Examples of biological hazards are viruses, disease-causing bacteria, prions and parasites. Some of these organisms are ubiquitous. These hazards are of important concern and are usually caused by poor sanitation, poor personal hygiene, contaminated ingredients, improper cooling or heating, etc.
• Bacteria: Some of the bacteria, such as lactic acid bacteria are beneficial and play an important role in many foods such as yoghurt, sauerkraut, sour beer, etc. while some are pathogenic, thereby causing food infections and intoxication, e.g. Clostridium botulinum, Bacillus cereus, pathogenic Escherichia coli, Streptococcus pyogenes, etc. The activity of some bacteria on food also leads to food spoilage, e.g. Acinetobacter, Pseudomonas and Moraxella spp cause meat spoilage.
• Viruses: Significant numbers of viruses can cause food-borne illness. The viruses are smaller in size, cannot grow and reproduce without a host, are incomplete cells and do not multiply in foods. Consuming a food with only a few viral particles is sufficient to cause an illness. Therefore, viruses are transmitted through faecal contaminated water or contact with sewage. Undercooked and raw sea foods such as scallops, mussels, clam, oysters and shellfish are the most frequently encountered foods carrying food-borne viral diseases.
• Parasites: Parasites depend on a host for survival and derive their food at the expense of their host. The most common food-borne parasites are Anisakis simplex and Cryptosporidium parvum, which are all protozoa or single-celled organisms.
8.2.2 Chemical Safety of Foods
Agricultural chemicals, such as pesticides, antibiotic, fertilizers, drugs, allergens, naturally occurring toxins and food additives are all chemical hazards. The inappropriate use of animal drugs may lead to the presence of residues in the tissues of slaughtered animals, which can be harmful to consumers. The pesticides include herbicides, insecticides, fungicides, rodenticides and disinfectants, which are used to control weeds, insects, fungi, rodents and microorganisms, respectively. It is estimated that nearly three-quarters of the pesticides are used in agriculture (mainly during the growing stages of crops). Pesticides are also used during the storage and transportation of commodities.
In addition to pesticides, which are artificial chemicals, the food chain also contains several naturally occurring toxins. Examples of naturally occurring toxins are solanine in potato, gossypol in cotton seed, hydrogen cyanide in cassava, caffeine in coffee, etc. In addition, food products are usually packaged to make them acceptable, safe and appealing to consumers but some chemical hazards may be present in foods due to packaging, residual monomers, production chemicals (e.g. lubricants) and packaging ink. The 4-Methylbenzophenone was reported to have contaminated a packaged food in Germany in 2009. It was found in breakfast cereals and other foods to the proportion of 5 mg/kg, and its source was the printing ink on the outside of the carton.
Mycotoxins are chemical hazards that have been of public health concern; they are secondary metabolites of fungi which may cause both chronic and acute toxic effects in man and animals such as carcinogenic, mutagenic, teratogenic and estrogenic effects (Bankole and Adebanjo, 2003). Mycotoxins have attracted world-wide attention due to the significant losses associated with their impact on human and animal health, and its effect on the economy in terms of food supply (Bhat and Vashanti, 1999). The five agriculturally significant toxins from fungi are aflatoxins, ochratoxin A, fumonisins, deoxynivanelol and zearalenone (IARC, 1993). Some are produced during and immediately after harvest, while some are produced predominantly during storage (Bhat and Vasanthi, 2003). Among the mycotoxins, aflatoxin is the most significant, because it is commonly found in foods in higher concentrations than others. The examples of some outbreaks due to chemical hazards are listed in Table 8.1.
Table 8.1 Examples of some outbreak due to chemical hazards
S. No. | Outbreaks | Year | Country | Reference
1 | Pyrrolizidine alkaloids | 1920 | South Africa | Kakar (2010)
2 | Acute aflatoxicosis | 2004 | Kenya | Azziz et al. (2005)
3 | Chemical intoxication due to consumption of seed beans and maize | 2008 | Nigeria | WHO (2014)
4 | Pesticide residues outbreak from cabbage and other vegetables | Senegal | WHO (2014)
5 | Scombroid fish poisoning | 2010 | Dakar, Senegal | Demoncheaux et al. (2012)
8.2.3 Physical Safety of Foods
Physical hazards are foreign objects such as insects, dirt, jewellery, pieces of metal, wood, plastic, glass, insect parts, machine filings, etc. that inadvertently get into a food and could cause harm to someone eating that food. Because it is economically impractical, and sometimes impossible to grow, harvest or process raw products that are totally free of natural defects, there are established maximum levels for natural or unavoidable defects, which are called Food Defect Action Levels.
By understanding of how to reduce or eliminate food hazards, it is then possible to set up food safety controls, which may lower the risks to consumers.
8.3 Hazard Analysis Critical Control Point (HACCP)
The hazard analysis critical control point (HACCP) is a systematic approach to the identification, assessment and control of hazards. The system offers a rational approach to the control of microbiological hazards in foods and avoids many weaknesses inherent in the inspectional approach and circumvents the shortcomings of reliance on microbiological testing. By focusing attention on the factors that directly affect the safety of a food, it eliminates wasteful use of resources on extraneous considerations, while ensuring that the desired safety and quality levels are met and maintained (Bryan, 1992). It is applicable to all phases of food production and considered as a proactive tool that focuses on preventive measures rather than end product testing.
8.3.1 Pre Steps for HACCP
Prerequisite programmes involve several steps and procedures to provide a safe environment and condition for the production of foods. The prerequisite programmes include:
1. Assemble HACCP team: It is also critical to use a multidisciplinary team to develop the programme, especially for conducting risk assessment and determining critical control points. The team should be trained in HACCP and include members with expertise in microbiology, production, engineering, chemistry and food technology. Where such expertise is not available on site, expert advice could be obtained from other sources.
2. Describe the product: A full description of the product should be drawn up, including relevant safety information about such as composition, how the product is to be packaged, labelling instructions, how the product is to be used, target groups, shelf life, conditions of storage, method of distribution, etc.
3. Identify intended use: The intended use is based on the expected uses of the product by the end user or consumer. In specific cases, vulnerable groups of the population, for example, institutional feeding, may have to be considered.
4. Construct flow diagram: The flow diagram should be constructed by the HACCP team. Through the diagram, it is easier to identify routes of potential contamination and to discuss and develop methods of control among the HACCP team. The process flow diagram will identify the important processing steps used in the production of the specific product being assessed.