Chlorates in drinking water-and thus, in food and beverages-present health risks. Four years after Efsa’s warning about the dangers to infants and children, the Commission defines the limits to be applied on different categories of food and beverages. ABC to follow.
Chlorates in the food chain. Drinking water, food and beverages
Chlorates are inorganic byproducts of chemical disinfection of water by chlorine and its compounds (chlorine dioxide, hypochlorite). Their formation is influenced by the type and dose of the disinfectant used and its residual action (disinfection residue). As well as by other factors such as pH and temperature, the constituents of water, and the concentration and properties of organic matter therein.
Chlorate in foods can be residual due to several causes:
– potable water
from the water supply network, used in processing (starting with washing of fruits and vegetables and agricultural raw materials and packaging),
– process waters when subjected to chlorination to lower their microbiological contamination levels (particularly when they come from wells),
–
carry-over
of biocide residues used to disinfect food processing machinery, utensils and surfaces,
– Processing aids and additives (not allowed in EU) on flours, carotenoids and other natural pigments, bleaching agent for modified starches. Chlorine and compounds can be used in the processing of paper and paperboard for packaging. (1)
Some pesticides (with herbicidal, fungicidal and desiccant functions) in turn contain sodium chlorate. Their use in the EU-but not in other countries from which Europe imports agri-foodstuffs-was banned in 2008 (effective 10.5.10).
Chlorites and chlorates, rules (disapplied) in place
Chlorites, as well as chlorates, are nonvolatile by-products derived from disinfection with chlorine dioxide (DBPs, Disinfection By-Products). The World Health Organization (WHO) has recommended a threshold for chlorates and chlorites in drinking water (0.7 mg/l). (2) In contrast, the European regulation setting maximum residue limits (MRLs) for pesticides in food and feed establishes a general limit of 0.01 mg/kg, which applies to all substances-such as chlorites and chlorates-for which no specific threshold is established. (3)
However, drinking water itself falls under the definition of food, and it is inconceivable that a limit of chemical contamination 70 times higher than that allowed on the generality of food should be tolerated on it. (4) This last strict limit, on the other hand, refers to the presence of chlorate residues that derive from pesticides and not also from various other sources. (5) And while it is the drinking process water itself that is the first source of contamination, it is on the other hand impossible to distinguish among the different sources of chlorates the share-part that may come from pesticide residues in agriculture (meanwhile banned in the EU).
Thus, the rules in place are both contradictory and misapplied at the same time. Out of 1087 samples of fruits, vegetables and cereals taken throughout Germany in 2012-2013, 266 revealed the presence of chlorates ranging from 0.01 to 0.27 mg/kg. With an average contamination level of the substance-positive samples, 0.022 mg/kg, just over twice the legal limit. The highest levels included U.S. grapefruits, Ugandan chilies, and various commodities from Cambodia (beans, broccoli, basil, and cilantro). (6)
The European Commission therefore commissioned the European Food Safety Authority (Efsa) to conduct an analysis of the presence of chlorates in food and the possible public health risks associated with its exposure.
Chlorates in food, Efsa’s scientific assessment
EFSA completed its investigation in 2015, publishing a scientific assessment where it found that current levels of chlorate in drinking water and food are too high compared to the food safety targets set in Europe. With negative impact, in particular, on the health of infants and children.
‘
The inhibition of iodine intake
in humans has been identified as the critical effect for chronic chlorate exposure. (…) Methemoglobin formation has been identified as the critical acute effect of chlorate. (…) Chronic exposures are of particular concern in younger age groups with mild or moderate iodine deficiency.
Assuming a chlorate concentration of 0.7 mg/kg for all food and drinking water consumed in a day, acute exposures would increase to about 5-fold and ARfD (Acute Reference Dose) in infants and children and, at the 95th percentile, in other minors and adults‘ as well. (7)
Previous studies cited by WHO show a relationship between drinking water quality and the occurrence of prostate, bowel and rectal cancer. Nine percent of all cases of prostate cancer and 15 percent of rectal cancer are attributed to chlorinated byproducts of drinking water (Morris, 1992). Another study showed the significantly increased risk of bladder cancer (1.8-fold increase) following prolonged exposure (30 years) to byproducts of chlorine- or chloramine-treated drinking water (Mc Gehinn, 1993).
Other studies confirm that there is a relationship between long-term exposure to disinfection byproducts and the risk of prostate cancer (Kogevinas, 2003).
