Evaluating Contaminants in Fish: Plastic Additives and Pesticides in the Context of Food Safety ^†

Abstract

The World Health Organization reports that foodborne illnesses cause millions of disease cases globally, resulting in approximately 33 million lost healthy years of life. Over the past decade, global awareness of food safety grew significantly, highlighting various hazards from biological, chemical, and environmental factors in our food supply, including marine sources. Emerging contaminants like pharmaceuticals, personal care products, pesticides, plastic additives, and microplastics are concerning, with some remaining unregulated. Our work focused on analyzing plastic additives and pesticides in fish captured in the Atlantic Ocean and available in local Oporto supermarkets. We used QuEChERS extraction and gas chromatography for the analysis of organophosphate ester compounds in fish samples. Our goal is to ensure safe and healthy seafood, aligning with the principles of the blue economy and sustainable fisheries.

1. Introduction

In recent years, the World Health Organization has highlighted the alarming global impact of foodborne illnesses, leading to millions of disease cases worldwide and an estimated loss of around 33 million healthy years of life, which may be an underestimation [1]. This recognition has spurred a significant increase in the global awareness of the critical importance of food safety [2].

It has become increasingly evident that our food supply is vulnerable to a range of hazards, spanning biological, chemical, and environmental factors, even including threats from the marine environment. Many emerging contaminants, such as pharmaceuticals, personal care products, pesticides, plastic additives, and microplastics, have been present in our environment for some time [3,4,5]. However, some of these contaminants have only recently come to our attention, and a concerning number of them remain unregulated.

To address these concerns, researchers have developed advanced analytical methods capable of measuring the concentrations, toxicity, and potential risks associated with various families of contaminants. This ongoing effort is vital for safeguarding public health and ensuring the safety of our food supply in a world where threats to food safety continue to evolve.

The aim of this study was to explore an analytical method for the assessment of contaminants of emerging concern, namely, plastic additives and pesticides, in fish samples.

2. Material and Methods

The extraction of 6 organophosphorus pesticides (OPPs) and 8 organophosphate esters (OPEs) from fish samples was performed using the QuEChERS method, and their analysis by gas chromatography with a flame photometric detector. The analytical methodology was optimized and validated based on reported work [4,6]. The fish samples acquired consisted of 7 horse mackerel, 7 mackerel, and 2 Atlantic chub mackerel and were bought in batches from Portuguese supermarkets. All samples were from wild fish, caught at sea in the Northeast Atlantic Ocean.

3. Results and Discussion

3.1. Method Validation

Method validation experiments were conducted in terms of linearity, limit of detection (LOD) and quantitation (LOQ), repeatability, recoveries, and matrix effect. All the compounds at low spiking levels could be quantified at a LOQ higher than 7.9 μg/L. The linearity of the solvent (10–150 μg/L) and the matrix-matched calibration curves (1.5–12.4 μg/kg) for each compound presented a coefficient of determination R2 > 0.991. Satisfactory recovery values of 70–120% with a relative standard deviation ≤20% were obtained for all compounds in the fish samples. A matrix effect between −87 and 5% was observed in 100% of the compounds. For repeatability, a sample of 50 μg/L was prepared and measured ninefold on the same day. With the regressions of the solvent, the concentrations were measured. Then, the standard error and relative standard error (RSE) were calculated, and the RSE was less than 20% for all the compounds studied. As an example,

Table 1. Summary injections of TPrP for the repeatability study.

TPrP
Injection	1	2	3	4	5	6	7	8	9
Area	2,330,779	1,359,183	1,601,568	2,288,192	1,436,445	1,693,913	2,030,356	1,951,238	1,675,209
Conc (μg/L)	47.9	29.3	33.9	47.1	30.8	35.7	42.1	40.6	35.0
Average conc (μg/L)	38.1
Standard error	6.70
Relative standard error	18%

shows the results for tri-propyl phosphate (TPrP). Therefore, according to the guidelines established by SANTE/11312/2021, this analytical method meets most of the requirements and can contribute to OPE and OPP residue analyses of fish samples in routine laboratory testing.

3.2. Application of the Analytical Procedure in Fish Sample Analysis

After validating the methodology, OPPs and OPEs were evaluated in the 16 samples under study. As shown in Figure 1 displaying the complete chromatogram, all peaks were clearly defined, and the compounds were successfully separated. The screening analysis was performed, and the comparison between the chromatograms of the standards and those of the samples indicated that two OPE compounds were present in four Atlantic chub mackerel and one horse mackerel samples.

Tri-cresyl phosphate (TCP) was observed in four Atlantic chub mackerel samples. Tris (2-butoxyehyl) phosphate (TBEP) was observed in one Atlantic chub mackerel and one horse mackerel. After the screening analysis, the compounds were quantified using the respective calibration curves, and the values obtained were below the detection limits. No OPPs were observed in the samples. For this reason, we can see that the samples analyzed were safe for human consumption in terms of their selected OPP and OPE content.

There are still not much data in the literature about OPEs in fish samples. Indeed, there are no regulatory standards concerning the maximum OPE residue levels permitted in food. Although we observed the presence of these compounds, the values were below their LOD; however, in the literature, some studies showed the presence of these compounds in low concentrations in edible fish such as sardines, hakes, etc. [7].

4. Conclusions

Sample extraction using QuEChERS demonstrated good performance, as evidenced by the recoveries and matrix effects. The regressions and the LOD and LOQ values were satisfactory and allowed the applicability of the method to the samples, as previously discussed. However, the method can be improved, mainly concerning its sensitivity, in order to improve the LOD and LOQ values.

While plasticizers and flame retardants are indeed detected in numerous samples as a result of widespread environmental pollution stemming from the disposal of plastic waste in our oceans, with plastic forming a substantial portion of this waste, as well as of the presence of OPEs, which serve as flame retardants and are utilized in various industries, it is worth noting that the concentrations of these target compounds in the examined fish were below the levels of concern for toxicity. As such, consuming these types of fish remains safe. In our research, we encountered a notable gap in regulatory standards concerning the maximum OPE residue levels permitted in food. This absence of specific regulations highlights the need for further attention regarding the assessment of OPEs in food safety guidelines to ensure the protection of public health and the environment. Addressing this regulatory void is crucial to establishing comprehensive safety measures for OPEs in our food supply chain.