Reaction mass of copper oxide and manganese dioxide

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

No data are available for the registration substance. However adequate and reliable studies performed with each of the two constituents or respective analogues of the registration substance are at hand.

In a combined repeated dose and reproductive/developmental toxicity study (OECD TG 422) with copper monochloride,which is a structural analogue to copper oxide, in rats, no fertility parameters were affected, thus leading to a NOAEL for reproduction - fertility of 80 mg/kg bw/day corresponding to 51.4 mg Cu/ kg bw/day and thus to 285.7 mg hopcalite/kg bw/day (highest dose group tested).

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “assessment report”.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Dose descriptor:

NOAEL

Effect level:

4.64 mg/kg bw/day (actual dose received)

Based on:

test mat.

Remarks:

value calculated based on ratio of MnO2 and CuO in the reaction mass

Sex:

female

Basis for effect level:

histopathology: non-neoplastic

Dose descriptor:

NOAEL

Effect level:

17.8 mg/kg bw/day (actual dose received)

Based on:

test mat.

Remarks:

value calculated based on ratio of MnO2 and CuO in the reaction mass

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

12.8 mg/kg bw/day (actual dose received)

Based on:

test mat.

Remarks:

recalculated to copper from test material

Sex:

male/female

Basis for effect level:

gross pathology

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

71.4 mg/kg bw/day (actual dose received)

Based on:

test mat.

Remarks:

value calculated based on ratio of MnO2 and CuO in the reaction mass

Sex:

male/female

Basis for effect level:

gross pathology

Reproductive effects observed:

yes

Lowest effective dose / conc.:

71.4 mg/kg bw/day (actual dose received)

Treatment related:

yes

Relation to other toxic effects:

not specified

Dose response relationship:

yes

Relevant for humans:

yes

Conclusions:

In this combined repeated dose and reproductive/developmental toxicity study (OECD TG 422) with copper monochloride,which is a structural analogue to one of the main constituents of the registration substance, in rats, there was an increase in the number of icteric and runt pups at birth in the high dose group, leading to a NOAEL for developmental effects of 20 mg/kg bw/day corresponding to 12.8 mg Cu/ kg bw/day and thus to 71.4 mg hopcalite/kg bw/day . At this dose level there were already several effects present in parental animals as well, however the most critical effects in parental animals was the increase in squamous cell hyperplasia of the stomach. Based on these findings, the NOAELs were concluded to be 5 mg/kg bw/day corresponding to 3.2 mg Cu/ kg bw/day and thus to 17.9 mg hopcalite/kg bw/day in male rats and 1.3 mg/kg bw/ day and 0.83 Cu/ kg bw/day and thus to 4.64 mg hopcalite/kg bw/day (low dose group) in female rats.

Executive summary:

The study used as source investigated copper monochloride.The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross reference “assessment report”.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Effect on fertility: via inhalation route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

most reliable results are from an epidemiological study

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

-         Copper

In a combined repeated dose and reproductive/developmental toxicity study (OECD TG 422) with copper monochloride rats were exposed via oral gavage at 0, 1.3, 5, 20, or 80 mg/kg/day. Male rats were dosed for a total of 30 days beginning 14 days before mating. Female rats were dosed from 2 weeks before mating to day 3 of lactation throughout the mating and gestation period. In this study there wereno treatment-related effects on any of the reproductive indices or fertility parameters analysed ( i.e. precoital interval, copulation index, fertility index, delivery index, gestation length, copora lutea, implantations, stillborns, live young at birth, gender ratio; testis weight, epididymis weight, sperm head counts, sperm motility, sperm morphology, serum testosterone levels).

