When soybean rust was found in Dallas County during 2007, fungicides were applied throughout the state to combat the effects of the rust. Concerns about the level of these fungicides prompted the Iowa Department of Natural Resources to ask the State Hygienic Laboratory to develop a method that would monitor the amount of approved fungicides applied to streams and rivers.

Trees are stripped of their bark and debris is scattered across Parkersburg, Iowa, after an EF5 tornado hit the small town. The Hygienic Laboratory developed a method to test for contamination in water that may have spilled into streams as a result of the tornado.

To do so, the Hygienic Laboratory used a technique known as liquid chromatography-tandem mass spectrometry (LC-MS/MS). The laboratory developed, validated and implemented a highly specific and very sensitive method to measure levels of several fungicides used to combat soybean rust.

The Hygienic Laboratory has used that same technique to identify contaminants in water following a natural disaster. It also plans to use LC-MS/MS to test levels of toxins in blue-green algae scum found in surface water during warm months.

EF5 Tornado and Environmental Effects

In 2008 when an EF5 tornado hit Parkersburg, much of the city – including an agricultural chemical storage facility – was destroyed. The Hygienic Laboratory method that was created for the soybean rust project was used to test for levels of fungicides spilled into a local stream from that storage facility.

The laboratory continued to expand uses of LC-MS/MS, which now can detect most triazole, strobilurin and chlorinated fungicides at very low concentrations in a wide variety of samples, including drinking water and surface water, soil, vegetation and food products.

Rising Concerns for Toxins in Water

Cyanotoxin contamination produced by blue-green algae (cyanobacteria) has occurred during active blooms in public surface water supplies. Last year, this public health concern resulted in the EPA issuing drinking water health advisories for the cyanobacterial toxins microcystins and cylindrospermopsins.

The Hygienic Laboratory routinely screens water samples for microcystin toxins using the rapid test enzyme-linked immunosorbent assay (ELISA). Toxins can be detected in water using the freeze and thaw cycles to rupture the cyanobacterial cells. The laboratory plans to implement an LC-MS/MS procedure to determine specific microcystin toxins, as well as nodularins, anatoxin-A and cylindrospermopsin.

Cyanotoxins may be found from mid-spring to mid-autumn in warm, nutrient-rich water bodies; they are an increasing health risk. Toxins may affect the liver, nervous system and the gastrointestinal system. Exposure can occur by ingestion, inhalation of aerosolized toxins or dermal contact through activities such as swimming or fishing.

EPA set the drinking water advisory limit for children six years old or younger to 0.3 μg/L for total microcystins and 0.7 μg/L for cylindrospermopsin. The drinking water advisory limit for school-age children to adults is 1.6 μg/L for total microcystins and 3.0 μg/L for cylindrospermopsin. EPA is also considering the inclusion of select drinking water toxins in its Fourth Unregulated Contaminant Monitoring Rule. The World Health Organization has recommended a maximum total microcystins exposure limit of 1 μg/L in finished drinking water.

EPA has published two guidance methods for the determination of cyanotoxin in drinking water. EPA Method 544 is for the extraction and analysis of microcystin variants and nodularin by LC-MS/MS. EPA Method 545 is for the analysis of cylindrospermopsin and anatoxin-a by direct injection analysis by LC-MS/MS.

Public health laboratories that test for cyanotoxins often use the following approaches.

ELISA - A useful screening tool for the detection of all microcystins (ADDA Kit) with a low detection limit. This assay is prone to matrix interference; confirmatory analysis (e.g., LC-MS/MS) is recommended for any positive samples.

LC-MS/(MS) - A powerful and highly-specific technique used in confirmatory analysis to accurately identify and quantify specific microcystin and nodularin variants. Either a scan or tandem mass spectrometry (MS/MS) can be conducted on a suite of microcystins, including those that are commercially attainable: [DAsp3]MC-RR, MC–RR, MC-YR, MC-LR, [DAsp3]MC-LR, MC-WR, MC-HilR, MC-LY, MC-LA, MC-LF, MC-LW and nodularin.

MMPB LC-MS/MS – Chemical oxidation of microcystins produces 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB). MMPB can be detected equally regardless of the variant. MMPB analysis allows for the determination of total microcystins, bound and unbound, in water samples, although this technique may not be suitable for heavily-chlorinated water samples.