Lead (Pb) both in paints and children's Polyvinyl chloride (PVC) toys is a major public health concern which has attracted attention of the international community. Concentrations of Pb both in lead-based paints and children's PVC toys have been assessed through various studies across the globe. Therefore, the purpose of this article was to summarize the results reported in these studies and provide some comprehension on their implications to human health for law enforcement as well as for awareness raising to the general public. Highlights on identified gaps have been provided to pave ways for further research interventions in order to establish comprehensive information on the subject.Regardless of regulatory limits on the content of lead, both in paints and children's PVC toys existing in different countries in the world, some of the reviewed articles have revealed significant levels of lead in these two items far above the permissible limits.High lead levels in paints have been recorded in China (116,200 ppm), Cameroon (500,000 ppm), South Africa (189,000 ppm), Tanzania (120,862.1 ppm), Uganda (150,000 ppm), Thailand (505,716 ppm) and Brazil (170,258.4 ppm) just to mention a few.Lead poisoning cases in children have been reported in several countries including France, Morocco, South Africa and United States. Countries where high levels of lead in children's PVC toys have been recounted include; China (860,000 ppm), South Africa (145,000 ppm), United States (22,550 ppm), Thailand (4,486.11 ppm), Palestine (6,036 ppm) and India (2,104 ppm).Awareness raising among parents is vital to impart them with knowledge on the matter so that they can take strenuous measures to protect their children from lead poisoning emanating from playing with toys and paint dust. Law enforcement on phasing out lead-based paints and control of lead content in children's PVC toys worldwide is also highly recommended.

A comparative study was conducted to (1) assess the potential of raw sewage used for urban agriculture to disseminate bacterial resistance in two cities of different size in Cameroon (Central Africa) and (2) compare the outcome with data obtained in Burkina Faso (West Africa). In each city, raw sewage samples were sampled from open-air canals in three neighbourhoods. After DNA extraction, the microbial population structure and function, presence of pathogens, antibiotic resistance genes and Enterobacteriaceae plasmids replicons were analysed using whole genome shotgun sequencing and bioinformatics. Forty-three pathogen-specific virulenc e factor genes were detected in the sewage. Eighteen different incompatibility groups of Enterobacteriaceae plasmid replicon types (ColE, A/C, B/O/K/Z, FIA, FIB, FIC, FII, H, I, N, P, Q, R, T, U, W, X, and Y) implicated in the spread of drug-resistance genes were present in the sewage samples. One hundred thirty-six antibiotic resistance genes commonly associated with MDR plasmid carriage were identified in both cities. Enterobacteriaceae plasmid replicons and ARGs found in Burkina Faso wastewaters were also present in Cameroon waters. The abundance of Enterobacteriaceae, plasmid replicons and antibiotic resistance genes was greater in Yaounde, the city with the greater population.In conclusion, the clinically relevant environmental resistome found in raw sewage used for urban agriculture is common in West and Central Africa. The size of the city impacts on the abundance of drug-resistant genes in the raw sewage while ESBL gene abundance is related to the prevalence of Enterobacteriaceae along with plasmid Enterobacteriaceae abundance associated to faecal pollution.

Over 700 million people in Sub-Saharan Africa depend on solid biomass fuel and use simple cookstoves in poorly ventilated kitchens, which results in high indoor concentrations of household air pollutants. Switching from biomass to biogas as a cooking fuel can reduce airborne emissions of fine particulate matter (PM2.5) and carbon monoxide (CO), but households often only partially convert to biogas, continuing to use solid biomass fuels for part of their daily cooking needs. There is little evidence of the benefits of partial switching to biogas. This study monitored real-time PM2.5 and CO concentrations in 35 households in Cameroon and Uganda where biogas and firewood (or charcoal) were used. The 24 h mean PM2.5 concentrations in households that used: (1) firewood and charcoal; (2) both firewood (mean 54% cooking time) and biogas (mean 46% cooking time); and (3) only biogas, were 449 μg m⁻³, 173 μg m⁻³ and 18 μg m⁻³ respectively. The corresponding 24 h mean CO concentrations were 14.2 ppm, 2.7 ppm and 0.5 ppm. Concentrations of both PM2.5 and CO were high and exceeded the World Health Organisation guidelines when firewood and charcoal were used. Partially switching to biogas reduced CO exposure to below the World Health Organisation guidelines, but PM2.5 concentrations were only below the 24 h recommended limits when households fully converted to biogas fuel. These results indicate that partial switching from solid fuels to biogas is not sufficient and continues to produce concentrations of household air pollution that are likely to harm the health of those exposed. Programmes introducing biogas should aim to ensure that household energy needs can be fully achieved using biogas with no requirement to continue using solid fuels.

