Executive Summary
Human Health
Scenarios relevant to the consumer exposure to polycarboxylates have been identified and assessed using a Margin of Safety approach.
Polycarboxylates are of low toxicity by all exposure routes examined. Polycarboxylates are of low acute toxicity to the rat (LD50 > 5 g/kg bw/d). The copolymers (P-AA/MA) show no irritating potential on either target tissue (skin/eye) based on the given data. Further PAA/MA has no sensitising potential. The adverse effect after repeated inhalation dosing (91- d/rat) was a mild, reversible pulmonary irritation. This effect is considered as not substancerelated owing to the physical property of the respirable dust, which caused local and not systemic lung effects. Nevertheless, in a worst case scenario, the NOEC of 1.0 mg/m3 for PAA/MA was taken forward into a Margin of Exposure calculation under the worst case assumption of a ten percent deposition into the lung and 100% absorption of the deposited material. There was no evidence for a genotoxic potential of P-AA/MA using a variety neither of genetic endpoints in vitro and in-vivo, nor for developmental toxicity or reprotoxicity in the rat. Based upon the available data, it is considered that exposure to polycarboxylates does not imply any particular hazard to humans.
Owing to the presence of polycarboxylates in many commonly used household detergents, consumers are exposed to polycarboxylates mainly via the dermal route, but also to a minor extent via the oral and inhalation route.
The exposure resulting from dermal contact was estimated for P-AA/MA as 26 µg/kg bw/day. The exposure by oral uptake was estimated for P-AA/MA as 2.36 µg/ kg bw/day. For P-AA/MA, an MOE of 7.2 x 104 is calculated from the NOEL of a 28 d dermal study in rabbits. The exposure resulting from oral uptake via substance residues on machine washed eating utensils and via drinking water is estimated to amount to approx. 4.21 µg/ kg bw/ day for PAA/MA. For P-AA/MA based on a NOAEL of 1,871 mg/kg bw/d from a subchronic drinking water study in rats an MOE of 7.9 x 105 is established for this scenario. For inhalative exposure of P-AA/MA, a worst case MOE of 1.7 x 105 was calculated assuming 100% bioavailability of a hypothetical inhalable dust burden. All MOEs indicate no risk for human health.
Environment
The main pathway of polycarboxylates into the environment is via domestic waste water and sewage treatment to surface waters. Thus, the removal of polycarboxylates from waste water before and during waste water treatment is the crucial factor that governs the distribution of polycarboxylates into the environment.
Over the past 25 years, the elimination of P-AA/MA homopolymers from waste water has been investigated in multiple laboratory studies. The results indicate that P-AA/MA differ to some extent in their eliminability although they are alike in many other physical and ecological attributes. While adsorption onto solids and precipitation are the principal mechanisms of abiotic elimination for this type of polymer, the degree of elimination differs and is strongly influenced by test concentration and water hardness. To refine the Predicted Environmental Concentrations (PEC), all available elimination data with good quality were used for the calculation of a geometric mean of removal rate in the current risk assessment. In addition, to better understand the distribution of the polymer between water phase and solid phase, partition coefficients (Kd) of the activated sludge, soil and sediment were determined with radiolabelled material.
Predicted No Effect Concentrations (PNECs) were calculated based on multiple acute as well as chronic data for different environmental compartments including water, sediment, soil, and sewage treatment plants (STP). This updated version 3.0 incorporates new toxicity data on the terrestrial compartment. In particular, recently generated data on soil microorganism have been used to derive a refined PNEC in soil. As the result, revised Risk Characterisation Ratio (RCR, expressed as the PEC/PNEC ratio) was established, which were below one for all relevant environmental compartments including water, soil, sediment, and STP. The outcome of this current environmental assessment provides a sound basis for the conclusion that the use of polycarboxylates copolymers in detergent products does not pose risk to the environment.
Hera Comments
The key changes versus the previous version include the following: – For more clarity, the report has been split into two parts in order to cover separately homo-polymers (P-AA, Part I) and co-polymers of (P-AA/MA, Part II). – The refined assessment has been based on updated tonnages of polycarboxylates used in detergents (EU data 2011 collected in 2012). – New experimental data have been generated and included in order to: o address the sorption behaviour (adsorption study using radio-labelled materials performed) o refine the effect assessment (new terrestrial studies performed). – The new reports include more detailed explanations than the previous version, including re-assessment of the whole available dataset. On that basis new risk characterisation ratios have been calculated for both types of polymers.