Toxicity Testing Laboratory Intercalibration Study

Lead Agency	SCCWRP
Status	100% Complete
Project Budget	$65,000
External Project Partners:
Aquatic Bioassay & Consulting Laboratory	Marine Pollution Studies Laboratory
Aquatic Testing Laboratories	MBC Applied Environmental Services
Aquatic Toxicity Lab (University of California, Davis)	City of Los Angeles Environmental Monitoring Laboratory
Los Angeles County Sanitation District
Nautilus Environmental
Pacific Ecorisk
Technical Lead	Ken Schiff, SCCWRP

Key Words: toxicity test, Ceriodaphnia dubia

The SMC established a continuing goal of compiling local monitoring data to make region-wide assessments (SCCWRP 2004, 2007, 2010). In order to compile local monitoring programs into regional assessments, the SMC expended considerable effort to design monitoring programs with similar goals and objectives, integrated sampling efforts, establish standardized data protocols, and provide focused training opportunities. However, none of the SMC agencies have their own laboratories, and reviews of local contract laboratories indicated differences in analysis methods and the levels of quality control including internal requirements for accuracy and precision. Therefore, the SMC also holds periodic laboratory intercalibration studies to ensure comparability in analytical measurements. Beginning in 2003, and continuing in 2006 and 2009, the SMC implemented a series of intercalibration studies to promote comparability of water chemistry measurements. The 2003 intercalibration study established common reporting levels and target analytes, and utilized iterative round robin exercises to minimize interlaboratory variation. The success of the 2003 exercise was primarily due to three factors:

• communication and commitment among laboratory personnel;
• setting performance-based criteria for establishing standards of success; and
• using locally derived reference materials including using a stormwater matrix.

The intercalibration exercise lead to the creation of a performance-based chemistry guidance manual for adoption by SMC monitoring programs. The SMC’s second laboratory intercalibration in 2006 focused on the same constituents (total suspended solids, nutrients, total trace metals) and increased the number of participating laboratories. The success of the 2006 intercalibration rivaled the 2003 intercalibration, which indicated consistent performance by laboratories participating in the study and reinforced the confidence of the SMC member agencies that laboratory performance would result in consistently high quality data during the intervening years.

These early intercalibration exercises focused primarily on water chemistry, and it was recognized several years ago that toxicity testing also represented an important segment of each member agency programs.

The toxicity laboratory intercalibration exercise, which began in mid-2015, is the first time SMC member agencies will undertake an effort to intercalibrate toxicity testing results. Given the successes and benefits derived from the chemistry laboratory intercalibration, the toxicity testing intercalibration study provides an important first step towards improving toxicity testing data quality and comparability on a regional basis. This study is intended to directly support the management efforts of both the regulated and regulatory stormwater agencies.

5.1.1    Project Status Update

The scope of work was prepared and samples were collected in July 2015 for distribution to the participating laboratories. The toxicity testing focused on two marine species and two freshwater species, which was two more species than originally requested by the SMC. The following four samples were delivered to each laboratory blind:

1. Non-toxic sample to serve as the control,
2. Toxic sample using a chemical spike added to laboratory dilution water,
3. Duplicate spiked sample identical to sample 2, and
4. Artificial runoff sample to test sample matrix effects.

Performance criteria was based on:

• Test acceptability based on standard criteria established in state or USEPA guidance documents,
• Intra-laboratory precision based on the comparability of the duplicate sample within the same laboratory, and
• Inter-laboratory precision based on the comparison of each sample between laboratories.

Based on the results from the first iteration of the intercalibration exercise, the laboratories are going to repeat the testing for the two freshwater species, including Ceriodaphnia dubia which is the most commonly used test organism among the SMC member agencies. Laboratories will be standardizing on certain testing protocols in an effort to increase inter-laboratory precision.

The second round of testing and preparation of the Guidance Manual should be completed in the 2015-16 fiscal year.

5.1.2    Project Related Publications

• Gossett, R. and Schiff, K. 2010. Stormwater Monitoring Coalition Laboratory Guidance Document, 3rd Southern California Coastal Waters Research Project, Technical Report 615.
• Gossett, R. and Schiff, K. 2006 Stormwater Monitoring Coalition Laboratory Guidance Document, 2nd Southern California Coastal Waters Research Project, Technical Report 521.
• Gossett, R. Renfrew, D. and Schiff, K. 2004 Stormwater Monitoring Coalition Laboratory Guidance Document, 1st Southern California Coastal Waters Research Project, Technical Report 420.