Chemical food contaminants are substances that are not intentionally added to food but may be present in various food products. They include inorganic and organic substances that enter the food chain from a range of sources, such as environmental pollution, agricultural methods, storage conditions, production and processing procedures, and packaging. Some of these contaminants are formed naturally in the soil, water or air; others are byproducts of the processing and production process itself.
Toxic substances such as dioxins, per- and polyfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), mycotoxins, alkaloids, heavy metals, and polycyclic aromatic hydrocarbons (PAHs) are present almost everywhere in the environment. They can be found in animal feed and, consequently, in food products of animal origin. In addition, veterinary pharmaceuticals and pesticides are used in animal husbandry and, thus, may be present in animal-based food products.
For many of these chemical food contaminants there is no safe threshold value. However, international organizations such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and regional organizations such as the European Food Safety Authority (EFSA) have calculated acceptable exposure values for many of them. Exposure to these contaminants above a certain level may adversely affect human health depending on the type of contaminant, the level and duration of exposure, and the specific characteristics of the exposed individual.
In Israel, as in many places in the Western world, each food company is responsible for taking the necessary measures to reduce the levels of chemical food contaminants to a minimum. Responsibility for producing, importing, and selling safe food is set forth in the Public Health Protection (Food) Law, enacted in 2015. The Ministry of Health (MoH) has set maximum permitted levels for food contaminants such as heavy metals, dioxins, PCBs, PAHs, and mycotoxins.
Progress since 2017
The Environmental Health in Israel 2017 report defined challenges related to Chemical Food Contaminants. Progress achieved in this area during the past three years is outlined below.
Human exposure to aluminum takes place primarily through food. Toxicological research on animals has shown that several aluminum compounds may cause neurotoxicity and affect the male reproductive system. In human studies conducted on dialysis patients, neurological effects were observed in prolonged exposure to high concentrations of aluminum compounds. Several studies revealed an association between exposure to aluminum and degenerative diseases but were not sufficiently robust.
Infants are a vulnerable population whose food consumption is not varied. To assess their exposure to aluminum, the National Food Service (NFS) at MoH conducted a survey to quantify aluminum in infant formulae. The formulae sampled were those commonly used in the Israeli market and in hospitals, including powder for preparation at home and ready-to-feed liquid. The survey included an exposure assessment that compared aluminum levels with the threshold value set by JECFA and EFSA. Levels of aluminum above the limit of quantification (LOQ) were found in all samples of plant-based infant formulae and were not found in about 40% of samples of milk-based formulae. The aluminum levels in plant-based infant formulae were higher on average than those found in milk-based formulae. Aluminum in infant formulae may originate in packaging, soybeans (which naturally accumulate aluminum), aluminum residue from other ingredients of soy-based formulae, and contamination in processing the formula.
Phthalates, a group of chemicals used to increase the strength and flexibility of plastic products, can contaminate food and beverages by migrating from food packaging.
Standard 5113, a mandatory Israeli standard for plastic packaging that comes into contact with food, applies to aluminum packaging with plastic coating, the kind typically used for infant formula. The standard has been updated several times since 2017 and now establishes maximum permitted levels for phthalates in food packaging that are consistent with European regulation. Packages of infant formula are imported to Israel and, in accordance with the Free Import Ordinance, are tested to determine whether they meet Standard 5113. In these tests, no excessive levels of phthalates were found relative to the standard. In light of the findings, and since most of infant formula in Israel is imported, NFS decided that it was unnecessary to conduct a survey to identify and quantify phthalates in infant formulae.
As part of the National Health and Nutrition Survey (Rav-MABAT), data on food consumption were collected from different sub-populations that together comprise a representative sample of the population in Israel. To use the collected data to assess the exposure of the general population and sub-populations to contaminants that originate in food, the foods reported by the survey participants must be broken down by their ingredients. In addition, the Rav-MABAT data are being used in preliminary assessments of pesticide exposure in children of various age groups.
