOE

Baseline 

Inhalation 

MOE

Liquids/ Low 

Pressure Handwand 0.45 lb 63 0.018 0.035 0.000101 571 198000

Liquids/ Hose End 

Sprayer, Lawn 0.45 lb 13.4 0.022 0.0075 0.000124 2666 161290

Backpack Sprayer 0.45 lb 130 0.014 0.073 0.000078 273 256410

Risks were calculated using the Margin of Exposure (MOE) approach, which is a ratio of the body burden to the 

toxicological Point of Departure (PoD). For this material a MOE greater than 100 indicates that the exposure scenario 

does not exceed the Agency’s level of concern. For all residential handler scenarios, risk estimates are not of concern 

for both the dermal and inhalation assessments. These exposure models are highly conservative and therefore the true 

risk of the anticipated exposure to these chemicals is believed to be less than what is shown.

Margins of Exposure (MOE) express the Agency’s Level of Concern (LOC). For this review, 

MOE < 100 exceed the Agency’s level of concern. MOEs are the ratio of toxicological endpoint

(NOAEL) to estimated Dose, both are expressed as mg inert/kg bw/day. 

MOE = NOAEL (mg/kg/day)/Dose (mg/kg/day). Since the estimated MOEs exceed 100, the 

proposed use patterns do not exceed the Agency’s level of concern.

Table 3. Residential Postapplication Short-term Exposures and Risks for 23328-53-2

Exposure Scenario Application Rate Exposed 

Population & 

Exposure Duration

Daily Dose 

(mg/kg/day)

MOE

Outdoor Lawn Products

Dermal Exposure to 

Treated Lawns

0.45 lb/day

Adult 0.00091 21,980

Child 0.0017 11,770

Hand-to-Mouth from 

Treated Lawn Child 0.00066 30,300

Object-to-Mouth 

from Treated Lawn

Child 0.000042 476,000

Soil Ingestion Child 0.000098 20,400

Total Lawn 

Combined 

Exposures*

Child 0.0025 8,000

The Agency’s 2010 assessment included some assessments of intermediate-term exposures i.e., 

exposures from one to six months. In the current re-evaluation, the Agency does not expect 

intermediate-term exposures for the use patterns listed. This is consistent with the guidance set 

forth in the “Standard Operating Procedures for Residential Pesticide Exposure Assessment” 

(Health Effects Division/Office of Pesticide Programs/U.S. EPA; January 2012). Intermediateterm exposures are exposures expected for a period of 1 – 6 months that are continuous or a series 

of intermittent exposures. Intermediate-term residential are generally not required because 
Page 23 of 38

individuals are not expected to re-treat the same sites repeatedly day after day for this duration, nor 

are a large number of pesticide applications resulting in intermediate-term exposures expected over 

this duration (Section 1 page 8). Further, due to dissipation over time for intermediate-term postapplication exposures, short-term exposures are generally considered to be protective of 

intermediate-term exposures. However, for the sake of continuity, adjusted Margins of Exposure 

are presented. The 2010 assessment was based upon 0.6 % concentration. The current request is 

for the use of 10 % concentration, an increase of approximately 17 times the original amount. The 

Health Effects Division assumes a linear response relationship to increases or decreases in dose 

and subsequent Margin of Exposure. Therefore, the 2010 intermediate-term Margins of Exposure 

(which were quite large) are divided by 17 and presented here. 

 Table 4. Intermediate-term Residential Post-application Margins of Exposure

Exposure Scenario Exposed 

Population & 

Exposure Duration

MOE

2010

Assessment

MOE

2015

Assessment

Dermal Exposure to 

Treated Lawns

Adult IT 63000 3705

Child IT 38000 2235 Hand-to-Mouth from 

Treated Lawn Child IT 100000 5882

Object-to-Mouth 

from Treated Lawn Child IT 200000 11764

Soil Ingestion Child IT 15000000 882352

Total Lawn 

Combined 

Exposures*

Child IT 28000 1647

Residential Postapplication Outdoor Exposure and Risk Calculations

Potential dermal postapplication exposure was calculated using the following formulas:

Adult and Child Dermal Exposure to Treated Lawns (from SOP 2.2):

Where:

ADD= Average Daily Dose (mg/kg/day)

TTR= Turf Transferable Residue (μg/cm2)

TC = Transfer Coefficient (cm2/hr) (14,500 cm2/hr for adults, 5,200 cm2/hr for children for shortterm exposure durations)

ET = Exposure Time (2 hr)

CF1 = Conversion Factor (1 mg / 1000 μg)

DA = Dermal Absorption Factor (%) (10%)

BW = Body Weight (70 kg for adult, 15 kg for toddler)

ADD = TTR * TC * ET * CF1 * DA

BW
Page 24 of 38

Where:

AR = Application Rate (0.45 lb inert/day as derived from 2010 assessment)

F = fraction of inert retained on foliage or 5% (unitless)

D = fraction of residue that dissipates daily or 10% (unitless)

t = number of days after application day (Day 0; day of application)

CF1 = 4.54 x 108 μg/lb

CF2 = 24.7 x 10-9 acre/cm2 

0.45 lb inert/day * 0.05 (%) * 4.548 μg/lb * 2.47-9 A/cm2 = 0.025μg/cm2  

0.025μg/cm2 * 14,500 cm2/hr * 2hr * 1 mg/1000 μg * 10 % (DA) ÷ 80 kg = 0.00091 mg/kg/day 

(adult)

0.025μg/cm2 * 5,200 cm2/hr * 2hr * 1 mg/1000 μg * 10 % (DA) ÷ 15 kg = 0.0017 mg/kg/day 

(toddler)

Assumptions for Dermal Dose from Pesticide Residues on Turf:

 On the day of application, it was assumed that 5% of the application rate is available from 

the turfgrass as dislodgeable residue. 

