The effects of heavy metal exposure in agriculture soil on chlorophyll content of agriculture crops: A meta-analysis approach

Soil can be contaminated by the accumulation of heavy metals and metalloids through emissions from rapidly developing industrial areas. Due to the possibility of chemical change (speciation) and their bioavailability, the presence of toxic metals in the soil can greatly inhibit the biodegradation of organic contaminants. The researchers aimed to analyse the effect of heavy metal levels in agricultural soil on chlorophyll levels in agricultural crops through a meta-analysis method which is expected to provide results in the form of a summary of data that already exists in journals that have been published so far. Here we present a meta-analysis of 6 studies (56 data collected) published between 1997 and 2020 that reported the effects of heavy metal content on plant chlorophyll content. Based on the meta-analysis of the effect of heavy metal exposure in agricultural soil on the chlorophyll content of agricultural crops, the value “effect size overall” was -0.285 in the range of -0.380 to -0.190, where most of the values “effect size” were on the left. Plants growing on soil contaminated with heavy metals result in decreased growth due to changes in physiological and biochemical activities, especially when heavy metals inhibit plant growth and development. Furthermore, environmental risk assessment due to mercury exposure is very important to control the transport and accumulation of mercury in the biosphere to reduce the impact of mercury on the environment.

Life History Traits in Two Drosophila Species Differently Affected by Microbiota Diversity under Lead Exposure

Life history traits determine the persistence and reproduction of each species. Factors that can affect life history traits are numerous and can be of different origin. We investigated the influence of population origin and heavy metal exposure on microbiota diversity and two life history traits, egg-to-adult viability and developmental time, in Drosophila melanogaster and Drosophila subobscura, grown in the laboratory on a lead (II) acetate-saturated substrate. We used 24 samples, 8 larval and 16 adult samples (two species × two substrates × two populations × two sexes). The composition of microbiota was determined by sequencing (NGS) of the V3–V4 variable regions of the 16S rRNA gene. The population origin showed a significant influence on life history traits, though each trait in the two species was affected differentially. Reduced viability in D. melanogaster could be a cost of fast development, decrease in Lactobacillus abundance and the presence of Wolbachia. The heavy metal exposure in D. subobscura caused shifts in developmental time but maintained the egg-to-adult viability at a similar level. Microbiota diversity indicated that the Komagataeibacter could be a valuable member of D. subobscura microbiota in overcoming the environmental stress. Research on the impact of microbiota on the adaptive response to heavy metals and consequently the potential tradeoffs among different life history traits is of great importance in evolutionary research.

Quantification of Some Metals in Commonly Consumed Canned Foods in South-west Nigeria: Probable Pointer to Metal Toxicity

Canned foods are one of the most commonly consumed products, due to benefits like the taste, handiness and convenience derived from them. On the other hand, these dietary products may be a means of heavy metal exposure and toxicant. This study aimed to quantify metals content in some frequently consumed canned foods in Nigeria as a possible source of toxicity. Twenty-two different commonly consumed brands of canned foods (Sweet corn, Green peas, Corned beef, Hotdog, Mushroom, Tin tomato, Mixed fruit, Baked beans, Mackerel (tomato sauce canned fish), Sardine (canned fish in vegetable oil) and Red kidney were analyzed for Ni, Cr, Cu, Pb and Al using Atomic Absorption Spectrophotometer after wet digestion. The results showed that the heavy metals concentration in the samples under study ranged from 0.55 to 0.86mg/kg (Ni), 0.00 to 0.41mg/kg (Cr), 1.40 to 1.76 mg/kg (Pb), 0.07 to 0.2mg/kg (Cu) and 4.71 to 16.4mg/kg (Al). The levels of Pb, Ni and Al were above FAO/WHO recommended limit of 0.01mg/kg, 0.05mg/kg and 7mg/kg respectively. The presence of heavy metals like lead (Pb) above the permissible limit calls for caution during production and in the frequent consumption of canned foods which may lead to accumulation of metals, toxicity and the sequelae.

Dietary Heavy Metal Exposure among Finnish Adults in 2007 and in 2012

For the non-smoking and non-occupationally exposed population in Europe, food is the main source of heavy metal exposure. The aim of the study was to estimate the dietary exposure of the Finnish adult population to cadmium, lead, inorganic arsenic, inorganic mercury and methyl mercury as well as nickel using governmental as well as industry data on heavy metal occurrence in foodstuffs and the data from two national food consumption surveys conducted in 2007 and 2012. The sources of heavy metal exposure were estimated for the working-age population (25 to 64 years) and for the elderly (65 to 74 years). Exposure differences between years and between population groups were compared statistically. The mean exposure of women aged 25 to 45 years to cadmium and lead was statistically significantly (p < 0.001) higher, and the methyl mercury exposure lower (p = 0.001) than that of women aged 46 to 64 years. For nickel and inorganic arsenic the differences were lower but still statistically significant (p < 0.05). Between genders, significant difference (p < 0.05) was only seen for lead and nickel. Mean cadmium exposure was significantly higher in 2012 than in 2007. For at least 95% of the adult population, the risk of health damage from mercury or nickel exposure is negligible, but the margin of exposure for lead and inorganic arsenic is small and shows a possible risk of cancer or neurotoxic effects.