In addition, in a 13-week repeated dose toxicity study male and female Fisher F334/N rats received cupric sulfate pentahydrate (CASRN 7758-99-8) via feed. Based on histopathological changes in forestomach, liver and kidney and changes in clinical chemistry and urine analysis, the NOAEL of this study was determined to be 1000 ppm (mg/kg diet) for systemic effects. During the study also reproductive parameters were investigated. No effect on male parameters (epididymus, cauda epididymus and testis weight; spermatid and spermatozoal measurements) or female parameters (oestrous cycle length, proportion of cycle spent at each stage) were observed at doses up to and including 68 mg Cu/kg bw/day (corresponding to 378 mg hopcalite/kg bw/day).

Conclusion on classification for fertility for copper (II) oxide

Thus in conclusion based on the available results no classification for developmental toxicity is required as effects on the pups was only visible at concentrations already toxic to maternal animals.

-         Manganese dioxide

There are two epidemiological studies investigating the effects on fertility after manganese dioxide exposure. 

In the first epidemiological study, the manganese-exposed workers (n=85) exhibited a statistically significant deficit in the number of children during their period of exposure to the metal compared to the matched control group. The airborne concentration of manganese dusts at the different workplaces ranged from 0.07 to 8.61 mg Mn/m3 with a geometric mean of 0.94 mg Mn/m3, which corresponds to a range of 0.16 to 19.5 mg hopcalite/m³ and a geometric mean of 2.1 mg hopcalite/m³ (Lauwerys et al. 1985).

In a second study the effect of exposure to different metals, amongst others manganese, on male reproductive function was examined in 1988-1989 in Belgian blue-collar workers (later investigation by the same group). The workers were exposed to manganese (as manganese dioxide) in a dry alkaline battery plant (n = 70; median atmospheric concentration of total manganese dust = 0.71 mg/m3; mean duration of exposure = 6.2 years). Fertility in these workers and in an unexposed population (n =138) was assessed by examining the birth experiences of their wives through a logistic regression model.The probability of a live birth was not different between the unexposed workers and the manganese-exposed workers before or after the onset of exposure(Gennart et al., 1992).

Effects on fertility of manganese dioxide are also assessed in one animal study. In this assay male rabbits were exposed to a single high dose of manganese dioxide via intratracheal instillation (250 mg/kg bw, corresponding to approximately 350 mg hopcalite/kg bw; particle size <5 μm). Testes of animals were investigated at intervals of 2, 4, 6, and 8 months after test material administration. The test material caused a severe degenerative change in seminiferous tubules, which can lead to sterility. This effect was not obvious immediately, but developed slowly over a time period of 4 -8 months (study by Seth/Chandra et al., 1973 cited from Greim et al. 1994; OECD-SIDS, 2012).

Conclusion on classification for fertility for Manganese dioxide

The discrepancy between the results of the two epidemiological studies was put down to differences in the solubility of the manganese salts. In the first study, the exposures involved not only manganese dioxide but also dusts of the more readily soluble carbonate and sulfate salts (Gennart et al., 1992).

The single animal study available identified effects on male fertility, however the study used an unphysiological exposure pathway and is of low reliability due to limited reporting. In addition from the non-guideline study generally investigating developmental toxicity in mice (Lown et al., 1984) no effect on birth rates was seen (even increase of litter size in manganese dioxide exposed animals was observed). Thus in conclusion based on the available results no classification for reproduction toxicity – fertility is required.

Effects on developmental toxicity

Description of key information

No data are available for the registration substance. However adequate and reliable studies performed with each of the two constituents or respective analogues of the registration substance are at hand.

In a combined repeated dose and reproductive/developmental toxicity study (OECD TG 422) with copper monochloride,which is a structural analogue to copper oxide, in rats, there was an increase in the number of icteric and runt pups at birth in the high dose group, leading to a NOAEL for developmental effects of 20 mg/kg bw/day corresponding to 12.8 mg Cu/ kg bw/day and thus to 71.4 mg hopcalite/kg bw/day . At this dose level there were already several effects present in parental animals as well, however the most critical effects  in parental animals was the increase in squamous cell hyperplasia of the stomach. Based on these findings, the NOAELs were concluded to be 5 mg/kg bw/day corresponding to 3.2 mg Cu/ kg bw/day and thus to 17.9 mg hopcalite/kg bw/day in male rats and 1.3 mg/kg bw/ day and 0.83 Cu/ kg bw/day and thus to 4.64 mg hopcalite/kg bw/day (low dose group) in female rats.

