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Administrative data

Description of key information

No systemic effects observed in all parameters examined, minimal barely perceptible skin erythema at the application site in all treated groups without dose-dependence.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Referenceopen allclose all

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
90 days
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Only purity and physical chemical properties of test substance not given.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
no ophthalmoscopy was performed
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
other: Charles River
Sex:
male/female
Details on test animals and environmental conditions:
Rats were included in the test at an age of 28 days. No information on environmental conditions reported.
Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
Dechlorane Plus 25 was blended into the diet in a high-speed blending apparaus. Fresh diets were prepared each week. The diet was offered ad libitum.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
90 days
Frequency of treatment:
daily
Dose / conc.:
0 ppm
Remarks:
Basis: nominal in diet
Dose / conc.:
10 000 ppm
Remarks:
Basis: nominal in diet
Dose / conc.:
30 000 ppm
Remarks:
Basis: nominal in diet
Dose / conc.:
100 000 ppm
Remarks:
Basis: nominal in diet
No. of animals per sex per dose:
15 males and 15 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
Groups of 15 male and 15 female rats were given diet containing Dechlorane Plus 25 at 0, 10,000, 30,000, or 100,000 ppm daily for 90 days.
Positive control:
none
Observations and examinations performed and frequency:
mortality and clinical signs of toxicity daily, food consumption weekly, bodyweights weekly, haematology and clinical chemistry including urinalysis on days 45 and 84, macroscopic pathology including organ weight determination and microscopic pathology at the end of treatment.
Sacrifice and pathology:
All rats were subjected to necropsy and organ weight determination (weights of brain, gonads, heart, kidneys, liver, and spleen), in control animals and animals of the high dose group, microscopic pathology examination was performed. A total of 37 organs and tissues were examined histologically.
Statistics:
Analysis of variance, Tukey's or Scheffe's Multiple Comparison tests, Kruskel-Wallis Statistics and Multiple Comparisons.
Clinical signs:
no effects observed
Description (incidence and severity):
2 deaths accidental at blood collection in the high dose group
Mortality:
no mortality observed
Description (incidence):
2 deaths accidental at blood collection in the high dose group
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
slightly increased liver weight at the high dose
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
At the high dose level, slightly increased liver weight was seen without histological correlate. No other test substance related effects occurred.
Key result
Dose descriptor:
NOAEL
Effect level:
>= 100 000 ppm
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: Besides slightly increased liver weights at the highest dose level without histological correlate, no test substance related effects at all were seen.
Critical effects observed:
not specified
Conclusions:
Dechlorane Plus 25 was essentially nontoxic upon administration in the diet at concentrations up to 10000 ppm.
Executive summary:

Dechlorans Plus 25 was administered to groups of 15 male and 15 female rats in the diet at concentrations of 0, 10,000, 30,000, or 100,000 ppm daily for 90 days. The following parameters were recorded: mortality, clinical signs of toxicity, bodyweights, food consumption, haematology, clinical chemistry and urinalysis, macroscopic and microscopic pathology including organ weights. Besides slightly increased liver weight without histological correlate, thus indicating a functional adaption of the liver to an increased metabolic load, no substance related effects were seen. Dechlorane Plus was essentially nontoxic. The NOAEL was determined at 100,000 ppm in diet corresponding to about 5,870 mg/kg bw for males and to about 7,670 mg/kg bw for females.

