Occurrence and fate of pharmaceuticals, personal care products (PPCPs) and pesticides in African water systems: A need for timely intervention.

The occurrence of emerging contaminants (ECs) such as pharmaceuticals, personal care products (PPCPs) and pesticides in the aquatic environment has raised serious concerns about their adverse effects on aquatic species and humans. Because of their toxicity and bioactive nature, PPCPs and pesticides have more potential to impair water systems than any other contaminants, causing several adverse effects, including antibiotic resistance, reproductive impairment, biomagnification, bioaccumulation, etc. Over 35 publications from Africa have reported on the occurrence and fate of PPCPs and pesticides in African water systems with little or no data on remediation and control. As a result, adequate intervention strategies are needed for regulating the persistence of PPCPs and pesticides in African water systems.

The relative sensitivity of freshwater species to antimony(III): Implications for water quality guidelines and ecological risk assessments.

Antimony (Sb) is a pollutant in many jurisdictions, yet its threat to aquatic biota is unclear. Water quality guidelines (WQGs) for Sb are not well established and large uncertainty factors are commonly applied in derivation. We constructed freshwater species sensitivity distributions (SSDs) for Sb(III) using available acute toxicity data sourced from temperate and tropical regional studies. A tiered ecological risk assessment (ERA) approach using risk quotients (RQs) was applied for characterisation of risks presented by Sb(III) concentrations measured in the freshwater environment. Multiple parametric models were fitted for each SSD, with the optimal model used to derive the 5% hazardous concentration (HC5), defined as protective of 95% of species, and the corresponding predicted no effect concentration (PNEC). The HC5 values for whole and temperate SSDs were estimated at 781 and 976 µg L-1 Sb(III), respectively, while the PNECs for both datasets were 156 and 195 µg L-1 Sb(III), respectively. Due to limited tropical data, a temperate-to-tropic extrapolation factor of 10 was used to estimate an interim PNEC for tropical regions of 20 µg L-1 Sb(III). Based on published freshwater Sb(III) concentration values across a range of locations, potential ecological risks posed by Sb(III) in some freshwater systems studied would be classified as medium to high risk, but the majority of locations sampled would fall into the low ecological risk category. Our results facilitate the understanding of toxic effects of Sb(III) to freshwater species but also demonstrate that data for Sb ERA are extremely limited.

A Market Basket Survey of Horticultural Fruits for Arsenic and Trace Metal Contamination in Southeast Nigeria and Potential Health Risk Implications.

BACKGROUND: Elevated arsenic and trace metal contamination of the terrestrial food chain represents one of the most significant environmental risk exposures for human populations in developing countries. Metalloid and metal contamination in horticultural crop produce such as fruit is a public health concern in Nigeria. Local fruits are cheap sources of vitamins and minerals for the resident population and pose an important dietary threat of metal(loid) toxicity through consumption. OBJECTIVES: Market basket investigation of five locally grown (guava, pineapple, orange, and pawpaw) and imported (apple) fruits was conducted to measure the total concentrations of arsenic (As), mercury (Hg), copper (Cu), and lead (Pb) present in these fruits from southeastern Nigeria (Awka, Anambra). METHODS: Fruits were analyzed for As and the three metals using atomic absorption spectrophotometry. Moisture content of fruits was determined and used to transform metal concentrations in dry weight to wet weight and compared to Codex food grade standards and assorted (sub)tropical fruits, edible and inedible peels. RESULTS: The mean ± standard deviation of elemental concentrations in dry weight ranged from 20.0±0.71-96.84±0.00 µg g-1 for As, 0.02±0.02 - 0.89±0.33 µg g-1 for Hg, 0.11±0.01 - 0.18±0.40 µg g-1 for Cu, and <0.001 - 0.03±0.05 µg g-1 for Pb. The As concentrations (wet weight) in fruits were ~32-166 orders of magnitude higher than Codex Alimentarius Commission (Codex) maximum As food grade levels. Guava and apple methyl Hg concentrations were ~6-~1 orders of magnitude higher than Codex maximum levels, while the content of Cu and Pb in fruits were within acceptable standard limits. CONCLUSIONS: The significant concentrations of As and Hg in the examined fruits indicate a potential public health threat. Efforts are needed to initiate and sustain continued monitoring of trace elements in fruits and food sold to consumers due to variation in contaminating sources to ensure food safety. Although a great deal of information exists on Hg toxicity, research on metalloids such as As remains limited in Nigeria and no reliable guidelines exist. Further research is recommended to determine the ecotoxicity of As in Nigeria.