Heavy metals and potential health risk assessment of Lactuca sativa and Daucus carrota from soil treated with organic manures and chemical fertilizer.

The large-scale production of food crops with heavy application of chemical fertilizers in the effort to meet the astronomical increase in food demands may be counterproductive to the goal of food security. This study investigated the effect of different soil treatments on the levels of heavy metals (Cr, Cu, Fe, Ni, Pb, and Zn) in two types of vegetables Lactuca sativa (lettuce) and Daucus carrota (carrot). The potential carcinogenic and non-carcinogenic health risks from their consumption were also evaluated. Planting experiment was set up in a randomized block design, with different soil treatments of soil + cow dung (CD), soil + sewage sludge (SS), soil + chemical fertilizer (nitrogen-phosphorus-potassium (NPK)), and untreated soil (UNTRD). The vegetables were harvested at maturity, washed with distilled water, and subjected to an acid digestion process before the levels of heavy metals were measured by inductively coupled plasma spectrometry (ICP-MS). The mean concentrations of the metals in the vegetables across all treatments were below the maximum permissible limits. The pattern of heavy metal accumulation by the vegetables suggested that the lettuce from SS treatment accumulated higher concentrations of heavy metals like Cr (0.20 mg/kg), Cu (3.91 mg/kg), Ni (0.33 mg/kg), and Zn (20.44 mg/kg) than carrot, with highest concentrations of Fe (90.89 mg/kg) and Pb (0.16 mg/kg) recorded in lettuce from NPK treatment. The bioaccumulation factor (BAF) showed that lettuce, a leafy vegetable, has bioaccumulated more heavy metals than carrot, a root vegetable. The BAF was generally below the threshold value of 1 in both vegetables, except in lettuce from NPK and CD treatments and carrot from NPK treatments, with BAF values of 1.6, 1.69, and 1.39, respectively. The cancer risk assessment factors were well below the unacceptable maximum range of 10-4 suggesting that consuming these vegetables might not expose an individual to potential risk of cancer development. The hazard quotient estimations were below the threshold values of 1 for all heavy metals; however, the hazard index (HI) values of 1.27 and 1.58 for lettuce from NPK and SS treatments indicate a potential non-carcinogenic health risk to consumers from intake of all the heavy metals.

Trace metals concentrations in fresh milk from dairy farms and stores: An assessment of human health risk.

Milk may be consumed daily for the supply of essential nutrients in the body, however, depending on the source, milk may contain different concentrations of trace metals. The present study investigated the presence of trace metals in fresh milk purchased from different dairy farms and stores to determine the possible health risks to humans. A total of 15 fresh milk samples were purchased from various dairy farms (7 fresh milk samples) and stores (8 milk samples). Trace metals in collected milk samples were determined using Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The human health risk was determined through the Hazard Quotient (HQ), Carcinogenic and Non-carcinogenic Risk. The results showed the presence of trace metals in fresh milk stores in the following order Pb>As>Se>Cr>Ni. The highest concentration for all the elements was recorded in Mg from milk purchased from the stores and ranged from 3.37±0.16 mg/L to 4.70±0.43 mg/L. In all the milk samples analyzed, levels of As, Pb, Se, Cr, and other elements were within the acceptable range recommended by the World Health Organization (WHO). Differences obtained in the concentrations of trace metals from both the purchased milk samples and those from the dairy farms were not significant (p<0.05). The Estimated Daily Intake (EDI) and Hazard Quotient Index showed no potential health risk for each trace metal indicating no health risk for the milk consumers at this stage. The traces of trace metals in the milk samples suggest the need for regular monitoring of trace metals in milk samples because prolonged exposure to these trace metals may seriously endanger the health of consumers.

Blood lead concentrations in exposed forecourt attendants and taxi drivers in parts of South Africa.