 Postapplication exposure is assessed on the same day the pesticide is applied because it is 

assumed that the homeowner could be exposed to turfgrass immediately after application. 

Therefore, postapplication exposures and risk are based on residues expected to be present 

on day 0 (i.e., the day of application). 

 The upper percentile dermal transfer coefficient is assumed to be 14,500 cm2/hr for adults 

and 5,200 cm2/hr for children for short-term durations. The transfer coefficient cm2/hr is a 

calculated mean, based on the Jazzercise method, which is believed to result in an upper 

percentile estimate of the transfer coefficient for this scenario.

 The duration of exposure for children and adults is assumed to be 2 hours per day. The 95th

percentile value for playing on grass is 121 minutes per day for both age groups 1-4 years 

and 18-64 years (U.S. EPA 1996).

Hand to Mouth (HTM) Exposure to Child on Treated Turf (from SOP 2.3.2):

The following equation is used to calculate the nondietary ingestion exposures that are attributable 

to hand-to-mouth behavior on treated turf.

Where:

ADD = Average daily dose (mg/kg/day)

TTR= turf transferable residue (μg/cm2)

SA= Surface area of child hand- 3 fingers (20 cm2/event)

SE = Saliva Extraction Factor (0.5)

TTR = AR * (1-D)t * F * CF1 * CF2

ADD = TTR * SA * SE * Freq * CF1 * ET

BW
Page 25 of 38

Freq = Frequency of hand-to-mouth events (20 events/hr for short-term exposures, 9.5 events/hr 

for long-term exposures)

CF1 = 1 mg/ 1000 μg

ET = Exposure Time (2 hours)

BW = Body weight (15 kg for toddler)

0.025μg/cm2 * 20 cm2/event * 0.5 (saliva extraction) * 20 events/hr * 1mg/1000μg * 2 hr = 0.00066 mg/kg/day 

15 kg bw 

Assumptions for Potential Dose among children from Incidental Nondietary Ingestion of Pesticide 

Residues on Residential Lawns from Hand-to-Mouth Transfer:

 On the day of application, it was assumed that 5% of the application rate is available on the 

turfgrass as dislodgeable residue. 

 Postapplication activities are assessed on the same day that the pesticide is applied because 

it is assumed that children could play on the lawn immediately after application. 

 The surface portion of three fingers of a toddler’s hand put in mouth is 20 cm2.

 The Hand-to-Mouth (HTM) exposure frequency is 20 times per hour for short term 

exposures. 

 The duration of exposure for toddlers is assumed to be 2 hours per day. The 95th percentile 

value for playing on grass is 121 minutes per day for both age groups 1-4 years and 18-64 

years (U.S. EPA 1996).

 Toddlers (age 3 years), used to represent the 1 to 6 year old age group, are assumed to 

weigh 15 kg. (U.S. EPA 1996).

 The saliva extraction factor is 50%.

Object to Mouth (OTM) Exposure to Child (from SOP 2.3.3):

The following equation is used to calculate the nondietary ingestion exposures that are attributable 

to object-to-mouth behavior on treated turf:

Where:

TTR = object transferable residue (μg/cm2)

IgR = Ingestion Rate for mouthing per day (25 cm2/day)

CF1 = 1 mg / 1000 μg

BW = Body weight (15 kg for child)

0.025 μg/cm2 * 25 cm2/day * 1 mg/1000 μg/ 15 kg bw = 0.000042 mg/kg/day 

Assumptions for Potential Dose among Toddlers from the Ingestion of Pesticide-Treated 

Turfgrass:

ADD = TTR * IgR * CF1

BW 
Page 26 of 38

 On the day of application, it may be assumed that 20% of the application rate is available 

on the turfgrass as dislodgeable residue.

 Postapplication activities are assessed on the same day that the pesticide is applied because 

it is assumed that children could play on the lawn immediately after application. 

 The assumed ingestion rate for grass for toddlers (age 3 years) is 25 cm2/day. This value is 

intended to represent the approximate area from which a child may grasp a handful of 

grass. 

Soil Ingestion Exposure to Child (from SOP 2.3.4): 

The following equation is used to calculate the nondietary ingestion exposures that are attributable 

to soil ingestion on treated turf:

Where:

ADD = Average daily dose (mg/kg/day)

SR = Soil Residue, 1 cm depth of surface soil, (μg/g)

IgR = Ingestion Rate for daily soil ingestion (100 mg/day)

CF1 = Conversion Factor (1 g / 1,000,000 μg)

BW = Body weight (15 kg for child)

Where:

AR= application rate (lb inert/A)

CF1 = Conversion factor (4.54 x 108 μg/lb)

CF2 = Conversion factor (2.47 x 10-9 acre/cm2)

CF3 = Conversion factor (0.67 cm3 / g soil)

F = fraction of inert retained on soil or 100% (unitless)

D = fraction of residue that dissipates daily (unitless)

t = postapplication day on which exposure is being assessed (t = 0, day of application)

19.6 lb inert/A * 4.548* 2.47-9 A/cm2* 0.67 cm3/g soil * 1 on day zero. = 14.7 μg/g thus:

14.7 μg/g * 100 mg/day * 1 g/1,000,000 μg ÷ 15 kg bw = 0.000098 mg/kg/day 

NOTE: As has been noted above and in keeping with the Agency’s 2010 assessment, the amount 

handled/applied per day is five gallons of product which in this case equals 0.45 lb inert per day. 

