Human health risk assessment of heavy metals in cosmetics in Nigeria.

Forty two different cosmetics were purchased from supermarkets and cosmetic shops within Unitsha Main Market and Eke-Awka markets in Anambra, Nigeria. Of the cosmetics, 16% were locally manufactured in Nigeria while 83.33% were imported into Nigeria. The cosmetics were ashed before digestion and filtration. The filtrates were assayed for lead, cadmium, manganese, nickel, chromium, mercury, and arsenic with atomic absorption spectrophotometry at 205 Å. The health risk assessment methods developed by the United States Environmental Protection Agency were employed to explore the potential human health risk of heavy metals in cosmetics. About 61.91% of the cosmetic samples contained lead with concentration in the range of 0.10-42.12 mg/kg. Cadmium levels of the cosmetics ranged from 0.01 to 1.32 mg/kg, manganese from 0.02 to 67.65 mg/kg, nickel from 0.05 to 17.34 mg/kg, chromium from 0.11 to 9.81 mg/kg, mercury from 0.003 to 0.07 mg/kg, and arsenic from 0.002 to 0.005 mg/kg. Although the target hazard quotients and the hazard indices suggest a measure of safety, cosmetics may add to the body burden of potential toxic metals after chronic exposure.

Precipitation chemistry and occurrence of acid rain over the oil-producing Niger Delta region of Nigeria.

This study investigated the nitrate, sulfate, total dissolved solid (TDS), electrical conductivity, total hardness (TH), and bicarbonates of rainwater samples collected from Warri and Port Harcourt between April-June, July-August, and September-October of 2005 and 2006 to depict onset of rainy season, mid-rainy season, and end of rainy season for the two major crude oil-producing cities of the Niger Delta region of Nigeria (although Port Harcourt is also noted for non-oil manufacturing industries). The same was done in Awka, a non-oil producing city in the hinterland of southeastern Nigeria. In each of the cities, rain samples were collected from three points in a triangular equilibrium using a clean plastic basin fastened to a table 2 m above ground level and 115 m away from tall buildings and trees. The parameters were determined after filtering, using their respective standard methods. Averages of 1.50, 1.81, 1.13 and 2.14, 1.50, 1.86 mg/l of nitrate for April-June, July-August, and September-October were recorded for Warri in 2005 and 2006, respectively. While 15.21, 3.23, 22.31 and 20.89, 9.96, and 14.27mg/l were recorded in Port Harcourt. Sulfate levels for Warri and Port Harcourt for the same periods are follows: 1.38, 1.88, 1.06, 1.50, 1.43, 1.50 and 2.64, 1.15, 5.88, 4.73, 1.90, 1.55 mg/l, respectively. Nitrate levels were higher than sulfate. Other parameters include TDS (5.44, 4.79, 3.30 and 7.63, 3.69, 2.56 mg/l for Warri in 2005 and 2006; 12.57, 2.07, 25.214 and 28.87, 6.73, 7.80 mg/l for Port Harcourt for the same periods). Other parameters also varied in that order for the 2 years in same cities. Crude oil exploration and gas flaring in the Niger Delta, and multiplicity of cottage industries in Awka, impacted on the inorganic ion pollution of the rainwater. This may have public health implications in the region.

Heavy metal contamination of foods by refuse dump sites in Awka, southeastern Nigeria.

The impact of heavy metals from refuse dumps on soil, food, and water qualities in Awka, Nigeria was studied. Soil samples (top and 1.35 m deep) were collected from five refuse dumps digested with conc. HNO3 and HClO4. The heavy metals (lead, manganese, arsenic, chromium, cadmium, and nickel) in vegetables (spinach, fluted pumpkin), root crop (cocoyam), and surface and ground water were determined using an atomic absorption spectrophotometer (AAS). Chemical properties of the soil and bacteria were determined. Heavy metals were found to be more concentrated at a depth of 1.35 m. Manganese was high in shallow wells and borehole water samples with the highest levels as 0.538 and 0.325 mg/l, respectively. Nickel levels in the borehole sample ranged from 0.001 to 0.227 mg/l, whereas the highest level of lead was 0.01 mg/l. The Obibia stream had the highest levels of manganese and lead. Linear regression analyses showed that the relationship between soil heavy metals and farm produce heavy metals was strong. Taken together, we may conclude that the consumption of leafy vegetables and crops produced on contaminated soils may pose a health risk to those that reside around the refuse dumps.