October 6, 2011
The prospect of a ban on the Maryland poultry industry’s use of arsenic-based drugs has become more complicated with a request by Delegate Maggie McIntosh (D–Maryland House of Delegates, District 43) and Senator Joan Carter Conway (D–Maryland State Senate, District 43) for a review of the scientific literature on the environmental effects of arsenic-based drugs in poultry. As a medical doctor and epidemiologist, I am disappointed that Delegate McIntosh and Senator Conway have not contracted with a research body with the capacity to assess potential human health hazards of Roxarsone and other arsenical drugs used by the Maryland poultry industry.
In their request, McIntosh and Conway have asked the Harry R. Hughes Center for Agro-Ecology to conduct the literature review and submit a report to the Maryland General Assembly (the scope of the study can be found here). As the Hughes Center states in their Scope of Work (read Scope of Work Hughes Center 2011 here),“We are not public health/human health experts and therefore cannot comment on concerns in these areas.”
Since the 1940s, Roxarsone has been widely used as an additive in chicken, turkey and swine feed, both as an antiparasitic drug and as a growth-promoter. But in the last several years, numerous scientific studies have shown that Roxarsone is quickly converted from its original organic form into the inorganic form of arsenic when consumed by the chickens.
The fraction of inorganic arsenic present in the meat has yet to be determined, but an FDA study demonstrated that feeding Roxarsone to chickens increased the levels of inorganic arsenic in chicken livers. (While FDA looked at total arsenic in the meat, they did not identify the fraction of the arsenic that is inorganic.) Inorganic arsenic is a human carcinogen and is also associated with increased risks of several noncancer endpoints, including cardiovascular disease, diabetes, neuropathy, neurocognitive deficits in children, and adverse pregnancy outcomes.
The health risks posed by Roxarsone are not limited to contaminated poultry meat. (For earlier blogposts on this topic, click here and here.) As Center for a Livable Future’s Keeve Nachman, director of the Farming for the Future program, reported in a 2005 paper in Environmental Health Perspectives, “… organic arsenicals used in poultry feed are converted to inorganic arsenicals in poultry waste, limiting the feasibility of waste management alternatives. The presence of inorganic arsenic in incinerator ash and pelletized waste sold as fertilizer creates opportunities for population exposures that did not previously exist.”
In order to assess comprehensively whether Roxarsone and other arsenical drugs should be banned from use in Maryland, the risks from human dietary and environmental exposures to arsenic must be assessed. If the Hughes Center is not capable of assessing human health risks, McIntosh and Conway should assign a review to a research body that is. Anything less ignores the risk to the public’s health and only perpetuates the state’s delay in taking measures to protect it.
(McIntosh is the Chair of the Environmental Matters Committee of the Maryland House of Delegates. Conway is the chair of the Maryland Senate’s Education, Health and Environmental Affairs Committee.)