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Indoor Marijuana Growing Operations: Questions from Home Buyers

Use of residential houses for marijuana growing operations (simply referred to as grow ops) is increasing at an alarming rate. Buyers of houses across the country want to know if their potential properties were ever used for grow ops. The question I have been asked several times is, “if a house was renovated after these operations, is there a simple test that can be conducted to tell if the house was ever used for these operations?” Their major concern is mould. Unfortunately there is no mould test that I know of that can tell whether a property was ever used for marijuana growing. As a potential buyer my concern would not be whether the property was used for grow ops or not, unless the fact that it was ever used for grow ops would bother me or my family. I would be concerned about 2 things:

  1. Whether the property was structurally sound and met all the building codes. Grow ops may involve tempering with some of the building systems thus violating the building codes. Also, due to high humidity, mould growth may damage and weaken the wooden structure of the building.
  2. Whether there were abnormally high concentrations of hazardous contaminants such as pesticides, biological contaminants (mould, bacteria, mites, etc.), and other well known indoor contaminants.

If I am happy with 1 & 2 above, only other considerations would stop me from buying the property if I liked it.

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Indoor Mould Infection: Can Mould Cause Bad Breath?

A person was exposed to mould in an office and they have developed bad breath which they didn’t have before. Could the bad breath be due to mould infection in their lungs? This is not a ‘yes/no’ question because whatever answer one gives should be supported with facts derived from documented evidence or tests conducted to such as person by a qualified person. The first answer that came to my mind was to say no. But then I realized there is still a lot that is not known about mould and their health effects. I was imagining that if the person had mould infection and the mould was actively growing in their lungs to the level of causing or producing odour, such a person would be critically ill. But my thinking is not based on any facts. It is just thinking.

The most well known lung mould infection is aspergillosis caused by some species of Aspergillus (hence the name aspergillosis). Moulds that are known to cause aspergillosis are Aspergillus fumigatus, Aspergillus flavus and occasionally Aspergillus terreus, Aspergillus nidulans, and Aspergillus niger. These moulds are widespread in the environment. They are found in soil, decomposing organic matter, household dust, building materials, and air. The people at risk of infection by these moulds are mainly those undergoing certain medical treatments that affect their immune system. In these people the disease is manifested as invasive pulmonary infection, usually with fever, cough, and chest pain. In healthy people, the disease is manifested as localized pulmonary infection. Aspergillus species also cause allergic reactions.

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Indoor Moulds: The Penicillium Species

Penicillium species are very common moulds. About 200 species have been described. They are commonly called the blue or green moulds because they produce enormous quantities of greenish, bluish or yellowish spores which give them their characteristic colours. Their spores are found everywhere in the air and soil. They are the most common causes of spoilage of fruits and vegetables. For example, Penicillium italicum and Penicillium digitatum are common causes of rot of citrus fruits, while Penicillium expansum is known to spoil apples. Most species are active producer of toxins.

Mould identified as Penicillium chrysogenumThe most common Penicillium species in indoor environment is Penicillium chrysogenum. It is widespread and has a wide range of habitats. In indoor environment, it is extremely common on damp building materials, walls and wallpaper, floor, carpet mattress and upholstered furniture dust. It produces a number of toxins of moderate toxicity. It is allergenic and can infect immuno-compromised patients.

Do you have a question on mould? Send it to My Question.

How Much Indoor Mould Is Too Much In A Building?

They say “the dose makes the poison”. But what’s the dose for indoor mould? Currently there is no answer to this question. Determining this dose would be a difficult task for a number of reasons:

  • There are several species of moulds with differing health effects.
  • People are not just exposed to mould but also to other environmental pollutants including bacteria, protozoa, dust mites and non-biological compounds.
  • Some people are highly sensitive to mould even at concentration levels that may be considered ‘normal’.

It is generally accepted that no amount of mould should be allowed in occupied dwellings. However, it is impractical to get rid of all the mould in a building. A number of organisations have provided some guidelines in the past on what levels of mould would be considered a problem in occupied dwellings. But none of these guidelines have been accepted widely and some have even been dropped as more information concerning indoor mould became available. Below is a summary of some of these guidelines.

