Molybdenum trioxide

Monitoring data

Administrative data

Endpoint:

monitoring data

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Reliable ambient monitoring data were collected from various national and international environmental agencies. Methodology and procedures for data analyses were in line with the guidance given by ECHA (European Chermicals Agency) and with the methodology that was followed in exsisting compulsory and voluntary risk assessments for some other metals (e.g., Zn, Cu, Ni, Pb)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: ECHA, 2008. RIP 3.2: Guidance on information requirements and chemical safety assessment. Chapter R.16: Environmental Exposure Estimation

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EC, 2003. Technical Guidance Document in support of Commission Directive 93/67/EEC on risk assessment for new notified substances and Commission Regulation (EC) No 1488/94 on risk assessment for existing substances. Part II: Environment.

GLP compliance:

no

Type of measurement:

other: ambient concentration levels

Media:

surface water

Test material

Test material information

Constituent 1

Reference substance name:

Molybdenum

EC Number:

231-107-2

EC Name:

Molybdenum

Cas Number:

7439-98-7

Molecular formula:

Mo

IUPAC Name:

molybdenum - dissolved

Details on test material:

no Mo-compounds added to water; determination of ambient levels in the environment

Results and discussion

Details on results:

The regional (EU) ambient reasonable-worst-case concentration of dissolved molybdenum in european surface waters is 2.30 µg/L.

Any other information on results incl. tables

Table 1 gives an overview of the different RWC-ambient PECs that were derived for dissolved and total molybdenum levels. Measured-based reliable values for dissolved molybdenum were obtained for seven countries/areas. Country/area-specific RWC-ambient PEC values were situated between 0.62 μg/L and 5.1 μg/L. For the United Kingdom a value of 2.03 was put forward as the country-specific RWC-ambient PEC. This value is close to the value of 2.27 µg Mo_diss./L that was found with the data taken from HMS. However, the value of 2.03 µg Mo_diss./L is based on a larger data set (n=2164 for the rivers that were witheld), and covers relevant water bodies covering different areas in the UK. Therefore this value is proposed as a relevant RWC-ambient PEC for dissolved molybdenum in the United Kingdom.

For total Mo, a RWC-ambient PEC was found for Belgium, Germany and The Netherlands. Application of a factor of difference of 0.91 on the total RWC-ambient PEC that was found for Germany resulted in estimated dissolved RWC-ambient PECs of 1.86 μg/L. This factor of 0.91 is based on the observed difference between the median total and median dissolved Mo-concentration in the river Thames (Neal et al., 2000). This factor of 0.91 is well in line with the total:dissolved ratios of 0.79 and 0.85 that were derived with the total/dissolved RWC-ambient PECs for Belgium and The Netherlands, respectively.

With these data a EU-regional RWC-ambient PEC of 2.30 µg Mo_diss./L is calculated.

Table 1: Overview of total and dissolved RWC-ambient PEC values for molybdenum in the aquatic compartment

Country/Area	Total RWC-ambient PEC (µg/L)	Dissolved RWC-ambient PEC (µg/L)
Belgium - Flanders	7.6	5.1
Germany – Elbe – Umweldbundesamt Average:	2.04 2.10 2.07	1.86
Finland - Geological Survey of Finland		0.70
The Netherlands – Rhine	2.93, 3.58, 3.58 Mean: 3.36	2.85
Sweden – SLU dataset – Lake Vettasjärvi – SEPA, 1997 (watercourses) – SEPA, 1997 (lakes)		0.62 0.45 (supp.data) 0.22 (supp. data) 0.26 (supp.data)
United Kingdom – HMS-database – Neal & Robson, 2000 – Thames – single location	3.08	2.27 (supp. data) 2.03 2.80 (supp. data)
Granitic waters		2.96
France – Seine & Marne		3.38
Regional RWC-ambient PEC		2.30 µg/L (median value)

Applicant's summary and conclusion

Conclusions:

Based on the monitoring data that were collected for different EU-countries, a reliable regional RWC-ambient PEC of 2.30 µg/L has been derived.