Certain organochlorine and organobromine contaminants in Swedish human milk in perspective of past 20–30 years

This Conference Report was prepared by a multidisciplinary ad hoc committee of the Assembly on Environmental and Occupational Health.

Respiratory Health Hazards in Agriculture

Established risk factors for breast cancer explain breast cancer risk only partially. Hence, there has been interest in evaluating what role environmental chemicals, especially those with evidence of being hormonally active agents, play in breast cancer risk. Organochlorine pesticides have received the most attention because of their persistence in the environment, ability to concentrate up the food chain, continued detection in the food supply and breast milk, and ability to be stored in the adipose tissue of animals and humans. Although several early descriptive studies and a cohort study identified a strong positive association with breast cancer risk and adipose or blood levels of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) and/or its metabolite dichlorodiphenyldichloroethylene (DDE), most of the more recent case--control and nested case--control studies have not supported this association. In this review I discuss these findings and explore how exposure to different forms of DDT with varying estrogenicities may have affected the results of these studies. I also address how other factors influence the interpretation of the studies on DDT, DDE, and breast cancer risk. These include the effect of analytic methods, dietary factors, menopausal status, use of different types of control populations, lactation history, estrogen receptor status, ethnic/racial subgroups, breast tumor characteristics, and polymorphisms. I also discuss the emerging research on whether serum levels of the persistent organochlorine insecticide dieldrin are related to breast cancer risk in Danish and American women. Further research needs are also identified.

Pesticides and breast cancer risk: a review of DDT, DDE, and dieldrin.

The organochlorine insecticide dichlorodiphenyltrichloroethane (DDT) was initially introduced for control of vector-borne discases It was banned in the United States by the Environmental Protection Agency in 1972 because of potential harmful effects on humans, wildlife and the environment. Since it is a potential human carcinogen, the United Nations Environmental Program (UNEP) has recently restricted the use of DDT in developing countries until alternative methods of vector control are sought. DDT and its metabolite, dichlorodiphenyltrichloroethylene (DDE) are lipid soluble, and bioaccumulate more in human adipose tissue, than breast milk and serum. This article is a review of DDT and DDE levels in human tissues from different countries in the world. Data on p,p'-DDT and p,p'-DDE levels in human adipose tissue, breast milk and serum were selected from more recent literature. It was discovered that countries in Africa, Asia, and Latin America with more recent exposure to DDT and DDE have higher levels in human tissue than in Europe and the United States. The global concern for DDT and DDE is the environmental spread and persistence in the food chain. Hypothetically, there is a potential risk of harmful effects of DDT and DDE to human health. UNEP has cautiously taken action to protect human health, the environment and the earth from further destruction by persistent organic pollutants. Further exposure to DDT should be prevented to achieve this goal.

http://www.imp.lodz.pl/upload/oficyna/artykuly/pdf/full/Jaga1-01-03.pdf

Global surveillance of DDT and DDE levels in human tissues.

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

Assessment of environmental pollution by PCBs, DDT and its metabolites using human milk of mothers in Zimbabwe.

Researchers analyzed data from interviews with 40 mothers living in suburban Harare Zimbabwe and analyses of their breast milk to study contamination levels of organochlorine pesticides in breast milk. The 14 mothers living in the low-density suburbs of Milton Park Queensdale Avondale and Borrowdale had a higher socioeconomic status and a higher educational status than the other mothers. These 14 mothers also had a nutritious diet and adequate knowledge of pesticides and their use (group 1). The high-density suburbs included Mbare Mufakose-Kambuzuma Dzivaresekwa and Epworth. The 26 mothers living in these areas tended to be of a low socioeconomic status and have only primary education poor diet and limited pesticide knowledge (group 2). Breast milk of Group 2 mothers contained a higher mean level of total DDT (as expressed in ppm mg/kg of fat weight) and DDT/DDE ratio than group 1 breast milk but the differences were insignificant (7.39 vs. 3.44 and 0.93 vs 0.37). The total DDT intake surpassed the acceptable daily intake (ADI) for infants based on the FAO/WHO ADI for adults. Yet no evidence existed that this amount was harmful to infants. The only metabolite found in the breast milk of all mothers was pp-DDE (the major metabolite of pp-DDT). Its mean was highest in group 2 breast milk (2.72 vs. 2.18). These results reflected the continued use of DDT in agriculture and effects of the malaria control program in Zimbabwe. The persistent levels of pp-DDE also indicated that the women ate meat from animals in which pp-DDE had accumulated. Residues of 3 lindane isomers were present in 58-100% of the breast milk samples with beta-HCH being the most persistent. Dieldrin and heptachlor epoxide levels were quite low (mean 0.05 and 0.01 respectively) indicating minimal use Zimbabwe. The researchers reiterated a commitment to breast feeding but further research about the effects of pesticide residues is needed.