According to HED policy, five gallons applied per day is for 1000 square feet or a “a spot 

treatment”. Therefore to derive the amount of inert per acre: 43,580 ft2/A ÷ 1000 ft2/0.45 lb inert 

=

19.6 lb inert per acre.

Soil Residue (SR) = AR * CF1 * CF2 * CF3 * F * (1-D)t

ADD = SR * IgR * CF1

BW
Page 27 of 38

Assumptions for Potential Dose among Toddlers from Incidental Ingestion of Soil from PesticideTreated Residential Areas:

 On the day of application “Day 0”, it was assumed that 100% of the application rate is 

located within the soil’s uppermost 1 cm. 

 Postapplication exposure was assessed on the same day the pesticide is applied because it is 

assumed that toddlers could play on the lawn or other outdoor treated areas immediately 

after application.

 The assumed soil ingestion rate for children (age 1-6 years) is 100 mg/day (U.S. EPA 

1996).

Where HED has identified a common endpoint for this inert ingredient for the dermal and oral 

routes of exposure; it is HED’s policy to conduct an aggregate residential assessment which 

combines a child’s dermal exposure from contact with treated turf with the incidental oral 

exposure from the hand-to-mouth exposure from exposures that occur on treated turf. Once daily 

dermal and incidental oral (non-dietary) exposures are combined, they are then compared to the 

appropriate PoD.
Page 28 of 38

Occupational Exposure 

Estimates of occupational exposure and risk are derived in the same manner as the Agency’s 2010 

assessment. However, the current estimates are adapted to reflect current policy regarding Unit 

Exposure (UE) and body weight. As with the 2010 assessment, the rates of application are taken 

from: 

‘‘JITF Inert Ingredients. Residential and Occupational Exposure Assessment Algorithms and 

Assumptions Appendix for the Human Health Risk Assessments to Support Proposed Exemption 

from the Requirement of a Tolerance When Used as Inert Ingredients in Pesticide Formulations’’ 

(D364751, 5/7/09, Lloyd/LaMay in docket ID number EPA–HQ–OPP–2008–0710) found at 

http://www.regulations.gov.

The rates of application are typical insecticide formulations and are adjusted for the requested 10% 

maximum versus the 0.6% assessed in 2010. Only short-term exposures are presented as they are 

the highest (most conservative) as compared to intermediate-term exposures also reported in 2010.

Occupational Unit Exposures are taken from “Occupational Pesticide Handler Unit Exposure 

Surrogate Reference Table”, Health Effects Division, Office of Pesticide Programs, U.S. 

Environmental Protection Agency, March 2013 and are for a single layer of work clothing (longsleeved shirt, long pants, shoes plus socks) and the use of protective gloves. Pilots in enclosed 

cockpits are considered to have the engineering control of the enclosed cockpits. Flaggers are 

assumed not to wear protective gloves.

For occupational assessment the algorithm is:

AR x Units x UE x AF ÷ BW where

AR = Application rate in lb inert/A (adjusted for 10% maximum requested)

Units = Acres treated/day

UE = Unit Exposure in mg per pound handled

AF = Absorption Factor (10% dermal; 100% inhalation)

BW = body weight (80 kg average adult).
Page 29 of 38

Table 5. Estimated Exposure and Risk for Occupation Pesticide Handlers

Exposure 

Scenario 

(Formulation/ 

Application/ 

Crop)

Application 

Rate (lb 

inert/ A)

Area 

Treated 

Daily

(acres)

Dermal 

Unit 

Exposure 

(mg/lb 

inert)

Inhalation 

Unit 

Exposure 

(mg/ lb 

inert)

Baseline 

Dermal 

Dose 

(mg/kg 

/day)

Baseline 

Inhalation 

Dose 

(mg/kg/ 

day)

Baseline 

Dermal 

MOE

Baseline 

Inhalation 

MOE

Liquids/ Aerial 

Application/ High 

Acreage Crops (ST)

0.2 1200

0.0376 0.000219

0.011 0.000657 1,820 30,440

Liquids/ Groundboom/ 

High Acreage Crops 

(ST)

0.2 200 0.00188 0.00011 10,640 181,800

Liquid/ Aerial 

Application/ High 

Acreage Crops (ST)

0.2 1200

Eng control 

only: 

0.002

Eng control 

only: 

0.0000049

0.0006 0.000015 33,000 1.3M

Groundboom/ High 

Acreage Crops (ST) 0.2 200 0.0161 0.00034 0.00081 0.00017 24,700 118,650

Liquid/ Low Pressure 

Handwand/ 

Ornamentals (ST)

0.72 5 0.39 0.0039 0.0018 0.00018 11,100 111,100

Liquid/ Flagger/ High 

Acreage Crops (ST) 0.2 1200 0.011 0.00035 0.0033 0.0011 6,100 18,200

Margins of Exposure (MOE) express the Agency’s Level of Concern (LOC). For this review, 

MOE < 100 exceed the Agency’s level of concern. MOEs are the ratio of toxicological endpoint 

(NOAEL) to estimated Dose, both are expressed as mg inert/kg bw/day. 

MOE = NOAEL (mg/kg/day)/Dose (mg/kg/day). Since the estimated MOEs exceed 100, the 

proposed use patterns do not exceed the Agency’s level of concern.