The transport of non-indigenous species in ship's ballast water represents a threat to marine biodiversity. This study is the first on marine bioinvasion in Sub-Saharan Africa. The Port of Douala (PoD), located in the Gulf of Guinea, is experiencing increasing maritime traffic, hence the importance of preventing biological invasions. PoD received ballast water from 41 ports and 20 ecoregions during the study period (2018–2021). We used a biological invasion model and showed that ships from the ports of Antwerp, Durban, Dar es Salaam, Pointe-Noire (Southern Gulf of Guinea) and Dakar (Sahelian Upwelling), with their associated ecoregions present a major invasion risk. Treating ballast water from these ships to IMO D-2 standards could reduce their probability of biological invasion by 97.18, 98.43, 98.80, 98.77 and 98.84 %, respectively. Climate change may also mitigate the risk of biological invasion, particularly for ships in the North Sea ecoregion from the port of Antwerp.

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 – 27.4, and 83 – 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

Mangroves are critically threatened by human activities, despite the important ecosystem functions and services they provide. Mangroves in Cameroon represent no exception to the worldwide trend of mangrove destruction, especially around Douala, on the Wouri river estuary. In two sites around Douala, we assessed the presence of sterols, PAHs, PCBs, DEHP, DDT and its metabolite p,p'-DDE and potentially toxic metals in sediment samples. As a proxy of ecological quality, we measured the diversity and abundance of macrobenthos assemblages. We detected p,p'-DDE contamination, with concentrations higher than 3μgkg−1 in 16 out of 26 samples which were attributed to recent widespread use of DDT. The detection of sterols revealed faecal contamination. Significant sensitivity of the macrobenthos to contaminants was revealed, with possible implications on the overall mangrove vulnerability to climate change and on the provision of ecosystem services to local populations.

Hydrocarbons are ubiquitous and persistent organic pollutants in the environment. In wetlands and marine environments, particularly in mangrove ecosystems, their increase and significant accumulation result from human activities such as oil and gas exploration and exploitation operations. Remediation of these ecosystems requires the development of adequate and effective strategies. Natural attenuation, biostimulation, and bioaugmentation are all biological soil treatment techniques that can be adapted to mangroves. Our experiments were performed on samples of fresh mangrove sediments from the Cameroon estuary and mainly from the Wouri River in Cameroon. This study aims to assess the degradation potential of a bacterial consortium isolated from mangrove sediment. The principle of our bioremediation experiments is based on a series of tests designed to evaluate the potential of an active indigenous microflora and three exogenous pure strains, to degrade diesel with/without adding nutrients. The experiments were conducted in laboratory flasks and a greenhouse in microcosms. In one case, as in the other, the endogenous microflora showed that it was able to degrade diesel. Under stress of the pollutant, the endogenous microflora fits well enough in the middle to enable metabolism of the pollutant. However, the Rhodococcus strain was more effective over time. The degradation rate was 77 and 90 % in the vials containing the sterile sediments and non-sterile sediments, respectively. The results are comparable with those obtained in the microcosms in a greenhouse where only the endogenous microflora were used. The results of this study show that mangrove sediment contains an active microflora that can metabolize diesel. Indigenous and active microflora show an interesting potential for diesel degradation.

