suggests that most American waste pickers are male, as waste picking is widely considered too dirty and strenuous a job for women. During an ethnography of homeless recyclers in San Francisco, sociologist Teresa Gowan claims to have met hundreds of male waste pickers, but only four female waste pickers. Costs and benefits Social and ecological benefits Waste picking offers significant ecological, economic, and social benefits: Job creation: Waste picking provides a source of livelihood to extremely poor people with few other employment opportunities. Though many waste pickers practice their trade as a full-time profession, its flexible hours make it accessible to women with other care responsibilities and to people looking to supplement income from other jobs. During times of need, waste picking serves as a safety net to street children, orphans, the elderly, widows, migrants, the disabled, the unemployed, and victims of armed conflicts. Waste picking also benefits the broader economy by supplying raw materials to industry and creating many associated jobs for middlemen who purchase, sort, process, and resell materials collected by waste pickers. Public health and sanitation: Waste pickers collect garbage from neighborhoods that lack public services. Without waste pickers, residents would be forced to burn trash, or dispose of it in rivers, streets and empty lots. Waste pickers provide the only solid waste removal service in many cities. Municipal savings: Waste pickers provide between 50 and 100% of waste collecting services in most cities of the developing world, according to a 2010 UN Habitat report. This is effectively serves as a mass subsidy for city governments, who do not pay for the labor. Moreover, recycling expands the lifespan of city dumps and landfills. Reducing pollution and mitigating climate change: By cutting the quantity of virgin materials needed for production, waste pickers save room in landfills, lessen water and energy consumption, reduce air and water pollution, and abate climate change. Since 2009, international delegations of waste pickers have attended at least five global climate change conferences to demand that climate funds invest in resource recovery programs that will help ensure waste pickers' livelihoods, rather than waste disposal technologies like incinerators. Social costs Waste pickers not only generate social benefits, but also potential costs as well. These include: Occupational hazards: See discussion below. Child labor: Children commonly work as waste pickers. This may interfere with their education, or harm their physical, emotional, and social well-being. Litter: Waste pickers working