Tag Archives: pesticide residue

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FDA Withdraws Guidance on Enforcement of Human Food with Chlorpyrifos Residues

By Food Safety Tech Staff
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The FDA is withdrawing a 2022 guidance document titled Questions and Answers Regarding Channels of Trade Policy for Human Food Commodities with Chlorpyrifos Residues: Guidance for Industry, following a decision by the U.S. Court of Appeals for the Eighth Circuit to vacate, or void, an Environmental Protection Agency (EPA) final rule that revoked all tolerances for the pesticide chemical chlorpyrifos.

In April 2021, the U.S. Court of Appeals for the Ninth Circuit ordered EPA to issue a final rule either revoking all chlorpyrifos tolerances or modifying the chlorpyrifos tolerances, provided EPA could make a determination that those modified tolerances met the safety standard mandated by the Federal Food, Drug, and Cosmetic Act (FFDCA). As a result of the short timeframe, EPA found that, based on the available data and anticipated exposure from registered uses of chlorpyrifos, it could not determine that there was a reasonable certainty of no harm from aggregate exposure, including food, drinking water and residential exposure. Consequently, on August 30, 2021 EPA issued a final rule amending 40 CFR 180.342 to revoke all tolerances for residues of chlorpyrifos.

Gharda Chemicals and several grower groups challenged EPA’s revocation of the tolerances in the U.S. Court of Appeals for the Eighth Circuit. On November 2, 2023, the Eighth Circuit issued its decision, vacating EPA’s final rule and remanding the matter to EPA for further proceedings. As a result of this ruling, EPA issued the final rule to reinstate previous tolerances for chlorpyrifos; 40 CFR 180.342 reflects the current legal status of the tolerances for chlorpyrifos. The FDA guidance was intended to explain the agency’s enforcement policy for foods containing chlorpyrifos residues after the tolerances expired, per the 2021 final rule, which is now void.







Gitte Barknowitz

Technology and Farming: An Essential Relationship as Pesticide Restrictions Impact Agriculture in the EU

By Gitte Barknowitz, Ph.D.
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Gitte Barknowitz

Pesticides and other chemical compounds are widely used in agriculture because they protect crops and improve the efficiency of food production. However, it is necessary to identify what type and how much chemical residues are in food, water and soil as these residues may pose a potential threat to human health as well as the environment. Reducing pesticides in food will result in a lower toxic chemical burden entering the body and accumulating in the tissues and organs, but it will take a concerted effort.

The European Union (EU) member states are implementing extensive policy changes to improve soil quality and ultimately improve the quality of crops. Among them is a “proposal for a new Regulation on the Sustainable Use of Plant Protection Products, including EU wide targets to reduce by 50% the use and risk of chemical pesticides by 2030.” In July 2023, the European Commission also “adopted a package of measures for a sustainable use of key natural resources, which will also strengthen the resilience of EU food systems and farming.”

Reducing the use of chemicals is an important step to ensuring enough safe food for the growing human population. This challenge comes at a time when arable land is being lost, the demand for food is increasing and the world population is expected to increase to 9.7 billion in 2050, according to the United Nations. This will require food growers and processors to implement more sustainable growing practices often referred to as Integrated Pest Management (IPM). While the benefits of natural pest control are already well understood—clean water, healthy soil and improved biodiversity—reducing reliance on synthetic pesticides will require increased analysis, and as a result, generating a lot of data.

It all begins with the analysis of chemical residues found on crops.

Naming the Culprits

With more than 1,000 pesticides in use around the world, it is important to know the properties and toxicological effects of each. A group of pesticides commonly used to curb weeds is herbicides. Glyphosate, (N-(phosphonomethyl)glycine), a widely-used, broad-spectrum, systemic herbicide and crop desiccant, has in the recent years come under scrutiny as the International Agency for Research on Cancer (IARC), a branch of the World Health Organization, classified glyphosate as “probably carcinogenic to humans.”

In the coming years, more data will be gathered on pesticides in the EU, with part of that information coming from control measures and agricultural practice reviews. A large part will come from laboratory measurements to meet data requirements mandated by the new regulations. Compiling consistent, accurate data depends on the equipment that produces it. This is particularly important for food safety.