Residues of Organochlorine Pesticides in Human Milk From Mothers Living in the Greater Harare Area of Zimbabwe

Despite rising use of pesticides in agriculture in Zimbabwe, poor monitoring and lack of community-based assessment implies that there is little documentation of the extent and nature of poisoning in the agricultural working class. The paper presents the results of a longitudinal study of exposure to organophosphates in twelve farms in Mashonaland Central during the 1985/6 spraying season. Significant reductions in cholinesterase activity were observed in the group of workers spraying pesticides during the spraying season compared to non-spraying controls in the same period. State farms had significantly lower levels of exposure than private farms. Reductions in cholinesterase activity did not correspond with reported symptoms, given the non-specific nature of these symptoms. Levels of protective clothing, of knowledge of correct practice of pesticide use and of associated hazards was found to be low in users. Regular monitoring of workers using toxic pesticides is recommended.

Health hazards in organophosphate use among farm workers in the large-scale farming sector.

Objective To investigate ARV utilisation in Harare in order to gather necessary data to help in the formulation of treatment guidelines to be used in Zimbabwe. Design A cross sectional study. Setting Doctors' rooms and retail pharmacy outlets. Subjects 68 primary care physicians, 80 pharmacists and 92 patients. Main outcome measures Number of physicians prescribing antiretroviral agents (ARVs) and pharmacists stocking ARVs. Type of ARV utilised, cost to the patient and information on ARV available. Results Out of the 68 private practitioners interviewed 18 were prescribing ARVs during the period of study. There were 92 patients on ARVs whose mean age was 35 +/- 5 years and consuming an average total of 17 tablets daily. Thirteen out of the 18 doctors had access to laboratory facilities to determine CD4 counts and viral load. The rest were using other approaches to treat and manage HIV/AIDS patients. About a quarter, 27.0%, of the retail pharmacists stocked ARVs. The majority, 82.0%, of the patients appeared to be on Zidovudine (AZT) mainly in combination with other drugs. The most popular combination was that of AZT, Lamivudine (3TC) and Indinavir prescribed to 29.0% of the patients, followed by that of Didanosine (DDI) and hydroxyurea prescribed to 17% of patients. At least 17% of the patients were on AZT monotherapy. There was no significant difference (p = 0.06) in the number of tablets consumed by patients who had other conditions secondary to HIV infection. Only 39 out of the 92 patients reported untoward experiences with ARVs. The major problem being associated gastro-intestinal disturbance which accounted for 56% of the reports. It was not possible to ascertain adherence. Conclusion There appeared to be therapeutic anarchy in the private sector in Harare in the way ARVs were being used. Patients need to be told that deciding to take one of the combinations means making a serious commitment to the drugs on schedule if they want to enjoy the benefit. At the same time there is need to develop and publicize HIV/AIDS treatment guidelines and effective Information, Education and Communication (IEC) materials specific to Zimbabwe.

Antiretrovial (ARV) drug utilisation in Harare.

A study to investigate the prevalence of schistosomiasis and hepatitis B viral (HBV) infection, among pregnant women was carried out at Howard Hospital in Chiweshe District, Zimbabwe. Urine and stool specimens, for the determination of Schistosoma haematobium and Schistosoma mansoni respectively, were collected from 299 pregnant women attending an antenatal clinic. In addition, five ml of blood was collected from each of the women for the determination of hepatitis B serum markers, HBsAg and anti-HB antibodies. S. haematobium and S. mansoni infection prevalence was 50 pc among the pregnant women. About 13 pc of them had both infections. Frequency of stillbirth or infant mortality was 16 pc among expectant mothers who previously had schistosoma infection compared to 8 pc among those who had no history of schistosomal infection. Only 2 pc of the pregnant women tested positive for the two hepatitis B markers. However, further hepatitis B prevalence B studies still have to be carried out with a larger cohort of pregnant women in schistosomiasis endemic areas. At the same time the seroconversion rates of children born from mothers living in schistosomiasis endemic areas would need to be compared with those of non-endemic areas before any changes in the recommended vaccination schedule are made.

N.Z. Nyazema

Papers

Assessment of environmental pollution by PCBs, DDT and its metabolites using human milk of mothers in Zimbabwe.

Residues of Organochlorine Pesticides in Human Milk From Mothers Living in the Greater Harare Area of Zimbabwe

Health hazards in organophosphate use among farm workers in the large-scale farming sector.

Antiretrovial (ARV) drug utilisation in Harare.

Schistosomiasis and hepatitis B infection in pregnancy: implications for vaccination against hepatitis B.