E. Addressing Environmental Justice

Exposure to Lead & Income

The U.S. EPA website defines Environmental Justice as

"... the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. EPA has this goal for all communities and persons across this Nation. It will be achieved when everyone enjoys the same degree of protection from environmental and health hazards and equal access to the decision-making process to have a healthy environment in which to live, learn, and work."

This project aimed to gather baseline information on how different racial/ethnic and socioeconomic communities within San Francisco may (or may not) be exposed to heavy metals through urban gardens.  The following maps created in ArcGIS demonstrate visually the distribution of lead by income and race/ethnicity using 2000 Census data.  These maps will be updated when 2010 Census data is available for California at the Block Group level.  Actual income of participants was not used because many gardeners did not disclose their income, many gardeners lived in shared housing and were not able to provide their housemates' income, and shared community garden & school garden plots would have had to be excluded.

This map shows approximate locations of the 100 gardens that were tested within the 5 target zip codes with median household income by block group (U.S. Census, 2000

     (Click on image to enlarge)

As shown in the table below, the percent of gardens that fall within the three different levels (Safe/green, Potentially Unsafe/yellow and Hazardous/red) are very similar between higher and lower income areas. This implies that there is not a significant difference in exposure to heavy metals by San Francisco gardeners when looking at income grouped by Census Block Group above and below San Francisco's median household income.      

Percent of Gardens Considered Safe or Unsafe by Income,  Census Block Group (2000)

Income over $55,221

 Income under $55,221
(Human Health Screening Levels)

 Potentially Unsafe
(Between Safe and Hazardous)
 Hazardous Waste
(CA Code of Regulations)


Total Gardens 

Exposure to Lead & Race/Ethnicity

The next map shows the relationship between race/ethnicity and the levels of heavy metals found in the 100 vegetable gardens.  Race/ethnicity was determined using 2000 Census data by block group, using the categories used by the U.S. Census Bureau.  Census data was used for the map, rather than the actual race/ethnicity of the gardeners, since it is likely that the metals have accumulated over time and thus the race/ethnicity of the current occupant of the property may not be as important as longer-term trends of the neighborhood.

     (Click on image to enlarge)

As the above map shows, most of the gardens with unsafe or potentially unsafe levels of lead are located in areas that are predominately White.  Specifically, 7 or the 9 gardens with concentrations of lead that are considered hazardous are in neighborhoods with a majority of White residents, with the remaining 2 gardens with very high lead levels being located in areas dominated by Hispanics but that also border mostly White neighborhoods. 

Exposure to Lead & the Age of Homes

One possible explanation of why particular communities are more or less exposed to lead may have to do with the age of the homes in the neighborhood.  As the table below shows, the three zip codes with the highest average lead levels also have the oldest homes.  Home ages are for backyard gardens only (not school or community gardens), and were verified using the City & County of San Francisco's SFParcel website.

 Zip Code
Average Lead Level (ppm)
Household Income*
Dominant Ethnic Group* Average Age of Home (years)**
 94110 428 $53,795 Hispanic 102
 94114 527 $75,727 White 95
 94124 139 $37,146 Black 65
 94134 168 $54,342 Asian 65
* U.S. Census Bureau, 2000
** City & County of San Francisco, Office of the Assessor-Recorder

In San Francisco, the oldest homes are primarily of the Victorian-era architectural style, and tend to be found in more affluent neighborhoods.  These older homes were likely re-painted with lead-based paint many times over the past 90 to 100 years, and subject to renovations and repairs that may have involved paint removal.  In that it was not until the 1970's that lead-based paint was banned, it is reasonable to assume that lead found in soil within close proximity to older homes will have more lead than soil of newer homes.

More Project Details:

A.  Project Summary

B.  Project Demographics

C.  Raised Beds vs. In-Ground Gardens

D.  Distribution of Metals by Zip Code

E.  Addressing Environmental Justice