VII. AGGREGATE RISK

In addition to consideration of single, acute exposures, the Agency also considers to possibility of 

aggregate exposures. Aggregate exposure refers to the sum(s) of individual exposures that might 

occur within a limited time frame. Aggregate exposure assessments are conducted for nonoccupationally exposed individuals i.e., for adults and toddlers (residents). In this case aggregate 

exposures consider oral (dietary) exposure, handler (residential applicator) exposure and postapplication exposure from treated lawns or turf. 

For adults the Agency uses the highest residential applicator exposure (use of back-pack sprayer), 

dietary exposure as estimated by the I-DEEM model (results attached) and from estimated postapplication exposure. For toddlers, the Agency combines post-application dermal exposure from 

treated lawns with hand-to-mouth exposure from treated lawns and dietary exposure as estimated 

with the I-DEEM model.

Residential Handler/Backpack sprayer 0.073 mg/kg/day 

Adult Post-application dermal exposure/treated lawn 0.0091 mg/kg/day 

Adult Dietary exposure/I-DEEM model 0.0378 mg/kg/day 

Total Adult Aggregate Exposure 0.1199 mg/kg/day 

Toddler/Total Exposure from lawn and turf

 (Dermal + Hand-to-Mouth) 0.0034 mg/kg/day 

Toddler Dietary from I-DEEM 0.141248 mg/kg/day

Total Toddler Aggregate Exposure 0.145 mg/kg/day 
Page 30 of 38

Margins of Exposure for aggregate exposures. Margin of exposure is:

NOAEL ÷ Total Aggregate Exposure thus

For adult 20 mg/kg/day ÷ 0.1199 mg/kg/day = 170.

For toddler 20 mg/kg/day ÷ 0.145 mg/kg/day = 140.

Table 6. Intermediate-term Aggregate Exposure: 2010 Estimates Adjusted for Rate Increase

Population

2010 Estimated

Aggregate MOE

(food and 

residential)

2015 Adjusted

Aggregate MOE

Adult Male 55000 3235

Adult Female 54000 3176

Child 16000 941

The estimated exposures are based upon highly conservative (protective) assumptions. The 

margins of exposure exceed 100 therefore, the estimated risks do not exceed the Agency’s level of 

concern. 

VIII. CUMULATIVE EXPOSURE

Cumulative effects from substances with a common mechanism of toxicity. Section 

408(b)(2)(D)(v) of FFDCA requires that, when considering whether to establish, modify, or revoke 

a tolerance, the Agency consider “available information” concerning the cumulative effects of a 

particular pesticide's residues and “other substances that have a common mechanism of toxicity.”

EPA has not found Phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- to share a 

common mechanism of toxicity with any other substances, and Phenol, 2-(2H-benzotriazol-2-yl)-

6-dodecyl-4-methyl- does do not appear to produce a toxic metabolite produced by other 

substances. For the purposes of this tolerance action, therefore, EPA has assumed that Phenol, 2-

(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- does not have a common mechanism of toxicity with 

other substances. For information regarding EPA's efforts to determine which chemicals have a 

common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see 

EPA's website at http://www.epa.gov/pesticides/cumulative.

IX. ENVIRONMENTAL FATE & EFFECTS

It was noted earlier in this document, there is not a complete data set for phenol, 2-(2Hbenzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2) with regards to toxicological 

effects on mammals and the same is true with regards to environmental fate and effects. Also as 

discussed earlier phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-

2) is classified among the phenolic benzotriazole (PBTZ) class of chemicals. The PBTZ class of 

chemicals consists of mono and di-substituted phenolic derivatives of 1,2,3-benzotriazole. Data 
Page 31 of 38

have been published regarding a number of PBTZ chemicals regarding chemical properties, 

mammalian toxicity and environmental fate and effects. Much of the discussion of environmental 

fate and effects is taken from MRID 49358003.

There are four compounds which are structurally and toxicologically similar to phenol, 2-(2Hbenzotriazol-2-yl)-6-dodecyl-4-methyl- and which the Agency has previously reviewed relative to 

environmental fate and effects. The Agency’s High Production Volume (HPV) Challenge 

Program contains the results of that review and may be found in 

http://www.epa.gov/chemrtk/index.htm and in 

http://www.epa.gov/chemrtk/pubs/general/guidocs.htm. The four compounds similar to phenol, 

2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2) are:

1) drometrizole (Tinuvin® P; CAS Reg. No. 2440-22-4)

2) octrizole (UV 329; CAS Reg. No. 3147-75-9)

3) Tinuvin® 234 (CAS Reg. No. 70321-86-7) and

4) Tinuvin® 328 (CAS Reg. No. 25973-55-1).

Phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2) is currently 

approved for use under 40 CFR § 180.020 at a maximum of 0.6% on adzuki beans, canola, 

chickpeas, cotton, fava beans, field peas, lentils, linola, linseed, lucerne, lupins, mung beans, navy 

beans, pigeon peas, safflower, sunflower and vetch. Drometrizole is approved for use in cattle ear 

tags at a maximum of 0.5%. 

Regarding environmental fate and effects, the Agency found that the phenolic benzotriazoles are 

solids with low water solubilities and low to negligible vapor pressures. They are expected to have 

low mobility in soil. Volatilization of phenolic benzotriazoles is considered low based on the 

respective Henry’s Law constant. The rate of hydrolysis of phenolic benzotriazoles cannot be 

measured due to a lack of water solubility. However, the chemical structures of these compounds 

suggests that hydrolysis is likely to be negligible under environmental conditions. The rate of 

atmospheric photooxidation is considered rapid for CAS Reg. No. 2440-22-4 and CAS Reg. No. 

