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Before reaching for that weed killer this summer, read its safety label!
June 20th 2022

Before reaching for that weed killer this summer, read its safety label!


Understanding pesticides

You may have heard the term ‘pesticide’ before, but what does it mean? In the simplest terms, a pesticide is any substance used to kill, repel, or control plant or animal life that is considered to be a pest. Pesticides include herbicides (which destroy weeds or unwanted vegetation), insecticides (which kill/repel insects), fungicides (which prevent the growth of mold and mildew), and bactericides (which prevent the spread of bacteria).

Because of the widespread use in agriculture and food production, people are inherently exposed to low levels of pesticide residues. People may be exposed in a variety of settings, including homes, farms, schools, hospitals, and workplaces. Children are particularly susceptible to adverse effects, including neurodevelopment.

Per the EPA (Environmental Protection Agency), pesticide products contain both ‘active’ and ‘inert’ ingredients. Active ingredients are the chemicals that act to control the pest and these must be identified by name on the product’s label. Inert ingredients are combined with the active ingredients to make the product, and these ingredients do not imply they are non-toxic. All inert ingredients must be approved by the EPA before they can be included, but they are not required to be identified on the product label, only the total percentage of all inert ingredients.

Multiple federal laws have been enacted in North America. These laws define registration, label directions, authorized limitations of use, governance over registrations, training, and defined tolerance levels (also known as Maximum Residue Limit (MRL)). An MRL is the highest level of a pesticide that is legally tolerated in/on food or feed.

Mérieux NutriSciences has the pesticide testing you need:

All across the globe, Mérieux NutriSciences offers a number of multi-residue panels, as well as single-residue methods, and can even build a custom reporting package. Our network of laboratories globally and in North America has the capability to analyze more than 450 pesticide molecules. We’ve been at the forefront of pesticide residue analysis to fulfill our mission to protect the health of our customers. In Peru and Chile, Mérieux NutriSciences is the number one provider of analytical services for the fruit and vegetable market.

Our various methods utilize QuEChERS extraction and determination by both GC-MS/MS and LC-MS/MS instrumentation. The most common matrices tested in the Mérieux NutriSciences Network are fruits, vegetables, cereal grains, meat, dairy, processed foods, beverages, feeds, some oils, and dietary supplements finished & raw products.

Reach out today for our current analytical offerings in Pesticide testing!

Mérieux NutriSciences continues to expand our offerings:

In order to meet the challenges stemming from the global market and differences in regulation in various countries, Mérieux NutriSciences is on a path to enhance our capabilities by adding another 300 molecules to the scope of our comprehensive multi-residue screen. These new compounds will include newer, more commonly used insecticides, fungicides, and herbicides. This list of added compounds will also include isomers and breakdown products of many pesticides.

This screen will be available in three of our laboratories in North America; one in Canada and two in the US. Reporting limits will be consistent with MRLs in all jurisdictions, and this screen will involve a single run by GC-MS/MS and two runs on LC-MS/MS. See Table 1 below for matrices to be validated.

Cereal GrainsFruits & VegetablesDairy & Egg
NutsCoffee, Tea, & CocoaColoring & Sweeteners
Table 1

In addition to our multi-residue screens, Mérieux NutriSciences will continue to add dedicated methods for pesticide compounds not amenable to multi-residue techniques. We are also working to combine single-residue methods to create more efficient mini-screens. For example, we are in the process of combining Chlormequat, Paraquat, & Diquat together, as well as Glyphosate, Glufosinate, AMPA, & Ethephon together.

In fruit and vegetable matrices, certain pesticides degrade, producing metabolites. These additional metabolites often have a similar deleterious effect (as the parent molecule) on human health. These metabolites might require hydrolysis in addition to the standard methodology to get a complete quantification, otherwise, the reported result will be inaccurate. Mérieux NutriSciences offers expansive options to include these metabolites using hydrolysis to give our clients the most complete result possible.

See Table 2 for a selected list of pesticides most commonly requiring hydrolysis for complete quantification of an intact molecule and its metabolites:

Free AcidResidue Definition
2,4-DSum of 2,4-D, its salts, esters, and conjugates
2,4-DBSum of 2,4-DB, its salts, esters, and conjugates
AcibenzolarSum of acibenzolar-S-methyl and acibenzolar acid
BispyribacSum of bispyribac, its salts, and esters
DichlorpropSum of dichlorprop (including dichlorprop-P), its salts, esters, and conjugates
DiclofopSum of diclofop-methyl, diclofop acid, and its salts
EthofumesateSum of ethofumesate, 2-keto-ethofumesate, open-ring-2-keto-ethofumesate and its conjugate
FluazifopSum of all the constituent isomers of fluazifop, its esters, and conjugates
FluroxypyrSum of fluroxypyr, its salts, esters, and conjugates
MCPA & MCPBSum of MCPA, MCPB, their salts, esters, and conjugates
PyridateSum of pyridate, its hydrolysis product CL 9673 (6-chloro-4-hydroxy-3-phenylpyridazin) and hydrolysable conjugates
PyridateSum of quizalofop, its salts, esters (including propaquizafop), and its conjugates
Table 2

Citrus fruits, especially, cause hydrolytic degradation of pesticide residues. Mérieux NutriSciences scientists have identified the following list and compiled the matrices in Table 3. To address these challenges, analytical methods developed based on EN and NA standards, our scientists are diligently working to enhance our testing capabilities, capacities, and validated commodities to detect and quantify results to parts per billion levels of pesticide residues, including known hydrolytic degradation residues.

See Table 3 for a list of citrus fruits our scientists are working with:

Citrus Product (Scientific Name)

Grapefruit (Citrus paradisi)Natsudaidais (Citrus natsudaidai)Pomelos (Citrus maxima)
Oroblancos (Citrus grandis)Tangelo (Citrus x tangelo)Ugli (Citrus reticulata x paradisi)
Organes (Citrus sinensis)Bergamots (Citrus bergamia)Bitter Oranges (Citrus aurantium)
Blood Oranges (Citrus sinensis)Cara Caras (Citrus sinensis)Chinottos (Citrus myrtifolia)
Trifoliate Oranges (Poncirus trifoliata)Lemons (Citrus limon)Buddha’s Hands (Citrus medica var. sarcodactyla)
Citrons (Citrus medica)Limes (Citrus aurantiifolia)Indian Sweet Limes (Citrus limettioides)
Kaffir Limes (Citrus hystrix)Sweet Limes (Citrus limetta)Tahiti Limes (Citrus latifolia)
Limequats (Citrus aurantiifolia x Fortunella spp.)Mandarins (Citrus reticulata)Calamondins (Citrus madurensis)
Clementines (Citrus clementina)Cleopatra Mandarins (Citrus reshni)Minneolas (Citrus tangelo)
Satsumas (Citrus unshiu)Tangerines (Citrus tangerina)Tangors (Citrus nobilis)
Table 3

Mérieux NutriSciences is here to help you with your Pesticide needs—contact us today!

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