As technologies advance and more information can be obtained, including residues on food, the requirements for the type of data are also changing. For example, quantifying how much of a predetermined pesticide residue is in a sample is a narrow parameter. Identifying all of the compounds that can be found will provide more data to characterize the sample. Ideally, collecting both will provide the most complete answer to the question, “How much and what kinds of pesticides remain on our food?”

Once that information is available, it is possible to choose appropriate remediation steps. But it takes sensitive laboratory equipment to both identify and quantify residues.

Connecting the Dots Between Pesticides and Food

The most common technology currently used to monitor pesticides is liquid chromatography-mass spectrometry (LC-MS). First, the sample (e.g., soil, water, fruit or vegetable) is injected onto the liquid chromatograph (LC). The LC separates the complex mixture based on the chemical properties of the individual pesticides before being analyzed by the mass spectrometer (MS). MS instruments analyze samples based their masses—or more correctly their mass-to-charge ratio—in a very accurate and precise manner. MS/MS instruments also break apart the pesticides and are able to look for these fragments. These are used to quickly determine if a specific compound is present and in what amount, known as identification and quantitation.

Amadeo Rodríguez Fernández-Alba, professor in analytical chemistry at the University of Almeria and head of the European Reference Laboratory for Pesticide Residues, has valued the benefits of using LC-MS/MS for pesticide residue analysis for years. Over time, the technology and methods have evolved to identify and measure the amount of chemicals in food plants and soil.

In his recent work, Fernández-Alba showed the analysis of 30 compounds of emerging concern (CECs) in soils irrigated with simulated reclaimed water on trial farmland using a targeted MS/MS approach. An accumulation of 13 pesticides and 5 pharmaceuticals could be found at different rates, highlighting the importance of increased analysis for reclaimed water testing.

Regarding the testing method, the authors pointed out that, “a modified QuEChERS method showed the best results in terms of extractability and accuracy. The extraction procedure developed provided adequate extraction performances (70% of the target analytes were recovered within a 70–99% range), with good repeatability and reproducibility (variations below 20%) and great sensitivity (LOQ < 0.1 ng/g in most cases). No matrix effects were observed for 70% of the compounds. Finally, the analytical methodology was applied in a pilot study where agricultural soil was irrigated with reclaimed water spiked with the contaminants under study. Of the 25 CECs added in irrigation water, a total of 13 pesticides and 5 pharmaceutical products were detected…”

Reduction in pesticide usage needs to be monitored in both field and food samples for a wide range of analytes including unknown substances to build confidence in the food system. Using mass spectrometry can provide that data.

Glyphosate, mentioned above, is one of the most widely used agrochemicals in the world and also one of the most difficult to detect. In Europe, EFSA has proposed MRLs for a wide range of commodities for glyphosate. Monitoring this kind of highly polar, small-organic pesticide in food and water from diverse sources can be complex, time-consuming and expensive. NofaLab, a sampling and testing lab in the Netherlands, collaborated with SCIEX to create a high throughput method using LC-MS/MS to test for as many polar pesticides in a single analysis as possible.

The final method utilized the sensitivity of QTRAP technology and was “found to be considerably more robust and sensitive than other approaches described in various publications and have achieved the target limits of detection required to meet existing and proposed future regulations.” In addition, the “ion chromatographic approach to the analysis of polar pesticides offers the ability to include multiple analytes in a single injection without derivatization…allowing high-throughput laboratories to manage samples efficiently and minimize running costs.”

Targeted MS/MS analysis has long been the gold standard for pesticide analysis in the industry, but advanced high-resolution MS systems enable even greater accuracy and confidence, helping to identify more contaminants, even unknowns. The ZenoTOF 7600 system uses electron activated dissociation (EAD) to create a higher number of fragments as compared to collision induced fragmentation (CID), which is traditionally used in targeted MS/MS analysis on other systems, allowing for highly confident identifications of pesticides in food samples. The ZenoTrap technology additionally enhances sensitivity, which is needed in pesticide analysis to meet regulatory limits. Regardless of the type of sample, whether taken from the soil in a field or from harvested crops, mass spectrometers can identify the type and amount of chemicals present in a sample within several minutes of run time and analyze hundreds of samples in a day.