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Although the study as such appears reliable and well documented, compared to OECD 408 guideline there were quite some shortcomings, as the study focused mainly on investigating the accumulation pattern of DP: Only 7 animals per dose group were used, maximum dose applied was only 100 mg/kg bw/d. The description of the study design and observations focusses on points relevant to assess accumulation of DP in tissue but hardly on classical OECD 408 endpoints and observations. It remains unclear, whether no effects were seen or whether such further observations and endpoints on histopathology were not made. Thus, to cover the subchronic oral toxicity endpoint, the study in considered reliabale with restrictions, suitable as supportive study only.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
only 7 animals/dose group but two additional dose groups with 45 days exposure and 45 days depuration period. Animals were dosed only up to 100 mg/kg bw/d. Reporting of histopathology and clinical observation, body weight, food consumption, etc. is poor.
GLP compliance:
not specified
Remarks:
GLP requirements were not mentioned in the publication.
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals and environmental conditions:
Forty-two Male SD rats (35-d-old) with average weight of 110 g were obtained from the Weitong Lihua Experimental Animal Central (Beijing, China) and were housed individually in a mass air-displacement room with a 12-h light–dark cycle at 20 - 26 °C and a relative humidity of 50 - 70%. After 1 week acclimation, they were separated into six groups: the rats in four groups were exposed to consecutive dosages of 0, 1, 10, and 100 mg/kg/d for 90 d, while the other two groups were exposed to 0 and 100 mg/kg/d for 45 d followed by 45 d of depuration during which the rats were fed unfortified food. All rats were euthanized after their exposure period. Liver, muscle, and serum were immediately collected from each rat and were frozen in liquid nitrogen and stored at -20 or -80 °C until the chemical analysis and toxic experiments, respectively.
Route of administration:
oral: gavage
Vehicle:
corn oil
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
Analytical methods described are very sensitive and appropriate but apparently were used solely to investigate the substance in tissues (liver, muscle and serum) in order to assess accumulation. No information is provided in the publication on dose verification by analytical means and thus it is assumed that the doses applied (0, 1, 10, and 100 mg/kg bw/d) are nominal doses of substance dissolved in corn oil as vehicla and applied by gavage. No significant error in dosing is expected by this exposure method.
Duration of treatment / exposure:
90 days exposure
Frequency of treatment:
once daily
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Basis: actual ingested
Dose / conc.:
1 mg/kg bw/day (nominal)
Remarks:
Basis: actual ingested
Dose / conc.:
10 mg/kg bw/day (nominal)
Remarks:
Basis: actual ingested
Dose / conc.:
100 mg/kg bw/day (nominal)
Remarks:
Basis: actual ingested
No. of animals per sex per dose:
7 animals per dose, all male
Control animals:
yes, concurrent vehicle
Details on study design:
From available information in the publication the study follows a classical 90d-oral subchronic toxicity study approach. However, only limited information is reported on findings as the study mainly focussed on assessing and measuring accumulation of the substance in tissues.
Positive control:
none
Observations and examinations performed and frequency:
To evaluate whether or not DP has the adverse effects of rats, the weight change and clinical biochemistry parameters, such as alanine amino transferase (ALT), aspartate amino-transferase (AST), albumin (ALB), alkaline phosphatase (ALP), total bile acids (TBA), urea nitrogen (BUN), creatinine (CRE), cholesterol (CHO), triglycerides (TG), high density lipid–cholesterol (HDL-C), low density lipid–cholesterol (LDL-C), creatine kinase (CK), and glucose was observed .
Sacrifice and pathology:
no details reported in the publication
Other examinations:
The focus in this study was to assess accumulation of DP in tissue (liver, muscle and serum), but also serum parameters and gene expression and enzyme activities were assessed.
Sample preparation: Details of the analytical procedures for liver and muscle are described in the supplementary data. Pre-treatment for serum was performed as Malmberq (Malmberg et al., 2005) with minor modification. Two milliliter of serum were spiked with surrogate (BDE- 181). The protein was denatured with 1 mL of hydrochloric acid (6 M) and 6 mL of 2-propanol, and the mixtures were shaken vigorously. The DP and its metabolites were twice extracted with 6 mL of 1:1 hexane/methyl tert-butyl ether (MTBE) (V/V = 1:1) mixture. The combined organic extracts were washed with a potassium chloride solution (1%, 3 mL), and the solvent was concentrated to dryness under N2 for gravimetric lipid weight determination. The extract was redissolved with 6 mL of hexane, and the aqueous phase compounds were separated from neutrals by partitioning with potassium hydroxide (0.5 M in 50% ethanol). The aqueous phase was re-extracted again with hexane (6 mL) for complete extraction. Neutral phase was treated with 2 mL of concentrated sulfuric acid to remove lipids, and subsequent processing was eluted with 40 mL hexane/dichloromethane (V/ V = 1:1) in multi-layer silica column (i.d. = 1 cm) packed with 8 cm neutral silica and 8 cm acidified silica. Elutes were concentrated to near dryness under N2 and redissolved in 270 µL of isooctane and spiked with a known amount of internal standard (30 µL BDE-128) before instrumental analysis.
The DP was scanned by an Agilent 6890 gas chromatograph coupled with an Agilent 5975C mass spectrometer (GC/MS) using electron capture negative ionization (ECNI) in the selective ion- monitoring (SIM) mode and separated by a DB-XLB (30 m x 0.25 mm x 0.25 µm, J&W Scientific) capillary column. The initial oven temperature was set as 110 °C (held for 1 min), ramped at 8 °C/min to 180 °C (held for 1 min), and then 2 °C/min to 240 °C (held for 5 min), 2 °C/min to 280 °C (held for 15 min), and finally 10 °C/min to 310 °C (held for 10 min). We manually injected 1 µL of sample in the pulsed splitless mode. The temperature of the injection port was set at 280 °C. The monitored and quantitative ions were as follows: m/z 653.8 and 651.8 for DP isomers (syn-DP and anti-DP), m/z 618 and 620 for anti-Cl11-DP and syn-Cl11-DP, and m/z 584 and 586 for anti-Cl10-DP. The syn-Cl11-DP was previously identified as a dechlorinated product of syn-DP by Wang et al. (2011). Semi-quantitation was achieved to syn-Cl11-DP by reference to the response of anti-Cl11-DP on GC/MS. We also attempted to screen some possible methoxy- and/or methylsulfone-DP in rat serum and liver. Such DP metabolites, if present, would ionize similar to OH-CB and/or MeSO2-CB by scavenging an electron to show a dominant M- in ENCI ion source. Corresponding m/z values of potential oxidative metabolites were demonstrated by Tomy et al. (2008).
QA/QC and data analysis: Procedural blanks covering the whole procedure were performed in parallel with the samples on each batch of extraction. The average relative standard deviations (RSDs) among triplicates samples ranged from 3% to 9.6% for all targets. The recoveries for surrogates ranged from 71.7% to 112.9% in all detected samples. The method detection limit (MDL) was defined as the mean value plus 3-fold standard deviation for analytes, which were detected in the procedural blanks (n = 6) and for others which were not detected in blanks, a signal-to-noise ratio of ten was set as MDL. The MDLs for syn-DP, anti-DP, and anti-Cl11-DP were 108.31, 70.44, and 0.98 ng/g lw in muscle and liver, and were 0.20, 0.054, and 0.042 ng/ml for syn-DP, anti-DP and anti-Cl11-DP in serum, respectively. Statistical analysis was performed using SPSS 16.0 for Windows (SPSS Inc., Chicago, IL) for comparisons of means between and within treatment groups. The f anti was elegated to ratio of anti-DP/(anti-DP + syn-DP), which was used to evaluate the profiles of DP in the tissue of experiment animals. One-way analysis of variance (ANOVA) was used to determine differences in concentrations and other experimental statistics. Significance was set at p < 0.05.
Serum biochemical parameter and thyroid hormone analysis: Standard spectrophotometric methods for the HITAC 7170A automatic analyzer were applied to measure serum parameters including alanine amino transferase (ALT), aspartate aminotransferase (AST), albumin (ALB), alkaline phosphatase (ALP), total bile acids (TBA), urea nitrogen (BUN), creatinine (CRE), cholesterol (CHO), triglycerides (TG), high density lipid-cholesterol (HDL-C), low density lipid-cholesterol (LDL-C), creatine kinase (CK), and glucose. The levels of thyroid hormones, total triiodothyronine (T3) and thyroxine (T4), free T3 and T4 in serum were detected by chemiluminescence. To avoid fluctuation in thyroid hormone levels, serum was collected from the control and exposed groups at the same time during 1 d.
Gene expression and enzyme activities analysis: Gene response to environmental pollutants was detected, including Nat2 and SULT isomers. Total RNA from the 90-d exposed rat livers were isolated by Trizol reagent and measured by absorbance at 260 nm performed in a UV1240 spectrophotometer (Shimadzu, Japan) and 260/280 nm absorbance ratio for estimating its purity. Every sample was analyzed in triplicate. β-actin was chosen for the housekeeping gene and was used as an internal control. Cycle threshold (Ct) data were normalized to β-actin, and the fold changes in target genes were calculated using the 2-ΔΔCt. Enzyme activities were measured according to CYP1A2, CYP2B1, CYP2B2, CYP3A, and GST kit, respectively (Genmed Scientifics Inc. USA).
Statistics:
One-way analysis of variance (ANOVA) was used to determine differences in concentrations and other experimental statistics. Significance was set at p < 0.05.
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
not specified
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
see details on results
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
see details on results
Urinalysis findings:
not specified
Behaviour (functional findings):
not specified
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not specified
Details on results:
Clinical chemistry parameters: To evaluate whether or not DP have the adverse effects of rats, we observed the weight change and clinical biochemistry parameters, such as alanine amino transferase (ALT), aspartate amino-transferase (AST), albumin (ALB), alkaline phosphatase (ALP), total bile acids (TBA), urea nitrogen (BUN), creatinine (CRE), cholesterol (CHO), triglycerides (TG), high density lipid–cholesterol (HDL-C), low density lipid–cholesterol (LDL-C), creatine kinase (CK), and glucose. No significant changes in absolute body and liver weight or in relative liver weight were observed in the exposure and depuration groups compared to the controls. This may indicate that the dosage levels used did not cause overt toxicity. The activities of ALT, ALP, TBA, and level of glucose were significantly decreased (p < 0.05) (Table A3). We did not observe histopathological liver damage in our experiment. To investigate the potential influence of DP and its metabolites on endocrine-related processes, thyroid hormone levels (FRT4, FRT3, TSH, TT3, and TT4) in serum were also measured. Results showed no significant influence or related dose diversification (Table A3). No systemic toxicity was observed in rats gavaged with the high concentration of 1500 mg/kg bw/d following repeated oral dosing over a 28-d period (Brock et al., 2010). Taken together, we inferred that DP did not cause adverse effects on the liver and its lipid metabolism or on endocrine levels.
Key result
Dose descriptor:
NOAEL
Effect level:
>= 100 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male
Basis for effect level:
clinical signs
mortality
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
Critical effects observed:
not specified