A Total Diet Study project examines all food that an individual consumes and the way it is consumed. This includes sampling food consumed by the general population and sub-populations from the various markets, preparing the food in the conventional way of consuming it, and combining the types of food into several composite samples. These mixed samples are examined to identify and quantify contaminants originating in food, including pesticides, environmental contaminants, natural toxins, substances that migrate from food packaging, and more. The goal of this sort of project is to produce a quantitative assessment of chemicals to which the public is exposed from food, parsed by subgroups in the population. Such data are very helpful in assessing the potential health impact of exposure to contaminants in food. The TDS approach has an advantage of testing the food as it is consumed (for example, after rinsing, peeling or cooking), thus yielding a more accurate picture of exposure to chemicals in food. Accordingly, several countries have initiated national TDS projects.
To establish its own TDS project, Israel must develop a sampling plan that represents food consumption countrywide, prioritize the chemicals that are important to check, write clear protocols for food sampling and preparation, build an array that accounts for preparing food in the way it is consumed, develop the logistical capacity for transporting and storing food, and establish laboratory capacity for testing the requisite substances according to their prioritization. These phases, taken together, entail substantial personnel and budgetary resources. Due to budget constraints, the project has yet to be initiated.
Research on Chemical Food Contaminants in Israel
- Researchers from the Agricultural Research Organization’s Volcani Center examined the effects of phosphine fumigation on stored wheat grain and on the wheat grain microbiome, including mycotoxigenic fungi. The use of phosphine induced changes in the composition of the bacterial community: As the number of phosphine treatments increased, the diversity of the bacterial community in the stored wheat decreased. However, no similar effect on fungal diversity was detected. Mycotoxin analysis of the treated wheat revealed the presence of Fusarium toxins, primarily deoxynivalenol.1
- Following the discovery of ergot disease in sorghum fields for the first time in Israel, a large amount of produce from the affected fields had to be destroyed. Researchers from the Volcani Center examined and identified the ergot alkaloid profile in the infected fields and, for the first time, detected dihydrolysergol as a significant ergot alkaloid component. In an assessment of the infected sorghum silages, taking the alkaloid profile into consideration, the silage was found to be safe for use as animal feed.2
- In a study conducted by researchers at the Volcani Center and the Kimron Veterinary Institute, a method was developed for detecting a range of mycotoxigenic fungi and mycotoxins in wheat.3
- Researchers from Volcani Center examined samples of bovine and goat milk sold in markets in Israel and detected pesticides and pharmaceutical residues. In about 50% of the milk samples tested, residues from several pesticides were found in the same sample.4
Estimating exposure to contaminants originating in food is an important step in the process of assessing the risks that these contaminants present, and the use of food consumption data is important for tailoring exposure assessments to the population of Israel. Although extensive food consumption data is collected routinely in Israel in nutrition surveys (such as Rav-MABAT), these data are currently underutilized in assessing the risk of food contaminants. Conducting exposure assessments for contaminants such as heavy metals, on the basis of Rav-MABAT surveys and biomonitoring data, is an ongoing challenge.
NFS conducts periodic surveys on food contaminants (including mycotoxins in food, arsenic in rice and rice products, and aluminum in baby food). Some of these data are currently unpublished. As part of an effort to increase transparency, NFS intends to publish these data.
Climate change is affecting the proliferation of toxigenic fungi; rising mycotoxin levels have already been observed in edible crops in various places in the world. Israeli law sets maximum permitted levels of major mycotoxins in several food categories such as nuts, milk, grains, and legumes. Given the growing knowledge in this field and progress in the analytical capacity to identify and quantify mycotoxins, NFS is planning to update and significantly expand existing legislation by setting maximum levels for additional types of mycotoxins and adding more food categories.
