Perchloric acid

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Most sensitive endpoint:

repeated dose toxicity

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Most sensitive endpoint:

acute toxicity

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

Acute/short term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Most sensitive endpoint:

repeated dose toxicity

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Most sensitive endpoint:

acute toxicity

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

Acute/short term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

high hazard (no threshold derived)

Additional information - workers

The main toxic property of perchloric acid is its strong corrosivity as it is classified corrosive (classified as corrosive to the skin into category 1A according to the Regulation (EC) 1272/2008 and as C;R35 according to the Directive 67/548/EEC).

Perchloric acid is also classified STOT-RE category 2 because of effects on the thyroid. This classification is due to an analogy with ammonium perchlorate and more specifically with perchlorate moiety which is known to compete with iodide for uptake into the thyroid gland. Iodide is necessary to the maturation of thyroid hormones (T3 and T4) and this inhibition is triggering a compensation mechanism consisting in the increase in thyroid stimulating hormone (TSH). Ultimately, if this competitive inhibition is overwhelming this compensation mechanism on a sufficient length of times it will lead to thyroid hypertrophy and hyperplasia which are considered as adverse effects. On the other hand, perchlorate is small very soluble molecule known to be rapidly excreted and not bioaccumulable. Epidemiological studies on workers from an ammonium perchlorate plant have shown, that despite high level of perchlorate in their serum, no adverse effects could be seen with chronic exposition.

In conclusion, despite the potential effect of perchloric acid on the thyroid, we consider that the local effects induced by its high corrosivity on the skin and the respiratory tract will occurred at levels where no adverse systemic effects are expected and thus the protection from perchloric acid corrosive effects will ensure protection from adverse systemic effects related to perchlorate.

As it is highly corrosive, protection from perchloric acid local effects will be performed by a qualitative risk assessment.

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

58 µg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

By inhalation

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

10

Modified dose descriptor starting point:

NOAEC

Value:

0.58 mg/m³

Explanation for the modification of the dose descriptor starting point:

Corrected inhalatory NOAEC = Human Oral NOAEL x Average human weight / sRVhuman24h = 0.167 (mg/kg bw/day) x 70 (kg) / 20 (m3/person) = 0.58 mg/m3. The origin of the human NOAEL is an epidemiological study (Braverman et al., 2005) where the exposition is by inhalation but the NOAEL is extrapolated from serum perchlorate concentrations. Therefore, lung absorption rate is already included in this value.

AF for dose response relationship:

1

Justification:

Not applicable

AF for differences in duration of exposure:

1

Justification:

Chronic exposure

AF for interspecies differences (allometric scaling):

1

Justification:

Human study

AF for other interspecies differences:

1

Justification:

Human study

AF for intraspecies differences:

10

Justification:

Standard factor applied for general population

AF for the quality of the whole database:

1

Justification:

Appropriate completeness and adequacy of the database and confirmed by another study (Lamm et al., 1999)

AF for remaining uncertainties:

1

Justification:

Not applicable

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Most sensitive endpoint:

acute toxicity

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

Acute/short term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Most sensitive endpoint:

repeated dose toxicity

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Most sensitive endpoint:

acute toxicity

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

Acute/short term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

16.7 µg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

By inhalation

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

10

Modified dose descriptor starting point:

NOAEL

Value:

0.167 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The origin of the human NOAEL is an epidemiological study (Braverman et al., 2005) where the exposition is by inhalation but the NOAEL is extrapolated from serum perchlorate concentrations. Therefore, despite the study being by inhalation route the results are expressed as a NOAEL. It is assumed that oral absorption is not superior to lung absorption.

AF for dose response relationship:

1

Justification:

Not applicable

AF for differences in duration of exposure:

1

Justification:

Chronic exposure

AF for interspecies differences (allometric scaling):

1

Justification:

Human study

AF for other interspecies differences:

1

Justification:

Human study

AF for intraspecies differences:

10

Justification:

Standard factor applied for general population

AF for the quality of the whole database:

1

Justification:

Appropriate completeness and adequacy of the database and confirmed by another study (Lamm et al., 1999)

AF for remaining uncertainties:

1

Justification:

Not applicable

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Most sensitive endpoint:

acute toxicity

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

high hazard (no threshold derived)

Additional information - General Population

As there is no consumer use there is no general population direct exposition to perchloric acid and thus no risk assessment is to be performed. However, if released into the environment, perchloric acid is expected to be found as perchlorate moiety and DNEL for systemic long term exposition by inhalation and oral route have been derived based on thyroid potential effects of perchlorate in order to performed man via environment risk assessment.