DP distribution in rat tissues: To investigate the distribution profile of DP in the rat, syn-DP, anti-DP, syn-Cl11-DP, and anti-Cl11-DP were detected in liver, muscle, and serum. In the control group, detection frequencies of syn-DP and anti-DP were 100% in all tissues measured. The average concentrations of anti-DP and syn-DP were found in liver up to 2800 ± 1200 and 890 ± 400 ng/g lw, respectively, which indicate that syn-DP and anti-DP accumulated in organs from background exposure such as feed or air-borne dust, which may be due to the fact that DP was widespread in the environment including the food (Venier and Hites, 2011). Neither syn-Cl11-DP nor anti-Cl11-DP was found in the tissues of the control group. In the exposure groups, the highest concentrations of syn-DP and anti-DP were both detected in liver from the 100 mg/kg bw/d dose group, which were nearly 12 - 15-folds than that in muscle and 4.8 - 5.4-folds that found in serum from the same group, respectively (Fig. 1A). In liver, the concentration of syn-DP and anti-DP increased with DP exposure dosage. In muscle, the highest content of syn-DP occurred in the 10 mg/kg/d group (84 ± 39 µg/g lw). However, the highest concentration of anti-DP was detected in the 1 mg/kg/d group in muscle, which reduced with increasing DP exposure dosage (Fig. 1A). In serum, the concentration of syn-DP increased with DP exposure dosage and anti-DP was also prone to accumulate in the 1 mg/kg bw/d group (Fig. 1B). We next analyzed the Cl11-DP in rat tissues. The highest average concentration of syn-Cl11-DP and anti-Cl11-DP occurred in liver in the 100 mg/kg bw/d group, reaching 140 ± 51 and 480 ± 170 ng/g lw, respectively. The average concentrations of syn-Cl11-DP and anti-Cl11-DP in liver in the 100 mg/kg bw/d group were 4.7- and 8.3-fold greater than that found in muscle in the same group. In liver, syn-Cl11-DP and anti-Cl11-DP increased with DP exposure dosage. In muscle, syn-Cl11-DP and anti-Cl11-DP were accumulated; however, no significant change was observed among the DP exposure groups (Fig. 1C). In serum, the highest concentration of anti-Cl11-DP was detected in the 1 mg/kg bw/d group (Fig. 1D). It is worth noting that the contents of anti-Cl11-DP in the three tissues were higher than those of syn-Cl11-DP in corresponding groups, indicating that anti-Cl11-DP was more accumulated than syn-Cl11-DP in the tissues measured. Since syn-Cl11-DP and anti-Cl11-DP are also detected in commercial DP-25, we could not exclude the possibility that these chemicals originated from commercial products. To further explore possible DP degradation in tissue samples, we conducted three photolytic degradation experiments by exposing anti-DP, syn-DP, and commercial DP solutions to UV light, the degradations were mainly [-Cl + H] and [-2Cl + 2H] processes. Compared to rat liver samples, syn-DP, anti-DP, syn-Cl11-DP, and anti-Cl11-DP were mapped to the syn-DP (UV), anti-DP (UV), and commercial product (Fig. 2). In addition to syn-DP, anti-DP, syn-Cl11-DP, and anti-Cl11-DP, at least two unknown products (U1 and U2) were identified in all samples and in commercial DP. Although it was difficult to make an accurate identification for U1 and U2, our results showed that U1 and U2 were possibly prone to accumulate in liver. However, we could not exclude that U1 and U2 were biotransformed from DP or its metabolites or originated from the commercial product. This result was consistent with reports that found unidentified peaks in sediment samples (Sverko et al., 2010). To investigate the elimination of DP in tissues, rats were exposed to 100 mg/kg bw/d DP for 45 d followed by 45 d depuration. The amounts of syn-DP and anti-DP in muscle and liver showed no significant change after depuration, although the amounts of syn-DP and anti-DP in serum significantly decreased after depuration (Fig. 3A and B). However, the content ratio of syn-DP and anti-DP in liver to those in liver plus muscle significantly increased after depuration compared with exposed group in 45 d (Fig. 3D). In addition, the content ratio of syn-DP and anti-DP in liver to those in liver plus muscle demonstrated no significant change in any group after 90 d exposure (Fig. 3C). These data suggest that DP was more prone to accumulate in liver or that the eliminating rate in liver was lower than that in muscle. The content of both syn-Cl11-DP and anti-Cl11-DP in the liver decreased significantly after depuration and neither was detected in serum after depuration (Fig. 3E and F). Our result showed that the contents of anti-Cl11-DP were more than syn-Cl11-DP in liver and muscle, indicating that anti-Cl11-DP might be more accumulative than syn-Cl11-DP in liver and muscle. However, since the content of anti-Cl11-DP is much higher than syn-Cl11-DP in the commercial product (Fig. 2) as well as both anti- and syn-Cl11-DP could be biotransformed from DP in different rate, we could not exclude this coming from above reasons. In addition, elimination half-life of syn-DP was about 179 d in liver, 44 d in muscle, 24 d in serum, 54 d of anti-DP in muscle, and 25 d of anti-DP in serum. These results suggest that anti-DP and syn-DP in liver were more difficult to eliminate than in muscle and serum; in other words, DP isomers were more likely to accumulate in the liver. We did not calculate the elimination half-life of anti-DP as it increased, albeit not significantly, after depuration. These results implied that anti-DP in the liver was more difficult to eliminate than syn-DP or anti-DP possibly transfer to liver from other organs. Our results for elimination half-life of syn-DP are similar to previous reports that demonstrated biological half-lives in the whole body of lake trout (minus the liver) of 53 d for the syn-DP isomers dosed with syn-DP in food for 49 d followed by 112 d of depuration (Tomy et al., 2008). For anti-DP, our results may differ from Tomy’s et al. report due to the different species (rat versus rainbow trout) or the different tissue (liver versus whole body). Our results are consistent with previous research which showed that anti-DP was more persistent than syn-DP in walleye and gold-eye and accounted for more than 90% of the total body burden of DP (Tomy et al., 2007). The mechanism of the different DP isomers accumulation dependent with its concentration is needed to be elucidated in the further. Like most persistent halogenated compounds, DP showed higher accumulation in the liver than in the muscle tissue. Distribution of DP in tissues may not only be controlled by transport and equilibration among lipid pools, but other mechanisms such as specific protein binding in the liver may also exist for DP isomers during their partitioning within the body. Hepatic protein association has also been observed for other persistent chlorinated and brominated contaminants, for example, polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polybrominated diphenyl ethers in organisms and humans (Guvenius et al., 2002; Iwata et al., 2004).