BACKGROUND: Leaded fuel was banned in South Africa in 2006, in order to improve human health and reduce environmental pollution. Lead (Pb) has been suggested to contribute to the development of neurodegenerative disorders, and the role of respiratory exposure to Pb from petrol fumes should not be neglected in this context. In addition to Pb, petrol contains various harmful chemicals including other neurotoxic metals and hydrocarbons. OBJECTIVES AND METHODS: Here, we investigated concentrations of Pb and other metals in blood from petrol station forecourt attendants (n = 38), taxi drivers (n = 21), and unexposed controls (n = 36). Taxi drivers and forecourt attendants were divided into three groups each, based on number of years worked. A questionnaire was designed to investigate the health status of the participants. Blood samples were collected by medical professionals and analyzed for metal concentrations by ICP-MS. RESULTS: A positive correlation between number of years worked and Pb blood concentrations was found. The highest Pb concentration (60.2 µg/L) was observed in a forecourt attendant who had worked 11-20 years, and the average Pb concentration in this group (24.5 µg/L) was significantly (p < 0.05) higher than in forecourt attendants who had worked 2-5 years (10.4 µg/L). Some individuals had elevated concentrations of manganese, arsenic, cadmium, chromium and cobalt, yet not significantly elevated at the group level. The blood levels of arsenic appeared to be related to smoking. Mood swings, dizziness, headaches and tiredness were reported by the workers. CONCLUSION: Blood Pb concentrations in petrol station forecourt attendants and taxi drivers exposed to leaded petrol are elevated and correlate to exposure time. A health monitoring program should be erected for all individuals working in these industries, and preventive measures should be implemented to eliminate metal exposure from petrol.

Corrigendum to "Assessment of heavy metals and their human health risks in selected spices from South Africa" [Toxicol. Rep. 11 (2023) 216-220].

[This corrects the article DOI: 10.1016/j.toxrep.2023.09.008.].

Assessment of heavy metals and their human health risks in selected spices from South Africa.

The concerns of food safety are rising in developing countries such as South Africa as a result of heavy metal contamination of culinary herbs and spices. Spices and herbs are used for therapeutic purposes as well as flavoring and coloring food. Heavy metals in spices represent significant health risks due to their high toxicity in high quantities. A total of 20 spices samples were purchased from different registered shops, for heavy metals analysis. The samples were prepared, digested, and analyzed with an inductively coupled plasma mass spectrometer (ICP-MS). To ensure the method's accuracy, Polish Certified Reference Mixed Polish Herbs (INCT-MPH-2) from the Food and Drugs Control Center, Poland, was analyzed. The concentrations of Fe (32.22 ± 1.22-131.1 ± 3.26 mg/kg), As (ND to 0.12 ± 0.04 mg/kg), Cr (0.08 ± 0.01-3.2 ± 0.09 mg/kg), Pb (N.D - 0.21 ± 0.02 mg/kg) and Cd (ND to 0.14 ± 0.08 mg/kg) mg/kg were measured. The results revealed that the concentrations of Cr in all spice samples tested were much higher than the Maximum permissible limit (MPL) values. All spices in this study had THQ and HI values less than one, indicating that consumers will experience no potential health hazards from consuming specific metals through spices. However, continual scrutiny should be maintained.

An assessment of university students and staff perceptions regarding the use of human urine as a valuable soil nutrient in South Africa.

BACKGROUND: The declines in soil fertility associated with insufficient commercial fertilizers have resulted in the use of organic manure (human urine and faeces) as a source of fertilizers for production and cultivation of crop plants. The aim of this study was to assess perceptions of students and workers at the University of Limpopo (Medunsa Campus) regarding the fertilizing effect of urine. METHODS: A total of 225 questionnaires were administered to staff and students. The questionnaire sought to establish the knowledge, attitude and behavioural changes as regards the use of urine as a fertilizer for the cultivation of vegetables. RESULTS: Descriptive statistical analysis of the data indicated that 86.8% of the respondents were unaware of any human urine use as a fertilizer, 82.7% and 81.1% would not eat spinach and maize fertilized with urine respectively. Only 38.3% said they would eat vegetables fertilized with animal urine making it more tolerable as compared to human urine. Health reasons were given as the main reasons why respondents were unwilling to eat crops fertilized with human urine. However, 69.9% of the respondents [74.3% females, 69.9% students, 75.0% (27-36) age group] were willing to change their attitudes and unwillingness if they were better informed about the safety of human urine use for agricultural purposes. CONCLUSION: Education, awareness and reassurance on the importance and safety of urine would have to be done so that urine for agricultural purposes could become more acceptable to people.