Paraffin waxes and Hydrocarbon waxes, chloro

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence(P, vP)

LCCPs are not considered to be readily biodegradable; however, data indicate the potential for biodegradation, especially with acclimated microorganisms. The potential for biodegradation appears to increase with decreasing chlorine content. There is also information to suggest that biodegradation of LCCPs may occur under anaerobic conditions. LCCPs have not be shown to be toxic to microorganisms, so they should not inhibit biodegrading microorganisms.

Half-live estimates are difficult to determine accurately based on the biodegradation data set. Based on the relatively slow degradation rates in studies both the ECB TC NEC PBT Working Group (ECB 2007) and the Environment Agency (UK EA 2009) concluded that LCCPs may meet the criteria for P or vP.

Bioaccumulation (B, vB)

Given the very low water solubility of LCCPs, it is difficult to obtain reliable measured bioaccumulation data. The estimated BCFs in fish for the LCCP are as follows (method taken the well accepted method from the EU Technical Guidance Document parabolic equation, application for substances with log Kow >6 and molecular weight < 700 g/mol: log BCF = -0.2 x(log Kow)²+ (2.74 x log Kow – 4.72); (Veith et al, 1979):

C_18‑20liquid LCCP   BCF = 1,096 L/kg

C_20-30liquid LCCP   BCF = 192 L/kg

C_20-30solid LCCP     BCF <1 L/kg

There is evidence from feeding studies that LCCPs can be taken up via the diet, but in all cases the concentrations reached in the animals were less than those in the diet. This indicates that although uptake of the substance can occur via the food, the levels should not increase through the food chain (UK EA 2009).

Based on the estimates of BCF it is concluded that LCCPs are unlikely to meet the B or vB (very bioaccumulative) EU criteria (ECB 2007, OECD 2009, UK EA, 2009).

Toxicity (T)

LCCP have a low order of toxicity to both mammalian and environmental species. They are not classified as dangerous to either human health or the environment.

There is long-term animal toxicity data for LCCPs which indicates that LCCP are not CMRs or meet any of the other criteria for healthclassifications (e.g., T, R48, or Xn, R48) according to Directive 67/548/EEC.

There is a relatively large amount of aquatic toxicity data available for LCCPs. LCCPs havevery low water solubility andshow no toxicity at concentrations at or below their water solubility. (OECD 2009).