f anti in DP: Interestingly, the fractions of the anti-isomer (ratio of the anti- DP concentration to total DP concentration, or f anti ) were 0.75, 0.77, and 0.80 for muscle, liver, and serum, respectively, in the lower exposed group (1 mg/kg bw/d), which were close to ratio in commercial DP-25 (0.8) (Fig. 4A). However, the f anti significantly decreased in the 10 mg/kg bw/d and 100 mg/kg bw/d exposed groups (0.26 and 0.26 in muscle, 0.29 and 0.30 in liver, 0.27 and 0.27 in serum, respectively). The DP trend of f anti after depuration was similar to the higher DP exposure group, near 0.3 (Fig. 4B). The f anti for all tissues in the low DP exposure group was similar to the findings in most wild animals from Northern America and Europe, where no significant stereoselective enrichment were detected in wildlife such as birds relative to the commercial mixture (Gauthier andLetcher, 2009; Guerra et al., 2011; Munoz-Arnanz et al., 2011).However, in this study the f anti values decreased with the increase in DP exposure dose. Similarly, greater amounts of syn-DP than anti-DP have been reported in the serum of workers and birds ine-waste dismantling regions (Ren et al., 2009; Zhang et al., 2011).An enrichment of syn-DP could be explained by the following factors: (1) isomer-specific structural configuration and (2) different binding affinity to protein. The structure of syn-DP could block effectively metabolism than anti-DP since the configuration of the pendant chlorocyclopentene moieties of anti-DP render it more susceptible to biological attack than the less sterically hindered syn-DP (Hoh et al., 2006; Tomy et al., 2008). It could be that anti- and syn-DP have different binding affinity to protein in liver, and that of syn- is much higher than anti-DP due to its steric hindrance. At lower dosage, there are enough binding sites for both syn- and anti-DP; at higher dosage, the binding sites are mostly available for syn-, resulting the discriminating of anti-DP. In addition, Tomy et al. (2008) had found that the biomagnification factor of syn-DP (5.2) was greater than anti-DP (1.9) in exposed rainbow trout, which suggested that syn-DP was more bioavailable. They also reported that the uptake rate of syn-DP (0.065 nmol/d in liver) was significantly faster than anti-DP (0.024 nmol/d in liver) in chicken (2008).