Streamlining Data Review and Adhering to Data Standards

In an effort to standardize pesticide use, the Codex Alimentarius Commission (CAC) established standards for pesticide residues and developed international standards for food products. This framework for providers at various points in the food supply chain can help reduce the risk of contamination and toxicity.

In the U.S., the Environmental Protection Agency (EPA) establishes tolerances, also known as maximum residue limits (MRL) in other countries, for the type and quantity of pesticides that can remain on food. The agency sets these to ensure pesticides can be used with “reasonable certainty of no harm.”

Producers adhering to these guidelines must handle and present extensive data sets from test results, and any new future regulations will require robust data to track the success of the initiatives and effectively enforce their use. Reviewing and understanding data in order to make decisions is tricky and labor-intensive. It can take laboratories hours every day to process, interpret and manage the data. Software enables fast data processing and fast review by exception flagging, which is valuable in food safety laboratories that typically see a high turn-around in samples every day.

Maintaining resilient food systems will be rooted in data-driven decisions that improve food safety, including limiting pesticide and other chemical uses. By using modern mass spectrometry technology, researchers can be more confident that their food analyses will lead to better-informed policies, more sustainable agricultural practices, and healthier food for future generations.

Karen Everstine, Decernis
Food Fraud Quick Bites

Food Authenticity: 2020 in Review

By Karen Everstine, Ph.D.
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Karen Everstine, Decernis

It is fair to say that 2020 was a challenging year with wide-ranging effects, including significant effects on our ongoing efforts to ensure food integrity and prevent fraud in the food system. COVID-19 caused major supply chain disruptions for foods and many other consumer products. It also highlighted challenges in effective tracking and standardization of food fraud-related data.

Let’s take a look at some of the notable food fraud occurrences in 2020:

  • Organic Products. The Spanish Guardia Civil investigated an organized crime group that sold pistachios with pesticide residues that were fraudulently labeled as organic, reportedly yielding €6 million in profit. USDA reported fraudulent organic certificates for products including winter squash, leafy greens, collagen peptides powder, blackberries, and avocados. Counterfeit wines with fraudulent DOG, PGI, and organic labels were discovered in Italy.
  • Herbs and Spices. Quite a few reports came out of India and Pakistan about adulteration and fraud in the local spice market. One of the most egregious involved the use of animal dung along with various other substances in the production of fraudulent chili powder, coriander powder, turmeric powder, and garam masala spice mix. Greece issued a notification for a turmeric recall following the detection of lead, chromium, and mercury in a sample of the product. Belgium recalled chili pepper for containing an “unauthorized coloring agent.” Reports of research conducted at Queen’s University Belfast also indicated that 25% of sage samples purchased from e-commerce or independent channels in the U.K. were adulterated with other leafy material.
  • Dairy Products. India and Pakistan have also reported quite a few incidents of fraud in local markets involving dairy products. These have included reports of counterfeit ghee and fraudulent ghee manufactured with animal fats as well as milk adulterated with a variety of fraudulent substances. The Czech Republic issued a report about Edam cheese that contained vegetable fat instead of milk fat.
  • Honey. Greece issued multiple alerts for honey containing sugar syrups and, in one case, caramel colors. Turkey reported a surveillance test that identified foreign sugars in honeycomb.
  • Meat and Fish. This European report concluded that the vulnerability to fraud in animal production networks was particularly high during to the COVID-19 pandemic due to the “most widely spread effects in terms of production, logistics, and demand.” Thousands of pounds of seafood were destroyed in Cambodia because they contained a gelatin-like substance. Fraudulent USDA marks of inspection were discovered on chicken imported to the United States from China. Soy protein far exceeding levels that could be expected from cross contamination were identified in sausage in the Czech Republic. In Colombia, a supplier of food for school children was accused of selling donkey and horse meat as beef. Decades of fraud involving halal beef was recently reported in in Malaysia.
  • Alcoholic Beverages. To date, our system has captured more than 30 separate incidents of fraud involving wine or other alcoholic beverages in 2020. Many of these involved illegally produced products, some of which contained toxic substances such as methanol. There were also multiple reports of counterfeit wines and whisky. Wines were also adulterated with sugar, flavors, colors and water.

