Resin acids and Rosin acids, manganese salts

Endpoint summary

Description of key information

The hazard of bioaccumulation is derived from published data on the organic anion and manganese.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Additional information

Oral route

No repeated-dose oral studies are available for the Manganese salts of resin and rosin acids. The water solubility of 1.1 mg/L indicates that its bioavailability to aquatic systems is low. In an acute oral toxicity study with a poorly soluble formulation containing 12% Resin acids and rosin acids, manganese salts , no adverse effects were noted at the highest dose tested, which contained 1200 mg/kg bw of the substance.

Information on Mn²⁺ is summarized from a large number of publications that have investigated the fate of Manganese compounds with various solubility and oxidation states, and an absorption rate of 3-5% with biliary clearance has been reported (reviewed in Santamaria 2010, Dorman 2007).

Manganese is an essential trace element that is subject to homeostatic control. Tissues accumulate manganese if serum protein binding and biliary clearance capacities are exceeded. Solutions of Mn (II) are susceptible to oxidation at neutral and basic pH and oxidative processes in the small intestine can be assumed. Mn(III) is bound to transferrin whereas Mn (II) is bound to albumin and b-globulin and other proteins. It is found in the central nervous system and in all other mammalian tissues.

After gavage administration of 24.3 mg Mn/Kg bw (as soluble MnCl₂) to rats, Mn was detected in blood at the earliest measured time of 0.5 h, with a peak concentration after 1 h (Roels 1997). Blood concentrations returned to normal within 12h.

After 9 or 15 months of dietary administration of MnSO₄ at 1500, 5000 and 15000 ppm to rats and mice, increased Mn levels were observed in the following organs: liver, kidney, brain and pancreas, the highest being a seven-fold increase in the kidney (US NTP 1993). Other organs were not investigated in this study.

Whole body retention of manganese in six female human volunteers was investigated following ingestion of eggs enriched with an isotope ⁵⁴Mn and was determined to be in the range of 10% and 3% after 5 and 10 days, respectively (Davidsson 1988).

Inhalation route

Experimental inhalation data is available for low molecular weight, highly soluble Manganese salts showing that these forms of Mn are systemically absorbed by the body upon inhalation. A threefold increase in manganese concentration in bone was determined after a 14-day inhalation study of 3 mg/m³ Mn using ⁵⁴MnCl₂ as tracer; olfactory bulb concentrations were increased approximately 2-fold at 0.3 mg/m³ in air and about 5-fold at 3 mg/m³ in air. Relative regional concentrations of Mn were olfactory bulb > striatum> cerebellum (Dorman 2001).

An overall low increase in Manganese concentrations in lung, liver, pancreas, testes or ovary was also observed in a 13 - week inhalation study in rat with MnSO₄ at air concentrations doses of 0.01, 0.1, or 0.5 mg Mn/m3 (Dorman 2004).

For the chelated manganese in the resin and rosin acid salt, the situation is expected to be different. Based on the poor water solubility and the molecular weight of >200, respiratory absorption is not favoured (ECHA Guidance Document R.7.c, May 2008). For the same reasons, uptake via the olfactory bulb is not expected to contribute significantly to the overall body burden.

Systemic availability of Resin acids and rosin acids, manganese salts following inhalation is expected to be mainly via clearance into the gastrointestinal tract. Since the uptake of manganese from the gastrointestinal tract is poor, the overall manganese body burden from inhalation expected to be lower than that of inorganic salts.

Dermal route

No data is available.

Overall, systemic availability of Resin acids and rosin acids, manganese salts can be assumed for oral and inhalation exposure. Accumulation of Manganese can be assumed for chronic exposure to doses that overload biliary clearance.

The above data corroborates the information available for other members of the category Rosins and their salts.

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. Please refer to the Category endpoint summary for further information on the toxicokinetics of Rosins and their salts.