[No public or meaningful name is available]

Endpoint summary

Description of key information

 - With LD50values consistently exceeding 2,000 mg/kg bw, zinc oxide (LD50ranges between 5,000 and 15,000mg/kg bw), shows very low level of acute oral toxicity. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Used in EU risk assessment for zinc oxide, limited study details provided

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

no information

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

single dose by oral gavage and observed for 14 days

Doses:

single dose of 15 gZnO/kg bw

No. of animals per sex per dose:

10 males

Control animals:

not specified

Details on study design:

no further information

Statistics:

no data

Preliminary study:

no further information

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 15 000 mg/kg bw

Mortality:

no mortality

Clinical signs:

other: ruffled fur

Gross pathology:

no adverse signs of toxicity

Other findings:

none

none

Interpretation of results:

practically nontoxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

LD50 >15,000 mg ZnO/kg bw was determined.

Executive summary:

In an acute oral study, ten male Wistar rats received a single dose of 15 g ZnO/kg bw by gavage. No mortality occurred. Signs of toxicity were ruffled fur, decreased body weights and diarrhoea. The LD₅₀value for rats was >15 g ZnO/kg bw. No furher information available.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Additional information

- With LD₅₀values consistently exceeding 2,000 mg/kg bw, zinc oxide (LD₅₀ranges between 5,000 and 15,000mg/kg bw), shows very low level of acute oral toxicity.

Of significance for humans from an acute toxicity standpoint is the occurrence of metal fume fever following exposure to ultrafine particles of special grades of zinc oxide in context of very specific operations such as cutting or welding of galvanised steel. Metal fume fever is exclusively associated with freshly formed ultrafine particulate zinc oxide (<0.1 µm). As these ultrafine particles (nanoparticles) rapidly agglomerate to bigger particles, which are normally encountered at production and processing sites, at these sites there is no indication for metal fume fever. According to the response from 11 zinc companies to a questionnaire, there have been no observations of zinc metal fume fever over the last decade and in recent occupational practice (EU RAR, 2004a-f). However in light of responsible care and since no studies are available that allow the establishment of a NOAEL for metal fume fever with a reasonable degree of certainty, a LOAEL (5 mg ZnO/m³) for 2 hours (showed the typical metal fume fever symptoms beginning 4 to 8 hours after exposure and disappearing within 24 hours) can be used for metal fume fever based on the study by Gordon et al.(1992).

Justification for classification or non-classification

Zinc oxide is of low acute, dermal and inhalation toxicity not requiring a classification for acute toxicity according to the EC criteria.