β-methyl-3-(1-methylethyl)benzenepropanal

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

PERSISTENCY :

FLORHYDRAL has been demonstrated to be READILY BIODEGRADABLE (74% biodegradation after 28 days, fulfilling the 10-Day window crietria) under the strict testing conditions of the OECD 301F test guideline, and, was also observed in a separate OECD 302C study to undergo 100% biodegradation during the 28 day test period.

FLORHYDRAL is a primary aldehyde and under typical aerobic environmental conditions will be rapidly oxidised to the Carboxylic acid metabolite (GR-81-6079), which then undergoes mineralisation (c.f. results of the OECD 301F Ready Biodegradation study).

BIOCONCENTRATION :

FLORHYDRAL has a LogPow of 3.1, which is below the screening threshold criteria for P, vP of LogPow of 4.5.

In addition, predictive QSAR models (EPISuite BCFBAF, OASIS-CATALOGIC BCF BaseLine) indicate that FLORHYDRAL has a low potential to bioaccumulate in fish. The latter model indicated that the metabolism step would derive the Florhydral-Acid in the first instance.

In addition to this, an In vitro metabolism study using Rainbow Trout liver S9 (equivalent to the OECD 319B Test Guideline) was performed to determine the metabolism kinetics of FLORHYDRAL and establish the intrinsic clearance rate (CLint). This assay illustrated > 90% metabolic turnover of FLORHYDRAL within 20 minutes of exposure. Both Florhydral-Acid and Florhydral-Alcohol were identified as metabolites as was the glucuronide conjugate of the alcohol derivative. This assay further confirmed the low potential to bioaccumulate of FLORHYDRAL.

ENVIRONMENTAL TOXICITY :

AQUATIC TOXICITY :

FLORHYDRAL does not have any EC/LC50 values lower than or equal to 0.1 mg/L, and no Chronic (EC10, NOEC) end-points of less than or equal to 0.01 mg/L.

A full set of Acute toxicity studies are available for three trophic levels of freshwater species for FLORHYDRAL - Algae, Daphnia and Fish. The key Acute end-points are :

Algae 72 hour ErC50 = 11 mg/L

Daphnia 48 hour EC50 = 2.26 mg/L

Fish 96 hour LC50 = 4.6 mg/L

Chronic end-points available for FLORHYDRAL are :

Algae 72 hour ErC10 = 6.4 mg/L

Daphnia Reproduction 21-day NOEC = 0.71 mg/L

Additionally, full base-set aqautox studies are available for Florhydral-Acid (GR-81-6079) and Florhydral-Alcohol (GR-82-4332). Florhydral-Acid is the most relevant transformation product of FLORHYDRAL (via direct oxidation of the aldehyde group). The end-points determined are, as follows :

Florhydral-Acid (GR-81-6079) :

Algae 72 hour ErC50 > 90.6 mg/L

Algae 72 hour ErC10 = 54.7 mg/L

Daphnia 48 hour EC50 = 47.6 mg/L

Fish 96 hour LC50 = 20.8 mg/L

Florhydral-Alcohol (GR-82-4332) :

Algae 72 hour ErC50 = 16.8 mg/L

Algae 72 hour ErC10 = 6.69 mg/L

Daphnia 48 hour EC50 = 12.2 mg/L

Fish 96 hour LC50 = 5.81 mg/L

Thus, in the natural environment, FLORHYDRAL is rapidly transformed in to metabolites of lower toxicity than the Parent. The Alcohol will be transformed to the Acid, which is significantly less toxic (5- to 20-times less) than the Parent.