NFS is also planning to regulate heavy metal content in food by converting the existing guidelines into regulations. To promote such regulations, more in-depth collaboration with the Veterinary Services unit at the Ministry of Agriculture (MoAg) is needed. A survey conducted by this unit to identify and quantify heavy metals in food of animal origin indicated that the consumption of animal-based food may be a source of exposure to heavy metals. In 2018, arsenic residues were found in about 65% of samples of pond-bred fish and mercury was found in 49% of the samples (at levels lower than the permitted maximum). In samples of seafish, numerous arsenic exceedances were found and residues of cadmium and mercury were detected in about 50% of the samples (at levels below the permitted maximum). Residues of cadmium (below the permitted maximum) were also found in 98% of turkey samples and over 40% of fattened poultry samples.5 To account for potential exposure to heavy metals in plant-based and animal-based foods, risk assessment based on data collected by different regulatory agencies (MoH and MoAg) is needed.
Dioxins are byproducts of uncontrolled combustion including those in industrial processes. Dioxins have been found everywhere including soil, air, water, precipitation, and food. Prolonged exposure to dioxins is associated with immunotoxic effects and adverse effects on nervous system development, the endocrine system, fertility, and the risk of cancer. The most recent published survey on dioxins in food in Israel was published in 2013. Based on findings of that survey, average adult exposure was calculated for dioxins, furans and dioxin-like PCBs. NFS is planning to conduct a new survey to identify and quantify dioxins in food in Israel and to perform an exposure assessment based on the results of the survey.
Another goal is to submit data from surveys on food contaminants in Israel to international databases such as that of the World Health Organization (WHO), which includes monitoring data on food contaminants. The database yields information—for governments, the Codex Alimentarius Commission and other relevant institutions, and the general public—on levels and trends of food contaminants, their contribution to total human exposure, and their implications for public health and international commerce. NFS has begun to align data on food contaminants sampled in Israel with the format of the WHO database and plans to submit data to this international database regularly.
PFAS are a group of man-made chemicals that have been used for many years in a wide range of industries worldwide. They are very persistent in the environment and are not metabolized in the human body; therefore they accumulate over time. Prolonged exposure to PFAS may lead to adverse health effects including high cholesterol, thyroid disease, immunotoxic effects, and certain types of cancer. The food we consume may contain PFAS that originates in polluted soil, animals’ drinking water, irrigation water, food packaging, or food processing equipment that contains these substances. While preliminary data is being collected on PFAS contamination in drinking water in Israel, no data on PFAS in food are available. A survey to measure the levels of PFAS in food in Israel is planned.
This chapter and all other chapters in the report was written by a team of scientists and professionals from the Ministry of Health, in collaboration with Environment and Health Fund.
(1) Solanki, M. K., Abdelfattah, A., Britzi, M., Zakin, V., Wisniewski, M., Droby, S., & Sionov, E. (2019). Shifts in the composition of the microbiota of stored wheat grains in response to fumigation. Frontiers in Microbiology, 10, 1098. https://doi.org/10.3389/fmicb.2019.01098
(2) Shimshoni, J. A., Cuneah, O., Sulyok, M., Krska, R., Sionov, E., Barel, S., & Meller Harel, Y. (2017). Newly discovered ergot alkaloids in Sorghum ergot Claviceps africana occurring for the first time in Israel. Food Chemistry, 219, 459–467. https://doi.org/10.1016/j.foodchem.2016.09.182
(3) Sadhasivam, S., Britzi, M., Zakin, V., Kostyukovsky, M., Trostanetsky, A., Quinn, E., & Sionov, E. (2017). Rapid detection and identification of mycotoxigenic fungi and mycotoxins in stored wheat grain. Toxins, 9(10), 302. https://doi.org/10.3390/toxins9100302
(4) Bommuraj, V., Chen, Y., Gal, O., Ben Ari, J., Kertsnus-Banchik, E., Barel, S., & Shimshoni, J. A. (2020). Human pharmaceutical and pesticide residues in Israeli dairy milk in association with dietary risk assessment. Food Additives & Contaminants. Part B, Surveillance, 1–11. https://doi.org/10.1080/19393210.2020.1764114
(5) Israel Ministry of Agriculture and Rural Development, Veterinary and Livestock Health Services Unit (2019). 2016-2018 Report (Hebrew). https://www.moag.gov.il/vet/dochot-shnatiim/Documents/doch_shnati_2016-2018.pdf.pdf (retrieved June 2020).