We have currently captured about 70% of the number of incidents for 2020 as compared to 2019, although there are always lags in reporting and data capture, so we expect that number to rise over the coming weeks. These numbers do not appear to bear out predictions about the higher risk of food fraud cited by many groups resulting from the effects of COVID-19. This is likely due in part to reduced surveillance and reporting due to the effects of COVID lockdowns on regulatory and auditing programs. However, as noted in a recent article, we should take seriously food fraud reports that occur against this “backdrop of reduced regulatory oversight during the COVID-19 pandemic.” If public reports are just the tip of the iceburg, 2020 numbers that are close to those reported in 2019 may indeed indicate that the iceburg is actually larger.

Unfortunately, tracking food fraud reports and inferring trends is a difficult task. There is currently no globally standardized system for collection and reporting information on food fraud occurrences, or even standardized definitions for food fraud and the ways in which it happens. Media reports of fraud are challenging to verify and there can be many media reports related to one individual incident, which complicates tracking (especially by automated systems). Reports from official sources are not without their own challenges. Government agencies have varying priorities for their surveillance and testing programs, and these priorities have a direct effect on the data that is reported. Therefore, increases in reports for a particular commodity do not necessarily indicate a trend, they may just reflect an ongoing regulatory priority a particular country. Official sources are also not standardized with respect to how they report food safety or fraud incidents. Two RASFF notifications in 2008 following the discovery of melamine adulteration in milk illustrate this point (see Figure 1). In the first notification for a “milk drink” product, the hazard category was listed as “adulteration/fraud.” However, in the second notification for “chocolate and strawberry flavor body pen sets,” the hazard category was listed as “industrial contaminants,” even though the analytical result was higher.1


RASFF, melamine detection
Figure 1. RASFF notifications for the detection of melamine in two products.1

What does all of this mean for ensuring food authenticity into 2021? We need to continue efforts to align terminology, track food fraud risk data, and ensure transparency and evaluation of the data that is reported. Alignment and standardization of food fraud reporting would go a long way to improving our understanding of how much food fraud occurs and where. Renewed efforts by global authorities to strengthen food authenticity protections are important. Finally, consumers and industry must continue to demand and ensure authenticity in our food supply. While most food fraud may not have immediate health consequences for consumers, reduced controls can lead to systemic problems and have devastating effects.


  1. Everstine, K., Popping, B., and Gendel, S.M. (2021). Food fraud mitigation: strategic approaches and tools. In R.S. Hellberg, K. Everstine, & S. Sklare (Eds.) Food Fraud – A Global Threat With Public Health and Economic Consequences (pp. 23-44). Elsevier. doi: 10.1016/B978-0-12-817242-1.00015-4

USDA PDP Report: Farmers Doing a Good Job Complying with Regulations

By Food Safety Tech Staff
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Fruit and vegetable farmers are doing an “impressive” job of complying with the laws and regulations related to pesticide use in production, according to the USDA’s annual Pesticide Data Program (PDP) report. Based on data from 2016, the report found that more than 99% of samples had pesticide residues that were “well below” the EPA’s established tolerances, and more than 23% had no detectable residues. Less than half-a-percent of samples (0.46%) had residues that exceeded the EPA established tolerance.

To compile the PDP report, surveys were conducted in 2016 on several foods, including eggs, milk, and fresh and processed fruit and vegetables. The report contains data from more than 10,000 samples collected throughout the United States.

A release from the Alliance for Food and Farming states that the U.S. food supply is one of the safest in the world, yet: “Activists groups often manipulate the findings from the USDA PDP report taking the very positive results and somehow turning them into something negative. This tactic has been used routinely for 20-plus years to create a so-called ‘dirty dozen’ list, which has been repeatedly discredited by scientists.”

Debadeep Bhattacharyya, Thermo Fisher Scientific
In the Food Lab

Pushing The Limits Of Targeted Pesticide Residue Quantitation: Part 1

By Debadeep Bhattacharyya, Ph.D.
Debadeep Bhattacharyya, Thermo Fisher Scientific

Robust, reproducible quantitation of pesticide residues in food is the most important step in ensuring food safety, and hence, forms one of the most important responsibilities of every food safety laboratories. The analytical process involves characterization and identification followed by quantitation of pesticides across different food matrices. Considering the growing list of pesticides and their adverse effects even for very low concentrations, quantitation with confidence for every sample can pose some significant challenges to the analytical scientist.