The mRNA expression levels of certain enzymes N-acetyltransferase 2 (Nat2) plays an important role in metabolism of methylsulfone-PCBs and the sulfide acid metabolic pathway (Saneto et al., 1982). The sulfotransferase (SULT) family is comprised of important phase II conjugation enzymes for the detoxification of xenobiotics and activity modulation of physiologically important endobiotics such as thyroid hormones, steroids, and neurotransmitters. Sulfotransferase activity may be inhibited in humans when exposed to certain xenobiotics including certain pharmaceuticals and environmental chemicals (hydroxylated polychlorinated biphenyls, hydroxylated polyhalogenated aromatic hydrocarbons, pentachlorophenol, triclosan, and bisphenol A) (Wang and James, 2006). Accordingly, we further investigated the transcriptional effect of DP on the liver in relation to mRNA expressions of Nat2, SULT1A1, 1C2, 1C3, 1E1, and 2A1 in rats. The expression of Nat2 decreased markedly in the 10 mg/kg bw/d group (Fig. 5A) (p < 0.05), and a significant reduction was also observed in the expression of SULT1A1, SULT1C2 and SULT2A1 in the 1 mg/kg bw/d group (p < 0.05) (Fig. 5A). These changes may relate to biological responses when the body is stimulated by DP exposure. Crump et al. also detected CYP1A4, CYP1A5, CYP2H1, CYP3A37, UGT1A9, DI2, THRSP14-a, L-FABP, and IGF-1 in chicken embryonic hepatocytes and chicken embryos following injection of DP into the air cell of eggs prior to incubation at 24 or 36 h, which showed no adverse effect of DP on embryonic viability or pathways associated with the genes (Crump et al., 2011).

Determination of enzyme activities: Cytochrome (CYP) monooxygenases are a group of proteins responsible for the oxidation of pharmaceuticals, environmental pollutants, and endogenous compounds (Guengerich, 1991). Because mRNA expression increases or decreases cannot fully explain changes in enzyme activity, we measured the activities of CYP1A2, CYP2B1, CYP2B2, CYP3A, and glutathione S-transferase (GST). Significant changes in CYP2B1 were observed in the 1 mg/kg bw/d group compared with the control group (Fig. 5B) (p < 0.05), but no significant variation was observed in the activity of the other enzymes (Fig. 5C). Taken together, no adverse effect on enzyme activity was observed after subchronic exposure to DP.

Conclusions:
Dechlorane plus was assessed in a 90d-oral subchronic toxicity study. No significant changes in absolute body and liver weight or in relative liver weight were observed in the exposure and depuration groups compared to the controls. No histopathological liver damage was observed. No significant influence or related dose diversification on endocrine-related processes, assessed via thyroid hormone levels (FRT4, FRT3, TSH, TT3, and TT4) in serum were noted. Taken together, the authors concluded that DP did not cause adverse effects on the liver and its lipid metabolism or on endocrine levels. Although the authors derived no NOAEL in the publication, from content no adverse effects were observed at the highest dose tested (100 mg/kg bw/d); thus, the NOAEL is set to ≥100 mg/kg bw/d. Thus, the NOAEL may be set to 100 mg/kg bw/d, the highest dose applied in this study.
Executive summary:

Dechlorane plus was assessed in a 90d-oral subchronic toxicity study. No significant changes in absolute body and liver weight or in relative liver weight were observed in the exposure and depuration groups compared to the controls. No histopathological liver damage was observed. No significant influence or related dose diversification on endocrine-related processes, assessed via thyroid hormone levels (FRT4, FRT3, TSH, TT3, and TT4) in serum were noted. Taken together, the authors concluded that DP did not cause adverse effects on the liver and its lipid metabolism or on endocrine levels. Thus, the NOAEL may be set to 100 mg/kg bw/d.

Effects seen, not considered adverse were:

- The activities of ALT, ALP, TBA, and level of glucose were significantly decreased (p < 0.05)

- The expression of Nat2 decreased markedly in the 10 mg/kg bw/d group (Fig. 5A) (p < 0.05), and a significant reduction was also observed in the expression of SULT1A1, SULT1C2 and SULT2A1 in the 1 mg/kg bw/d group (p < 0.05) (Fig. 5A). These changes may relate to biological responses when the body is stimulated by DP exposure.

- Interestingly, the fractions of the anti-isomer (ratio of the anti- DP concentration to total DP concentration, or f anti ) were 0.75, 0.77, and 0.80 for muscle, liver, and serum, respectively, in the lower exposed group (1 mg/kg bw/d), which were close to ratio in commercial DP-25 (0.8) (Fig. 4A). However, the f anti significantly decreased in the 10 mg/kg bw/d and 100 mg/kg bw/d exposed groups (0.26 and 0.26 in muscle, 0.29 and 0.30 in liver, 0.27 and 0.27 in serum, respectively).

- The average concentrations of syn-Cl11-DP and anti-Cl11-DP in liver in the 100 mg/kg bw/d group were 4.7- and 8.3-fold greater than that found in muscle in the same group. Since syn-Cl11-DP and anti-Cl11-DP are also detected in commercial DP-25, we could not exclude the possibility that these chemicals originated from commercial products.

- In the exposure groups, the highest concentrations of syn-DP and anti-DP were both detected in liver from the 100 mg/kg bw/d dose group, which were nearly 12 - 15-folds than that in muscle and 4.8 - 5.4-folds that found in serum from the same group, respectively.

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
28 days
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Deviations:
no
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
strain CD(Crl:CD(SD))
Route of administration:
oral: gavage
Vehicle:
olive oil
Details on oral exposure:
Daily oral administration by gavage at dose levels of 0, 750, 1,500, 5,000 mg/kg bw nominal.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
analytical dose levels:
0 mg/kg nominal = 0 mg analytical
750 mg/kg nominal = 660 - 677 mg/kg analytical
1,500 mg/kg nominal = 1,426 - 1,494 mg/kg analytical
5,000 mg/kg nominal = 4,842 - 5,395 mg/kg analytical
Duration of treatment / exposure:
28 days
Frequency of treatment:
daily
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
750 mg/kg bw/day (nominal)
Dose / conc.:
1 500 mg/kg bw/day (nominal)
Dose / conc.:
5 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
10 males and 10 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
Dechlorane Plus was administered daily orally by gavage to groups of 10 male and 10 female rats at nominal dose levels of 0, 750, 1,500, and 5,000 mg/kg bw for 28 days.
Positive control:
none
Observations and examinations performed and frequency:
The following parameters were examined: mortality twice daily, clinical signs of toxicity twice daily, neurobehavioural examination weekly, functional observational battery observation pretest and in week 4, bodyweights twice weekly, food consumption weekly, motor activity pretest and in week 4, haematology and clinical chemistry at study end, macroscopic pathology including organ weights, microscopic pathology
Sacrifice and pathology:
All animals were subjected to necropsy and histopathology as well as organ weight determination in a large range of organs and tissues.
Statistics:
Levene's /ANOVA- Dunnett's / Welch's and Log Transformation/Group Pair-wise Comparison
Clinical signs:
no effects observed
Description (incidence and severity):
only accidental deaths due to misdosing occurred
Mortality:
no mortality observed
Description (incidence):
only accidental deaths due to misdosing occurred
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
No test substance related effects were observed in all parameters investigated.
Key result
Dose descriptor:
NOEL
Effect level:
>= 5 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: No test substance related effects were observed in any parameter investigated up to the highest dose level administered.
Critical effects observed:
not specified
Conclusions:
No test substance related effects at all were observed up to the highest dose level of 5,000 mg/kg bw (nominal). Dechlorane Plus is essentially nontoxic. The NOEL is at or above 5,000 mg/kg bw.
Executive summary:

Dechlorane Plus was tested in a 28 day study in rats with oral administration of nominal dose levels of 0, 750, 1,500, and 5,000 mg/kg bw. The following parameters were examined: mortality twice daily, clinical signs of toxicity twice daily, neurobehavioural examination weekly, functional observational battery observation pretest and in week 4, bodyweights twice weekly, food consumption weekly, motor activity pretest and in week 4, haematology and clinical chemistry at study end, macroscopic pathology including organ weights, microscopic pathology. No test substance related effects were observed in any parameter at any time at any dose level. The NOEL was determined at 5,000 mg/kg bw.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
5 870 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
Two studies, one subchronic and one subacute study, in rats with oral administration available. Both studies of good quality with high numbers of rats per group and extensive examinations. Overall quality good. Study results are supported by a 90d-oral toxicity study, dosed up to 100 mg/kg bw/d.

Repeated dose toxicity: inhalation - systemic effects

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Reference
Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 days
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Purity of test substance not reported, whole body exposure in a test chamber.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
Deviations:
yes
Remarks:
particle size distribution not determined
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
other: Charles River COBS
Sex:
male/female
Details on test animals and environmental conditions:
Young adult rats, no further details reported.
Route of administration:
inhalation: dust
Type of inhalation exposure:
whole body
Vehicle:
air
Remarks on MMAD:
MMAD / GSD: About 60% of particles with particle size of 10 µm or less.
Details on inhalation exposure:
Target concentrations of 0, 0.5, and 1.0 mg/l were administered for 6 hours per day for 5 days per week for 4 weeks.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analytical concentrations of 0, 0.640, and 1.524 mg/l were determined, total dust weight per volume of air was recorded.
Duration of treatment / exposure:
6 hours per day for 5 days per week for 4 weeks.
Frequency of treatment:
5 days per week
Dose / conc.:
0 mg/L air (analytical)
Dose / conc.:
0.64 mg/L air (analytical)
Dose / conc.:
1.524 mg/L air (analytical)
No. of animals per sex per dose:
5 males and 5 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
Dechlorane Plus 25 was administered by inhalation for 6 hours per day for 5 days per week for 4 weeks to groups of 5 males and 5 females at concentrations of 0, 0.5, or 1.0 mg/l nominal concentration corresponding to 0, 0.64, and 1.524 mg/l analytical concentration.
Positive control:
none
Observations and examinations performed and frequency:
The following parameters were recorded: mortality daily, clinical signs of toxicity daily, bodyweights weekly, haematology at study start and end, clinical chemistry at study start and end, urinalyses at study start and end, macroscopic and microscopic pathology, organ weights.
Sacrifice and pathology:
All animals were subjected to macroscopic and microscopic pathology and organ weight determination.
Other examinations:
Haematolog and clinical chemistry including urinalysis.
Statistics:
not reported
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
Slight diuresis in both treated groups
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
increased liver and lung weights in both treated groups
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
hepatocellular hypertrophy
Histopathological findings: neoplastic:
no effects observed
Details on results:
Increased liver weights with hepatocellular hypertrophy, increased lung weights without histological correlate, slight diuresis, all changes in both dose groups without dose-dependence, no clear adverse effect observed.
Key result
Dose descriptor:
NOAEC
Effect level:
1.524 mg/L air
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
body weight and weight gain
haematology
clinical biochemistry
organ weights and organ / body weight ratios
histopathology: non-neoplastic
histopathology: neoplastic
Critical effects observed:
not specified
Conclusions:
NOAEC at 1.524 mg/l dust in air with slight effects on liver and lung and slight functional effects on the kidneys, no clear adverse effect observed, all changes are compatible with functional adaption, but occurred in both dose groups.
Executive summary:

Groups of 5 male and 5 female rats were exposed to Dechlorane Plus for 6 hours per day for 5 days per week in whole body exposure chambers at nominal concentrations of nominal 0.5 and 1.0 mg/l corresponding to analytical 0.64 and 1.524 mg/l for 28 days. In both dose groups slightly increased liver weights with hepatocellular hypertrophy, slightly increased lung weights, and slight diuresis were seen without dose-dependence. No clear adverse effect occurred. The NOAEC was determined at 1.524 mg/l.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
1 mg/m³
Study duration:
subacute
Species:
rat
Quality of whole database:
One study with 28 days whole body exposure available, quality acceptable to demonstrate the nontoxicity of Dechlorane Plus.

