Copper iodide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

18.13 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

60.01 µg/L

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

11 mg/L

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

3.99 mg/kg sediment dw

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

20.22 mg/kg sediment dw

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

5.95 mg/kg soil dw

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

COPPER IODIDE

Copper iodide is an inorganic compound with low water solubility at environmentally relevant pH. Upon dissociating in aqueous media, copper iodide gives rise to cuprous copper ions (Cu+) and iodide ions (I-) that may then be subject to further transformation. The resulting ionic species will be more bioavailable than the parent compound and will therefore be independently responsible for any effects seen in the event that copper iodide enters the environment as a result of its production and/or use.

In view of this fact, please refer to the separate Chemical Safety Reports (CSR) previously produced in support of the REACH registrations of copper and iodine for detailed assessments of their hazard to organisms in the following environmental compartments:

• Aquatic compartment (including sediment) (Section 7.1).
• Terrestrial compartment (Section 7.2).
• Atmospheric compartment (Section 7.3).
• Microbiological activity in sewage treatment systems (Section 7.4).
• Non-compartment specific effects relevant for the food chain (secondary poisoning) (Section 7.5).

These documents are attached in their entirety to Section 13 (Assessment Reports) of the copper iodide IUCLID dossier.

Summary information on the ecotoxicology of iodine is presented below and in IUCLID Sections 6.1 - 6.6.

IODINE:

Hazard for aquatic organisms:

Freshwater:

Hazard Assessment Conclusion:       PNEC aqua (freshwater):       18.13µg/L

Justification for PNEC freshwater derivation:

The derivation of the PNECfreshwater for iodine is not appropriate based on standard methodology as iodine is present at a natural (background) concentration in a range of environmental compartments. The PNECfreshwater for iodine is set using the “added risk” approach as the background level of iodine is significantly different to the PNEC of 0.13 μg/L [calculated using the lowest available and relevant EC50 in algae (0.13 mg/L) by an assessment factor of 1000 as there are three short term studies available for each trophic level (fish, crustacea and algae)]. The added risk approach is referenced in ECHA guidance (Chapter R7 - Appendix R7.13 -2), which was originally reported by T. Crommentuijn et al., RIVM (1997). The highest average concentration of iodine reported in river water, 18 μg/L (WHO CICADS review, 2009), is over 100 times higher than the initial calculated PNEC of 0.13 μg/L. As this PNEC falls just above the 0.1 to 18 μg/L average range reported, a PNEC of 0.13 μg/L could result in iodine deficiency in environmental organisms and is therefore not an appropriate PNECfreshwater. The added risk approach assumes that species are fully adapted to the natural background concentration. For iodine, the natural background concentration is not known due to anthropogenic input in the past or present. Therefore 18 μg/L is used as a realistic ambient background concentration. By adding the maximum concentration (0.13 μg/L) allowed to be put on top of the assumed background concentration of iodine (18 μg/L) this gives a calculated PNECfreshwater of 18.13 μg/L.

 

Marine water:

Hazard Assessment Conclusion:       PNEC aqua (marine water):       60.01 µg/L

Justification for PNEC marine water derivation:

The derivation of the PNECmarine water for iodine is not appropriate based on standard methodology as iodine is present at a natural (background) concentration in a range of environmental compartments. A PNEC marine water is determined based on the available freshwater data and consideration of the background concentrations of iodine in seawater. Oceans are the primary source of iodine, and iodides in the sea accumulate in seafish, shellfish and seaweed. The only available data for iodine concentrations in marine water is from the WHO, 2009, which states an average iodine concentration in the sea of 45 to 60 µg/L. Therefore 60 µg/L is assumed to be the ambient background concentration, as there is no data available on a natural background concentration. The PNECmarinewater for iodine is set using the “added risk” approach as the background level of iodine is significantly different to the PNEC of 0.013 μg/L [calculated using the lowest available and relevant EC50 in algae (0.13 mg/L) by an assessment factor of 10000 as there are three short term studies at each trophic level (fish, crustacea and algae)]. The added risk approach is referenced in ECHA guidance (2008), which was originally reported by T. Crommentuijn et al., RIVM (1997). The added risk approach assumes that species are fully adapted to the natural background concentration. For iodine, the natural background concentration is not known due to anthropogenic input in the past or present. Therefore 60 μg/L is used as a realistic ambient background concentration. By adding the maximum concentration (0.013 μg/L) allowed to be put on top of the assumed background concentration of iodine (60 μg/L) this gives a calculated PNECfreshwater of 60.01 μg/L.

 

Intermittent releases:

A PNECintermittent has not been derived as iodine is not discharged in an intermittent manner.

 

STP:

Hazard Assessment Conclusion:       PNEC STP       11 mg/L

Assessment factor:        10                 Extrapolation method: assessment factor

Justification for PNEC STP derivation:

The activated sludge respiration inhibition test conducted to OECD Guideline 209 derived an EC10 of 110 mg/L. Using a standard assessment factor of 10, the calculated PNECstp is 11.0 mg/L. This is considered to be a realistic PNECstp for iodine, when considering data on the background concentration of iodine in municipal wastewater is an average concentration of 4 μg/L (WHO 2009). If the background concentration was considered, this would still result in a PNECstp of 11.0 mg/L .