Typical practices of using pesticides to control pests and improve yields can often pose a serious risk to human health if and when used inappropriately. Improper use of pesticides in breach of approved procedures, or those that are applied to crops for which their use has not been authorized, unacceptable amounts of these potentially dangerous compounds can find their way onto the plates of consumers.

In order to ensure food is safe for consumption, laboratories require robust, reliable and cost-effective workflows, incorporating highly effective sample preparation steps, separation methods and detection techniques. Owing to its selectivity, specificity, sensitivity, robustness and universal approach, liquid chromatography coupled to triple quadrupole mass spectrometers (LC-MS/MS) are widely used for quantitation of pesticides in food.

Food standards are growing increasingly stringent, so leading laboratories must ensure they consistently meet the requirements of regulators. Thankfully, the latest comprehensive pesticide workflow solutions are helping laboratories deliver the very highest quality of pesticide quantitation, on time and on budget.

Optimizing Sample Preparation

Regardless of the food product that is being tested, pesticide residue workflows typically start with sample preparation, following homogenization and residue extraction steps. This stage is one of the most important parts of the workflow, however, very often they are not highlighted.

The heterogeneity of the sample matrix, as well as the wide variety of pesticide compounds that must be extracted, can significantly add to the complexity of this task. For example, pesticide residues can be lost during sample grinding, compromising the accuracy of quantitative analysis. Loss of critical pesticides can also occur through hydrolysis by water or enzymatic degradation as enzymes are released from cells, or by the formation of insoluble complexes due to interaction of the analyte with matrix components. Each of these factors can impact the quantitation of pesticide residues in food.

Homogenization is followed by solvent extraction and cleanup. Extraction could traditionally be a time-consuming process, often requiring relatively large amounts of sample, and involving use of multiple solvents and work-up steps. In addition, results from this step can vary based on matrix type and pesticides that are being monitored. Time-consuming sample cleanup steps, based on separation techniques such as gel permeation chromatography, could also be necessary, thereby adding another layer of complexity.

The widespread adoption of sample preparation strategies based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) methods has significantly simplified the process of residue extraction for a wide range of food types, especially for high-moisture content samples. These generic extraction approaches, coupled with “quick and easy” cleanup techniques such as dispersive solid phase extraction, are able to comprehensively extract residues with a range of different chemical properties, resulting in more consistent and reliable quantitation.

The universal and easy-to-implement nature of QuEChERS methods has also allowed laboratories to reduce the complexity of their workflows. Their simplicity is such that many suppliers are now offering all-in-one kits containing all of the necessary pre-weighted reagents and supplies, which laboratories can use straight from the box. And as they require very little sample material, solvent or equipment, and eliminate the need for time-intensive homogenization steps, they are also helping to reduce laboratory waste and cut operational costs.

The Need for LC-MS/MS Technology

Once analytes are extracted from the matrix, food safety laboratories require reliable, sensitive and precise separation, detection and quantitation technologies to determine their concentration.

As indicated above, LC-MS/MS technology with triple quadrupole mass spectrometers are often the go-to choice for quantitation applications. The high selectivity and sensitivity of these instruments allow analysts to confidently identify pesticides against target lists and accurately quantify even trace levels. Figure 1 shows the distinct separation obtained for a leek sample spiked with more than 250 pesticides at a concentration of 100 µg/kg. The mass range, robustness, specificity, selectivity of the triple quadrupole instrument ensures the ability to handle a wide variety of sample types and deliver reliable results in a cost-effective manner.

Pesticide Residue Quantitation
Figure 1. LC-MS/MS chromatogram of leek extract spiked with more than 250 pesticides at 100 μg/kg. Results were obtained using a UHPLC system coupled with a triple quadrupole MS.


To ensure the food on our plates does not contain potentially harmful levels of pesticides, laboratories require robust workflows for their analysis and targeted quantitation. Improvements in the sample preparation methods that are used to extract pesticide residues from food samples, as well as in the sensitivity, accuracy, robustness and reliability of the triple quadrupole instruments used for analyte detection, are helping food safety laboratories confidently quantify these compounds even in trace amounts.


