Henk Bouwman

Bio: Henk Bouwman is an academic researcher from North-West University. The author has contributed to research in topics: Indoor residual spraying & Dichlorodiphenyldichloroethylene. The author has an hindex of 18, co-authored 47 publications receiving 2185 citations. Previous affiliations of Henk Bouwman include Potchefstroom University for Christian Higher Education.

Bisphenol A (BPA) in China: A review of sources, environmental levels, and potential human health impacts

Abstract: Bisphenol A (BPA), identified as an endocrine disruptor, is an industrially important chemical that is used as a raw material in the manufacture of many products such as engineering plastics (e.g., epoxy resins/polycarbonate plastics), food cans (i.e., lacquer coatings), and dental composites/sealants. The demand and production capacity of BPA in China have grown rapidly. This trend will lead to much more BPA contamination in the environmental media and in the general population in China. This paper reviews the current literature concerning the pollution status of BPA in China (the mainland, Hong Kong, and Taiwan) and its potential impact on human health. Due to potential human health risks from long-term exposure to BPA, body burden of the contaminant should be monitored.

The Pine River statement: human health consequences of DDT use.

Abstract: ObjectivesDichlorodiphenyltrichloroethane (DDT) was used worldwide until the 1970s, when concerns about its toxic effects, its environmental persistence, and its concentration in the food supply le...

Simultaneous presence of DDT and pyrethroid residues in human breast milk from a malaria endemic area in South Africa.

Abstract: DDT and pyrethroids were determined in 152 breast-milk samples from three towns in KwaZulu-Natal, South Africa, one of which had no need for DDT for malaria control. All compounds were found present in breast milk. Primiparae from one town had the highest mean SigmaDDT whole milk levels (238.23 microg/l), and multiparae from the same town had the highest means for permethrin (14.51 microg/l), cyfluthrin (41.74 microg/l), cypermethrin (4.24 microg/l), deltamethrin (8.39 microg/l), and Sigmapyrethroid (31.5 microg/l), most likely derived from agriculture. The ADI for DDT was only exceeded by infants from one town, but the ADI for pyrethroids was not exceeded. Since the ADI for DDT was recently reduced from 20 to 10 microg/kg/bw, we suggest that this aspect be treated with concern. We therefore raise a concern based on toxicant interactions, due to the presence of four different pyrethroids and DDT. Breastfeeding however, remains safe under prevailing conditions.

DDT contamination from indoor residual spraying for malaria control.

Abstract: The insecticide DDT is still used in specific areas of South Africa for indoor residual spray (IRS) to control malaria vectors. Local residents could be exposed to residues of DDT through various pathways including indoor air, dust, soil, food and water. The aims of this study were to determine the levels of DDT contamination, as a result of IRS, in representative homesteads, and to evaluate the possible routes of human exposure. Two villages, exposed (DV) and reference (TV) were selected. Sampling was done two months after the IRS process was completed. Twelve homesteads were selected in DV and nine in TV. Human serum, indoor air, floor dust, outside soil, potable water, leafy vegetables, and chicken samples (muscle, fat and liver) were collected and analyzed for both the o,p'- and p,p'-isomers of DDT, DDD and DDE. DDT was detected in all the media analyzed indicating a combination of potential dietary and non-dietary pathways of uptake. DV had the most samples with detectable levels of DDT and its metabolites, and with the exception of chicken muscle samples, DV also had higher mean levels for all the components analyzed compared to TV. Seventy-nine percent of participants from DV had serum levels of DDT (mean [summation operator]DDT 7.3microg g(-1) lipid). These residues constituted mainly of p,p'-DDD and p,p'-DDE. [summation operator]DDT levels were detected in all indoor air (mean [summation operator]DDT 3900.0 ng m(-3)) and floor dust (mean [summation operator]DDT 1200.0 microg m(-2)) samples. Levels were also detected in outside soil (mean [summation operator]DDT 25.0 microg kg(-1)) and potable water (mean [summation operator]DDT 2.0 microg L(-1)). Vegetable sample composition (mean [summation operator]DDT 43.0 microg kg(-1)) constituted mainly p,p'-DDT and p,p'-DDD. Chicken samples were highly contaminated with DDT (muscle mean [summation operator]DDT 700.0 microg kg(-1), fat mean [summation operator]DDT 240,000.0 microg kg(-1), liver mean [summation operator]DDT 1600.0 microg kg(-1)). The results of the current study raise concerns regarding the potential health effects in residents living in the immediate environment following DDT IRS.

Dioxin-like chemicals in soil and sediment from residential and industrial areas in central South Africa.

Abstract: Persistent organic pollutants (POPs) are a global concern due to their ubiquitous presence and toxicity. Currently, there is a lack of information regarding POPs from South Africa. Here we report and interpret concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs) and co-planar-biphenyls (PCBs) in soils and sediments collected from central South Africa. High resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) and the H4IIE-luc bio-assay were used to identify and quantify individual PCDD/F congeners and to report the total concentration of 2,3,7,8-tetrachloro dibenzo-p-dioxin equivalents (TCDD-EQ), respectively. TCDD-EQs determined by use of the bio-assay, and concentrations of WHO(2005)-TEQ (toxic equivalents) determined by chemical analysis, were similar. The limit of detection (LOD) for the bio-assay was 0.82 and 2.8 ng TCDD-EQ kg(-1), dw for sediment and soil, respectively. EQ20 concentrations determined by use of the bio-assay ranged from

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

Bisphenol A--sources, toxicity and biotransformation.