In 1989, the American Conference of Governmental Industrial Hygienists (ACGIH®) had considered fewer than 100 colony forming units per cubic meter of air (CFU/m3) as of no concern. For duct insulation, the Department of Environmental Health and Safety (DEHS) of the University of Minnesota, considers 10,000 CFU/gram as low, 10,000 to 100,000 CFU/gram as medium, 100,000 to 1,000,000 CFU/gram as medium to heavy and > 1,000,000 as heavy contamination. The Health Canada Technical Guide, 1993, states that if more than 50 CFU/m3, of the same species other than Cladosporium or Alternaria were detected in indoor air, there may be reason for concern. It also states that up to 150 CFU/m3 would be acceptable if there was a mixture of species reflective of outdoor air. Also, up to 500 CFU/m3 would be acceptable in the summer, if the species present were primarily Cladosporium.

There are other guidelines. The German Federal Environmental Agency (Umweltbundesamt, 2002) has probably the most comprehensive guidelines. Unfortunately the guide is only available in German language.

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The Bright Side of Mould

In recent years we have been hearing a lot concerning the health effects associated with mould. Few people would think of the numerous benefits we get from mould.

First, mould contributes immensely to the decomposition of organic matter hence helping in recycling of nutrients. Imagine the mountains of garbage we could be having (unless we burn it) without the help of mould and other soil micro-organisms. Moulds also play an important role in waste treatment and the breaking down of pesticides.

Mould Contribution to Food Industry

Hardly do we think the mushrooms that we so much enjoy eating belong to the same group as the moulds, i.e., the fungi. As a small boy, we used to eat the smutted inflorescence of sorghum. I can only imagine the billions of spores of the fungus we ate and probably helped in spore dispersal. We never got sick! What about our favourite blue cheese? Some people may not be aware that it is made with the help of a mould called Penicillium roquefortii. Other cheeses such as Camembert and Brie are ripened by Penicillium camembertii. Some sweet wines such as the Sauternes are made from grapes infested by a mould called Botrytis cinerea. In the Far East there are a number of popular foods and sauces processed with the help of moulds. Tempeh for example is made by inoculating soybean with Rhizopus oligosporus and leaving the mould to colonize the soybean for some time. A high-protein meat-like product called ‘Qourn’ is made from a strain of Fusarium venenatum.

Mould Contribution to Human and Veterinary Medicine

Probably not many people know that the first antibiotic ever, penicillin, discovered by Sir Alexander Fleming in 1927, is produced by moulds within the genus Penicillium (primarily Penicillium chrysogenum). There are other antibiotics, antifungal compounds, cholesterol-reducing drugs, immunosuppressant compounds, and important enzymes from moulds.

Mould Contribution to Crop Protection

Some moulds have been used successfully in biological control of agricultural pests and diseases. Fusarium oxysporum fsp. cannabis, for example, is used as bioherbicide against marijuana plants while Beauveria bassiana is widely used in formulation of bio-insecticides.

Do you have a question on mould? Send it to My Question.

Salmonella food poisoning and symptoms

Salmonella food poisoning has been a growing concern in recent news. It has frequently lead to recalls of beef, salads and organic products and, even peanut butter products. Salmonella food poisoning occurs when one eats raw or undercooked foods such meat, poultry, eggs or egg products. Properly cooked food can get contaminated with Salmonella if […]

Legionella pneumophila – Guidelines for Laboratory Interpretation

Legionella pneumophila is a Gram negative, aerobic bacteria that is characterized as an opportunistic pathogen. It is the cause of Legionnaires’ Disease, a severe form of pneumonia and, it is the cause of Pontiac fever, a non-pneumonic form of L. pneumophila infection. Legionella spp.’s mode of transmission is through aerosols or aspiration of contaminated water. The Public Health […]

The Indoor Mold Is An Early Warning Device

The mold (or mould, in the Queen’s English) has been the victim of a bad press. Mention the word and it conjures up an image of something rotting or in the process of decomposition. And yet, were it not for the mold that inspired the discovery of penicillin millions of lives would have been lost. […]