70321-86-7 and moderate for CAS Reg. No. 3147-75-9 and CAS Reg. No. 25973-55-1. CAS Reg. 

No. 2440-22-4 is expected to have low potential for bioaccumulation but CAS Reg. No. 3147-75-9

and CAS Reg. No. 25973-55-1 are expected to have high potentials for bioaccumulation and CAS 

Reg. No. 70321-86-7 is expected to have moderate potential for bioaccumulation. However, the 

relatively low solubility of these compounds may mitigate the potential to bioaccumulate. All four 

phenolic benzotriazole derivatives are expected to have high persistence though the phenolic 

portion resembles many antioxidant phenols which might suggest that that portion of the molecule 

could oxidize. 

An acute toxicity study with the rainbow trout (Oncorhynchus mykiss) was conducted using 

(CAS Reg. No. 2440-22-4); 2-(2’-hydroxy-5’-methylphenyl benzotriazole at concentrations of 

0.022, 0.037, 0.061, 0.10 and 0.17 mg/L for 96 hr under static conditions. The highest dose tested 

approximated the limit of water solubility for the compound. No mortality or adverse effects were 

noted in the test. The 96 hr LC50 (mg/L) is determined to be > 0.17 mg/L. The Agency indicated 
Page 32 of 38

that since no effects were seen in fish at the limit of solubility, no further aquatic toxicity testing 

was necessary (MRID 49358003). 

An acute toxicity study was conducted using zebra fish. 2-(2’-hydroxy-5’-methylphenyl 

benzotriazole (CAS Reg. No. 2440-22-4; Tinuvin P) was used in a limit test at a concentration of 

100 mg/L according to OECD Guideline 203. Ten fish were exposed in duplicate 20 L glass 

aquaria to the test substance. The control group consisted of 10 fish. The test was a “static” test. 

Test vessels were dosed at a concentration of 0.09 g/L for 96 hr. No mortality or adverse effects 

were noted in any of the test or control fish. The 96 hr LC0 and 96 hr LC50 values were > 100 

mg/L.

In another static acute toxicity test, 2-(2’-Hydroxy-5’-octylphenyl)benzotriazole (CAS Reg. No. 

3147-75-9) and 4 mg alkyplhenolpolyglycol ether per liter were used according to OECD 

Guideline 203. Ten zebra fish per concentration were dosed at 10, 18, 32, 58 and 100 mg/L for 96 

hr in 20L aquaria. The control tanks contained water with 4 mg alkylphenolpolyglycol ether/L of 

water. Fish were not fed during the test period. At the end of the test (96 hr), there were no 

mortality or adverse effects observed in any of the test fish or control fish. The 96 hr LC50 was 

determined to be 100 mg/L.

An acute static toxicity test was conducted using zebra fish and 2-(2’-Hydroxy-3,5-di,5-tertamylphenyl)benzotriazole (CAS Reg. No. 25973-55-1). A limit test was conducted under static 

conditions according to OECD Guideline 203. Ten zebra fish were exposed in duplicate to the test 

material. The control group consisted of ten fish. Test vessels were dosed at 0.08 g/L for 96 hr. 

No mortality occurred in treated or control tests. However, in the treated tests, a precipitate 

formed indicating that the limit of solubility of the test material had been exceeded. The 96 hr 

LC50 value was > 100 mg/L.

An acute static toxicity test was conducted using Daphnia pulex. Nine benzo phenolic triazoles 

were tested including:

(CAS Reg. No. 23328-53-2) phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl-; (CAS Reg. 

No. 3147-75-9); 2-(2’-hydroxy-5’-octylphenyl benzotriazole; (CAS reg. No. 25973-55-1); 2-(2’-

hydroxy-3’,5’-di-t-amylphenyl)benzotriazole; (CAS Reg. No. 70321-86-7); 2-(2H-benzotriazole2-yl-4,6-bis(1-methyl-1-phenylethyl) phenol; HDBB (CAS Reg. No. 3846-71-1); phenol, 2-(2Hbenzotriazol-2-yl)-4,6-bis(1,1-dimethyl)- 4). Stock solutions were prepared in tetrahydrofuran 

(THF). No more than 0.01% (v/v) of THF was used in the final exposure solutions. Solvent 

controls showed no adverse effects at this level of solvent concentration. Daphnia pulex (20 

neonates/dose level) were placed in 30 mL glass beakers exposed to 25 mL of test solutions. Test 

concentrations ranged from 0.1 to 10 mg/L for all compounds tested. The 24- and 48-hr LC50

values for phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl were 6.35 and 2.59 mg/L 

respectively. No acute toxic effects were observed for the other phenolic benzotriazoles tested.

An acute static toxicity test was conducted on Daphnia magna using (CAS reg. No. 25973-55-

1); 2-(2’-hydroxy-3’,5’-di-t-amylphenyl)benzotriazole. The test was a component of the High 

Production Volume (HPV) testing program. Daphnia magna were exposed to concentrations of 

5.8, 10, 18, 32, 58 and 100 mg/L. A slight precipitate was noted at all levels indicating the limit of 

solubility in water had been exceeded. Ten Daphnia were exposed to each test solution and a 
Page 33 of 38

control solution for 24 hr. The EC0 concentration was determined to be 58 mg/L. Two daphnids 

were immobilized at 100 mg/L. The EC50 was determined to be > 100 mg/L.

