Chemical food contaminants, or “food pollutants”, refers to substances that are unintentionally added to food and whose presence derives from pollution during the process of growing, producing, processing, preparing, handling, packing, transporting, storing or maintaining food. These pollutants can be industrial and/or environmental contaminants (such as heavy metals, dioxins, or PCBs), natural toxins (such as mycotoxins), or toxins that are created during processing (such as acrylamide). This chapter primarily addresses those chemical food contaminants specifically defined as "food pollutants" and additional substances such as food contact materials, antibiotics, and hormones.
Exposure to food pollutants is linked to a wide range of acute and chronic negative health effects, including impacts on cognitive development (heavy metals), cancer (mycotoxins and dioxins), and damage to the reproductive system (dioxins). Long-term exposure to food pollutants – even at very low concentrations – can have negative health effects, particularly among sensitive subpopulations (pregnant women, children, and the elderly).
Current food pollutant regulations date from 1958 and 1983. Specific standards, regulations, and guidelines have been developed for those foods that are likely to have high concentrations of contaminants. These regulations, including those for mercury content in fish (1979), are due to be updated in 2014. In addition, specific regulations on mycotoxins in food (1996) and specific guidelines for heavy metals, melamine, polycyclic aromatic hydrocarbons (PAHs), and radionuclides in food were updated in 2013.
Maximum levels of contaminants in food are determined in accordance with the “as low as reasonably achievable” (ALARA) principle and the risk assessments conducted by the Risk Management Unit of the National Food Service at the Ministry of Health (MoH). The main parameters for determining maximum levels of contaminants are risk assessments and recommendations and regulations from international organizations such as the World Health Organization (WHO) (the Codex Alimentarious Commission), the European Union, and the US Food and Drug Administration. The MoH conducts supervision and enforcement in accordance with its authority, including destroying food that is deemed dangerous for consumption.
Regulations from 1977 restrict use of potentially hazardous materials in food containers and include specific restrictions regarding the use of polyvinyl chloride in food containers.
Regulations from 2004 passed by the Ministry of Environmental Protection (MoEP) establish maximum bacterial levels and heavy metal content of sludge, including sludge applied to agricultural land where produce for human consumption is grown. Regulations from 2010 (passed by the MoH and the MoEP) establish maximum bacterial levels and heavy metal content of treated wastewater used for agricultural irrigation.
Data on Chemical Food Contaminants
The MoH routinely samples imported food products at quarantine stations. Products that are more sensitive to food contaminants or in which excess levels of contaminants have been found in the past are inspected more frequently than products that are less sensitive to these pollutants. In addition, ongoing monitoring of mycotoxins is conducted in the framework of an annual sampling program. Testing for other food pollutants is conducted in periodic surveys, based on risk evaluation. If the survey shows an excess level of contaminants, sampling is expanded as needed. The Veterinary Services at the Ministry of Agriculture (MoAg) conduct annual surveys of animal products according to regulations from 2000. A professional steering committee coordinated jointly by the MoH and the MoAg determines the structure of the surveys. The summaries of the findings from the various surveys are available to the public on each ministry's website.
In 2013, the MoH in conjunction with the MoAg conducted a follow-up survey on the presence of dioxins, furans, and PCB-like dioxins in food. One hundred and ten samples of animal products and ten samples of animal feed were tested. Low or very low levels of the substances (up to one picogram per gram of fat) were detected in 87% of the samples. The average level of dioxins found relative to the maximum permitted level was 16.3% in milk and milk products, 3.4% in fish, 11.8% in meat and in beef fat, 6.4% in beef liver, 33.1% in chicken liver, and 72% in eggs. Overall dietary exposure was calculated at 56.2% of the tolerable intake as established by the WHO (120 pg/day for 60 kg adult). Compared to the previous survey results from 2008, there was a significant decrease in the level of exposure to dioxins, furans, and PCB-like dioxins from food in Israel. The joint survey in 2013 by the National Food Service and MoAg found high levels of dioxins in sampled eggs at 2.2 times the maximum permitted level. In the wake of these findings, additional testing, and an assessment of health risks, the MoH decided to halt the marketing of eggs from four suspected chicken farms.
