Plant-Derived Commodities
Foods of plant origin can become contaminated by pathogenic bacteria and toxigenic molds. Climate change and meteorological factors such as temperature, humidity and precipitation infuence the contamination or infection of crops by such organisms (Uyttendaele et al. 2015), thus negatively impacting the safety of these produce either at pre- or post-harvest. In the recent decades, vegetables are increasingly consumed raw in salads and foodborne disease outbreaks have been associated with the consumption of fresh produce. Findings have shown that the risk of foodborne disease is directly related with the prevalence of bacteria on leafy green vegetables (LGVs), and that LGV contamination is influenced by environmental conditions. This statement is supported by the fact that about one-third of salmonellosis cases in several European countries can be associated with increased temperatures. For the salmonellosis cases in the subtropical and tropical regions of Australia, temperature and rainfall were the climatic factors responsible (Liu et al. 2013).
Cereals are a staple food widely consumed by human and also for feed production for poultry and cattle. Unfortunately, cereal crops are one of the most severely affected in terms of fungal diseases caused by pathogenic and mycotoxigenic fungi. Fungal growth, survival, interaction with plants and ability to produce mycotoxins highly depend on environmental factors, especially temperature and moisture. Climate change and variability has been found to have an impact on the prevalence of mycotoxigenic fungi in cereals and grains, and to induce the emergence of novel fungal genotypes with increased mycotoxin production (Moretti et al. 2018). According to the European Food Safety Authority (EFSA)’s Emerging Risks unit, mycotoxin contamination in maize due to climate change, is a potential emerging hazard with a risk of afatoxin contamination which is expected to increase (Uyttendaele et al. 2015).
The three fungal genera of importance involved in food spoilage and production of mycotoxins in nuts are Aspergillus, Fusarium and Penicillium. Several nuts such as peanuts, tree nuts and Brazil nuts are often susceptible to mycotoxins produced by toxigenic Aspergillus. The most common mycotoxins present in nuts are afatoxin and ochratoxin A. For mycotoxin to be present in food, there should have been favourable conditions for the growth of the toxigenic fungus and for the production of mycotoxin. However, infection by the toxigenic fungi is also dependent on whether the fungal species can grow before harvest or during drying and storage. Nuts are most likely to be infected by toxigenic fungi during development of the plant. Drought is favourable for infection of the plant and facilitates production of afatoxin at the preharvest stage. At the post-harvest stage, nuts can be infected by ochratoxin A that is produced by the toxigenic fungi A. ochraceus, A. carbonarius and A. niger. Peanuts are mainly affected by A. favus and A. parasiticus and become contaminated with afatoxin. The level of afatoxin produced in peanuts at the pre-harvest stage is greatly affected by spells of droughts. In humid tropics or following fooding, drying of peanuts in storage rooms is slower and hence the level of moisture is increased. This results in a large increase in afatoxin level at the post-harvest stage. Tree nuts such as almonds, pistachios, walnuts and brazil nuts are more susceptible to A. favus at the post-harvest stage and become contaminated with afatoxins. When the nuts are moist, their hulls undergo early splitting, thus allowing the entry of the fungus at the preharvest stage (Taniwaki et al. 2018).
Animal-Based Commodities
Climate change has an impact on the survivability of pathogens in the environment, on their migration pathways, on the presence of disease carriers and vectors as well as changes in the natural ecosystems. This increases the spread of animal diseases and the transfer of zoonotic pathogens from animals to humans. Climate change can impact zoonotic foodborne diseases both directly and indirectly. As climate change affects the living conditions of animals, this makes them more susceptible to bacterial and parasitic diseases. A bacterial syndrome, mastitis, is often detected in cattle herds due to exposure to intense cold, droughts, excessive humidity or heat (Tirado et al. 2010). In the poultry sector, the pathways infuenced by climate change that act as a threat to food safety are the increased susceptibility of the animals to diseases and the abundance of animals as reservoirs or vectors of zoonoses. Additionally, the use of veterinary drugs such as antibiotics can be passed down from the animal into the food in the form of antibiotic residues, thus exacerbating the problem of antibiotic resistance in humans (Lacetera 2019).
Approximately 8% of the world’s population relies on seafood as a source of food, income or family stability. However, there is insuffcient data about the effects of climate change on the safety of seafood. As a consequence of climate change, hazards of concern to seafood can be in a chemical or biological form. Biological factors that may impair seafood safety include both allochthonous human pathogens that accidentally contaminate seawater as well as autochthonous pathogens of marine origin. Chemical hazards involve algal toxins and toxic metals. The main results of climatic changes projected to affect seafood safety are heating of the upper ocean, an accelerated water cycle, ocean acidifcation, increased stratifcation, and changes in the degree of weather disturbances and rainfall patterns (Kniel and Spanninger 2017).
References
Lacetera, N. (2019). Impact of climate change on animal health and welfare. Animal Frontiers, 9(1), 26–31.
Liu, C., Hofstra, N., & Franz, E. (2013). Impacts of climate change on the microbial safety of pre-harvest leafy green vegetables as indicated by Escherichia coli O157 and Salmonella spp. The International Journal of Food Microbiology, 163, 119–128.
Kniel, K. E., & Spanninger, P. (2017). Preharvest food safety under the infuence of a changing climate. Microbiol Spectrum, 5(2), PFS-0015- 2016.
Taniwaki, M. H., Pitt, J. I., & Magan, N. (2018). Aspergillus species and mycotoxins: Occurrence and importance in major food commodities. Current Opinion in Food Science, 23, 38–43.
Tirado, M. C., Clarke, R., Jaykus, L. A., McQuatters-Gollop, A., & Frank, J. M. (2010). Climate change and food safety: A review. Food Research International, 43, 1745–1765.
Uyttendaele, M., Liu, C., & Hofstra, N. (2015). Special issue on the impacts of climate change on food safety. Food Research International, 68, 1–6.