The elevated COHb level resulting from CH2Cl2 exposure has a biological half-life twice that of COHb produced from exposure to CO. This occurs because the absorbed CH2Cl2 is released slowly from storage in body tissues and then is metabolized to CO over a protracted period of time. Thus, because it is so sustained following exposure, the cardiovascular stress produced by elevated COHb levels, derived from CH2Cl2 metabolism, is greater than that resulting from equally high COHb levels derived from CO. The addition of methanol to paint-remover formulations extends the biologic half-life of COHb derived from CH2Cl2 (Figure), further prolonging the period of cardiovascular stress.
The ethical responsibility for informing the public about the potential hazard of CH2Cl2 in paint removers lies with the manufacturer who is obliged to market a product that can be used safely. This is the purpose of the label. It should warn the susceptible segment of the population of the CO hazard. The manufacturers of paint removers have been cognizant of the problem since 1972, yet product labels make no mention of CO. Only one manufacturer of paint removers has acted positively. This Racine, Wis, firm has withdrawn its product from the market.
The legal responsibility for protecting the public currently rests with the Consumer Product Safety Commission. It has remained mute, as did the governmental agency originally responsible, the Environmental Protection Agency, when in 1971 the CH2Cl2 hazard was formally called to its attention.
The medical responsibility for protecting patients unable to tolerate the cardiovascular stress of elevated COHb levels must rest with the physician until the general public is made aware of the CH2Cl2 hazard and all paint-remover formulations are appropriately labeled. This is a critical duty because one sixth of the 180 million kg of CH2Cl2 produced in the United States is being consumed in the rapidly expanding paint-remover market.13
This investigation was supported in part by contract HSM-99–72–84 from the National Institute of Occupational Safety and Health.
Anthony Wu, PhD, and Sally A.Graff provided technical assistance.
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13. Paint-remover sales take off. Chemical Week 65–66, Oct 20, 1971.