Concerning developmental effects there are two studies available which investigated the effects of manganese dioxide on newborns in mice (non guideline studies of low reliability). There were some effects observed, however these were of low relevance due to minor severity (e.g. only effects on body weight development) and or low reliability of the studies due to poor study design or reporting (missing information on maternal toxicity in both cases).

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “assessment report”.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Remarks on result:

other: no information was provided in the study on materanal toxicity

Dose descriptor:

LOAEC

Effect level:

138 mg/m³ air

Based on:

test mat.

Remarks:

calculated to registration substance

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

other: also behavioural changes

Remarks on result:

other: value calculated based on ratio of MnO2 and CuO in the reaction mass

Developmental effects observed:

yes

Lowest effective dose / conc.:

138 other: mg/m³; calculated to registration substance

Treatment related:

yes

Relation to maternal toxicity:

not specified

Dose response relationship:

not specified

Relevant for humans:

not specified

Conclusions:

In this study developmental effects were investigated, to this end Swiss-ICR mice were exposed to MnO2 dust, 7 hours daily, 5 days per week for 16 weeks before conception and until day 17 post conception.
During the first 12 weeks the animals were exposed to manganese levels of 49.1 ± 2.3 mg/m3 and after that to 85.3 ± 15.6 mg/m3 (mean effect level calculated 61 mg Mn/m³). The following groups were included in the study (pre - post conception exposure): group 1 - MnO2 - MnO2 ; group 2 - Control - MnO2; group 3: MnO2 - C; group 4: C-C.
The dams gave birth spontaneously. Within the groups the pups were pooled and 3 male and 3 female pups assigned to new dams of the same group or dams from other groups ("complete fostering/-cross-fostering design").
According to the authors this was done to separate effects of prenatal maternal exposure to MnO2 from postnatal exposure of offspring to Mn via suckling. However based on the study design provided earlier (exposure pre- and post-conception), no groups of animals receiving manganese dioxide during lactation could be identified.
The mice exposed to manganese before conception had larger litters than those not exposed at this time.
Prenatal exposure to manganese, on the other hand, resulted in reduced body weight gain and reduced activity of the pups. When the pups were also exposed during lactation via the milk, these effects were more pronounced. These pups stood up and explored their surroundings less frequently. Thus the mean exposure of 61 mg Mn/m³, corresponding to 138 mg hopcalite/m³ is viewed as LOAEC.

Executive summary:

The study used as source investigated manganese dioxide. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross reference “assessment report”.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

71.4 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

one reliable and adequate guideline study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

two studies available which investigated the effects of manganese dioxide on newborns in mice (non guideline studies of low reliability)

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

-         Manganese dioxide

Concerning developmental effects there are two studies available which investigated the effects of manganese dioxide on newborns mice (non guideline studies of low reliability).

In the study by Lown et al. (1984), Swiss-ICR mice were exposed to MnO2 dust, 7 hours daily, 5 days per week for 16 weeks before conception and until day 17 post conception (i.e. gestation day 17). During the first 12 weeks the animals were exposed to manganese levels of 49.1 ± 2.3 mg/m3 and after that to 85.3 ± 15.6 mg/m3 (mean effect level calculated 61 mg Mn/m³). The following groups were included in the study (pre - post conception exposure): group 1 - MnO2 - MnO2 ; group 2 - Control - MnO2; group 3: MnO2 - C; group 4: C-C.