Numerous other studies yielded similar results indicating the low levels of toxicity of 

benzotriazoles to aquatic invertebrates. 

In an acute toxicity test to aquatic plants (CAS Reg. No. 3147-75-9); 2-(2’-hydroxy-5’-

octylphenyl benzotriazole was used in an algal growth inhibition test (EEC Guideline 87/302). 

The toxicity of CAS Reg. No. 3147-75-9 was tested on the green alga Scenedesmus subspicatus. 

The test substance was mixed with acyl phenol polyglycol ether solution and nominal test 

concentrations were 1.23, 3.7, 11, 33 and 100 mg/L. Initial cell density was 104cells/mL. The 

control group was exposed to water and water plus 3.6 mg alkylphenolpolyglycol ether. The 72 hr 

EC50 was determined to be > 100 mg/L. A number of additional studies yield confirmative results 

indicating low toxicity of phenolic triazoles to aquatic plants.

X. DETERMINATION OF SAFETY

For phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2), aggregate 

risk include dietary exposure from food and water, exposure to adults from handling (applying the 

material) and from post-application dermal exposure. Exposures to toddlers (the most highly 

exposed population subgroup from dietary sources) include food and water, post-application 

dermal exposure and post-application “hand-to-mouth” exposures. “Residential exposures (adult 

and toddler) are discussed in Sections VI and VII earlier in this memorandum. Dietary exposure 

estimates for food and drinking water are below the Agency’s level of concern (<100% cPAD) for 

the U.S. population and all population subgroups. The total dietary exposure for food and drinking 

water is 18.9% of the cPAD for the U.S. population and 70.6% of the cPAD for children 1-2 yrs 

old, the most highly exposed population subgroup. 

XI. ENVIRONMENTAL JUSTICE

Potential areas of environmental justice concerns, to the extent possible, were considered in this 

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf).

As a part of every pesticide risk assessment, OPP considers a large variety of consumer subgroups 

according to well-established procedures. In line with OPP policy, HED estimates risks to 

population subgroups from pesticide exposures that are based on patterns of that subgroup’s food 

and water consumption, and activities in and around the home that involve pesticide use in a 

residential setting. Extensive data on food consumption patterns are compiled by the USDA under 

the Continuing Survey of Food Intake by Individuals (CSFII) and are used in pesticide risk 

assessments for all registered food uses of a pesticide. These data are analyzed and categorized by 

subgroups based on age, season of the year, ethnic group, and region of the country. Additionally, 

OPP is able to assess dietary exposure to smaller, specialized subgroups and exposure assessments 

are performed when conditions or circumstances warrant. Whenever appropriate, non-dietary 

exposures based on home use of pesticide products and associated risks for adult applicators and 
Page 34 of 38

for toddlers, youths, and adults entering or playing on treated areas post-application are evaluated. 

Further considerations are currently in development as OPP has committed resources and expertise 

to the development of specialized software and models that consider exposure to bystanders and 

farm workers as well as lifestyle and traditional dietary patterns among specific subgroups.

XII. HUMAN STUDIES

This assessment does not rely on any studies in which human subjects were intentionally exposed 

to a pesticide. 

XIII INTERNATIONAL LIMITS:

There are no international limits on CAS Reg. No. 23328-53-2.

XIV. RISK CHARACTERIZATION

CAS Reg. No. 25973-55-1 and CAS Reg. No. 23328-53-2 are currently used as packaging 

stabilizers (preventing UV light from yellowing or hardening product packages). They are also 

used in paints and coatings. In addition, the Food and Drug Administration (FDA), under 21 CFR 

175.105, has approved the use of CAS Reg. No. 25973-55-1 as an indirect food additive for use in 

food packaging. 

Acute studies revealed low acute toxicity with an oral LD50 >2325 mg/kg based on the highest 

dose tested. Acute inhalation, acute dermal toxicity, skin and eye irritation and skin sensitization 

studies have not been conducted on either of the chemicals contained in this petition; however, 

evidence does exist for structurally similar chemicals contained within the HPV document. Acute 

inhalation and dermal studies resulted in LC50 >1420 mg/m3and LD50 >2000 mg/kg, respectively. 

Skin irritation studies on rats and mice showed no local irritation and no systemic toxicity. The 

Agency concluded in the HPV document that CAS Reg. No. 2440-22-4 was slightly irritating to 

rabbit eyes. The document states that CAS Reg. No. 2440-22-4, in skin sensitization studies on 

guinea pigs, showed skin sensitization; however, studies conducted on humans showed no 

sensitization. 

In a 90-day study Wistar rats were given the test substance via their diet at 100, 200, 400, 800, or 

1600 ppm (approximately 5, 10, 20, 40, or 80 mg/kg/day). Decreased hemoglobin and packed cell 

volume were seen in males administered ≥~20mg/kg/day and increases in glucose-6-phosphatase 

activity was noted at all dietary concentrations; however, these values were within the normal 

range of variability and therefore, are not considered to be of toxicological significance. Liver, 

kidney, spleen, and testes weights were increased in higher exposure groups with an indication of 

increased thyroid weights. Increases in testes weights were seen at ~20, ~40, and ~80 mg/kg/day; 

however, the testes weights were reported as testes weight per 100g body weight. The increase in 

testes weight may be caused by the decreased body weight and not a toxicologically significant 

finding. Reproductive organs were not evaluated microscopically. The primary target organ was 

the liver which showed a greenish-drab discoloration in males and females at higher exposure 

levels. “Microscopic examination revealed foci of necrosis and slight proliferation of bile duct 
Page 35 of 38

epithelia.”(HPV, 2009) Enlargement of the parenchymal cells was also observed. Tubular necrosis 

was reported in the kidney of some males in the higher does groups. A treatment related yellowishbrown pigmentation was seen in the cytoplasm of the proximal tubular cells of females. No 

mortality was observed. The NOAEL of 20 mg/kg/day is based on blood, liver, and kidney effects 

seen at the LOAEL of 40 mg/kg/day. 

