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Description of key information

Endpoint specific guidance (ECHA, 2008) indicates that absorption of substances following exposure by inhalation, skin contact or ingestion may be predicted based on log Pow and water solubility. Experimentally determined results for substances in this category are as follows:

 

Substance

Log Pow

Solubility

(mg/L)

Rosin

3.0 - >6.0

0.9

Rosin, hydrogenated

3.4

1.2

Rosin, reaction products with formaldehyde

5.36

8.1

Resin acids and rosin acids, reaction products with formaldehyde, potassium salts

5.37->6.5

<438 mg/l

Rosin, oligomers

>6.5

<2.2

Resin acids and rosin acids, sodium salts

3.0 - 5.8

miscible

Resin acids and rosin acids, potassium salts

3.1 - 5.9

miscible

Resin acids and rosin acids, calcium salts

3.0

42.6

Resin acids and rosin acids, magnesium salts

0.74

65

Resin acids and rosin acids, calcium zinc salts

1.8

18.2

ECHA (2008) indicates that uptake of substances by the lung is favoured by moderate log P values (between -1 and 4) with micellular solubilisation favoured where log P is >4 and water solubility is low (< 1 mg/L). Data summarised above indicate that Rosin, Rosin, hydrogenated and Rosin, oligomers may be absorbed by lung tissue although the extent of uptake is unclear. No conclusion can be reached regarding possible uptake of Rosin, reaction products with formaldehyde. Absorption of the monovalent and divalent salts by the lung depends on pH: if ionised (as at alkaline pH for the monovalent cation), significant absorption is unlikely on the grounds of hydrophilicity while if the pH is lowered the unionised molecule (the acid) is insoluble and should behave similarly to parent substance. A low vapour pressure means that substances in this category are unlikely to exist as vapour, with exposure limited to inhalation of material deposited as particles.

Dermal absorption of highly water soluble substance may occur where the log Pow is between 1-4 with log Pow values between 2 and 3 favouring uptake. When log Pow exceeds 4, penetration may be limited by the rate of transfer between the stratum corneum and epidermis although uptake of a substance by the stratum corneum will be high. Uptake of substances where log Pow exceeds 6 will be low (ECHA, 2008). Data summarised above suggests that the unionised salts may be absorbed to some extent by skin while uptake of the parent substances is not expected.

Considering absorption after ingestion, uptake from the gastrointestinal tract by passive diffusion is favoured for substances with a log Pow between -1and 4. Absorption via micelle formation may occur where log Pow is >4 and water solubility is <1 mg/l (ECHA, 2008). Physico-chemical data summarised above suggest that Rosin, Rosin, hydrogenated and rosin, oligomers may be absorbed to some extent after ingestion if they form mixed micelles, whereas uptake of the monovalent and divalent salts is less likely as they will be in ionised form. No conclusion can be reached regarding possible uptake of Rosin, reaction products with formaldehyde.

No experimental data are available to characterise the toxicokinetic behaviour of substances in this category.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

Resin acids are the main constituents of rosin and rosin salt substances, and resin acids are not considered to bioaccumulate, based on measured bioaccumulation data from aquatic species. The different salts are not considered to affect bioaccumulation potential. Based on QSAR predictions for aquatic species, rosin dimer constituents are also considered unlikely to bioaccumulate. Members of the category rosin and rosin salts are therefore considered not to be bioaccumulative or very bioaccumulative.