In addition, it was decided to expand the testing of eggs, as well as testing of animal feed from various farms. The annual plan of the National Food Service also includes an additional survey of dioxins in all animal food products, using Chemical Activated Luciferase Gene Expression Assays.
The MoAg and the National Food Service at the MoH are currently examining the sources of dioxin contamination in food by testing samples across the food chain. The results of the study are likely to indicate those points along the production chain that can be improved in order to reduce the levels of dioxins and PCBs in food.
In the annual survey published by the Veterinary Services for 2011–2012, animal products from eight types of animals were tested for chemical food contaminant residues. Of the samples tested, 11 (1.8%) contained cadmium (in liver) above the maximum permitted level. Higherthan- permitted levels of aflatoxins were found in 25 (4.3%) of the 573 milk samples tested. The survey did not find levels of PCBs, lead, or mercury above the maximum permitted level in any of the tested samples. Results on arsenic levels were not reported. Pollutants were found in some of the samples: lead in milk products (3%); mercury in fish (58%); and cadmium in chicken liver (46%).
Hormones, including diethylstilbestrone, estradione, estradiol, and progesterone were tested in various samples of fish, poultry, and milk and none were detected in any of the samples. Pharmaceuticals were detected at above the permitted residue levels in more than 2% of samples for: tetracycline in sheep (6/230), ionophores in chicken (7/240), nicarbazin in chicken (8/300), sulfonamides in turkey (3/142), clopidol in eggs (54/300), ionophores in eggs (54/274), and tetracycline in eggs (5/170). In general, pharmaceutical compounds were detected at levels below the maximum permitted. Levels above the maximum permitted were detected in fewer than 1% of samples.
The National Food Service conducts ongoing monitoring of mycotoxins in food sold in Israel, in accordance with an annual plan and via the health bureaus of the MoH. Between the years 2008–2012, over 1,600 samples were analyzed so as to identify and quantify aflatoxins and ochratoxin A. It should be emphasized that the samples were collected from food that was defined as potentially containing mycotoxins (spices, legumes, cereals, nuts, and milk). In general, excessive levels of mycotoxins were found primarily in spices, especially in paprika. A re-evaluation is currently underway on lowering the maximum permitted levels for some mycotoxins and for defining maximum permitted levels for additional mycotoxins and additional categories of food.
Data on Chemical Contaminants in Treated Wastewater and Produce Irrigated with Treated Wastewater
According to a Water Authority Report from 2009, based on measurements in 11 different wastewater treatment plants, the main chemicals detected in wastewater were pharmaceutical compounds (primarily carbamazepine) and the flame retardant trichloroethyl phosphate.
A 2012 survey of leafy vegetables and root vegetables irrigated with treated wastewater, conducted by the MoH in cooperation with the Hebrew University of Jerusalem showed that the pharmaceutical carbamazepine was detected in about 30% of samples. Levels were between 0.35 and 12.4 μg/kg. Pharmaceutical compounds were not detected in crops irrigated with drinking water. Carbamazepine and additional pharmaceutical compounds (for example, diclofenac and naproxen), as well as pesticides and flame retardants (including tris [3-chloropropyl] phosphate) were detected in wastewater samples. Bisphenol A (BPA) was not detected in any of the wastewater samples. In a 2011 survey of vegetables including carrots, onions, tomatoes and cucumbers, carbamazepine and triclosan were detected in 7 out of 27 samples. BPA and hormones (such as estrone, estriol and testosterone) were not detected in any of the samples.
Research on Chemical Contaminants in Food
Researchers at the Hebrew University of Jerusalem have published studies on plant uptake of pharmaceutical compounds from wastewater, including studies on carbamazepine uptake by cucumber plants using different soil types irrigated either with fresh water or reclaimed wastewater. Numerous research groups in Israel are studying the removal of pharmaceuticals and other compounds during the wastewater treatment process.
