(3-chloropropyl)triethoxysilane

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

68 mg/m³

Most sensitive endpoint:

repeated dose toxicity

DNEL related information

Overall assessment factor (AF):

6

Modified dose descriptor starting point:

NOAEC

Acute/short term exposure

DNEL related information

Local effects

Acute/short term exposure

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

9.7 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

DNEL related information

Overall assessment factor (AF):

6

Modified dose descriptor starting point:

NOAEL

Acute/short term exposure

DNEL related information

Additional information - workers

(3-Chloropropyl)triethoxysilaneis a volatile liquid whichhydrolyses slowly(half-life 35 hours at pH 7)in contact with water, to formethanol and (3-chloropropyl)silanetriol. No reliable long-term mammalian toxicity data are available for (3-chloropropyl)triethoxysilane, therefore key data have been read-across from the related substance (3-chloropropyl)trimethoxysilane, which shares a common hydrolysis product. Further information on the use of read-across is given in Section 5.6.

There are two reliability score 1 studies for repeated inhalation of (3-chloropropyl)trimethoxysilane. The 90-day study was selected as the key study as it tested over the longest duration.

In the key 90-day inhalation study, microscopic examinations did not reveal any adverse findings in females exposed to 0.5 or 5 ppm. Eight of 10 male animals in the 0.5 ppm exposure group were reported as normal. The two remaining male animals exhibited minimal chronic cystitis of the urinary bladder. Nine of 10 male animals were reported as normal in the 5.0 ppm exposure group. The remaining male animals exhibited minimal chronic cystitis of the urinary bladder. Treatment-related histopathologic effects were observed in the 100 ppm group animals. Increased incidence of hyperplasia of the urinary bladder epithelium was noted in both sexes of this group.

It is not known whether the urinary bladder was inflated by a fixative before microscopic examination. Without inflation of the urinary bladder the relevance of the hyperplasia is questionable. Based onthe fact that the hyperplasia of the bladder was mild /minimal and in some cases associated with a minimal inflammation (cystitis) it can presumed that if the stimulus for the hyperplastic changes is removed the hyperplasia will resolve within a matter of weeks and the urinary bladder will return to a normal histologic appearance.A minimal/mild change of the urinary bladder not associated with any clinical symptoms or changes in urine parameters does not reflect a marked organ dysfunction. Therefore, the mild/minimal hyperplastic effects are not considered as adverse and the NOAEC is 100 ppm(813 mg/m³).

There are no repeat dose data for the oral and dermal routes. There is an OECD 414 developmental toxicity study conducted by the oral route (BSL, 2014).

(3-Chloropropyl)trimethoxysilanewas tested in an inhalation OECD 422 study (RCC, 2005), whole-body in rats, up to and including the highest concentration of 100 ppm. In this study there were no signs of adverse effects on reproduction or development parameters. The upper dose level was selected on the basis of the adverse findings at higher exposure concentrations in the 90-day study summarised above. Therefore based on these results the NOAEC was established to be at least 100 ppm (813 mg/m³) for these endpoints. Test animals were exposed for 6 hours per day, 5 days per week.

As discussed in Section 5.9 3-Chloropropyl)triethoxysilane was tested in an oral OECD 414 study (BSL, 2014) in which adverse maternal and foetal effects were noted at the highest dose tested, 1000 mg/kg bw/day. Therefore the maternal and foetal NOAEL was 300 mg/kg bw/day.

As discussed in Sections 5.6 and 5.9, the methanol hydrolysis product of the read-across substance, (3-chloropropyl)trimethoxysilane, and the ethanol hydrolysis product of the registered substance, (3-chloropropyl)triethoxysilanes, do not contribute to repeated-dose, reproductive or developmental toxicity in rats at the dose levels tested in these studies.

No significant effects were observed up to the maximum dose tested in an OECD 422 reproductive and developmental toxicity screening test in rats. It is therefore not possible to quantify DNELs for reproductive or developmental endpoints.

 

No quantitative DN(M)ELs could be derived for:

Acute toxicity – local effects (no effects)

Long-term toxicity – local effects (no effects)

Reproductive/developmental toxicity – no effects

Mutagenicity (not mutagenic)

Carcinogenicity (no data)

In the absence of any significant findings relating to reproductive or developmental endpoints in appropriate screening tests, the critical health effect is considered to be repeated-dose toxicity. (3-Chloropropyl)triethoxysilane is not classified as irritant, mutagenic, carcinogenic or sensitising.

The DNELs used for risk characterisation (workers) are therefore:

DNEL (long-term, inhalation): 68 mg/m³

DNEL (long-term, dermal): 9.7 mg/kg/day

General Population - Hazard via inhalation route

Systemic effects

Acute/short term exposure

DNEL related information

Local effects

Acute/short term exposure

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Acute/short term exposure

DNEL related information

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

4.2 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

DNEL related information

Overall assessment factor (AF):

10

Modified dose descriptor starting point:

NOAEL

Acute/short term exposure

DNEL related information

Additional information - General Population

No exposure of consumers will occur during normal handling and use therefore DNELs via the dermal and inhalation routes are not calculated for consumers. An oral DNEL for the general population is needed for risk characterisation for indirect exposure via the environment. The DNEL used for risk characterisation (consumers) is:DNEL (long-term, oral): 4.2 mg/kg/day.

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