Waste management and public health: the state of the evidence

A2.5 Landspreading of sewage sludge

 

1. Have studies been done on human populations?

 

No.

There were no studies about the health impacts of landspreading sewage sludge although there were two studies about the health impacts of working in facilities which prepare sewage sludge for landspreading ((Clark et al, 1984),(Baker et al, 1980). These were included in the section on occupational hazards of sewage treatment workers.

 

2. Have hazards been identified? Does the appearance of the hazard precede the health outcome? Is the association biologically plausible? Are there data on exposure?

 

No.

Hazardous substances have been identified in sewage sludge (e.g. (Dumontet et al 2001), (Rogers, 1996), (Ross et al, 1992; Straub et al, 1993) but there are no studies linking those hazards to human health effects. The Canadian Handbook on Health Impact Assessment ((Anon, 2000.)Vol 2) evaluated the risks to human health as minimal because:

 

•   Pathogens have a short lifespan and their persistent forms remain in the soil

•        Metals are not usually metabolised by soil micro-organisms and will persist in the soil

•        Most pollutants bind to soil components

•        Most organic compounds, i.e. dioxins, are broken down by soil micro-organisms

•        Most organic compounds don’t migrate into surface or ground waters because they adhere to soil components

•        Volatile organic compounds evaporate within 48 hours of landspreading.

 

However, there is a lack of understanding of the potential for transfer of toxic compounds to food and about the degradability and persistence of some toxic contaminants ((Rogers, 1996)).

 

3. Are there ANY hypothesis-testing studies?

 

No.

 

Judgement – insufficient.