The dams gave birth spontaneously. Within the groups the pups were pooled and 3 male and 3 female pups assigned to new dams of the same group or dams from other groups ("complete fostering/-cross-fostering design"). According to the authors this was done to separate effects of prenatal maternal exposure to MnO2 from postnatal exposure of offspring to Mn via suckling. However based on the study design provided earlier (exposure pre- and post-conception), no groups of animals receiving manganese dioxide during lactation could be identified.

The following effects are mentioned by different assessment entities: Prenatal exposure to manganese resulted in reduced body weight gain and reduced activity of the pups. When the pups were also exposed during lactation via the milk (most probably this means during lactation), these effects were more pronounced. These pups stood up and explored their surroundings less frequently. Thus the mean exposure of 61 mg Mn/m³, corresponding to 138 mg hopcalite/m³ is viewed as LOAEC (however no information of maternal toxicity was provided and based on the limited study design no dose-response relationship could be examined as only one dose group investigated). Also other expert groups concluded that a conclusive assessment of this study is not possible, as there are several problems with evaluation. E.g. the fact that the weight at birth was not determined and high standard deviations were obtained in the behavioural tests in this study makes evaluation problematic. Subdivision into quite a number of groups also reduces its statistical power, and it is also greatly influenced by chance findings (high standard deviation). Therefore, the observed sporadic effects in this study are of questionable relevance. A conclusive assessment of this study is therefore not possible(Hartwig, 2011).

In another study cited von OECD-SIDS (2012) mice were exposed to manganese dioxide by inhalation from 75 days of pre-pregnancy to gestation day 1 to 8. In this study a TCLo in mice was determined to be 143 mg/m³/day (corresponding to either 200 or 320 mg hopcalite/m³, as it is not clear from the secondary source if the effect level is expressed as MnO2 or Mn) due to reduced weight gains and behavioural changes in newborns (no information of maternal toxicity).

Conclusion on classification for developmental effects for Manganese dioxide

Concerning developmental effects there are two studies available which investigated the effects of manganese dioxide on newborns in mice (non guideline studies of low reliability). There were some effects observed, however these were of low relevance due to minor severity (e.g. only effects on body weight development) and or low reliability of the studies due to poor study design or reporting (missing information on maternal toxicity in both cases), thus these studies are not leading to classification for developmental effects induced by manganese dioxide.

 

-         Copper

In a combined repeated dose and reproductive/developmental toxicity study (OECD TG 422) with copper monochloride rats were exposed via oral gavage at 0, 1.3, 5, 20, or 80 mg/kg/day. Male rats were dosed for a total of 30 days beginning 14 days before mating. Female rats were dosed from 2 weeks before mating to day 3 of lactation throughout the mating and gestation period. Concerning developmental effects, there was an increase in the number of icteric and runt pups at birth in the high dose group, leading to a NOAEL for developmental effects of 20 mg/kg bw/day corresponding to 12.8 mg Cu/ kg bw/day and thus to 71.4 mg hopcalite/kg bw/day . At this dose level there were already several effects present in parental animals as well (e.g. changes in hematological or clinical biochemistry parameters), however the most critical effects in parental animals was the increase in squamous cell hyperplasia of the stomach. Based on these findings, the NOAELs were concluded to be 5 mg/kg bw/day corresponding to 3.2 mg Cu/ kg bw/day and thus to 17.9 mg hopcalite/kg bw/day in male rats and 1.3 mg/kg bw/ day and 0.83 Cu/ kg bw/day and thus to 4.64 mg hopcalite/kg bw/day (low dose group) in female rats.

Conclusion on classification for fertility for copper (II) oxide

Thus in conclusion based on the available results no classification for developmental toxicity is required as effects on the pups was only visible at concentrations already toxic to maternal animals.

Justification for classification or non-classification

As none of the constituents of the registration substance is classified for reproductive effects and the studies available for these constituents do not justify a classification according to the criteria set in Regulation (EC) No 1272/2008 regarding reproductive effects (fertility and developmental) no classification is required for the registration substance.