A large study conducted in Norway between 1995 and 1998, which considered 285,631 births, then associated exposure to disinfection byproducts during pregnancy and birth disorders (heart, respiratory system and urinary tract), with increased risk following higher exposures. (8)
Chlorate comes mainly, according to Efsa, from drinking water, which is by far the main contributor. As well as from chlorine-based disinfectants, which are widely used in compliance with current regulations to treat water and process food.
Chlorates, new EU limits on the way
Following the EFSA opinion
the European Commission launched an action plan.
General. With the twin goals of reducing dietary exposure to chlorates and solving the problem of systematic noncompliance with MRLs under the Pesticide Regulation. The action plan includes:
– The setting of a maximum level of chlorate in drinking water,
– The recommendation of good food hygiene practices to reduce chlorate from chlorinated disinfectants,
– The setting of MRLs for chlorate in foods,
– The retention of the more restrictive limit (0.01 mg/kg) for foods for infants and young children.
In January 2019 , the European Commission finally presented a regulatory scheme to set MRLs of chlorates for specific food categories. (9) The proposal is based on the monitoring done by EFSA between 2014 and 2018 and aims to set provisional MRLs for chlorates, according to the ALARA(As Low As Reasonably Achievable) principle. That is, at 95 percent of occurrence data reflecting levels that are realistically achievable by applying good hygiene practices.
The provisional limits will be subject to review within five years of the publication of the proposed regulation. In the light of further progress made by food business operators to reduce contamination levels, or at any time when new information and data are available that warrants revision.
It is noted how the framing of this issue in pesticide legislation is ontologically problematic, since the contaminant under consideration-as pointed out by Efsa-comes from a plurality of sources. All the more so since the release of chlorine-derived substances and its compounds into the environment is not due (at least in Europe, for the past 9 years) to the use of pesticides in agriculture. As much as water chlorination, in publicly operated water systems in the first place.
Chlorates, prevention and
compliance
Prevention is the basis of the system proposed by the WHO in the so-called ‘water safety plans‘ on which the European water quality framework itself is based (dir. 98/83/EC). Therefore, work should be done on identifying potential sources of contamination to remove the causes of noncompliance by first removing organic material from the water before applying disinfection.
A number of techniques (micro-, ultra-, nano-filtration, electromagnetic and biophysical treatments) have been added to the classical methods of treating water for human consumption in recent decades. Which have, in terms of sanitation, some advantages including reliability and practicality of use, less need for the use of chemicals. In short, in the nearly two centuries since the start of chlorine experimentation in water systems, research has continued (although the ‘classical method’ is still dominant).
Sanitization of pipelines using chlorine compounds among other things, in addition to presenting the food safety problems mentioned above, has significant costs for purchasing and handling the substances. And it is precisely in Italy that systems have been developed that can reduce chemical disinfection even dramatically. Thanks to fluid-contact sensors that analyze the bacterial frequency along the line in real time. In this way, the controller activates chlorination only when the bacteria form colony (before it matures and the pathogens detach from the biofilm), for as long as is strictly necessary, rather than on a continuous cycle.
Dario Dongo
Notes
(1) Cf. EPA, Environment Protection Agency, USA (1983), ‘Sodium chlorate: exemption from the requirement of a tolerance‘. CMA, Chemical Manufacturers Association, USA (1989), ‘A review of the uses, chemistry and health effects of chlorine dioxide and the chlorite ion’. FDA, Food & Drink Administration, USA (1990), ‘Food and drugs. Vol. 21, Parts 170-179
(2) The WHO guidelines, in their fourth revision (2011), at.
https://www.who.int/water_sanitation_health/publications/2011/dwq_guidelines/en/
(3) See reg. EC 396/05, ‘on maximum residue levels of pesticides in or on food and feed of plant and animal origin‘, consolidated text
(4) See reg. EC 178/02, General Food Law, Article 2
(5) See reg. EC 396/05, art. 14.2.b
(6) See Ingrid Kaufmann-Horlacher, Ellen Scherbaum, Dr. Diana Stroher-Kolberg, Cristin Wildgrube ‘Chlorate Residues in Plant-Based Food: Origin Unknown‘. CCVA Stuttgart (2014)
(7) EFSA Panel on Contaminants in the food chain (CONT). (2015). ‘
Risks for public health related to the presence of chlorate in food.
‘.
https://doi.org/10.2903/j.efsa.2015.4135
(8) Cf. WHO, (2005), ‘Chlorite and Chlorate in Drinking-water, Background document for development of WHO Guidelines for Drinking-water Quality‘
(9) By supplementing reg. EC 396/05, Annex III, Part A, with a special column of dedicated to ‘chlorate‘ in the various food categories
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
