The impacts of climate change could potentially increase foodborne disease, according to the Food and Agriculture Organization of the United Nations (FAO).

An FAO publication has identified and attempted to quantify some current and anticipated food safety issues associated with climate change.

Hazards considered are foodborne pathogens and parasites, harmful algal blooms, pesticides, mycotoxins and heavy metals with focus on methylmercury. The report also covers the benefits of forward-looking approaches such as horizon scanning and foresight, which should aid in anticipating future challenges instead of reacting to them and help build resilient food systems that can be updated when there is more knowledge. Alongside surveillance techniques, these tools will help countries keep food safe.

FAO said numerous gaps remain in the understanding of how climate change can affect various food safety issues. It has complex associations with a number of hazards, potentially leading to increased risks of foodborne illnesses. In 2019, a World Health Organization (WHO) report warned climate change was likely to have a considerable impact on food safety.

Impact on foodborne pathogens
Changes in food systems and increased globalization of supply means populations worldwide are at risk of exposure to various food safety hazards. Level of impact is likely to vary widely by pathogen and geography.

“Climate change and elongating food chains increase the likelihood of contamination issues arising from foodborne pathogens and parasites making it important to increase awareness of this in order to manage public health risks,” according to the report.

Changes in temperature, precipitation and other environmental factors are expected to affect the geographic distribution and persistence of foodborne pathogens and parasites. For example, there is evidence to link increasing temperatures to higher incidences of infections by several pathogens such as Salmonella and Campylobacter in different parts of the world.

Pathogens with low-infective doses such as Shigella and E. coli O157:H7 and those with high persistence in the environment like Salmonella are more likely to cause large outbreaks aided by environmental changes from climate change.

Increases in daily temperatures could result in more food poisoning cases and changes in precipitation patterns are also likely to influence incidence of foodborne diseases, according to the report.

Vibrio and parasites
Some species of Vibrio could become more common and certain Vibrio spp. also produce tetrodotoxin, a potent neurotoxin, which can be found in shellfish.

Climate change is also affecting the quality of water globally by exacerbating conditions that lead to algal blooms. There is evidence to show it is enabling various species that form harmful algal blooms to expand to new areas, most of which are not prepared to meet the challenges associated with their detection and surveillance, so it is putting public health at risk.

“Lack of appropriate regulatory frameworks in a number of countries often allows food contaminated with phycotoxins to reach the wider market. Greater investments are needed in the development of capacities for early detection, monitoring and data sharing in such countries,” said the report.

Many foodborne parasites have complicated life cycles spanning multiple hosts, and there are dynamic relationships among parasites, hosts and their environments, which are likely to decline or increase according to the sensitivity to climate change.

Positive associations between rising monthly temperatures and giardiasis illnesses — diarrheal disease caused by the microscopic parasite Giardia — have been reported in the U.S. and New Zealand. An association between more rainfall and a rise in cryptosporidium cases has been noted in New Zealand. A temperature increase in Mexico is associated with an increase in prevalence of toxoplasmosis. There is a predicted risk of more infections caused by foodborne Fasciola hepatica in the United Kingdom and Northern Ireland, scientists reported.

Heavy metals and mycotoxins
Heavy metal pollution and effects on public health are a “neglected area” that requires “urgent” attention, as stated by the report.

Rising soil temperatures are expected to facilitate uptake of heavy metals by plants including, arsenic in rice. Heavy metals of public health concern are lead, chromium, cadmium, mercury and arsenic, which are considered systemic toxicants even at low levels of exposure.

Mycotoxin contamination in staple crops is a major concern and barrier to international trade. Mycotoxins generated a high number of reported illnesses with 569 reports by the European Commission’s Rapid alert System for Food and Feed (RASFF) network in 2018. Aflatoxins, once considered solely an issue with imported food, are now a chronic problem in some parts of Europe.

Aflatoxins and fumonisins are common contaminants in cereals and cereal-based foods. Some of the important factors that influence increased mycotoxin production – temperature, relative humidity and crop damage by pests – are affected by climate change. As food chains grow longer, the risk of aflatoxin and ochratoxin production in food may increase due to inadequate storage and transport conditions across changing climate zones, according to the report.

Consumer choice and trends
Climate change is altering the geographic distribution and life cycles of pests, which in turn is expected to change pesticide application trends.

Food authorities, according to the report, must be mindful that consumer choices and dietary patterns are changing. Prolonged warmer seasons influence consumers’ behavior and practices to do with food handling and storage. A rise in ambient temperatures will also effect all aspects of the cold chain, from initial chilling or freezing of food to transport, storage and retail display.

Cellular agriculture — through which food items are produced from cultures of cells taken from plants, animals, fungi or microbes — is gaining more attention. However, the techniques prompt food fraud concerns and require appropriate processes for quality control.

Temperature fluctuations associated with the extrusion process in 3D printing may promote growth of microbial pathogens. More research into the storage and shelf-life of 3D-printed food is needed., according to the report.

Insect consumption raises food safety issues including microbial such as bacterial, viral and fungal  hazards; chemical hazards such as pesticides, antibiotics and heavy metal; toxic compounds that insects produce; potential allergens; and a lack of cross-border regulatory oversight.