Each time the MDA proposes to treat gypsy moth, we must weigh the trade-offs and carefully consider all potential impacts. All of this is done with the highest regard for the health and safety of all residents. It is critical that sound information and science be used in the discussion.

Based on careful review, the MDA uses the bacterium Btk, formulated in the product Foray 48B, for gypsy moth control.

What is Foray 48B?

Foray 48B is the commercial product containing Btk. The inert, or inactive, ingredients used in Foray 48B are certified organic food-grade ingredients and contain no petroleum solvents. The product is certified organic by the Organic Materials Review Institute (OMRI). The Foray 48B Btk is not genetically engineered and the product is gluten free.

What is Btk?

Bacillus thuringiensis kurstaki (Btk) as a naturally, occurring bacterium that is found in the soil. You may come into contact with it on a daily basis.

How might I be exposed to Btk?

People are exposed to Btk through contact with soil in the natural environment or through their diet, at very low levels. If you eat fresh fruits or vegetables, you probably have already ingested this bacterium. It is commonly used on commercial and organic food crops.

Is Btk safe?

Btk has a proven safety record with people, pets, birds, fish, livestock, and other insects such as bees; and has been registered and re-registered many times by the Environmental Protection Agency (EPA) for use in the U.S., to use on more than 200 food and fiber crops.

I have read several accounts on the Internet of people suffering adverse health effects after Btk treatments. What about that information?

Some people have reported mild skin reactions or mild eye, ear, and nose irritations after Btk treatments. Others have reported mild hay fever reactions. Health officials have studied these reports extensively and have not been able to determine if the reactions were caused by Btk or by pollens, molds, or dust generated during the treatments, or were unrelated to Btk treatments. The following are two cases often cited from the Internet.

A study of an entire community in New Zealand was done for a 2002 application of Foray 48B. Surveys of 292 study participants about their own symptoms and their self-perceptions of their health were conducted before and after the sprays; there were multiple applications of Foray 48B. Among the findings: there were significant increases in the rate of reported throat and gastrointestinal symptoms, and for sleep problems, following the sprays. Yet symptoms of exposure are quite general, and are often the same as those from other causes such as flu or food poisoning. The study authors cautioned that these self-reported symptoms were not necessarily confirmed by healthcare providers. Also, most participants in the New Zealand study reported their health (and that of their children) were not affected by the spray program, nor was there any reported increase in visits to either medical practitioners or alternative healthcare providers. 

There have also been concerns that aerial sprays of Btk-based pesticides, such as Foray 48B, could impact vulnerable populations in the spray zone. Canadian researchers explored this issue during a 1999 application of Foray 48B over Vancouver Island. The lung symptoms and breathing capacity (lung function) of 29 children with asthma living in spray zone were compared to those of 29 children with asthma living outside the spray zone. Measurements, as conducted by parents, were done before and after the spray period. There were no differences in asthma symptom scores between either groups, neither before nor after the spray. There were there no significant changes in measured lung function, as reported by parents of study participants, after the sprays.

Public health officials state Btk is not a public health risk.

Is there a concern for people with weakened immune systems and people with allergies?

Although we don't have evidence that Btk will affect any given group of people, individuals with a weakened immune systems or serious food allergies may choose to avoid any potential for exposure by staying indoors during and at least 30 minutes after the treatment, or leaving the area during the application. 

Will Btk and Foray 48B cause cancer?

Given the long history of use and the knowledge that regulatory and public health officials have about Btk and Foray, there is no reason to suspect that either Foray or Btk is carcinogenic.

You can read more about Bt and human health from the National Pesticide Information Center.