 

Sediment (freshwater):

Hazard Assessment Conclusion:       PNEC Sediment (freshwater):       3.99 mg/kg sediment dw

Assessment factor:                       Extrapolation method: partition coefficient

Justification for PNEC sediment (freshwater) derivation:

Calculation of PNECsediment using the equilibrium partitioning method was 0.19 mg/kg of wet sediment. However, the calculation of this PNEC sediment is not considered to be appropriate for iodine. Iodine naturally occurs in sediments, and data from the ATSDR review indicates an iodine concentration in river and river terrace alluvium in the UK of 3.8 (0.5 – 7.1) μg/g dry soil (Whitehead 1979 - reported by ATSDR, 2004). This background concentration is greater than the calculated PNECsediment above. It is assumed that benthic organisms have adapted to the background level of iodine over time. Using the added risk approach, the PNECsediment is revised as set out below.   3.8 μg/g dry soil is assumed to be equivalent to 3.8 mg/kg of wet sediment in the absence of any other data. This value is also considered to be the ambient background concentration, as there is no data available on a natural background concentration. It is also assumed that the background concentration is fully bioavailable in the absence of sufficient data. The addition of the initial PNECsediment (0.19 mg/kg of wet sediment) + 3.8 mg/kg of wet sediment = PNEC sediment = 3.99 mg/kg of wet sediment.

 

Sediment (marine water):

Hazard Assessment Conclusion:       PNEC Sediment (marine water):       20.22 mg/kg sediment dw

Assessment factor:                       Extrapolation method: partition coefficient

Justification for PNEC sediment (freshwater) derivation:

Calculation of PNECmarine sediment using the equilibrium partitioning method was 0.616 mg/kg of wet sediment. However, the calculation of this PNEC marine sediment is not considered to be appropriate for iodine. Iodine naturally occurs in sediments, and data from the ATSDR review indicates an iodine concentration in marine and estuarine alluvium in the UK of 19.6 (8.8 – 36.9) μg/g dry soil (Whitehead 1979 - reported by ATSDR, 2004). This background concentration is greater than the calculated PNECmarine sediment above. It is assumed that benthic organisms have adapted to the background level of iodine over time. Using the added risk approach, the PNECmarine sediment is revised as set out below.   19.6 μg/g dry soil is assumed to be equivalent to 19.6 mg/kg of wet sediment in the absence of any other data. This value is also considered to be the ambient background concentration, as there is no data available on a natural background concentration. It is also assumed that the background concentration is fully bioavailable in the absence of sufficient data. The addition of the initial PNECmarine sediment (0.616 mg/kg of wet sediment) + 19.6 mg/kg of wet sediment = PNEC marine sediment = 20.22 mg/kg of wet sediment.

 

Hazard for terrestrial organisms:

Soil

Hazard Assessment Conclusion:       PNEC Soil:       5.95 mg/kg soil dw

Assessment factor:                       Extrapolation method:

Justification for PNEC soil derivation:

Based on the NOEC of 10 mg/kg soil from a 50 day plant life cycle bioassay in Brassica rapa that investigated the effects of iodide (applied as KI) divided by a default uncertainty factor of 100 for a chronic plant study results in an initial PNECsoil of 0.1 mg/kg soil. However, the calculation of this PNEC soil is not considered to be appropriate for iodine. Iodine naturally occurs in soils, and data from the ATSDR review indicates an average soil content for iodine as high as 5.85 ppm (range: 1.5 – 13.5 ppm) (NAS, 1974 - reported by ATSDR, 2004). This background concentration is greater than the calculated PNECsoil above. It is assumed that terrestrial organisms have adapted to the background level of iodine over time. Therefore, using the added risk approach, the PNECsoil is revised. 5.85 ppm or 5.85 mg/kg soil is assumed to be the ambient background concentration, as there is no data available on a natural background concentration. It is also assumed that the background concentration is fully bioavailable in the absence of sufficient data. It is considered appropriate to combine the iodine background concentration with the PNECsoil for iodide as iodine is present as the iodide anion (I-) in soils. The addition of the initial PNECsoil + background concentration = PNEC soil = 5.95 mg/kg soil.

 

Hazard for predators:

Secondary Poisoning

Hazard Assessment Conclusion: No potential for bioaccumulation

Justification for PNEC secondary poisoning derivation:

The environmental release levels of Iodine have been demonstrated to be relatively low. This coupled with the low potential for bioaccumulation in higher organisms and the essential nutrient status of Iodine, indicate that risks from secondary poisoning are negligible.

 

Discussion:

Refer to attached document for a discussion on the PNECs derived and the references used.

 

Conclusion on classification

Special guidance is available for the environmental classification of metals and metal compounds. For metals, classification is based on comparing the soluble metal concentration, measured after Transformation/Dissolution (T/D) with the Ecotoxicity Reference Values (ERVs) of the corresponding metal ion. 

Accordingly, for the environmental classification of copper iodide, ERVs based on ecotoxicity data for soluble copper compounds are compared to the results of T/D testing on this compound (Section 1.3, Physicochemical properties).

Acute and chronic ERVs developed in the copper CSR are summarised in the following Table:

Summary of the acute and chronic ERVs used for the classification of coppercompounds

pH range	Acute ERV L(E)C50 (mg Cu/l)	Chronic ERV NOEC (mg Cu/l)
pH 5.5-6.5	0.025	0.020
pH >6.5-7.5	0.035	0.0074
pH >7.5-8.5	0.0298	0.0114
Across pHs	0.0344	0.0149

 

The average dissolved copper concentrations measured in a 24 hour T/D screening test with a copper iodide loading of 100 mg/L were as follows:

• At pH 6 an average dissolved copper concentration of 3643 ± 49 µg Cu/L was found.
• At pH 8 an average dissolved copper concentration of 2201 ± 34 µg Cu/L was measured.

Comparing these values with the ERVs set out above, it is clear that the water solubility of copper iodide is too high to affect the environmental classification applied to soluble copper compounds. It is therefore assigned the same classification as copper sulphate as a worst case.

Conclusions on Acute classification for the environment:

Copper iodide is classified Acute Category 1. An M factor of 10 is applied.

Conclusions on Chronic classification for the environment:

Copper iodide is classified Chronic Category 2. An M factor of 1 is applied.