# Comparative Study of the Presence of Heavy Metals in Edible Vegetable Oils
## 2 Analysis of Publications and Trend of Heavy Metals in Edible Vegetable Oils
### Results of the Analysis of Heavy Metals in Edible Vegetable Oils
#### 2.3.3 Copper (Cu)  
Similarly to Cd, Cu has no specific international legislation for edible vegetable oils in its category as a heavy metal. The _Codex Alimentarius_ refers to Cu--together with Fe--as a precursor for the catalytic oxidation of edible oils and fats, even at trace levels, and only refers to threshold concentrations in oils as quality criteria. Copper or its alloys--such as brass or bronze--must not be used in storage or transport tanks and circuits that come into contact with oils, such as hoses, pipes, valves, etc. These recommendations are associated with maximum levels that should not be exceeded in the different types of oils [74]:  
Refined fats and oils: 0.1 mg/kg;  
Virgin fats and oils: 0.4 mg/kg;  
Cold-pressed fats and oils: 0.4 mg/kg.  
Therefore, there is a view of copper from the point of view of the quality of the oils rather than from the point of view of chemical contamination in regards to the health of consumers. Among other harmful effects on the body, high exposure to Cu can cause neurodegenerative disorders, such as [PERSON]'s disease [87]. In this regard, in 2021, Chinese regulations for the export of olive oils and olive pomace to that country established a maximum tolerance threshold of 0.1 mg/kg [67]; likewise, in 1983, Spanish regulations considered Cu as a heavy metal and established the maximum limit allowed in edible vegetable oils at 0.4 mg/kg [68].  
Given the current absence of regulation of toxicity thresholds in the case of Cu, the values issued by Chinese regulations for olive oils and olive pomace (0.1 mg/kg) and the values issued by the Spanish regulations for the rest of the edible vegetable oils (0.4 mg/kg) are considered in order to carry out the analysis of the results of this heavy metal in the present study.  
Table 5 shows both the results that are close to 0.10 mg/kg and the results that highly exceed it, in the case of olive oils. Due to its proximity, olive oil from Iran is found with values between 0.091 and 0.098 mg/kg [53]; while among the results that exceed this limit are the oils from Ukraine and Cyprus with values of 0.355 and between 1.02 and 3.81 mg/kg, respectively [54; 60]. In the case of the rest of the edible vegetable oils that are close to and exceeding the limit of 0.4 mg/kg established by Spanish regulations, there is coconut oil from India with values between 0.300 and 0.363 mg/kg [55] and rapeseed oil from Brazil with a value exceeded of 0.81 mg/kg, and sunflower oil, also from Brazil, with a value of 0.81 mg/kg [88], among others.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Types of Oils** & **Analytical Techniques** & **Limit of Detection (LD) 1** & **Limit of Quantification (LQ) 1** & **Results (Range or Average Value) 1** & **Region** & **Reference** \\ \hline Olive oil & GF-AAS & 5.00 \(\times\) 10\({}^{-4}\) & 2.00 \(\times\) 10\({}^{-3}\) & 0.355 & Ukraine & [54] \\ \hline Soybean oil & HR-CS ET-AAS & 0.041 & 0.14 & 0.83 & Brazil (Salvador) & [88] \\ \hline Sunflower oil & HR-CS ET-AAS & 0.041 & 0.14 & 0.81 & Brazil (Salvador) & [88] \\ \hline Rapeseed oil & HR-CS ET-AAS & 0.041 & 0.14 & 0.81 & Brazil (Salvador) & [88] \\ \hline Linseed oil & FAAS & - & - & 0.10 & Poland & [89] \\ \hline Soybean oil & AAS & 0.11 & - & 9.75–30.50 & Bangladesh & [85] \\ \hline Mustard oil & GF-AAS & 0.04 & - & 0.571–0.582 & India (Hyderabad) & [55] \\ \hline \hline \end{tabular}
\end{table}
Table 5: Copper (Cu) content in edible vegetable oils, expressed in mg/kg.