Repeated dose toxicity: inhalation - local effects

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Reference
Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 days
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Purity of test substance not reported, whole body exposure in a test chamber.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
Deviations:
yes
Remarks:
particle size distribution not determined
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
other: Charles River COBS
Sex:
male/female
Details on test animals and environmental conditions:
Young adult rats, no further details reported.
Route of administration:
inhalation: dust
Type of inhalation exposure:
whole body
Vehicle:
air
Remarks on MMAD:
MMAD / GSD: About 60% of particles with particle size of 10 µm or less.
Details on inhalation exposure:
Target concentrations of 0, 0.5, and 1.0 mg/l were administered for 6 hours per day for 5 days per week for 4 weeks.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analytical concentrations of 0, 0.640, and 1.524 mg/l were determined, total dust weight per volume of air was recorded.
Duration of treatment / exposure:
6 hours per day for 5 days per week for 4 weeks.
Frequency of treatment:
5 days per week
Dose / conc.:
0 mg/L air (analytical)
Dose / conc.:
0.64 mg/L air (analytical)
Dose / conc.:
1.524 mg/L air (analytical)
No. of animals per sex per dose:
5 males and 5 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
Dechlorane Plus 25 was administered by inhalation for 6 hours per day for 5 days per week for 4 weeks to groups of 5 males and 5 females at concentrations of 0, 0.5, or 1.0 mg/l nominal concentration corresponding to 0, 0.64, and 1.524 mg/l analytical concentration.
Positive control:
none
Observations and examinations performed and frequency:
The following parameters were recorded: mortality daily, clinical signs of toxicity daily, bodyweights weekly, haematology at study start and end, clinical chemistry at study start and end, urinalyses at study start and end, macroscopic and microscopic pathology, organ weights.
Sacrifice and pathology:
All animals were subjected to macroscopic and microscopic pathology and organ weight determination.
Other examinations:
Haematolog and clinical chemistry including urinalysis.
Statistics:
not reported
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
Slight diuresis in both treated groups
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
increased liver and lung weights in both treated groups
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
hepatocellular hypertrophy
Histopathological findings: neoplastic:
no effects observed
Details on results:
Increased liver weights with hepatocellular hypertrophy, increased lung weights without histological correlate, slight diuresis, all changes in both dose groups without dose-dependence, no clear adverse effect observed.
Key result
Dose descriptor:
NOAEC
Effect level:
1.524 mg/L air
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
body weight and weight gain
haematology
clinical biochemistry
organ weights and organ / body weight ratios
histopathology: non-neoplastic
histopathology: neoplastic
Critical effects observed:
not specified
Conclusions:
NOAEC at 1.524 mg/l dust in air with slight effects on liver and lung and slight functional effects on the kidneys, no clear adverse effect observed, all changes are compatible with functional adaption, but occurred in both dose groups.
Executive summary:

Groups of 5 male and 5 female rats were exposed to Dechlorane Plus for 6 hours per day for 5 days per week in whole body exposure chambers at nominal concentrations of nominal 0.5 and 1.0 mg/l corresponding to analytical 0.64 and 1.524 mg/l for 28 days. In both dose groups slightly increased liver weights with hepatocellular hypertrophy, slightly increased lung weights, and slight diuresis were seen without dose-dependence. No clear adverse effect occurred. The NOAEC was determined at 1.524 mg/l.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
1 mg/m³
Study duration:
subacute
Species:
rat
Quality of whole database:
One study with 28 days whole body exposure available, quality acceptable to demonstrate the nontoxicity of Dechlorane Plus.

Repeated dose toxicity: dermal - systemic effects

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Reference
Endpoint:
short-term repeated dose toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 days
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Purity and physical chemical properties of test substance not reported, the dose level was not analytically verified.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
Deviations:
yes
Remarks:
Only two dose levels were investigated, the suspension of the test substance was applied openly without any covering
GLP compliance:
no
Limit test:
no
Species:
rabbit
Strain:
New Zealand White
Sex:
male/female
Details on test animals and environmental conditions:
No further details reported
Type of coverage:
open
Vehicle:
other: 3% aqueous methylcellulose
Details on exposure:
After open application as 50% suspension in 3% aqueous methylcellulose, the substance remained in place for 24 hours until the next application. The animals received a plastic collar to avoid oral intake.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
28 days for up to 24 hours per day
Frequency of treatment:
daily
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
500 mg/kg bw/day (nominal)
Dose / conc.:
2 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
5 males and 5 females
Control animals:
yes, concurrent no treatment
Details on study design:
Dechlorane 25 was applied epicutaneously to groups of 5 males and 5 females openly epicutaneously at dose levels of 500 or 2,000 mg/kg bw once daily for 5 days per week for 28 days. The application site was not covered, but the animals received collars to prevent oral intake. Negative controls remained untreated. The skin was scarified in two rabbits per sex per group before substance application.
Positive control:
none
Observations and examinations performed and frequency:
The following parameters were recorded: mortality, clinical signs of toxicity, bodyweights, haematology, clinical chemistry, urinalysis, gross and microscoic pathology including organ weights.
Sacrifice and pathology:
All rabbits were subjected to necropsy and histological examination of a total of 38 organs and tissues including skin of the application site. Organ weights were recorded from brain, liver, kidneys, spleen, heart, gonads, thyroid gland, and adrenal glands.
Other examinations:
mortality, clinical signs of toxicity including skin reactions, haematology, clinical chemistry, urinalysis
Statistics:
not reported
Clinical signs:
no effects observed
Dermal irritation:
effects observed, treatment-related
Description (incidence and severity):
minimal barely perceptible erythema in both dose groups in both sexes
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
No systemic effects of treatment observed in any animal in any group, only minimal local erythema at the application site without histological correlate after 18 and 20 applications. No local irritation was seen after one or up to 17 applications.
Key result
Dose descriptor:
NOAEL
Effect level:
> 2 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
dermal irritation
body weight and weight gain
haematology
urinalysis
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
Critical effects observed:
not specified
Conclusions:
Not systemically toxic at dose levels up to 2,000 mg/kg bw applied dermally for up to 24 hours per day for 5 days per week for 28 days. Minimal local irritation after 18 - 20 applications.
Executive summary:

Dechlorane 25 was not systemically toxic at dose levels up to 2,000 mg/kg bw. The NOAEL for systemic effects was above 2,000 mg/kg bw. Minimal local irritation was only observed after repeated application for more than 18 days. No irritation was seen after one day of dermal application.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
2 000 mg/kg bw/day
Study duration:
subacute
Species:
rabbit
Quality of whole database:
Only one repeated dose dermal toxicity study available, quality of the study acceptable.