This article is based on research by Katerina Bousova, Michal Godula, Claudia Martins, Charles Yang, Ed Georg, Neloni Wijeratne & Richard J. Fussell, Thermo Fisher Scientific, Dreieich, Germany,  Thermo Fisher Scientific, California, USA, Thermo Fisher Scientific, Hemel Hempstead, UK.


The 2017 Dirty Dozen List Unveiled: How Contaminated Is Produce?

By Food Safety Tech Staff
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Every year the Environmental Working Group (EWG) releases its “Dirty Dozen”, a list of 12 produce items that contain the highest loads of pesticide residues. This year the organization analyzed tests conducted by the USDA, finding that nearly 70% of samples of 48 types of produce were contaminated with one or more pesticide residues, which remained even after the produce were washed (and peeled, in some instances). 178 pesticides and pesticide breakdown products were found on the samples that the USDA researchers analyzed.

“New federal data shows that conventionally grown spinach has more pesticide residues by weight than all other produce tested, with three-fourths of samples tested contaminated with a neurotoxic bug killer that is banned from use on food crops in Europe.” – EWG

For the following items that made this year’s list, EWG recommends always buying organic. Each food tested positive for several different pesticide residues, along with having higher concentrations of pesticides compared to other produce.

  1. Strawberries
  2. Spinach
  3. Nectarines
  4. Apples
  5. Peaches
  6. Pears
  7. Cherries
  8. Grapes
  9. Celery
  10. Tomatoes
  11. Sweet bell peppers
  12. Potatoes

EWG also released a Clean 15 list, produce that was found to have “relatively few” pesticides and a low concentration of residue.

However, there are groups that dispute EWG’s list, because the ranking of produce has been found to have a negative effect on the consumption of produce, whether conventional or organic, especially among low-income consumers. “EWG’s list has been discredited by scientists, it is not based upon risk and has now been shown to potentially discourage consumption of healthy and safe organic and conventional fruits and vegetables,” said Teresa Thorne, Executive Director of the Alliance for Food and Farming (AFF) in a press release. She referred to analysis conducted by a toxicologist with the University of California’s Personal Chemical Exposure Program, which found that a child could eat excessive amounts of produce daily without any negative consequences from the pesticide residues. “For strawberries, a child could eat 181 servings or 1,448 strawberries in a day and still not have any effects from pesticide residues,” Thorne said. AFF also lists some of the regulations regarding pesticide use [http://safefruitsandveggies.com/regulations/organic] on its website.


Pesticide Residues Not a Food Safety Risk, Says Federal Government

By Food Safety Tech Staff
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After publishing data from its 2014 Pesticide Data Program (PDP) earlier this week, the USDA has stated that it is not concerned with the level of pesticide chemical residues in the U.S. food supply. More than 99% of products sampled through the USDA’s Pesticide Data Program had residues below EPA tolerances (residues exceeding the tolerance were detected in 0.36% of samples).

“The PDP plays an essential role in ensuring the safety of the U.S. food supply. Under the Federal Food, Drug, and Cosmetic Act, the FDA has authority to take enforcement action when a food bears or contains unlawful pesticide chemical residues,” said Susan Mayne, Ph.D., director of FDA’s Center for Food Safety and Applied Nutrition in a press release. “By providing an accurate assessment of pesticide levels in the most commonly consumed commodities in America, the PDP generally confirms the U.S. food supply is safe with respect to pesticide chemical residues.”

Among the foods tested were fresh and processed fruits and vegetables, oats, rice, and salmon. The findings from the PDP annual summary can be accessed via the USDA’s website.

Understanding Pesticide Residue and Maximum Residue Limits

By Food Safety Tech Staff
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The idea of controlling pests dates as far back as 2500 B.C. From using soaps to copper sulfate to DDT, industry has evolved in how it controls pests in agricultural crops. In a video shot at Food Safety Tech’s 2015 Food Labs conference earlier this year, Angela Carlson of SGS discusses the regulations involving maximum residue limits (MRLs) as well as how MRLs are set at a global level.