Orchards and Arsenic

Unless you’re an environmental consultant or work in the orchard industry, you may not be aware of the contamination issues that are common at orchards due to historical pesticide use. Arsenic-based pesticides were at one time heavily used on orchards. Use of these pesticides, which included lead arsenate and lead arsenite, began in the late 19th century and continued well into the 20th century to protect fruit crops from pests. Due their low cost and ease of application as both a liquid spray and as a powder, these compounds gained wide popularity among farmers and orchard operators, who often performed multiple applications throughout a typical growing season.  At orchards, the pattern of impact to soils was most pronounced along ‘drip lines’, created as the excess liquid pesticide dripped from the edges of the fruit tree onto the ground surface between tree rows.   Although typically limited to shallow soils, the compounds could also be worked into deeper soils during tree replanting or after the conversion of an orchard into a row-crop field.  I’ve seen arsenic and lead concentrations in soils at orchards that were 10 times greater than residential cleanup standards. In addition to orchards, arsenic-based pesticides were also commonly used on golf courses, particularly on greens, which are most susceptible to pest infestation.

The unfortunate thing about pesticide contamination is that when a real estate investor looks at a farm or golf course property for development, environmental concerns often aren’t anticipated and creep up after substantial costs have been incurred for development planning. I’ve seen both orchard and golf course properties where tens of thousands of cubic yards of pesticide-impacted soil needed to be addressed. However, in recent years studies have been performed that have demonstrated that not all arsenic is bioavailable. In other words, if ingested, only a fraction of the available metal compound can be absorbed into the body through the gastrointestinal system.   Most regulatory standards are calculated using the characteristics of elemental arsenic rather than its complexed version as an arsenate or arsenite.  Thus, when performing a site-specific risk assessment, it is often possible to take this bioavailability adjustment into account, and calculate a more realistic, and higher, acceptable level of arsenic in soil.  These risk-based adjustments can reduce, or possibly even eliminate, the cost of remediation.

In addition to arsenic and lead, there is a class of pesticides known as organochlorine pesticides, which includes the commonly known pesticide DDT. These pesticides were commonly used from the 1940s through the 1960s, and while highly toxic, they are much less often encountered at high concentrations in soils when compared to arsenic and lead.

The lesson.  If purchasing an agricultural property or golf course, be sure to begin your environmental due diligence early in the planning stages so that remediation costs can be accounted for in your pro forma and soil management can be considered in the redevelopment plan for the site.