In a 90-day dog study male and female Beagles were administered 0, 15, 30, 60, 120, or 240 

mg/kg/day through their diet. Animals in the high-dose group showed decreases in body weight 

and food consumption. Males were more sensitive than females with mortality of one male dog in 

the highest dose group. Anemia and slight changes in blood chemistry parameters including 

increased serum bilirubin levels and gamma glutamyl transpeptidase (GTP), glutamyl oxalacetic 

transaminasae (GOT) and alkaline phosphatase activity were noted in the animals from the two 

highest dose groups. Males from these groups showed decreases in testes, prostrate, and 

epididymal weights and females showed deceases in body weight and uterus weight in the three 

highest dose groups. In higher dose groups, some animals showed atrophy of uterus, abnormal 

spermiogenesis, and atrophy of the prostate. The liver was reported to be the primary target organ 

for toxicity. Although the full study was not available, the submission summary for the HPV 

program states that at treatment levels of 60, 120, and 240 mg/kg/day, reduced food consumption 

and body weights were seen. In addition, histopathologic effects were noted in the liver, kidney, 

and testes of the 3 highest dose groups (details not provided). Increased liver weights associated 

with liver damage including icterus (jaundice) were observed upon gross and histopathological 

examination in a few dogs in the 120 and 240 mg/kg/day dose groups. Microscopically, fatty 

degeneration of hepatocytes, presence of protein globules in the cytoplasm, Kupffer cell 

hyperplasia and centrilobular choleostatis were seen. (HPV) The NOAEL for this study is 30 

mg/kg/day based on body weight, liver, and kidney effects seen at the LOAEL of 60 mg/kg/day.

Developmental studies have been conducted on two structurally similar chemicals. In one study 

rats and mice received the test substance containing CAS Reg. No. 2440-22-4 on days 6-15 of 

gestation. No maternal toxicity was evident and the rates of implantation and embryotoxicity were 

not affected by treatment. No teratogenic effects were observed however, the study did not specify 

what developmental endpoints were examined. The NOAEL for maternal and developmental 

toxicity was 1000 mg/kg/day (highest dose tested).

A second developmental rat study showed no maternal toxicity at any dose tested for CAS Reg. 

No. 70321-86-7 on gestation days 6-15. A significant reduction in fetal body weight and an 

increased delay of skeletal maturation was observed in the 1000 mg/kg dose group. However, there 

were no similar effects in the high dose group indicating that these effects may be “incidental”. An 

omphalocele was seen in one fetus in the high dose group. The maternal toxicity NOAEL was 

3000 mg/kg/day (highest dose tested). A developmental toxicity NOAEL of 1000 mg/kg/day was 

chosen based on the omphalocele seen at the LOAEL of 3000 mg/kg/day.

All genetic toxicity tests (in vitro and in vivo) conducted on the chemicals assessed in the HPV 

document indicated that this group of chemicals are not mutagenic and will not undergo

chromosomal aberrations. A 104 week feeding study administered up to 142 mg/kg/day to rats did 

not find evidence of carcinogenicity. The Agency does not believe that CAS Reg. No. 25973-55-1 

and CAS Reg. No. 23328-53-2 will be carcinogenic in humans. No clinical signs of neurotoxicity 
Page 36 of 38

were seen in any of the repeat dose studies. After evaluating the available data and the expected 

exposure from the intended use pattern of this inert ingredient, the Agency does not feel that CAS 

Reg. No. 25973-55-1 and CAS Reg. No. 23328-53-2 will cause neurotoxicity.

A combined repeated dose toxicity study with the reproduction/developmental toxicity screening 

test (OECD 422) was conducted using drometrizole (CAS Reg. No. 2440-22-4). Male and female 

Crl:CD(SD) rats (12/sex/group) were administered drometrizole by gavage at dose levels of 0, 30, 

100 or 300 mg/kg/day in olive oil. An additional group of 5 rats/sex were placed on test for the 

control and high dose group as recovery animals (15 days). Males were administered the test 

material for 42 days and females from 14 days prior to mating to d 4 of lactation. Offspring were 

terminated on PND 4. 

Mortality was unaffected by treatment and no clinical signs of toxicity were observed. No 

treatment-related effects were observed on body weights, food consumption, reflex/reaction, grip 

strength, locomoter activity, hematology parameters or reproductive parameters. 

The reproductive/developmental toxicity NOAEL was the highest dose tested at 300 mg/kg/day. 

The NOEL in males was considered to be < 30 mg/kg/day based on increased relative liver 

weights observed in all dose groups and 30 mg/kg/day based on effects on liver and kidney 

weights and kidney histopathology. The NOAEL was concluded to be 300 mg/kg/day for males 

and 30 mg/kg/day for females based on kidney lesions. 

