Lewis David L, Gattie David K, Novak Marc E, Sanchez Susan, Pumphrey Charles
US Environmental Protection Agency, National Exposure Research Laboratory, Athens, GA, USA.
BMC Public Health. 2002 Jun 28;2:11. doi: 10.1186/1471-2458-2-11.
Fertilisation of land with processed sewage sludges, which often contain low levels of pathogens, endotoxins, and trace amounts of industrial and household chemicals, has become common practice in Western Europe, the US, and Canada. Local governments, however, are increasingly restricting or banning the practice in response to residents reporting adverse health effects. These self-reported illnesses have not been studied and methods for assessing exposures of residential communities to contaminants from processed sewage sludges need to be developed.
To describe and document adverse effects reported by residents, 48 individuals at ten sites in the US and Canada were questioned about their environmental exposures and symptoms. Information was obtained on five additional cases where an outbreak of staphylococcal infections occurred near a land application site in Robesonia, PA. Medical records were reviewed in cases involving hospitalisation or other medical treatment. Since most complaints were associated with airborne contaminants, an air dispersion model was used as a means for potentially ruling out exposure to sludge as the cause of adverse effects.
Affected residents lived within approximately 1 km of land application sites and generally complained of irritation (e.g., skin rashes and burning of the eyes, throat, and lungs) after exposure to winds blowing from treated fields. A prevalence of Staphylococcus aureus infections of the skin and respiratory tract was found. Approximately 1 in 4 of 54 individuals were infected, including 2 mortalities (septicaemia, pneumonia). This result was consistent with the prevalence of S. aureus infections accompanying diaper rashes in which the organism, which is commonly found in the lower human colon, tends to invade irritated or inflamed tissue.
When assessing public health risks from applying sewage sludges in residential areas, potential interactions of chemical contaminants with low levels of pathogens should be considered. An increased risk of infection may occur when allergic and non-allergic reactions to endotoxins and other chemical components irritate skin and mucus membranes and thereby compromise normal barriers to infection.
用经过处理的污水污泥给土地施肥在西欧、美国和加拿大已成为常见做法，这些污泥通常含有低水平的病原体、内毒素以及微量的工业和家用化学品。然而，由于居民报告了不良健康影响，地方政府越来越多地限制或禁止这种做法。这些自我报告的疾病尚未得到研究，需要开发评估居民区接触来自处理后污水污泥中污染物的方法。
为了描述和记录居民报告的不良反应，对美国和加拿大10个地点的48个人进行了询问，了解他们的环境暴露情况和症状。还获取了宾夕法尼亚州罗贝索尼亚一个土地施用点附近发生葡萄球菌感染暴发的另外5个病例的信息。对涉及住院或其他治疗的病例的病历进行了审查。由于大多数投诉与空气传播污染物有关，因此使用空气扩散模型作为一种手段，以潜在地排除接触污泥是不良反应原因的可能性。
受影响的居民居住在距土地施用点约1公里范围内，通常在接触来自处理过的田地的风后抱怨有刺激症状（如皮疹、眼睛、喉咙和肺部灼痛）。发现皮肤和呼吸道金黄色葡萄球菌感染率较高。54人中约四分之一被感染，包括2例死亡（败血症、肺炎）。这一结果与尿布疹伴发的金黄色葡萄球菌感染率一致，在尿布疹中，这种通常存在于人体结肠下部的微生物往往会侵入受刺激或发炎的组织。
在评估居民区施用污水污泥对公众健康的风险时，应考虑化学污染物与低水平病原体之间的潜在相互作用。当对内毒素和其他化学成分的过敏和非过敏反应刺激皮肤和黏膜，从而损害正常的感染屏障时，感染风险可能会增加。