To effectively combat global warming, an enormous reduction in CO₂ emissions is required. Cameroon, which is currently the largest emitter of CO₂ in the CEMAC subregion, has committed to reducing its greenhouse gas emissions by 32% by 2035. However, previous studies in Cameroon have only addressed the relationship between economic growth, energy consumption, and CO₂ emissions without estimating all causal relationships at the same time. Moreover, no study has yet decomposed this country’s CO₂ emissions to date. To fill these research gaps and further assess the determinants of these CO₂ emissions, an extended Kaya identity and the Logarithm Mean Divisia Index (LMDI I) have been applied in this paper to identify, quantify, and explain the main drivers of Cameroon’s CO₂ emissions from 2007 to 2014. Seven effects were measured and the main findings show that carbon intensity and the emission factor increased by 0.57% and 107.50% respectively. Regarding contributions to the increase of CO₂ emissions, the population effect was the most positive followed by the activity effect, whereas the energy intensity, the substitution of fossil fuels and the penetration of renewable energies have contributed to reduce the CO₂ emission. To enable Cameroon to not only achieve the goals of its vision but also develop a low-carbon economy, this paper provides some proposed avenues that should be considered by policymakers.

The objective of the current study is to investigate the natural radioactivity of some building materials, the resulting long-term external and internal effective dose equivalents (EEDE and IEDE) analysis followed by indoor radon measurements, and the assessment of some radiological risk indicators associated with radon exposure. A total of 37 samples of building materials were analyzed with a sodium iodide detector (NaI (Tl)), and the computer code RESRAD-BUILD was used for the analysis of the EEDE and IEDE of the structural elements of the houses (walls and floor). For indoor radon measurements, 140 houses were selected, and in each of them was placed 01 RADTRAK dosimeter. Inhalation dose, total dose, and some radiological risk indicators were calculated. The specific activities of ²²⁶Ra, ²³²Th, and ⁴⁰K for the overall sampled building materials were found to vary between 10 ± 2–52 ± 7, 10 ± 1–95 ± 10, and 31 ± 1–673 ± 20 Bq kg⁻¹, respectively. The dwelling types with bare brick walls, cement mortar plastered walls, and concrete floors show EEDE and IEDE values well below the recommended limits. The corresponding dwelling type contributions to the measured average indoor radon concentration (42 ± 12 Bq m⁻³) are 22%, 13%, and 16%, respectively. Inhalation dose resulting from the measured indoor radon concentrations varies from 0.35 to 3.24 mSv y⁻¹ with a mean value of 0.96 ± 0.55 mSv y⁻¹, which represents about 65% of the total dose simulated (1.49 ± 0.88 mSv y⁻¹) by the RESRAD-BUILD code. The overall analysis of indoor radon-related radiological risk indicators shows low levels of risk relative to permissible limits.

Flood plains can make a significant contribution to food security due to their rich agricultural and aquaculture potentials but the misuse of pesticides in these ecosystems may seriously threaten their sustainability. We have assessed the risk of commonly used pesticides by rice and vegetable farmers on two major streams in the Ndop flood plain in Cameroon using the PRIMET model. Thirty pesticide formulations were identified containing 17 active ingredients belonging to fungicides (7), herbicides (3), and insecticides (7). Out of these, five posed acute and/or chronic risks to the streams. Chlorpyriphos-ethyl (ETR = 655), chlorothalonil (ETR = 250), and cypermethrin (ETR = 190) posed a definite acute risk to both streams. These pesticides also posed possible chronic risks with cypermethrin also posing a definite chronic risk (ETR = 1658) to fish in one of the streams. Mancozeb (ETR = 2.2) and λ-cyhalothrin (ETR = 2.8) posed a possible acute risk to both streams. It was interesting to note that most pesticides, including some of those that posed a risk, were applied at lower doses than their respective recommended doses. Differences in ETRs were also observed in the two streams with higher values occurring in the stream having a lower concentration of suspended solids. The higher velocity of the Ngwala-Mesaw stream did not affect the acute risk posed by pesticides. Pesticide toxicity was an important determinant in the risk posed and we recommend that appropriate mitigation measures be put in place to reduce the risk of these pesticides such as the implementation of an appropriate buffer zone between the edge of field and water body.