Repeated dose toxicity: dermal - local effects

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 days
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Purity and physical chemical properties of test substance not reported, the dose level was not analytically verified.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
Deviations:
yes
Remarks:
Only two dose levels were investigated, the suspension of the test substance was applied openly without any covering
GLP compliance:
no
Limit test:
no
Species:
rabbit
Strain:
New Zealand White
Sex:
male/female
Details on test animals and environmental conditions:
No further details reported
Type of coverage:
open
Vehicle:
other: 3% aqueous methylcellulose
Details on exposure:
After open application as 50% suspension in 3% aqueous methylcellulose, the substance remained in place for 24 hours until the next application. The animals received a plastic collar to avoid oral intake.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
28 days for up to 24 hours per day
Frequency of treatment:
daily
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
500 mg/kg bw/day (nominal)
Dose / conc.:
2 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
5 males and 5 females
Control animals:
yes, concurrent no treatment
Details on study design:
Dechlorane 25 was applied epicutaneously to groups of 5 males and 5 females openly epicutaneously at dose levels of 500 or 2,000 mg/kg bw once daily for 5 days per week for 28 days. The application site was not covered, but the animals received collars to prevent oral intake. Negative controls remained untreated. The skin was scarified in two rabbits per sex per group before substance application.
Positive control:
none
Observations and examinations performed and frequency:
The following parameters were recorded: mortality, clinical signs of toxicity, bodyweights, haematology, clinical chemistry, urinalysis, gross and microscoic pathology including organ weights.
Sacrifice and pathology:
All rabbits were subjected to necropsy and histological examination of a total of 38 organs and tissues including skin of the application site. Organ weights were recorded from brain, liver, kidneys, spleen, heart, gonads, thyroid gland, and adrenal glands.
Other examinations:
mortality, clinical signs of toxicity including skin reactions, haematology, clinical chemistry, urinalysis
Statistics:
not reported
Clinical signs:
no effects observed
Dermal irritation:
effects observed, treatment-related
Description (incidence and severity):
minimal barely perceptible erythema in both dose groups in both sexes
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
No systemic effects of treatment observed in any animal in any group, only minimal local erythema at the application site without histological correlate after 18 and 20 applications. No local irritation was seen after one or up to 17 applications.
Key result
Dose descriptor:
NOAEL
Effect level:
> 2 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
dermal irritation
body weight and weight gain
haematology
urinalysis
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
Critical effects observed:
not specified
Conclusions:
Not systemically toxic at dose levels up to 2,000 mg/kg bw applied dermally for up to 24 hours per day for 5 days per week for 28 days. Minimal local irritation after 18 - 20 applications.
Executive summary:

Dechlorane 25 was not systemically toxic at dose levels up to 2,000 mg/kg bw. The NOAEL for systemic effects was above 2,000 mg/kg bw. Minimal local irritation was only observed after repeated application for more than 18 days. No irritation was seen after one day of dermal application.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
12 mg/cm²
Study duration:
subacute
Species:
rabbit
Quality of whole database:
Only one repeated dose dermal toxicity available, quality acceptable to demonstrate the nontoxicity of Dechlorane Plus

Additional information

No systemic effects of Dechlorane Plus were observed even at a high dose levels of 2,000 mg/kg bw. The minimal barely perceptible erythema at the application site is considered to be not adverse and to represent no relevant irritation.

Dechlorane Plus was also assessed in a 90d-oral subchronic toxicity study. No significant changes in absolute body and liver weight or in relative liver weight were observed in the exposure and depuration groups compared to the controls. No histopathological liver damage was observed. No significant influence or related dose diversification on endocrine-related processes, assessed via thyroid hormone levels (FRT4, FRT3, TSH, TT3, and TT4) in serum were noted. Taken together, the authors concluded that DP did not cause adverse effects on the liver and its lipid metabolism or on endocrine levels. Thus, the NOAEL may be set to 100 mg/kg bw/d.

Effects seen, not considered adverse were:

- The activities of ALT, ALP, TBA, and level of glucose were significantly decreased (p < 0.05)

- The expression of Nat2 decreased markedly in the 10 mg/kg bw/d group (Fig. 5A) (p < 0.05), and a significant reduction was also observed in the expression of SULT1A1, SULT1C2 and SULT2A1 in the 1 mg/kg bw/d group (p < 0.05) (Fig. 5A). These changes may relate to biological responses when the body is stimulated by DP exposure.

- Interestingly, the fractions of the anti-isomer (ratio of the anti- DP concentration to total DP concentration, or f anti ) were 0.75, 0.77, and 0.80 for muscle, liver, and serum, respectively, in the lower exposed group (1 mg/kg bw/d), which were close to ratio in commercial DP-25 (0.8). However, the f anti significantly decreased in the 10 mg/kg bw/d and 100 mg/kg bw/d exposed groups (0.26 and 0.26 in muscle, 0.29 and 0.30 in liver, 0.27 and 0.27 in serum, respectively).

- The average concentrations of syn-Cl11-DP and anti-Cl11-DP in liver in the 100 mg/kg bw/d group were 4.7- and 8.3-fold greater than that found in muscle in the same group. Since syn-Cl11-DP and anti-Cl11-DP are also detected in commercial DP-25, these chemicals may have originated from commercial products.

- In the exposure groups, the highest concentrations of syn-DP and anti-DP were both detected in liver from the 100 mg/kg bw/d dose group, which were nearly 12 - 15-folds than that in muscle and 4.8 - 5.4-folds that found in serum from the same group, respectively.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:

Administration time 90 days at high dose levels.

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:

Quality acceptable, no other repeated dose inhalation study available.

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:

Quality acceptable, no other repeated dose inhalation study available.

Justification for selection of repeated dose toxicity dermal - systemic effects endpoint:

Quality acceptable, no other repeated dose dermal study available.

Justification for selection of repeated dose toxicity dermal - local effects endpoint:

Quality acceptable, no other repeated dose dermal study available.

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: liver

Repeated dose toxicity: inhalation - systemic effects (target organ) digestive: liver

Justification for classification or non-classification

Not toxic and not irritant upon 28 days of dermal administration of high dose levels. The minimal barely perceptible erythema at the application site is considered to be not adverse and to represent no relevant irritation.