Abstract: Bisphenol A (BPA) is a chemical compound used in massive amounts in the production of synthetic polymers and thermal paper. In this review, the sources of BPA, which influence its occurrence in the environment and human surrounding will be presented. Data concerning BPA occurrence in food, water and indoor environments as well as its appearance in tissues and body fluids of human body will be shown. The results of in vitro and in vivo studies and the results of epidemiological surveys showing toxic, endocrine, mutagenic and cancerogenic action of BPA will also be discussed. Moreover, data suggesting that exposure of human to BPA may elevate risk of obesity, diabetes and coronary heart diseases will be presented. Finally, biotransformation of BPA in animals, plants and microorganisms (bacteria, fungi, algae), resulting in the formation of various metabolites that exhibit different from BPA toxicity will be described.

Scientific Opinion on the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs: Executive summary

Abstract: This opinion describes the assessment of the risks to public health associated with bisphenol A (BPA) exposure. Exposure was assessed for various groups of the human population in three different ways: (1) external (by diet, drinking water, inhalation, and dermal contact to cosmetics and thermal paper); (2) internal exposure to total BPA (absorbed dose of BPA, sum of conjugated and unconjugated BPA); and (3) aggregated (from diet, dust, cosmetics and thermal paper), expressed as oral human equivalent dose (HED) referring to unconjugated BPA only. The estimated BPA dietary intake was highest in infants and toddlers (up to 0.875 µg/kg bw per day). Women of childbearing age had dietary exposures comparable to men of the same age (up to 0.388 µg/kg bw per day). The highest aggregated exposure of 1.449 µg/kg bw per day was estimated for adolescents. Biomonitoring data were in line with estimated internal exposure to total BPA from all sources. BPA toxicity was evaluated by a weight of evidence approach. “Likely” adverse effects in animals on kidney and mammary gland underwent benchmark dose (BMDL10) response modelling. A BMDL10 of 8 960 µg/kg bw per day was calculated for changes in the mean relative kidney weight in a two generation toxicity study in mice. No BMDL10 could be calculated for mammary gland effects. Using data on toxicokinetics, this BMDL10 was converted to an HED of 609 µg/kg bw per day. The CEF Panel applied a total uncertainty factor of 150 (for inter- and intra-species differences and uncertainty in mammary gland, reproductive, neurobehavioural, immune and metabolic system effects) to establish a temporary Tolerable Daily Intake (t-TDI) of 4 µg/kg bw per day. By comparing this t-TDI with the exposure estimates, the CEF Panel concluded that there is no health concern for any age group from dietary exposure and low health concern from aggregated exposure. The CEF Panel noted considerable uncertainty in the exposure estimates for non-dietary sources, whilst the uncertainty around dietary estimates was relatively low.

Global Assessment of Bisphenol A in the Environment Review and Analysis of Its Occurrence and Bioaccumulation

Abstract: Because bisphenol A (BPA) is a high production volume chemical, we examined over 500 peer-reviewed studies to understand its global distribution in effluent discharges, surface waters, sewage sludge, biosolids, sediments, soils, air, wildlife, and humans. Bisphenol A was largely reported from urban ecosystems in Asia, Europe, and North America; unfortunately, information was lacking from large geographic areas, megacities, and developing countries. When sufficient data were available, probabilistic hazard assessments were performed to understand global environmental quality concerns. Exceedances of Canadian Predicted No Effect Concentrations for aquatic life were >50% for effluents in Asia, Europe, and North America but as high as 80% for surface water reports from Asia. Similarly, maximum concentrations of BPA in sediments from Asia were higher than Europe. Concentrations of BPA in wildlife, mostly for fish, ranged from 0.2 to 13 000 ng/g. We observed 60% and 40% exceedences of median levels by the US Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey in Europe and Asia, respectively. These findings highlight the utility of coordinating global sensing of environmental contaminants efforts through integration of environmental monitoring and specimen banking to identify regions for implementation of more robust environmental assessment and management programs.

A Review of Solar and Visible Light Active TiO2 Photocatalysis for Treating Bacteria, Cyanotoxins and Contaminants of Emerging Concern

Abstract: Research into the development of solar and visible light active photocatalysts has been significantly increased in recent years due to its wide range of applications in treating contaminants of emerging concern (CECs), endocrine disrupting compounds (EDCs), bacteria and cyanotoxins. Solar photocatalysis is found to be highly effective in treating a wide range of CECs from sources such as pharmaceuticals, steroids, antibiotics, phthalates, disinfectants, pesticides, fragrances (musk), preservatives and additives. Similarly, a number of EDCs including polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), bisphenol A (BPA), organotins (OTs), volatile organic compounds (VOCs), natural and synthetic estrogenic and androgenic chemicals, pesticides, and heavy metals can be removed from contaminated water by using solar photocatalysis. Photocatalysis was also found effective in treating a wide range of bacteria such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhi and Micrococcus lylae. The current review also compares the effectiveness of various visible light activated TiO2 photocatalysts for treating these pollutants. Doping or co-doping of TiO2 using nitrogen, nitrogen–silver, sulphur, carbon, copper and also incorporation of graphene nano-sheets are discussed. The use of immobilised TiO2 for improving the photocatalytic activity is also presented. Decorating titania photocatalyst with graphene oxide (GO) is of particular interest due to GO's ability to increase the photocatalytic activity of TiO2. The use GO to increase the photocatalytic activity of TiO2 against microcystin-LR (MC-LR) under UV-A and solar irciation is discussed. The enhanced photocatalytic activity of GO–TiO2 compared to the control material is attributed to the effective inhibition of the electron–hole recombination by controlling the interfacial charge transfer process. It is concluded that there is a critical need for further improvement of the efficiency of these materials if they are to be considered for bulk industrial use.