Progress and Challenges
- The methodology of the joint survey conducted by the MoH and the MoAg for examining animal-based food products was improved in 2012 and consequently the number of samples taken and the statistical power of the survey increased significantly.
- Legislation on animal feed was recently updated to address issues related to the inspection and control of manufacturing animal feed, including testing for animal feed contaminants that might be passed on to humans.
- The use of animal waste as fertilizer in agriculture is currently being jointly evaluated by the MoAg and the MoH. Control and supervision will be introduced as part of regulations for using organic waste in agriculture in order to address the issue of pollutants originating in untreated animal waste that can reach humans via contaminated agricultural produce.
- Biosolids (treated sewage sludge), and coal ash (coal combustion residuals), both of which are applied on agricultural land used to grow crops for human consumption, can potentially contain low levels of contaminants, including heavy metals, pharmaceuticals, and radiation. The MoH is evaluating levels of heavy metals and radiation in crops treated with coal ash.
- Over 75% of the domestic wastewater in Israel is recycled, mostly for agricultural use. There are currently no regulations or guidelines that address permitted levels of pharmaceuticals and other contaminants in water used for irrigation. Issues pertaining to the presence of pollutants in irrigation water such as well water, water from fishponds, and gray water are currently being re-evaluated.
- Although aluminum was not considered a toxic metal in the past, recent studies indicate a link between long-term consumption of high levels of aluminum and a negative impact on cognitive health endpoints. The National Food Service at the MoH is currently evaluating possible adverse health outcomes associated with aluminum exposure, with an emphasis on infant food. A wide range of baby foods will be tested for the presence of aluminum.
- During the years 2010–2013, the National Food Service at the MoH conducted surveys on the presence of heavy metals and dioxins, furans, and PCBs in food. In 2014, the National Food Service will test for the presence of polycyclic aromatic hydrocarbons in various food products. The Food Service plans to repeat a survey conducted ten years ago on phthalates in infant food and to continue to analyze mercury content in fish.
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) Codex Alimentarius, Netherlands Ministry of Economic Affairs. Codex Committee on Contaminants in Foods (CCCF).
http://www.codexalimentarius.org/committees-task-forces/en/?provide=committeeDetail&idList=39 (retrieved July 2014).
(2) Goldstein M., Shenker M., Chefetz B. (2014). Insights into the uptake processes of wastewater-borne pharmaceuticals by vegetables. Environmental Science and Technology, 48(10), 5593-5600.
http://www.environmental-health.huji.ac.il (retrieved July 2014).
(4) National Food Service, Israel Ministry of Health (2013). Guidelines for maximum permissible concentrations of heavy metals in food 2009 (Hebrew).
http://www.health.gov.il/UnitsOffice/HD/PH/FCS/Documents/Regulations/Reg_01022007.pdf (retrieved July 2014).
(5) National Food Services, Israel Ministry of Health (2013). Summary of dioxins and dioxin-like PCB compounds in food survey 2013 (Hebrew).
http://www.health.gov.il/PublicationsFiles/dioxine2013.pdf (retrieved July 2014).
(6) National Food Service, Israel Ministry of Health (2013). Summary results of monitoring mycotoxins in food in Israel 2008-2012 (Hebrew).
http://www.health.gov.il/PublicationsFiles/mycotoxins2008_2012.pdf (retrieved July 2014).
(7) National Food Services, Israel Ministry of Health (2008). Survey of dioxins and dioxin-like PCB compounds in food in Israel (Hebrew).
http://www.health.gov.il/PublicationsFiles/Dioxins2008.pdf (retrieved July 2014).
(8) Programme for the Promotion of Chemical Safety, World Health Organization. Persistent Organic Pollutants.
http://www.chem.unep.ch/pops/indxhtms/manexp12.html (retrieved July 2014).
(9) Shenker M., Harush D., Ben-Ari J., Chefetz B. (2011). Uptake of carbamazepine by cucumber plants: A case study related to irrigation with reclaimed wastewater. Chemosphere, 82(6), 905-910.