In an extended one-generation oral reproduction study (OECD Test Guideline 443) with the rat 

(MRID 49358004), the no-observed-effect-level (NOAEL) for phenol, 2-(2H-benzotriazol-2-yl)-6-

dodecyl-4-methyl- for parental and reproductive toxicity was 10000 ppm (equal to 618 mg/kg/day, 

the highest dose tested). The NOAEL for offspring toxicity was 5000 ppm (equal to 311 

mg/kg/day) based on decreased body weight, and body weight gain, increased absolute spleen 

weights in males and increased incidence of splenic extramedullary hematopoiesis in males 

observed in pups at the LOAEL of 10000 ppm (equal to 618 mg/kg/day).

The data from the combined repeated dose toxicity study allow the Agency to reduce to the FQPA 

safety factor from 10X (originally applied due to data gaps) to 1X. Based on the discussion 

summarized above, Margins of Exposure > 100 based upon conservative (protective) assumptions, 

the Agency approves the use of phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl (CAS Reg. 

No. 23328-53-2) as an inert ingredient used in pesticide formulations under 40 CFR § 180.920 on 

all agricultural crops at a maximum end-use concentration not to exceed 10 % by weight. 
Page 37 of 38

REFERENCES

E.P.A. 2010. Memorandum, D. Sunderland, Decision Document for Petition Numbers 

8E7362 and 8E7363; 2-(2’-hydroxy-3’, 5’-di-tert-amylphenyl) benzotriazole (CAS Reg. 

No. 25973-55-1) and Phenol, 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methyl (CAS Reg. 

No. 23328-53-2)).

Federal Register. 2010. EPA-HQ-OPP-2008-0601 and EPA-HQ-OPP-2008-0602; FRL-8836-3. 

Volume 75, No. 159/Wednesday 18 August 2010. Pp 50884 – 50890. 2-(2’-hydroxy-3’, 

5’-di-tert-amylphenyl) benzotriazole and Phenol, 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-

methyl; Exemption fro the Requirement of a Tolerance.

MRID 49358001. Physical and Chemical Properties of Phenol, 2-(2H-benzotriazol-2-yl)-6-

dodecyl-4-methyl- (CAS Reg. No. 23328-53-2); Tinuvin®571) and related Phenolic 

Benzotriazides. Sponsored by Loveland Products, Inc., P.O. Box 1286, Greeley, CO 

80632; 6 November 2013. 67 pp.

MRID 49358002. Mammalian Toxicity of Phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-

methyl- (CAS Reg. No. 23328-53-2); Tinuvin® 571) and related Phenolic Benzotriazides. 

Sponsored by Loveland Products, Inc., P.O. Box 1286, Greeley, CO 80632; 25 March 

2014. 303pp.

MRID 49358003. Ecological Effects and Environmental Fate of Phenol, 2-(2H-benzotriazol-2-yl)-

6-dodecyl-4-methyl- (CAS Reg. No. 23328-53-2); Tinuvin® 571) and related Phenolic 

Benzotriazides. Sponsored by Loveland Products, Inc., P.O. Box 1286, Greeley, CO 

80632; 27 January 2014. 169pp.

MRID 49358004. Extended One-Generation Reproductive Toxicity Study of Tinuvin 571 in 

Wistar Rats. Sponsored by Loveland Products, Inc., P.O. Box 1286, Greeley, CO 80632; 

27 January 2014. 1322pp.
Page 38 of 38

ATTACHMENT

DEEM-FCID – Phenol, 2-(2H-benzotriazol-2-yl-6-dodecyl-4-methyl January 2015

US EPA Ver. 3.16, 03-08-d

DEEM-FCID Chronic analysis for PHENOL NHANES 2003-2008 2-day

Residue file name: J:\Phenol\INERTS_57ACTIVE_100PPBH2OREV.R08

 Adjustment factor #2 used.

Analysis Date 01-21-2015/13:37:36 Residue file dated: 01-21-2015/13:36:42

Reference dose (RfD, Chronic) = .2 mg/kg bw/day

NOEL (Chronic) = 20 mg/kg bw/day

COMMENT 1: Inert 57 active ingredients + drinking water (100ppb)

===============================================================================

 Total exposure by population subgroup

-------------------------------------------------------------------------------

 Total Exposure

 -----------------------------------

 Population mg/kg Margin of Percent 

 Subgroup body wt/day Exposure of RfD 

-------------------------------------- ------------- ---------- ----------

Total US Population 0.037869 528 18.9%

Hispanic 0.041352 484 20.7%

Non-Hisp-White 0.037160 538 18.6%

Non-Hisp-Black 0.035190 568 17.6%

Non-Hisp-Other 0.044671 448 22.3%

Nursing Infants 0.049641 403 24.8%

Non-Nursing Infants 0.091947 218 46.0%

Female 13+ PREG 0.033048 605 16.5%

Children 1-6 0.109335 183 54.7%

Children 7-12 0.045482 440 22.7%

Male 13-19 0.026752 748 13.4%

Female 13-19/NP 0.027186 736 13.6%

Male 20+ 0.028199 709 14.1%

Female 20+/NP 0.030632 653 15.3%

Seniors 55+ 0.030537 655 15.3%

All Infants 0.078886 254 39.4%

Female 13-50 0.029281 683 14.6%

Children 1-2 0.141248 142 70.6%

Children 3-5 0.097127 206 48.6%

Children 6-12 0.050111 399 25.1%

Youth 13-19 0.026960 742 13.5%

Adults 20-49 0.028948 691 14.5%

Adults 50-99 0.030358 659 15.2%

Female 13-49 0.029267 683 14.6%

-------------------------------------------------------------------------------

RDI: PV Shah, K. Leifer

M.I.Dow:S7958:PY1:(703)305-5533:IIAB:7505P